THROTTLE BODY - Correct Size???
Thread Starter
Pro
Joined: May 2002
Posts: 537
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From: Conway SC
THROTTLE BODY - Correct Size???
Based on a dyno run my modified LT1 is now producing a RWHP rating of 367 HP. The motor is still using the stock GM throttle body to achieve this level of RWHP. Is there a method to determine if a larger sized Throttle Body would allow for even more RWHP gain? Which would be the better Throttle Body, a 52mm or the 58mm?
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Yes look at the map sensor reading if at 100 kpa or whatever local atmospheric pressure is there is no gain to be had. Easy way is to look at MAP key on engine off then see how close youget during the dyno pull. If they are the same or very close there is no need to change.
Dave
Dave
Safety Car
Joined: Jul 2008
Posts: 3,966
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From: Made In America
St. Jude Donor '10-'11
48 is fine for as much power as a 350 is going to make. Once you hit 475+ hp or go 383 or beyond then it's time for a bigger TB. If you want to go bigger, a 52 mm will be more than fine for your application. Some people here say TBs are a waste of time and others say they are the best mod.
It aint going to help much if any on a 350. BBK & TPIS are good models. TPIS charges a 300 dollar core fee though.
It aint going to help much if any on a 350. BBK & TPIS are good models. TPIS charges a 300 dollar core fee though.
Racer
Joined: Oct 2007
Posts: 478
Likes: 1
Couple of thoughts and or discussion on air distribution in the plenum.
I would think cylinder #1 at the front of the plenum would get less air than say cylinder #8 at the back of the plenum. Would not the air velocity at wot favor the cylinders at the back of the plenum with the momentum of the air rushing to the back of the plenum?
If this is true would not a larger throttle body slow the air down at the front because of the larger CSA and maybe aid the front cylinders in getting more air? If the MAP sensor is at the back of the plenum if may not show what is happening at the front of the plenum. Just some thoughts for discussion.
I would think cylinder #1 at the front of the plenum would get less air than say cylinder #8 at the back of the plenum. Would not the air velocity at wot favor the cylinders at the back of the plenum with the momentum of the air rushing to the back of the plenum?
If this is true would not a larger throttle body slow the air down at the front because of the larger CSA and maybe aid the front cylinders in getting more air? If the MAP sensor is at the back of the plenum if may not show what is happening at the front of the plenum. Just some thoughts for discussion.
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
i read many times that TBs were not really needed for our 350s (i have a 355)
When i went with the SR intake,i decided to throw a Holley 58mm TB, just because
the SR originally came with a 58mm TB.
When i went with the SR intake,i decided to throw a Holley 58mm TB, just because
the SR originally came with a 58mm TB.
Racer
Joined: Nov 2006
Posts: 420
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From: Sierra Madre California
Consider having your stock TB increased to 52mm. It's cost effective (appx $150) and even with the restrictive stock intake, I got a small but noticeable increase in the top end, with absolutely no bottom end loss in response. I used a guy by the name of Matt Blum; he has a machine shop in Cedar Rapids, Iowa. He not only ports it to 52mm, but adds bearings to the shaft, which the stock TB does not have. Real quality workmanship, and a great guy to work with. Contact info is
http://www.advanced-machinellc.com/
http://www.advanced-machinellc.com/
