92 RSS

overkill?? and why?

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92 RS, 350, Street & Performance MPFI, TFS heads,
Crane Rollers,
MSD Digital 6 Plus, 22lb injectors,
ZZ3 cam, Edelbrock Headers 1 5/8, 3" Exhaust,
Hi Flow 3" Cat, stock T-5,
stock rear 3.08, koni yellow adjustable front, twin turbo glass hood, T-tops, Auto Meter Ultra Lite Series 2 5/8 gauges, Teal Green

Dan87IROC-Z

If a 58mm TB flows 1000cfm, I bet that the 1250 one would be like a 64mm or even a mono-blade TB, which is WAY over kill for anything other than a big block. For your car, I would suggest a 54mm TB from AS&M.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

F22Raptor

I speak fact and trust me when I say that you WILL lose a lot of torque with anything bigger than 52mm on a mild and sometimes hot engine. I personaly have a 58mm and the torque loss over the 48mm did not balance out with the hp gain, if any.
Rick

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'88 GTA 350 Full of Leprosy (rust)
Full Exhaust, Free mods, Xtreme Energy cam, Intake Pieces and 2100 RPM TQ

13.39@102.50 MPH
1.90 Sec ----- Best 60FT
104.23 MPH -- Best Trap Speed
AIM HIGH!

86Tra/maro

I was wondering about a comparison between the 52mm to the 58mm TB. With the two costing just about the same isn't it better to just go ahead & buy the 58mm , because of future mods that may need better air flow?

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86 Tramaro 90% Trans Am/ 10% IROC/Z (nose, hood,& fenders)
Trans Am Mods as of 1/10/01
3inch
T.E.S/Flowmaster setup,gutted cat,gutted maf,relocated mat,373 gears,upgraded factory chip,255 liter h/press. walpro f/pump & throttle body coolant bypass
njdaewoo@excite.com

Guest

58=useless on anything smaller than a 400.

There was a test in a mag about a year or so ago, Car Craft I think, with someones car from here and it went slower with the 58. Stick to the 52.

precision350

There are right, Don't go any bigger than a 52mm. I installed a 52mm when I was first getting started on my engine mods and I could tell the differance in torque loss just between the 48mm and the 52mm. Now it works wonderful with all of my mods.

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92 Camaro Z28
350 TPI
Dart Iron Eagle heads
10.5:1 cr
Lunati L54779 cam
52mm throttle body
Ported plenum
Home made AFPR ($2)
1 5/8 shorty headers
Ram air
255 lph Holley fuel pump
2.5 inch TRUE DUAL exhaust (no cats)
Flowmaster mufflers
4.10 gears
700R4 w/2000 stall
100HP nitrous
Best time before any of these mods:
15.1 @ 91.9
Best time after mods:
12.60 @ 108.3
That is at high alt.
5600 feet Morrison, Colorado Bandimere Speedway

IROCZZ3

It all depends on your mods...

IMO Superram or Miniram motors 350 or bigger should go with a 58mm...the throttle openings on the SR are 58mm (not sure on the MR though), why not get a matching TB?

Ported plenum setups should go with 52mm.

Just FYI, I picked up 2 mph in the quarter with no loss in low end torque on my SR equipped motor going from a 48mm to 58mm TB...top end pull was much better.

Again, it depends on your mods and your results may vary.

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1989 IROC-Z, ZZ3 shortblock with some bolt-ons.
13.20 @ 108.69, 2.2 60'

F22Raptor

Well, with the 48mm I wasn't able hook at the track and the engine felt a lot crisper; with the 58mm I got a best of 1.90sec 60ft pass and a best et of 13.39sec. All this with stock heads (unmodified) and 3.27 gears. The better 60 ft with the 58mm are due to the loss of torque and the car hooking up much much better.
Rick

mirage2991

loss of torque...humm don't know about that..I got a 58, and I can't hook..even if I try really hard (aka 1.3 sec react time in order to smothly get on the gas...) best I ever got was 2.0 with the track being sprayed...without, it ranges from 2.2 to 2.4...
fare as performance wise, I noticed a change in SOTP from 48 to 58...more power...but don't have ET's to compare...I'm going to put the 48 back on and see what that does...if it stays the same, I'll be saling the 58...
and for comparason, I got a friend that turns low 12's with a 48, but that's on an LT1, with just a cam and slicks.

92 RSS

I don't understand why would you loose torque? I thought that's the whole idea... to get as much in?
Can some one be more elaborate on this topic as to why you would loose torque. I can understand it if your exhaust is too restricted, but what if you run an open exhaust.


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92 RS, 350, Street & Performance MPFI, TFS heads,
Crane Rollers,
MSD Digital 6 Plus, 22lb injectors,
ZZ3 cam, Edelbrock Headers 1 5/8, 3" Exhaust,
Hi Flow 3" Cat, stock T-5,
stock rear 3.08, koni yellow adjustable front, twin turbo glass hood, T-tops, Auto Meter Ultra Lite Series 2 5/8 gauges, Teal Green

Ed Maher

I agree w/ 92 RS, i see absolutely no reason you would lose torque with a 58mm TB.
It's not like we're talking about going from a 600cfm carb to a 100cfm carb, the TB ONLY lets air in. Going to a bigger carb can lose you torque b/c of the poor atomization and mixture control at low flow levels in a big toilet bowl carb.
It's also not like we're talking about the difference between a small street intake/heads and a fully ported race set-up, again, you would lose torque their b/c of loss of velocity.
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OK, enough dramatic pause, i used that last example to weed out the retards. Yes, you are a retard if you think going to a 58mm TB will cost you torque b/c of a loss of veloctiy through the TB. Have you ever looked inside the plenum? Notice how it is cross sectionally MUCH larger than the TB. So no matter how high your velocity through the TB is, when the air hits the plenum all that velocity is moot anyway, it becomes part of the plenum air charge that doesn't flow in a straight line.
With that said, the 58mm TB may be overkill, but it sure can't hurt.
...ed

Guest

Ok, so then why dont we all just run out and get a twin 100mm TB and throw it on there? Match the plenum to the TB and it will cause no problems at all, correct?

mirage2991

right but then why have a billion CFM if you motor doesn't use it....if your motor only uses let say 800 cfm at the tb entrance, then having a 1250 won't do anygood. you'll max out the heads and cam befor the tb. I think the people like me that run 1000cfms is because since they are the same price as the 750, and in the futur we all kind of plan to have more hp, why not buy one tb! sure my stock motor is not in need of a 1000cfms, but I don't see how it could hurt it at all....well I could be wrong...but like the above staited, it only meters air and not a mixing of air and fuel, where a big, too big carb would hurt the performance....

IROCZ88

I have to agree with bigger TB's killing torque. I borrowed a 58mm Edelbrock and stuck it on my car, I lost noticeable torque down low, and I got ****tier gas milage. Then I slapped the stock one back on and the car ran much better down low.

F22Raptor

Go ahead, make my day! Nobody is gonna stop you!
If you think the 58mm is better that 52mm, then buy it. If any of you live close to San Antonio, TX and would like to trade a 52mm for my 58mm, then e-mail me.
No, I won't send you mine if you live somewhere else. My Accel 58mm sucks, but it's better than having no TB at all because some crackhead decided to keep mine and not send his.
If you wanna trade, send yours first and make sure it fits my '88 GTA