I do answer technical questions but you must write to my firstname.lastname@example.org address and I'll get back to you as soon as I can
Q: Does unleaded fuel really pound out the seats of the old style fuelie heads [3890462,3917291 etc]? And if so, how long will they last before they start causing problems in a non race application? 2) Do you have a nova 327 block to possibly build? 3) What heads would you put on a 327 for a 66 ChevyII 4spd 4:11 driven mostly on the street?
A: Hello Kent.
Stock old iron seat will last a long time, I don’t know probably 50,000 miles or so.
The concern is unleaded fuel burns hotter and drier which is harder on the seat, but don’t immediately kill them.
If you had a high lift cam with heavy springs the seats won’t like them.
I don’t keep used parts. I buy for customers as I take orders.
What heads to buy is a question of money.
All stock Chevy heads are much the same, but you need to use 64cc heads on a 327 to have enough compressions.
If you could find some decent used Vortehc heads that would be good.
New RHS Vortechs are better.
AFR aluminum are the best, but to get a set with enough compression will cost you $1600 because they need to be milled down.
Q. John whats the difference between torque and horsepower?
A. Hello Jake.
Horsepower is a mathematical equation take torque and RPM into consideration.
Torque multiplied by RPM divided by Constant
Torque is made from first cubic inches then air flow, therefore volume of fuel burned and then compression ratio.
A typical performance aluminum head motor with 10:1 compression will make 1.25lbs/ft of torque per CID.
Therefore a 302cid X 1.25 = 377Tq.
A 550cid X 1.25 = 687Tq
Torque is measured by a dynamometer, which is not so dis-similar to a torque wrench.
The number it generates from a running engine is the force it would take to stop the crankshaft from turning while under full throttle at a given RPM.
Or the weight at the end of a one foot leaver that is equal to.
Now horsepower takes measurement of force and compares it to RPM.
The torque an engine produces is a curve, but we compare it to a straight line as the desire is for the engine to make maximum torque at all RPMs, but this does not happen.
An engine has efficiency levels, largely dictated by the duration of the camshaft.
A motor with a short duration cam will be more efficient at lower RPM, a long duration at higher RPM.
So while the 302 above can make a peek of 377Tq, we can influence the engine to make it closer to 3000rpm or 5000rpm.
Therefore if we put a long duration cam in it, making peek Tq at 5000rpm then calculate the horse power at that RPM it will be higher than if we set the motor up to make peak Tq at 3000rpm.
The constant valve chosen by men of old is 5252. So...
377 X 3000 :- 215Hp
377 X 5000 : 359Hp
Even though the horsepower at 5000rpm is more impressive, the engine is really making the same power.
Further even though torque begins to diminish as RPM increases, horsepower will continue to rise for a time because the RPM factor of the calculation will create a larger number, until torque diminishes to a point where the RPM number is not large enough.
368Tq X 6000 :- 5252 = 420Hp
250Tq X 7000 :- 5252 = 333Hp
A simple way to think of horsepower is top speed.
Air resistance and friction drag on a car will limit it's top speed by using up all the energy put out by the engine at a given RPM.
Let's say you took you car to the salt flats and wound it out and found it would go 146mph at 5900rpm.
To go faster you would need to make more horsepower to turn say 6100rpm.
To do this you might add more duration to the camshaft to move the efficiency of the engine to the higher RPM, but doing so will reduce the power at the lower RPM.
This will reduce the rate of acceleration from a standing start.
So in building an engine you must decide what balance of acceleration verse top speed you want.
For a street car the typical RPM range is 2000rpm to 6000.
You drive on the freeway typically cruising at around 2200rpm without an overdrive.
If your engine was designed to make more torque at lower RPM, it will accelerate faster at full throttle without downshifting than if the motor was set up to make higher RPM horsepower.
But it's top speed will be less.
Therefore we must determine for any given application what is the preferred balance of where the maximum power is to be produced.
A 1200Hp 10,000rpm engine would be slower off the line that a stock Volvo unless it uses a 5000rpm stall speed torque convertor or slipper clutch to allow the motor to turn high RPM as it launches.
Finally my motto Bigger Engines Make More Power.
By this I saying torque, which I might call King, where horsepower is his Knight.
The king is the power, the Knight carries out his orders.
Because you make a given amount of torque per cubic inch, a larger engine will always make more torque.
Because horsepower comes from RPM it is more related to airflow and therefore the amount of fuel burned.
A large engine will make say 500Hp at a lower RPM the a small engine, but will be flowing a similar amount of air and fuel.
To more the horsepower up the RPM scale to where the smaller engine makes peak Hp require more cam duration and or larger port volume to air more air to flow into the engine.
This graph show both a 302 engine and a 550cid engine making 500Hp.
Note the difference in RPM where peak Hp occurs, but more importantly the huge difference in torque production.
I hope this gives you a better understanding of engine power.
A simple answer is torque is acceleration, horsepower is top speed.
Q: John, I have a resently rebuilt 327 in my 64 Chevy El Camino. It was built to stock with headers. It runs good but it just doesn’t have any guts. I get blown away by VWs. I live in L:a Verne CA and go to Victorville Offen. Can you help? Would like to keep the same engine if possible.
A: Hello John
If you must stay 327 the biggest improvement would be AFR 180cc heads for $1450.
327 is a small motor by today’s standards.
I had a guy bring me a boat with a stock 350 in it.
We put Edelbrock heads on it, not much help, so the AFR may not be enough to make you happy.
I found the boat guy a use Whipple screw compressor (supercharger) all installed $2100 with a new blower carb.
Now he is very happy.
Q: I am looking for advice for a carb. I have a 460 block with an 4340 Eagle crank putting me at 545CI with a .030 overbore on the pistons +3cc. I have edelbrock preformer rpm CJ 72cc heads and performer RPM cam,and a wieand stealth intake. I am currently deployed to afghanistan and am having a good friend build this engine for me so i am unsure if the block will be decked, but we are both unsure what to do for a carb. It is going in a 1963 f350 with a c6 and a dana 70 with 3.83 gears. I am not running any vaccum acessories at this time. This is just for fun and I wont be hauling or anything crazy like that. I dont plan to race it either. Thanks for your time.
A: Hello Jacob
It doesn’t hurt to over carb a little.
I never much liked 850s and 750 is a bit small for a 545.
You won’t find a vacuum secondary carb so I either recommend AED or Quickflow for price
you can find them on summitracing.com
Or any custom carb builder like http://www.performancecarburetors.com/
or ProSystems for quality http://www.prosystemsracing.com/proseries4150.html
Stay away from Dominators, not street friendly
Q: Hi I’m looking for a 454 about 500Hp for my ski boat which is a v drive.what engine do you suggest.how much and do you ship to Australia at what cost.
A: Hello Andrew.
It really depends on how much you are willing to spend.
A 454 block with a 4.250 stroke makes 489cid @ .030″ over.
With AFR CNC ported 315 heads on it, it will make 670Hp and 640lbs/ft torque.
With less expensive heads, maybe 640Hp, and 610Tq.
A new Dart block with 540 or 630 CID can make a lot more power.
Typically you can figure torque by multiplying CID by 1.25 to get potential torque when using decent heads.
So a 630 X 1.25 = 787Tq.
500Hp, a 489 with an iron crank and $1500 RHS iron heads are all you need, but investing $300 more for better AFR heads is a productive move.
As an engine builder, not an engine salesman I need to know your power desires and your budget.
You should compare engines being offered online.
Some are the GM built crate motors, good value for the money, as they cost less being built outside of the US.
Others are similar combinations built by shops focusing on the “crate engine” trend, a create engine being one that is already assemble and a clone of a formula.
Then you have motorheads like me who figure out the best combinations given client requirements for power and cost.
I don’t build very many engines each year, it takes a lot of time and labor to build unique motors, but I do get the most power out of a buck.
A boat motor is a little different than a car in that you are typically trying to turn a certain RPM.
For example if a current motor in a boat will only rev to 4000rpm, then changing the cam and cylinder heads very often will not increased the RPM to say 5000, because increased air flow will not produce more torque.
A dyno will measure an increase in horsepower, but Hp is a mathematical equation.
Torque is measured power output.
To push a boat through the water faster/higher RPM takes more energy/power.
Very often the best option is a Whipple screw compressor on the current engine.
Compression ratio is the most important consideration.
If an engine is to be built, more CID will make the boat go faster because it will have more energy to over come movement resistance.
Acceleration is much less important than a car, it is speed that matters.
As for international shipping, I charge a flat fee, $500 to most anywhere in the world.
That includes using an export approve shipping pallet and transportation to the harbor.
Air freight is actual cost and effected by weight, but is typically up around $2000
Q. Hi john. I came across your site while searching afr heads. I am after a set of Ford 225 72cc heads. I'm looking at building a 408 stroker with a Windsor big bore block with Cleveland 4 bolt mains. Probably just a world block. I'm hoping to make 500-600hp but I want it to be streetable. Any suggestions would be nice and also prices on the heads with postage to Melbourne. And I would be interested in prices on a block and crank also and maybe a cam if you can recommend one. Cheers.
A. Hello Joel
Thanks for visiting my website
I sell things to Australians at American prices.
I have compared and see many Aussie shops selling at twice the price.
Even taking into account shipping and taxes, the price doesn't need to be that much higher.
As for other parts, block, crank pistons etc I recommend looking on Summit Racing as these are the prices I will give you for their parts.
I can do RPM International Cranks & Rods http://www.racingpartsmaximum.com/ 10% below their listed price.
A top notch American crank will cost$1800 good for 1000Hp
To assemble an engine, $350 short block $500 long block, that's without the oil pan. $650 for a complete engine.
Machining the block, as new block still need boring and decking is $400 and balancing the crank is $180
Shipping stuff by air adds up real quick, a pair of heads would cost about $350.
Throw in a crankshaft and you are soon over $500.
A pallet cost $500 by ocean and you could stack enough parts for three engines, still $500
Be sure to look at this page in my website http://www.strokerengine.com/australia.html
I am currently looking to open an outlet in Oz, which really means shipping parts out in bulk so that the cost of shipping is greatly reduced, but I'm still a few months away from my first bulk shipment.
Q. My question is,, What is your opinion of short or long connecting rods? which is better,for torque and racing? And just wondering what your preference is,ford,chevy,dodge? I see that not many in texas use mopar v8's for racing,or torque purposes. I'm thinking about building a 440 out of a rv,for massive low speed high torque,but I want it to still have quick acceleration,up to 3000 rpm. I would like to achieve around,600 ft.lb. This engine will be going into a 1978 dodge ram d 350,coupled to a 727 torque flite. I thinking about using either 373 gears,or 392's.
A. Hello Chris
I use the longest rods that will fit without making the piston shorter than I have to.
I don't get overly concerned about the rod/stroke ratio.
This whole rod length issues comes from racing and means very little in a street motor.
Why shorter roads may make a little more torque, it's hardly noticeable.
Too short and pistons get pull out of the bottom of the cylinder, this and server rod angle increases wear, so I watch out for that.
I the monster motors you can fit as long a rod as you would like, so making torque trumps long life.
I recommend using Xado to help prevent wear.
ProStock motor used to run rod/stroke ratios as high as 1.9:1 and now they are back down to 1.65-1.75:1 and turn 10,500rpm
Short rods are good for nitrous motors for "snatching" away the piston from peak cylinder pressure.
Bottom line rod length isn't going to make a difference in a street motor that you will notice.
To make the most torque therefore the fastest acceleration to 3000rpm, use the long stroke possible, but keep you rod/stroke ratio above 1.4:1
and don't pull the piston out of the bore any more than you have to.
Currently I'm building a 440 with a 4.375 crank to make 520cid
I found the rod barely clears the oil pump pickup, so going 4.50" stroke would be a lot more work.
Q. I'm building a 347 stroker and would really like to get a set of the AFR 205cc SBF heads with the 72cc combustion chambers. Do you sell these? What is the price for a set? Can you ship to me in Canada or if you don't then can you ship to me in Pembina, North Dakota?
A. Hello Karl
I phoned AFR but they don't drop ship for me to Canada for me.
They charge me $42 friegt to me, so I'm thinking they'ell drop ship to Nth Dakota for about the same.
To ship them to Canada AFR said it cost a little over $100, so I'd say total cost figure $160.
I see AFR heads about $50 less than Summit, so $1790
I order the heads from AFR and it takes about 2 weeks.
If you need them faster, the extra $50 will get them from Summit or Jegs etc. right away
205s are big on a 347. Plan to rev it well over 6000rpm and use an open plenum manifold.
A 185cc head & RPM Airgap manifold will accelerate faster to 4000rpm and they cost $1350
Q. gday trying to build a motor, dart 8.2 deck 4.125 bore,want to use longest rods,5.4 but with a 2.87 stroke,or longer rods,the motor is for maximum power and high revs 8000+,will it hold together,also who would make pistons and conrods to suit here in oz. thanks
I don't know who makes pistons in Oz and I doubt anyone is making Rods.
Chinese rods cost $400 or so American $1000,
American made custom pistons cost about $600 plus.
I can't make promise at 8000rpm, but American made parts should hold.
As for rod length you are pretty much stuck with what is made, 5.4 or 5.7 which will work
Here's how you do the math to see what will fit.
Stroke :-2 > 2.87 :-2 =1.435
Plus rod length > 5.7 + 1.435 = 7.135
Minus block height > 8.20 - 7.135 = 1.065 Piston Compression Height.
You need at less an inch for the piston to have any rings on it.
You mentioned rod ratios.
Rod :- Stroke = Ratio. 1.4 is acceptable to make a stroker work when the goal is more torque.
1.5 seems to work just fine.
1.6 and higher helps in racing motors up at 7000rpm but means nothing in a 6000rpm street motor.
ProSock motors used to run 1.9 & 2.0:1, but are now running 1.65-1.75:1 I guess you can be too long.
Q. JUST RECENTLY READ ABOUT MAKING NEAR 400 CUBES FROM 8.2 DECK WINDSOR, BORING DART BLOCK OUT TO 4.250 AND INCREASING STROKE TO 5.5 I THINK, THEY SAID THIS LEAVES 130 THOU BORE CLEARANCE, HAVE U EVER BUILT ONE OF THESE ENGINES? IS 130THOU ENOUGH BETWEEN BORES,
You can always push things out further than recommended, you may or may not get away with it.
The Dart blocks have really good iron so 4.250 may hold.
I don't know who "they" are, but no I have built not that combination.
I stop at 4.20 which makes 387, but typically I stop at 4.165 so the block can be used in a rebuild down the road.
I can't afford to risk all that money for and extra 13lbs/ft
Q: Just had a read of your site and liked what I read. Anyhow I am contacting you to see whether you can advise on the edelbrock dual plane air gap and what you have experienced with this manifold. I have a 351 (or really 357 Clevo engine) that made 417 rear wheel horses using a 252 symmetrical cam at 0.050" and 108 lsa, 10.75;1 comp, 780 Holley and weiand xcelerator manifold. I would like to try a dual plane manifold on my next project. I want to use the same cam (BTW I adjust the solid tappets and open them up to improve bottom end torque, in the vicinity of 25 Inlet and 32-40 exhaust) and same engine specs, but I will be using a 3 barrel vac sec carb 1030 cfm, as a dual plane will handle this carb, I am sure. problem is there are not many dual planes available for the 351C (2v closed chamber head Aussie head). I have an edelbrock performer but I here there peak at about 5500? I want to rev the engine to about 6800 a sit can do the revs easy. Any experience with the performer rpm airgap (dont really care about the air gap, I don't buy the argument, but hey don't make the performer rpm for the 351c only the clevor 351).
A: Hello Bill
A duel plane manifold will increase power at low RPM and give it up above 4000rpm.
If you plan to use the same long duration cam, you will be out of "tune" in that the cam will give up power at low RPM and the manifold where the cam is really coming on.
I had a Cleveland that made 490 HP at 5800rpm
The customer wanted something milder.
I shorten the cam duration and swapped the open plenum manifold for a duel plenum.
It gave up 70Hp at the top and gain 70 torque at the bottom.
Running your valve clearance loose will hurt beat up on your valve train.
If is is a solid roller loose clearance will kill the lifter in short order.
A 1030cfm should show about 4Hp more at high RPM over a 750, but is probably a little slower to accelerate..
If you want to go 6800rpm, then stay with an open plenum. Add a JOMAR Power Cone spacer or HVH Super Sucker.
It is always difficult to increase both high and low RPM power.
I found with a close chamber Cleveland head wedging the squish area helps make more power at low RPM.
I read somewhere that someone tested the airgap design and found it made a little more power at the top, but less at the bottom compared to a non airgap.
The thinking is hot fuel atomizes better, but at RPM cool air allows you to put more fuel through the engine.
When I build a motor to go 7000rpm I pay special attention to the rockers and add a girdle or if the money is there shaft mount rockers.
Cylinder Head Style (application):Edelbrock Performer RPM
Application Notes:Fits the new Edlebrock 351-c Performer RPM cylinder head.
Engine Block Style:Stock/OEM standard deck
Intake Style:Dual plane
Basic Operating RPM Range:1,500-6,500
Edelbrock's Performer RPM Air-Gap intake manifolds incorporate race-winning technology that's been used on Victor series competition intakes for years. The open air space from the Air-Gap design separates the runners from the heat of the lifter-valley cover. So, the air/fuel mixture stays cooler all the way to the heads, which produces a denser charge for more power. Runners are tuned to move the power band 1,000 rpm higher than Performer Air-Gap manifolds, from idle-5,500 rpm up to 1,500-6,500 rpm.
When I build a Clevo it is to get more CID.
That Clevo on my website front page was 463CID head Yates heads and made 500Tq @ 2500rpm 641Tq @ 5100 and 711Hp @ 6400rpm and 708 @ 6800rpm where I clicked it off. I used a 258 @ .050 solid roller.
If it were a 351 I'd expect this cam to peak a 68-7000rpm
Q. I am building a world casting aluminum engine , did I read correctly ? That if plan to use studs to secure heads to the block that they are only finger tight . This scares me ! Is this correct ? Do I do the same with manifolds , any locktite in the equation
A. Hello Tomme
Yes that is correct.
Studs and bolts are different in the way they tighten.
With a bolt to turn it tight and the full length of the bolt twist including the thread in the hole.
The bolt is also stretched
A stud is tighten in the hole finger tight and then the nut is tighten on the other end.
Instead of twisting the stud is stretched only.
Whatever is being held in place just as well as a bolt, in fact more securely.
As the nut is tighten the stud will turn a little deeper in the hole.
Now keep in mind that the stud is tight in the block because it runs out of thread and is jamming up, not putting up tight in the threads like a bolt.
It will pull straight up once the nut is tightened.
This will cause less distortion of the threaded hole.
When studs are used to replace bolt in main caps, the main bore should be newly hone to make round again, as the original bolts distort the bore slightly differently than a stud does.
If you over tighten the stud in the hole it will not move or float properly as the nut is tighten.
Many technical thing need thinking about.
When you read a thing should be done a certain way, ask why, done assume it sounds like BS and go and do your own thing.
If the holes in the block were not blind in the World block like in a stock Chev 350, you might use a loctite sealer product or other product as the lack of twist in the thread does not seal the thread from the water. Using loctite to prevent the stud coming loose is pointless.
There are probably other things you need to understand about building motors, be sure to ready as many engine building books as you can, it may save you a lot of money and disappointment.
The following is something I copied.
Choosing whether to use head bolts or head studs in an automobile engine can be an important decision that affects the way a car runs. While they are both fasteners and ostensibly serve a similar function, there are a handful of differences that make studs and bolts distinct from one another. For one, bolts are usually partially or fully threaded, while studs are typically threaded on both ends and often have an unthreaded middle section of the shaft. In addition, studs do not have a head, whereas bolts always do.
When evaluating the various benefits of studs and bolts, it is helpful to keep a number of considerations in mind. Ease of engine assembly and disassembly can be a significant factor, as well as torque pressure, gasket alignment, and overall engine performance. The power and acceleration potential of an engine often dictates the type of head fastener that will be used. For example, a high-end or racing model car will have drastically different engine fastener requirements than a vehicle designed for everyday purposes.
Head Fastener Design
Comparatively speaking, head bolt design tends to focus on stability and convenience. Engine head bolts can be cold-fabricated to increase their integrity, and are often thermally treated before they are machined or have threads cut into them. They provide relatively high strength and durability, and frequently come packaged with hardened washers or nuts. Some manufacturers produce head bolts with wide flange dimensions, which reduce the need for removing the bolts or the valvetrain when conducting cylinder maintenance.
Like bolts, head studs are also thermally treated at high pressure to improve structural strength. Studs are carefully shaped to make them concentric, usually requiring a series of cuts to produce a straight, balanced component. They can be roll threaded before or after heat treatment, although post-heating roll threads provide higher mechanical strength and stress tolerance in the final product. Some head studs are designed with gasket and cylinder alignment in mind, and they are typically more expensive than the equivalent head bolt models.
During engine assembly or maintenance, a bolt must be installed by torqueing it into place. Due to the head bolt’s design, it has to be rotated into its slot in order to engage the threads and secure it into place. This process creates both twisting force and a vertical clamping force, which means that when the cylinders within the engine’s combustion chamber begin accumulating load, the bolt will both stretch and twist. Because the bolt has to react to two different forces simultaneously, its capacity to secure the head is slightly reduced and it forms a less reliable seal in high-powered engines.
By contrast, a head stud can be tightened into place without any direct clamping force applied through the tightening. A stud can be threaded into a slot up to “finger tightness,” or the degree to which it would be tightened by hand. Afterward, the cylinder head is installed and a nut is torqued into place against the stud. The nut torque provides the clamping force, rather than the torque of the fastener itself, and the rotational force is avoided entirely. Because the stud is torqued from a relaxed state, the pressure from the nut will make it stretch only along the vertical axis without a concurrent twisting load. The result is a more evenly distributed and accurate torque load compared to that of the head bolt. This ultimately translates into higher reliability and a lower chance of head gasket failure.
One of the main differences between head bolts and head studs involves the methods used to put together or repair an engine. Higher-end head studs that have been specially designed within exact tolerances are capable of securely positioning the head gasket and cylinders with near-perfect alignment. This feature makes it easier to assemble an engine using head studs. However, head bolts are far more convenient for disassembling an automobile engine or for performing maintenance, such as part replacement. Many everyday-use vehicles have master cylinders or other components that extend into the engine compartment. Under these specifications, head bolts allow the cylinders to be removed without removing the entire engine from the car, as is necessary with head studs.
In other words, head studs are better suited for high-performance vehicles with greater power requirements, while head bolts are more practical for personal, everyday automobiles. Therefore, it would be inaccurate to conclude that one type of fastener is categorically superior to the other. Rather, the preference depends on the automobile in question and the ways in which it will be put to use.
Q. I have a 2002 Land Rover Discovery. It has a 188hp 4.0 Bosch V8 engine that is tired leaks from front and rear main seals, about a qt. per week. Not to mention a terrible "knock" and some sticky valves. Basically time to put a new engine in. Do you have something that can bolt right in? With some REAL horse power? If so please let me know how I can purchase one from you, and its price tag, including shipping. Thank you, Vin Dana
A. Hello Vin.
No I don't have anything that will bolt straight in.
Land Rover is British, I only have access to American V8 engines.
You will need to take your engine to someone who knows how to increase your stock engines performance by increasing the compression slightly, using a longer duration camshaft and porting the cylinder heads.
The simplest most effective option would be to add a supercharger.
Q. 1/2 mile dirt track local track owners try to keep the cost of engines down So they think cast iron heads are the answer. 2 engine options are availabe #1 option 3200# car 361 ci 750 4bl no roller cams no port/polish of heads header permited. Option #2 3000# car really only specs are 500 cfm carb. Thinking with the 200# weight savings a 347 stoker might be way to go. can such a motor run with 1st option cars ? Talking Ford here with cast iron heads
A. Hello Ivan
I don't know the exact answer, but I'd always choose more power over less weight.
If the rule were perfectly fair both combinations would accelerate identically.
However that is for acceleration, you need to consider how fast you can go around corners and weight makes a second difference there..
Here are some drag racing examples
The 361 engine makes 750Hp or 2.07Hp per CID, so a 347 would make 721 with a big carb, but I doubt it with a 500cfm
Q: price the stage 3 lsx engine fo the c5 corvette
A: Hello Tony
By nature a stage 3 engine is a custom build and subject to many choices.
I'm sure you have seen this level of engine sells for around $20,000, but you can pay more form some shops.
After building a number of LS engines I have joint ventured with another engine builder to to these high LS motors for me.
So if you want an exact quote, tell me more about what you want and I'll get you a number.
Q. I have a GM 572 crate motor (I have the 620hp version, with no changes to it), and was wondering what you would recommend if I wanted to add more hp (add'l 100+hp or so). My car is a street/strip Camaro with a 5-speed. One thing I know I don't want is to switch to a mechanical camshaft & I'd like to keep the stock heads, but other than that...??? I want to be able to still run pump gas. Is it possible to keep the same compression (9.6 to 1) and change the carb & camshaft? What do you think? Would you be able to do the work for any changes that you recommend? Or I can pay you a consultation fee for your time and advice?
Horsepower is torque X RPM :- 5252
So a 620Hp 572 makes it at 5800rpm therefore it is making 561lbs/ft there.
To make 700Hp you need to push peak Hp RPM to 6500 and therefore push peek torque of 650lbs/ft from 4700rpm to 5500rpm.
Then 561 X 6500 :- 5252 = 694Hp
Be warned that doing so will take the same power gain away from rpms below 3500 resulting in the car accelerating slower through first gear unless you slip the clutch big time while keeping the RPM up.
In other words the short answer is no you can increase the power 100Hp everywhere which is what you are really imagining.
That's why people use nitrous oxide.
Increasing the compression ratio from 9.6 to 10.6 is worth 45 more power or 25Hp.
The 620Hp motors dyno at high power numbers than advertised.
Camshaft changes just more the torque curve making different Hp numbers because Hp is a mathematical equation, not real world power.
You want to make a real difference, put those crappy Edelbrock heads on ebay and buy so choice AFR heads.
I made 675Hp at 6000rpm with a 489cid using AFR $3200 315cc heads. That would be 750Hp or better in a 572.
Q. Are the latest version of afr 205 for small ford available for the advertized price of $1750? shipping costs?I'm running a small solid roller cam .560 and 230 @.050.I would like a spring package that would let the valve gear last a long time in a street rod but still turn 7000 rpm.thanks
The 2011 price is $1770 plus $45 shipping within the USA
I trying to sell for $50 to $80 less than Summit and Jegs.
Q. don't stock heads I order direct from AFR and drop ship to you.
Q. Can you explain to me how a stroker motor works? I know how a stock motor works, but i dont understand how a stroker works. Thanks, Joshua
A. Hello Joshua
A stroker motor is simply the same motor with a new crankshaft that has a longer stroke than the original crankshaft.
Using the original pistons and rods with a stroker crank will cause the piston to hit the cylinder head, so we must use a piston that has the wrist pin move up closer to the top of the piston.
This distance is called compression height(CH).
The math is deck height less half the stroke less the rod length equals the required height of the wrist pin.
Block Height 9.025
Stroke 3.48 :- 2 = 1.74
9.025 - 1.74 = 7.555 - 5.700 = 1.585 compression height
The factory height is 1.560 which causes the piston to be 0.025 inches below the deck and with a .040 gasket results with a piston to head clearance of 0.065.
This is not good for performance. Chevrolet often use a steel shim gasket of 0.015" to reduce this clearance to 0.040" which is ideal.
When you see Chevrolet advertising a compression ratio of 8.5:1, I have found if the motor comes with a 0.040 head gasket, this 0.065" actually results in a CR of 8.3:1.
When building a stroker 383 Chev we use the above math an either make a custom "CH" piston or look for an existing piston.
Differing brands offer slight variance on this height.
Many piston manufacture make pistons at 1.425 which using the about math comes to 9.00 total, so we mill the block down from 9.025 to 9.00.
There is also something call rod to stroke ratio.
This effects the angle the rod leans over at half stroke.
The short the rod to stroke ratio R/S the great the frictional load on the piston skirt on cylinder wall.
Therefore will desire to use a longer rod and shorter piston CH.
We look for the best compromise of dimensions.
350 Chev 5.700 rod :- 3.48 stroke = 1.637:1 ratio
383 5.700 :- 3.75 = 1.520:1 acceptable
383 6.00 rod :- 3.75 = 1.600:1 better.
The issue of longer rods generating long dwell time for increase power is minimum under 7000rpm.
You must also consider the fact that not only does increasing the stroke length result in pushing the piston higher in the block, but also pulling the piston lower toward the crank.
This can result in the piston being pulled out of the bottom of the cylinder and can even result in the piston hitting the crankshaft counterweight.
Therefore a longer rod maybe required.
The limit to increased rod rod length is moving the wrist pin up into the oil ring groove.
You can raise the pin to to just below the top of the oil ring groove.
To compensate the loss of the lower oil ring rail support, a strong steel rail is added during assembly to the oil ring groove.
The increase in stroke also cause the lower end of the rod to rotate in a greater radius and can result in striking the bottom of the cylinder and the oil pan rail.
This may requiring machining grooves to provide additional clearance.
Finally increasing stroke increase cylinder displacement.
If you use a piston with the same top as the stock piston the result is a higher compression ratio.
Therefore you need to do more math.
Cylinder volume also termed swept volume(SV) plus chamber volume including head gasket, clearance from the top of the piston to the top of the cylinder and the combustion chamber volume, termed clearance volume(CV) divided by this CV.
SV + CV :- CV = CR
If a 350 Chevy has a compression ratio of 9.00:1 with a flat top piston, doing the math will reveall a flat top piston in a 383 will bump the compression ratio to 9.70:1.
The final result of careful attention to all these details results in a reliable motor with increased cubic inches which results in more torque which will increase acceleration.
Using good performance cylinder heads can result in a factor of 1.25 lbs/ft torque per cubic inches.
350CID X 1.25 = 437.5 torque
383CID X 1.25 = 478.7 torque
an increase of 41lbs/ft
Q. How's a goin me and my dad are currently finishing a 1957 chevy sedan two door. It currently has a three speed auto street strip. Planing on changing to a five speed or six speed depending on motor.. Don't know if I should go with the 383 Stroker, or go fuel injected Ls2, ls3? Also noticed ls3 with cam and carb intake? What do u recommend? I like to street race a little and burn rubber, will be driving car alot to car shows and weekends, looking to get around 450 reliable hp. Thanks alot, Charlie..
A. Hello Charlie
450Hp is easy to make.
An LS motor looks trick in a 55 Chev but requires extra work to install.
You must choose the look you want first, then the engine choice will fall into place.
I build all kinds of motors.
Currently I'm building an LS3 415cid with twin carbs.
It will make 650Hp.
Q. hi look for a ford engine making 700hp but able to make 900hp in later builds
A. Hello Leigh
I recently built a 552cid big block Ford that made 674Hp at 5500rpm.
To get this to 700Hp will require more cam duration but will reduce the 640 torque at 3100rpm
Porting the cylinder heads will help bring it up to 700 plus Hp
To make 900Hp will require more expensive heads to flow more air and somewhere close to 7000rpm, meaning it will be a poor street motor.
Expect to spend about $13,000 plus for a turnkey motor.
Steeping up to Kaase Boss Nine hemi heads will get you to 900Hp at a lower RPM, but the heads, manifold, rockers and valve cover cost about $7000
&00Hp with a 200Hp nitrous shot is the easiest way to pull it off.
The best 900Hp motor would be a supercharged engine.
Q. Hi! I am looking to swap the 6.2l diesel out of my old suburban for something stronger. Basically, a small block tow truck motor. Lots of torque and decent mpg. Anything is going to have more hp than whats in it now. I was thinking a ht383 clone. I have a quadrajet sitting in the shop, but I live at 500 feet and play at 5500 feet elevation. Fuel injection would take care of that problem, but we don't have a dyno tuner anywhere close. Do you think a tpi (or even tbi) would work for my application? The only matrix I'm concerned with is gobs and gobs of big stupid torque to tow heavy trailers up steep hills with. And yes, we thought of a big block, but I cant stomach 8-9 mpg. Thanks:)
A. Hello Cory
If you go to a 350 Chev motor you will feel a major drop in power from idle to 2000rpm compared to the diesel.
Diesel have higher compression ratio that has a lot to do with their higher torque output per cubic inch compared to a petrol motor.
The 6.2 will run out of power above 3000rpm, because diesel just don't do RPM as well as gasoline motor.
However this power difference is short lived.
The GM 6.2 diesel is rated at 240lbs/ft @2000 and 257lbs/ft peak somewhere around 2600rpm
So a gas motor will make the wagon go faster, but not pull a heavy load as easily at 1500rpm,
but using an overdrive trans for 60mph plus and good mpg and dropping into drive to rev it up over 2000rpm going up a hill, will have you flying by any other 6.2 dogs on the road.
The GM TBI system is good for fuel economy, but terrible for making power
and putting it on a 383 just has it running out of power at a lower RPM than a 350.
The TPI is excellent for torque and mpg.
I had a 406 with a carb 3 speed auto and 3.4:1 gears getting 13mpg at 65mph
The same motor with TPI overdrive transmission and 3.08 gears got 17mpg.
The more money you spend on an engine the better the parts you can buy and make more power it will make.
GMs HT383 makes 435lbs/ft torque and 305Hp and their ZZ383 makes 450lbs/ft and 425Hp
whereas one of my AFR head 383 will make 500lbs/ft and 500Hp.
I can build a 408cid small block or for more money a 434cid.
Big blocks don't have to burn more fuel than a small block at cruising speed, but all bigger motors will burn more fuel at full throttle.
Big blocks do weigh more thereby increasing drag, and there is also increased friction from surface area inside the motor.
But 20mpg from a 500cid EFI big block is possible.
Bottomline start with they amount of money you are willing to spend.
Keep in mind a $5000 engine get 15mpg verses a $10,000 engine getting 20mpg takes a long time to pay off the extra $5000 a 5mpg @ $3.50 per gallon about 85,000 miles.
A 408cid with tunnelram (GM TPI or Ramjet or Edelbrock ProFlow) EFI will make for the most torque under 4000rpm combination, somewhere in the 525lbs/ft zone from 2000rpm to 4500rpm.That's twice as much torque as your smelly diesel.
Q. I have a 1990 GMCk3500 and did have a 454 TBI motor that overheated and I pulled out and wanting to rebuilt motor. Please advise if this motor is re buildable or not. The #1 & #7 EXHAUST VALVE LIP broken and the pcs stuck at the top of pistons and walls. The motor was 030 over as shown on piston top.
A. Hello Erine
If you just want to rebuild the motor, I would recommend finding a local shop to help you.
If you want more power and will buy many new parts I can help you.
Spending $400 to freight me your motor, then another $400 to get it back is a waste of a lot of money.
Q. Hi John i have a 2004 superformance cobra with a brand new 427 windsor from ford racing. It has a 185 thermastate and that is where it runs on the hiway. In traffic the fans come on at 195-200 degrees for a short time (this is in cold weather in san jose ca.)what is the max. temp. that is safe for this motor with ALUMINUN heads. The engine builder said they run a 160 thermastate is that to cold?
A. Hello Mike
180F is ideal.
Anything over 210F is asking for trouble, but the higher the cap pressure the higher F you can get away with.
160F isn't too, cold, but 180F is better.
Being too cold reduces power output and the pistons may run a little loose.
Fuel burns better in a hot chamber.
If it runs cold a lot you can probably run lower octane gasoline.
Q. I am looking at upgrading the motor in my 2009 chevrolet silverado 1500. I am debating a turbo kit on my current setup or just a nasty N/A motor. I am thinking I want a 6.0 liter block etc. I already have a fast lsxrt intake, 57lb injectors, long tubes etc. What are your suggestions.
A. Hello Travis
A turbo will make a lot more power than a new motor.
A STS tubo fits where the muffler is.
A Procharger supercharger kit is not difficult to fit.
Adding a lot of power with either a turbo or supercharge can break a stock motor.
If you go with a new motor an LS3 block with a 4" stroke crank makes 415cid and with AFR heads over 600Hp.
Q. Love your web sight! Looks like a full time job! My question is....can I get the same amount of horse power from less cu. inches ? I have a iron 11.625 DH block with Big Duke heads and a two four sheet metal intake. I planned on using a 5.300 crank to make a 706 but that gives me a really crappy rod ratio. I'm retired and on a tight budget. I don't want to change rods every 50 runs so I need a better ratio but I don't want to give up HP. What would be my best combo for the lease maintenance but the Most HP? Crank, rod length, piston, cam? I also want to run Nos.
Rod ratio does not effect horsepower very much.
Keep in mind Hp is only a mathematical equation.
Torque times RPM divided by 5252.
What a bad rod stroke ratio does is push the piston harder against the cylinder wall.
This means friction will reduces power output and wears the piston out. Also the cylinder wall, but more slowly.
The shortest piston you can use is about 1.250 compression height, so...
5.3 :- 2 = 2.65 + 1.25 = 3.90 - 11.625 = (-)7.725 this will be the rod length
7.725 :- 5.3 = 1.457:1 this is the ratio.
It is not bad, I could live with it.
However you'll probably need to have custom rods made. The cost close to $2000.
Currently I am building with a 11.625 block and a 5.750 stroke.
The best rod ration was 1.30:1, now that sucks.
So I took two honing torque plates, spends hours of work on them
attached them to the deck and will push eight sleeves through them.
Cost a fortune, plus custom rods.
13 inches tall, 8.8.850 rods 1.54:1 rod/stroke, awesome.
Photos will be added to my company facebook page over the next few months.
Now as for power verse cost, you decide.
If good heads make 1.25lbs/ft per CID, then on the lower performance engine at peak torque at 4500rpm...
Bore 4.6X stroke 4.50 is 632 stroke 5.3 is 705 stroke 5.75 is 765
Times 1.25 is
632 790Tq 677Hp
705 881Tq 755Hp
At higher RPM the torque goes down be the Hp still climbs for a while because it is only an equation.
Torque is King, Horsepower is his Bitch.
At the end of the day horsepower is limited by airflow.
So with the same cam and same heads a 705 will make the same Hp as a 632, but do it at a lower RPM.
What bigger motors do is make more torque from the lowest RPM to peak.
Further, because a longer stroke motor drags the rings further and at a higher speed friction loss increases as RPM goes up,
so a 632 or a 454 for that matter will have higher peak Hp number than a 705.
A bigger motor will have a faster 60 foot time, but a poorly set up car with a 705 can get beaten by a dialed in 632.
If you used an online drag racing calculator and typed in the peak Hp number you get the ET.
But if a 454 made 800Hp at 8500rpm and the 705 made 775 at 4200rpm the calculator would imply the 454 was faster,
but using a more sophisticated calculator would tell another story.
Additionally be less concerned with R/S and more concerned with piston speed.
Find an online calculator. Look for opinions on speed limitations.
NASCAR 3.25 stroke 9500rpm piston speed 5125 feet per minute
5.30 at 6500rpm 5718, at 6000 5278, at 5500 4838
Something to think about.
By the way I just built a 540 that made 711Hp at 5500rpm.
My best advice is go with a 5.0 stroke crank, cheaper 7.10 rods 1.42 R/S, add a street 8-71 6000rpm shifts and clean house.
If you don't use a blower, do a lot of computer dyno testing before building, this isn't rocket science, but most amateur engine builders only think they know what they are doing.
I am building a 351 Cleveland stroker. I am using a 4.170 stroke and a 6 in rod to make 426 cid. I need a forged 12:5.1 piston to accommodate. Do you offer these pistons in full float, if so, what is your price and availability? Thank You D.Everett
Stroker engines are limit by the deck height of the block and rod to stroke ratio requirements to avoid driving the piston into the cylinder wall.
For a 9.20 tall Cleveland block a Scat 4.00 stroke crank with a 6 inch rod is the practical limit.
To go 4.170 you need a Windsor block, which has been termed a Clevor because we adapt Cleveland heads onto a Windsor block.
However if you are determined you can use narrow rings placed extremely close together and minimal intake valve relief to make it work and ignore the poor, but acceptable below 6000rpm 1.438:1 rod to stroke ratio and make a 426 Cleveland.
I can supply 4032 forged piston made by Racetec if you want them.
Figure about $600 with rings.
While conducting some research on exactly what small block chevy engine I have, I came across your website, which I believe is the the same GM crate engine that I have as listed on your site (350, 290-300HP, 4-bolt main). My block # is GM 10066036, not sure what the heads # is, I did not take off the valve covers.
The new motor was installed on a new 3-wheel trike that I purchased in 2006, the motor also has an Edelbrock 600 carb/intake manifold, mallory ignition & ceramic coated headers.
QUESTION: Can you recommend a low cost set of aluminum heads that I will gain at least 20-30HP? Or, do the stock heads flow well & would it be a waste of money & would I possibly lose low-end torque with a replacement.
A. Hello Bill
I had a customer overseas who want a bunch of 350Hp 350 motors.
I tried to use the 260Hp GM create motor, which is the same as your 290, but with less cam so it makes more power at 2500rpm less at 5500.
After several attempts I gave up on the idea.
I had to replace the pistons and re-balance the motor which cost enough extra as to make more sense to spent a little more money and build a better engine from the ground up.
Your compression ratio is 8.3:1. They say 8.5, but the piston is 0.030" below the deck.
Swapping the 76cc heads for 64cc will get you to 9.3 and using 0.015" will get you to 9.5:1
All this will increase your current power by 5% but you will still be burning regular.
Chinese Procomp heads are the cheapest you'll find
Edelbrock are about the same for flow.
Brodix IK heads are better
AFR are the best value, but you said cheap.
Here is a page with cylinder heads flow numbers http://users.erols.com/srweiss/tablehdc.htm#Chevy
studying it will help you find the right heads for you.
The bigger the port the more it flows but the lazier it will be to wind up.
Say under 200cc.
If you want to burn super you need iron heads at 9.0-9.3:1 or milled down aluminum
If you swapped iron heads identical aluminum heads you would loss about 2% power.
Crane Cams now offers a new generation of precision machined, specially coated and processed steel distributor gears for popular Chevy and Ford engines using either cast flat-faced lifter or steel roller camshafts.
Since roller lifter cams are made from either induction hardened steel or carburized steel, neither of these materials are compatible with the normal stock distributor gears. In the past, “bronze” distributor gears were used. For street applications these gears can wear at a high rate and may have to be replaced on a regular basis.
By using modern heat-treating and manufacturing processes, Crane Cams has developed a series of steel distributor gears that are compatible with standard cast cams and induction hardened and carburized steel roller cams. Crane Cams now makes it possible to use a steel distributor gear that provides OEM-style life span, eliminating the need to frequently replace bronze alloy gears. These Crane steel gears are available for most Chevrolet and Ford engines for both stock and aftermarket distributors.
The use of these gears on camshafts that have been previously run with other types or materials of gears, or the unnecessary use of high volume/high pressure oil pumps, can be severely detrimental to the life of the camshaft gear.
Chevrolet 90° V-6 (1978-86) 200-262 c.i.d.
For .491˝ shaft diameter p/n 11951-1
For .500˝ shaft diameter with standard configuration gear p/n 11950-1
Chevrolet V-8 (1955-87) 262-400 c.i.d.
For .491˝ shaft diameter p/n 11951-1
For .500˝ shaft diameter with standard configuration gear p/n 11950-1
Chevrolet V-8 (1965-90) 396-501 c.i.d.
For .491˝ shaft diameter p/n 11951-1
For .500˝ shaft diameter with standard configuration gear p/n 11950-1