52 MM vs. 58 MM throttle bodies
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Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
52 MM vs. 58 MM throttle bodies
I bought an Accel super ram and it came with 24 lb injectors and a 58 MM Accel throttle body. I've been told the 58 MM is too big for my stock head/ cam 91 GTA 350. Is this true? Should I use a 52 MM one until I put my ZZ4 cam and 1.6 ratio rockers in, then slap the 58 MM on?
Any knowledge on this would be appreciated. Thanks.
Any knowledge on this would be appreciated. Thanks.
#2
Re: 52 MM vs. 58 MM throttle bodies
Even with rockers and cam it'll be more than you need, but you have it and it wont hurt anything to put it on so go for it.
You'll need a lot more cubes or lots of RPM's to get to the point that a 52mm TB becomes a serious restriction, either way you'll need serious heads too.
You'll need a lot more cubes or lots of RPM's to get to the point that a 52mm TB becomes a serious restriction, either way you'll need serious heads too.
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Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: 52 MM vs. 58 MM throttle bodies
The only issue with bigger TBs is that the Accell Enrichment routines are setup for roughly the amount of opening of the stock TB.
Basically you may get a lean spike when tromping it open because there will be less added fuel Vs the TPS position and the throttle blade opening.
(More opening for air per TPS movement than before)
Tuning in the chip can correct for this if it is too much of a problem on the setup.
Basically you may get a lean spike when tromping it open because there will be less added fuel Vs the TPS position and the throttle blade opening.
(More opening for air per TPS movement than before)
Tuning in the chip can correct for this if it is too much of a problem on the setup.
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Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
Re: 52 MM vs. 58 MM throttle bodies
The only issue with bigger TBs is that the Accell Enrichment routines are setup for roughly the amount of opening of the stock TB.
Basically you may get a lean spike when tromping it open because there will be less added fuel Vs the TPS position and the throttle blade opening.
(More opening for air per TPS movement than before)
Tuning in the chip can correct for this if it is too much of a problem on the setup.
Basically you may get a lean spike when tromping it open because there will be less added fuel Vs the TPS position and the throttle blade opening.
(More opening for air per TPS movement than before)
Tuning in the chip can correct for this if it is too much of a problem on the setup.
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Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
Re: 52 MM vs. 58 MM throttle bodies
Yes, I would prefer a dyno tune but every dyno tuner within 2 hours of me is out of business it seems.
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: 52 MM vs. 58 MM throttle bodies
FWIW
I did back to back testing of a stock vs BBK 58mm TB ; over 30 runs on same day
Stock TPI L98 w/ ZZ4 cam / intake mods / headers.
There was no difference in performance. 60ft times ( 1.7X ) were identical indicating no loss of bottom end.
Definately not a good bang for $$$ investment but also did not kill engine perf as some claim
I did back to back testing of a stock vs BBK 58mm TB ; over 30 runs on same day
Stock TPI L98 w/ ZZ4 cam / intake mods / headers.
There was no difference in performance. 60ft times ( 1.7X ) were identical indicating no loss of bottom end.
Definately not a good bang for $$$ investment but also did not kill engine perf as some claim
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Car: 87 Iroc-Z
Engine: 305 tpi
Transmission: 700-r4
Axle/Gears: 3.42
Re: 52 MM vs. 58 MM throttle bodies
I've got a 58 on my stock lb9 (i got it from a junkyard for 20$ when my orig. stoped returning to closed) and it threw my tune way off. I have to turn up the fuel pressure so that it's horribly rich at idle just to get a reasonable a/f at high rpm. Yes i know i seriously need to quit bs'ing and learn to tune.
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Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
Re: 52 MM vs. 58 MM throttle bodies
Thanks for the responses guys. I am going to stick with the 58 MM my super ram came with and I am having a custom chip made as we speak by pcmforless.
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Car: 91 B4C "police special service"
Engine: L98 494hp
Transmission: tko-600 on order
Axle/Gears: 3.23 true trac
Re: 52 MM vs. 58 MM throttle bodies
good choice with pcmforless....used them many times with great sucess. I would agree that 58mm is probably too big for stock engine/heads...wll cause slow throttle response compaired to the 48mm, but it will run with it on there, probably won't see any performance gain from it though...I probably wouldn't worry too much about it.
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: 52 MM vs. 58 MM throttle bodies
As I noted above , absolutely no difference in throttle response with 58mm
I drove home from track with 58mm on and only comment I will make is, off idle tip in was harder when tickling the throttle , say to move forward in traffic like when at lights because of the heaver spring BBK use on their TB's.
Hard to apply just enough pressure on pedal without going too far . Other than that could not tell any difference over stock TB .Have that TB on my 480Hp 383 and still gives the same problem
I drove home from track with 58mm on and only comment I will make is, off idle tip in was harder when tickling the throttle , say to move forward in traffic like when at lights because of the heaver spring BBK use on their TB's.
Hard to apply just enough pressure on pedal without going too far . Other than that could not tell any difference over stock TB .Have that TB on my 480Hp 383 and still gives the same problem
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Car: 91 B4C "police special service"
Engine: L98 494hp
Transmission: tko-600 on order
Axle/Gears: 3.23 true trac
Re: 52 MM vs. 58 MM throttle bodies
I noticed difference on a stock motor with throttle response, but on my built motor I did not. and I've not had any problems with the the BBK, that's the same one I have, no issues with mine....
#15
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: 52 MM vs. 58 MM throttle bodies
The early TPI cars have a straight pull at the linkage like on a carb
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