Trying to make it breathe
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Car: 1989 GTA
Engine: 5.7 ltr.
Transmission: 700R4
Axle/Gears: 3:27 9 Bolt Borg Warner
Trying to make it breathe
Well I have the headers, cold air intake, slp siamese intake runners on and now thinking about jumping up in size on the throttle body. Looking for comments and suggestions on which size to jump to from the stock 48mm. Should I go to 52mm or 58mm ? I will port the plenum to match at that time. Will I see any difference at all between the 52mm and 58mm ? I know heads and cam is involved as well, but that's down the road.
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: Trying to make it breathe
The runners in the lower manifold are too small. All the throttle body is going to do is keep the plenum full of air. If you install a vacuum gauge in the plenum and one before the tb and make a full throttle run, maybe that can help determine if the tb is a restriction.
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: Trying to make it breathe
You're talking about dual vs single.
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Re: Trying to make it breathe
The runners in the lower manifold are too small. All the throttle body is going to do is keep the plenum full of air. If you install a vacuum gauge in the plenum and one before the tb and make a full throttle run, maybe that can help determine if the tb is a restriction.
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: Trying to make it breathe
Everyone's car is turbocharged. It's called atmospheric pressure. The only problem with big throttle bodies is low speed torque suffers. A progressive tb would be best.
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: Trying to make it breathe
Not too big as such but of no benefit because as noted the TB is not the restriction point with a stock base.
Get better value out of spending $$ on something else
and FWIW
my L98 with 113 alum heads , ZZ4 cam , fully ported plenum and base , SLP big tubes , LT's and free flow exhaust ran exactly the same times with a stock 48mm TB and a 58mm TB.
( 30 runs ,same day , same track , same conditions )
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: Trying to make it breathe
Yes but when people ask questions about how to make thier engine breathe better they fail to realise that when the tb is opened air is forced in only by atmosheric pressure and nothing else. So to get the most power your plenum pressure needs to match atmosheric pressure otherwise the tb is a restriction. But then lowe speed torque will suffer actually making the car slower. So a progressive tb you can have low speed torque and max power. I mean the tiny little runners, tiny valves, cam, all need to be bigger for max effort but were focusing on throttle bodies here.
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Re: Trying to make it breathe
your missing the point of the op, The tpi base is the bottleneck and the tpi long runner design. A more suitable choice would be a hsr, super ram, t-ram sounds like a real mild 350. He never mention what cam he has or heads or compression ratio he is running or if its all stock and stock tune. There is no such thing as a progressive throttle body for tuned port. It sound like he has upgraded his exhaust but more information is needed from him to help guide him.
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: Trying to make it breathe
Yes I made that point in post #4. I've only had 2 tuned ports but have never disected them to verify their ****-poor design. I bet there aren't even radiused port entries. I figured there was no progressive tb for the tuned port available in the aftermarket but I'm sure there's one out there somewhere that could be adapted. But anyway I really doubt there are any gains to be had by a tb upgrade on a tuned port.
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Re: Trying to make it breathe
My point is the same as tunedperformanc, getting a 58mm throttle body will do zero for you if you're running the factory intake. Now, if you want it because of future plans, then by all means, but if you don't, then I wouldn't go over 52mm simply because you don't need it.
FTRspeedy, you are referring to the LS or Vortec 5.3L in the Silverado's? Those are entirely different than our old TPI motors, especially with their intakes.
FTRspeedy, you are referring to the LS or Vortec 5.3L in the Silverado's? Those are entirely different than our old TPI motors, especially with their intakes.
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Car: 67 ******mobile
Engine: 385 Solid roller
Transmission: T-56
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Re: Trying to make it breathe
5.3 can move more air than yours can
you dont need any more than a stock 48. Wasting your money
you dont need any more than a stock 48. Wasting your money
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