Limits to the TPI intake system
01-31-2004, 09:03 PM
#31
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Location: orlando,florida,usa
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ask around on the stealthram board also. i currently run a 12.13 @ 112. here's my personal site www.fl-thirdgen.org/mrr23 documents everything i've done to my car. click the suspension page to see all i've put on. also when you use the desktop dyno, set the induction airflow to say 670 @ 3.0hg (48mm TB) our TB is really a 2 barrel carb per say. not a 4 barrel. only two throttle blades. it'll bring the numbers to something more realistic. the 383 i'm putting together right now says about 466 hp.
02-01-2004, 02:48 PM
#32
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Location: Richmond, Va
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i made those changes to the dyno program and now it's pumpin out 464 @ 6000 rpms
are you sure it's only 650? that sounds pretty freakin low. Chances are i'll be using the Holley Stealthram and a larger TB (maybe a 52. i doubt i'd go as large as 58 unless it would really help a lot)
you think that counts for anything?
are you sure it's only 650? that sounds pretty freakin low. Chances are i'll be using the Holley Stealthram and a larger TB (maybe a 52. i doubt i'd go as large as 58 unless it would really help a lot)
you think that counts for anything?
02-01-2004, 03:07 PM
#33
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over at thirden.org i got a these numbers from someone there.
Stock Throttle Body 48mm 670
Stock with Airfoil 709
AS&M 52mm 750
i suggest not going above 52mm unless you are going to boost (super or turbo) it. even though mike davis runs a 58mm on his 355 and runs 11.83. i'll be using a 52mm holley when i put my 383 in next month.
Stock Throttle Body 48mm 670
Stock with Airfoil 709
AS&M 52mm 750
i suggest not going above 52mm unless you are going to boost (super or turbo) it. even though mike davis runs a 58mm on his 355 and runs 11.83. i'll be using a 52mm holley when i put my 383 in next month.
02-01-2004, 04:54 PM
#35
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Location: orlando,florida,usa
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when you go to select what type of induction you'll notice 2 barrel carbs are measured at 3.0 of mercury (Hg). 4 barrels are measured at 1.5Hg. even though it says 4 barrel or FI it's wrong. that's why it shows such higher numbers.
02-02-2004, 02:32 AM
#36
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Join Date: Oct 2003
Posts: 93
i've found in desktop dyno you need to make some adjustments to get accurate predictions
cam timing - seat-to-seat timings give more accurate numbers than 0.050"
exhaust - if you have small-tube headers, enter "factory manifolds", if you have large-tube headers, enter "small-tube and mufflers"
intake manifold - if you want to predict HSR or Miniram output, select "Single-plane"
good-luck
edit: a factory 48 mm TB might flow 670 cfm on a flowbench. once attached to a TPI intake flow drops to around 540 cfm. I imagine you'd see the same flow on a HSR manifold.
cam timing - seat-to-seat timings give more accurate numbers than 0.050"
exhaust - if you have small-tube headers, enter "factory manifolds", if you have large-tube headers, enter "small-tube and mufflers"
intake manifold - if you want to predict HSR or Miniram output, select "Single-plane"
good-luck
edit: a factory 48 mm TB might flow 670 cfm on a flowbench. once attached to a TPI intake flow drops to around 540 cfm. I imagine you'd see the same flow on a HSR manifold.
Last edited by ZWILD1; 02-02-2004 at 02:36 AM.
02-02-2004, 10:58 AM
#37
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Location: Richmond, Va
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why is it that desktop dyno has all these little things that arnt completely accurate? like the exhuast selection and what not?
even with all these things bringing down the numbers it's still listing 462hp and 439 torque. it's got 330 torque at 2000 rpms for gods sake. even those numbers, although they dont match up to what i had hoped for, are still worth working torward given that it would only cost about 2500 dollars for the build.
would you all agree?
even with all these things bringing down the numbers it's still listing 462hp and 439 torque. it's got 330 torque at 2000 rpms for gods sake. even those numbers, although they dont match up to what i had hoped for, are still worth working torward given that it would only cost about 2500 dollars for the build.
would you all agree?
01-25-2023, 03:36 AM
#38
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Re: Limits to the TPI intake system
From page 123 of John Lingenfelter on Modifying Small Block Chevy Engines:
"An interesting aside to this story is that there is no difference in size between the 305 and 350 TPI factory manifolds. This is because the TPI was originally designed to increase the 305's torque, since misguided GM planners at design time had dropped the 350 from future Chevrolet plans! Thankfully, Chevy discovered that performance wasn't dead and quickly rushed the 350 back into production plans. Unfortunately, Chevy was forced to use the 305 TPI manifold since no other performance manifold existed. This explains why the stock 350 TPI engine tends to give up around 4800 RPM as opposed to a higher RPM point, because the intake was originally designed for an engine 45 cubic inches smaller!"
"An interesting aside to this story is that there is no difference in size between the 305 and 350 TPI factory manifolds. This is because the TPI was originally designed to increase the 305's torque, since misguided GM planners at design time had dropped the 350 from future Chevrolet plans! Thankfully, Chevy discovered that performance wasn't dead and quickly rushed the 350 back into production plans. Unfortunately, Chevy was forced to use the 305 TPI manifold since no other performance manifold existed. This explains why the stock 350 TPI engine tends to give up around 4800 RPM as opposed to a higher RPM point, because the intake was originally designed for an engine 45 cubic inches smaller!"
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