TB upgrade
Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
Probly not much if any. The stock 48 pretty much flows as much air as the plenum and runners will allow into the motor. If your OEM one is worn out go ahead but if your thinking about peformance only forget it.
Thread Starter
Pro
Joined: Jul 2011
Posts: 544
Likes: 0
From: Atco Raceway in between Pa & Nj 13.073 @ 106 MPH
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I know of a friend who stuck a 58mm TB and felt improvement. Too bad the track times disagreed and it was worse but there it is. Without tuning and other mods, you won't achieve much. The only thing it will do is probably lightening your wallet.
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
And for anyone that feels the need to upgrade there's always the CFM ratings. As an example........a 383 at 7000 RPM will need 775 CFM. That about what a 48mm flows. The GM Ram Jet 502 Cu. In. 502 Horsepower uses a 48mm throttle body. The 502 at 5400 RPM uses about the same amount of air as a 383 at 7000.
Here are some real world numbers from a third party flow bench. As you can see the TB airfoil that everyone jokes about is actually a benefit if you're right on the edge of needing another throttle body.
Here are some real world numbers from a third party flow bench. As you can see the TB airfoil that everyone jokes about is actually a benefit if you're right on the edge of needing another throttle body.
Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm
Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm
TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm
TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm
Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm
TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm
TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm
Thread Starter
Pro
Joined: Jul 2011
Posts: 544
Likes: 0
From: Atco Raceway in between Pa & Nj 13.073 @ 106 MPH
And for anyone that feels the need to upgrade there's always the CFM ratings. As an example........a 383 at 7000 RPM will need 775 CFM. That about what a 48mm flows. The GM Ram Jet 502 Cu. In. 502 Horsepower uses a 48mm throttle body. The 502 at 5400 RPM uses about the same amount of air as a 383 at 7000.
Here are some real world numbers from a third party flow bench. As you can see the TB airfoil that everyone jokes about is actually a benefit if you're right on the edge of needing another throttle body.
Here are some real world numbers from a third party flow bench. As you can see the TB airfoil that everyone jokes about is actually a benefit if you're right on the edge of needing another throttle body.
Thanks Sarge, good info.
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Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
I did back to back testing on same day ;
30 runs
1/2 with stock TB
1/2 with 58mm.( because I had it for my 383 project )
L98 /big tubes/ ported intake and plenum / headers
WOT from idle w/2K stall and 3.07's
No difference in ET, 60 ft or speed
Similar 60ft times reflects no loss of throttle response as claimed by some, that having too large a TB will kill bottom end
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I have documented it here in the past.
I did back to back testing on same day ;
30 runs
1/2 with stock TB
1/2 with 58mm.( because I had it for my 383 project )
L98 /big tubes/ ported intake and plenum / headers
WOT from idle w/2K stall and 3.07's
No difference in ET, 60 ft or speed
Similar 60ft times reflects no loss of throttle response as claimed by some, that having too large a TB will kill bottom end
I did back to back testing on same day ;
30 runs
1/2 with stock TB
1/2 with 58mm.( because I had it for my 383 project )
L98 /big tubes/ ported intake and plenum / headers
WOT from idle w/2K stall and 3.07's
No difference in ET, 60 ft or speed
Similar 60ft times reflects no loss of throttle response as claimed by some, that having too large a TB will kill bottom end
Racer
Joined: Jun 2006
Posts: 361
Likes: 6
In 1984 while assigned to 2/327th Infantry, 101st Airborne, I had the opportunity to work with the 1st Marine Recon in the far North of Alaska. Best fighten, most drinkenest, ornery bastards I've ever had the honor of training with. Those were good times.
Last edited by Corvette40; Dec 4, 2011 at 10:45 PM.
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
Best fighten, most drinkenest, ornery bastards I've ever had the honor of training with.
