Base Test using GM 350 290hp motor Compression ratio adjusted from 8.5:1 to 5.8:1 to recreate published graph

The BSFC is ideal at .40-.45 This curve does not look good at .526 @ 1750rpm.

Fuel consumption at 1750rpm is 47.2 lbs/hr 

 1 gallon of gasoline equals 5.8 to 6.5 lbs.  Using 6.2 as an average 47.2  :- 6.2  

7.6 gal/hr or     .012gal/min

Mechanical Efficiency is 89.5% @ 1750rpm

This shows averaged gas speeds at peek hp. Exhaust is very high. I am using very restrict manifold to push the power down to the published numbers.

This following graph show intake speed

It shows about 100ft/sec @ 1750rpm. According to performance Trends we want about 250-350 ft/sec for best torque at given RPM, so this port is way too slow.

While not shown Ex is at 130ft/sec @ 1750rpm way too slow.

However the first graph shows ex at over 1500ft/sec yet this unshown graph only shows it reaching 430ft/sec.

I will use all these numbers as guides for finding the best intake port, but we have quite a bit of room, as engine performance is not changed much by anything at 1750rpm.

 

This graph shows cylinder pressure. (Future technology very expensive)

 

 

I want to use this info as a referance point to compare our improvements.
This next graph comparing torque gasoline to NG.

1 GM 290hp motor on petrol
2.On Natural Gas with 8.5:1 CR
4. NG with 10.5:1 CR
5. Stroker 355cid Engine 8.5:1 on petrol
6. SE 355 11.5:1 NG

 

Fuel Flow

Fuel consumption is greater for gasoline, the difference between the GM and the SE engine is not great

BSFC Above

This shows the increase in Intake velocity from 170cc down to 93cc (modified SE head)
the average sq/area is reduced from 1.63 down to 1.20
 

 

 This Show Torque in relation to port sizes note that 1.2 is beter than 1.1 and 1.3

Valve seat throat 1 3/8" less 11/32 valve stem is 1.383 sq/in.

 

http://www.onlineconversion.com/shape_area_circle.htm

 

Closer view with 1.15 being best

This shows that to make max torque at 1750rpm having the ideal port size avg port size 1.2sqin even though this next graph shows that velocity increases with reduction of port size

The perfect size is not know for sure, but  at 1750rpm all sizes are very close

1. 175 @ .050 lift 102 lobe sep 4 advance
2. 180 will use this grind
3. 192
4. GM 290 cam 222 114 lobe sep 0 advance

Note how 175 has a little more under 1750rpm but gives it up, the GM is too big.

 

These are GM 454 NG SE 355 GM 350 & SE V6 262 V8 missing cylinders

 

This is the fuel flow should give some idea to fuel consumption

Note that the SE 355 burns more fuel than the GM 350, but this is what it takes to make more power.

This shows the BSFC the V6 is the same as the SE 355

 

Now let's look at intake manifold. It seems to me that having small runners is what we need, but it test real world testing.    This Performance Trends program is pretty good but it shows so very large gains hard to believe but I think worth exploring.    We don't know how important duel verses open plenum is. 

These following manifolds show 4 barrel duel plenum worst 2 barrel better and 2 barrel open plenum better.       One mechanical fuel injection was better again but a racing Hilborn fuel injection very good having 18" ram tubes but that taking the ram tube off made it better.    This is strange because long tubes are meant to make better low speed torque, however this low speed engine has some querks, I expect come from pressure waves

Headers

Coatings and 60% faster burn rate

If 60% faster is 2 tq them 800% would be 27hp???

Final combination. Very close to 454 power output.

Final comparing fuel consumption of a GM 454 against the SE 355, you'll see it saves about 18%

GM-350  47.2 lbs/hr - 7.6 gal/hr  -  0.012 gal/min   

SE-355   40.0 lbs/hr - 6.45 gal/hr - 0.10 gal/min

GM-454  48.0 lbs/hr - 7.74 gal/hr - 0.13 gal/min

 

Mechanicall Efficiency

Thermal Efficiency

Volumatic Effeciency

 

 

 
  Sq inch from circle

 I recently ported a pair of TBI 350 193 swirl ports as an experiment. I went into it knowing that they are swirl ports and can only have so much potential. Thing is when I got done and had a buddy flow bench them, the flow #s suprised the hell out of me. Not bad for 8 hrs with a air grinder.

Valve Lift------Intake Flow---------Exhaust Flow
.050--------------35.6----------------------31.0
.100--------------72.4----------------------60.5
.150-------------105.8---------------------87.3
.200-------------133.4--------------------124.2
.250-------------154.1--------------------147.3
.300-------------180.6--------------------171.5
.350-------------195.5--------------------184.7
.400-------------209.3--------------------196.3
.450-------------217.4--------------------203.7
.500-------------224.3--------------------215.6

 

The port size on the 193 heads is in the 170 cc range (Dyno Don posted the size once) (The "perfect" cam for swirl port heads); he got 168 cc unported and 175 cc after porting. I doubt Fast355 removed enough material to make a dent in the port volume.... so the flow numbers aren't deceiving, especially given the use of the 1.94 and 1.50 valves. It's a math exercise to determine the flow velocity once you have the cfm values and the port & valve areas. Since the port volume is small (compared to other heads), and since the 193 uses small-ish 1.94/1.50 valves, then it stands to reason that the flow velocity has to be very good to make the flow numbers measured.

Using either the curtain-area of the intake valve, or using the facial area of the intake valve (the numbers are very close), the average flow speed at max lift (and max flow) is:

2182.5 in/sec, or
181.9 ft/sec, or
Mach index 0.165

which is well below Taylor's Mach index threshold of 0.5.

If we want the peak flow (rather than the average flow) then the numbers will roughly double to 364 ft/sec, and 0.33 Mach index which is still under 0.5, so there is room for more improvement -- probably by removing the swirl ramp, but that would defeat the swirl, and less swirl means more ignition advance.

I've said it before --- advance is needed to make optimum power because the combustion event inside the chamber is so slow --- but this also has the disadvantage of increasing pressure in the cylinder when the piston is still climbing twds TDC. It's a necessary tradeoff: give up some work done on the piston while the piston is still climbing in order to get more complete combustion so that optimum power can be made on the piston downstroke.

If you could reduce the need for lots of ignition advance, by making the flame/combustion event occur faster (via intaker swirl), then more work could be done on the piston during the downstroke. That's one reason for adding swirl, either via the ramp in the 193 casting, or via the inlet port and combustion chamber shape in newer heads (LT1, LS1 etc).

Fast355's heads are flowing as good as stock iron L31/LT1 heads on the intake, and much better than L31 LT1 heads on the exhaust. The combustion chamber shapes are basically the same on all three heads (193 L05, LT1, L31) so it's not a stretch to think that the LO5 heads still have better swirl among all three.

If Fast355 dynos the heads (on an engine) then it will be interesting to see how little ignition advance he needs to make optimum power.

 187 LO3 stock head flow data

I've got some data from some stock 187s. It was collected at 28 in/h20 pressure drop.

lift_in-----I-------E
.050-----35-----27
.100-----65-----54
.200-----90----113
.300----135----120
.400----158----133
.500----165----140

 

 Carburetor vs. TPI
It's not terribly surprising that the stock L98 TPI system produced more low-speed power than the conventional carb and dual-plane intake. What was interesting was the difference in power out past 4,500 rpm. Whereas the TPI signed off with 332 hp at 4,700 rpm, the carbureted setup continued pulling strong, reaching a peak of 363 hp at 5,900 rpm. Though the peak torque production differed by just 7 lb-ft, the TPI combination made a solid 20-25 lb-ft more from 2,500 rpm to 4,300 rpm. For a drag-race application, there's no question the carbureted setup would be the way to go. For throttle response, fuel mileage, and overall driveability, the story would be quite different.

http://www.theoldone.com/articles/The_Soft_Head_1999/

 

 http://www.sallee-chevrolet.com/Disc...tml?1045725665

http://www.sallee-chevrolet.com/Disc...tml?1049930156

http://www.sallee-chevrolet.com/Disc...tml?1050432892

http://www.sallee-chevrolet.com/Disc...3390/3180.html

http://www.sallee-chevrolet.com/Disc...3418/4522.html

 

 http://www.strokerengine.com/dangermouse.html

 

 

 

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