What is the most airflow and hp you can get out of a TPI setup. No MR or SR, just the long stube set up, aftermarket parts that go onto the Stock units is ok, such as siameased runners, 58mm TB etc.

 

there is no limit on the stock parts.

 

Camaro,

I think you'll have to refine your question a bit more to get the answer you might want.

The ODB is probably corect in theory. The air flow rates are of course a function of flow velocity, internal drag (losses), duct volume, AND pressure differential. Throw enough boost at it, and you can get enough flow to feed a whole lotta' engine with a pretty high power output....

If you're talking about a naturally aspirated engine in stock trim, that's a different matter. Practical limits of the OEM TPI system are probably around 650-700 SCFM on a really good (dense air) day. Numbers I've seen @ STP are more like 650 SCFM, but I've never verified that, since I know my engine really doesn't need much more than 580 SCFM to make peak power.

As a hint, most people I knew in teh '60s and '70s tended to over-carburate their engine and couldn't understand why all that extra carburetor flow actually cost them some power. Now that I'm back in the game with DFI systems, I see most people tending to make the same mistakes for the same reasons, and they can all make it look good on paper. Guess how many unnecessary 52 and 58mm TBs there are out there on the street right now, and you can see why Edelbrock/BBK, Holley, etc. aren't too quick to point out why the large bores aren't the best thing since sliced bread....

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Later,
Vader
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"What a Day..."
Adobe Acrobat Reader

 

Good point Vader. You wouldn't put a 1000 cfm carb on your mild street engine, so why would you put a 1000 cfm throttle body. Not needed.

 

I just talked a buddy of mine out of putting a 1000 cfm TB on his Camaro. I don't know how they can sell those things.

 

You can run over 1000 CFM's on a mild street engine with no problem. A larger throttle area will usually increase air density in the intake manifold and increase the potential for power output when naturally aspirated.

Vader,
normally air density and CFM are completely independant of each other ie: an engine that flows 700 CFM of air at 6000RPM naturally aspirated will still flow 700 CFM at 6000RPM when boosted to 20psi. You are correct that the TPI will flow more CFM with denser air because the long runner design depends heavily on air density to achieve very high efficiency.

Carburetors generally need decent signal to meter fuel with acceptable atomization, but this can still be accomplished with well over 1000 CFM of throttle (rated at 1.5"hg).

EFI is not dependant on vacuum or signal to meter or atomize fuel, so the same restrictions do not apply. A very large throttle opening could however upset the pulses returning to the intake valve and reduce efficiency in some RPM ranges.

 

With the proper components, i.e. good cam, heads, exhaust, ect, a fully up-graded TPI 350 car can make a good 350 horsepower. I know a guy at school who has a fully up-graded motor with high flow TPI parts (ported plenum, AS&M LTRs, TPIS Base) along with the ZZ4 Cam and AFR 190s and he can beat LS1 Camaros.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base