Bowtie Boy

97Z28 a4 , would a 58mm be too big?

MavrikTA

iTrader: (27)

YES. Do not bother. Wait until you have a reason to remove the intake(cam) and do it they because the intake bores are only 52mm. A 52MM TB would bolt right on, but with a stock car, it wont do you any good, really.

Bowtie Boy

So even a 52MM TB would be a waste? Just wait untill cam etc is changed and go to a 58mm?

mack

iTrader: (2)

You could get your stock TB ported to 52mm. Check the web and I believe Thunder Racing does it now.

96lt1m6

iTrader: (31)

save your money a stock tb is good to 450hp,the only engine that benefits from a 58mm being stock is a TPI engine.Lt1s are a little different they can actually breathe from the factory!spend the cash on the headers,stall,shift kit,cold air system of some kind,ngk tr55,msd wires,255 lph fuel pump &hot wire kit,some 3.73s,fan switch,160*stat and i would also invest in new injectors cause our Lt1 parts are gettin old and the low mileage clause dont work in this case with all this done you should be knockin out low 13s hope this helps i am sure some others will chime on in and add to the list, good luck with your ride

TurboZ28

Bigger throttles are kinda pointless until your pushing quite a bit of HP. And even then I don't really think they're necessary unless your pushing more than 346ci or you've got some forced induction.

I'm gonna get a 58 but I'm not expecting any gain. I just want one cuz they're purdy.

Camaroholic

iTrader: (1)

A 58mm likely won't hurt anything, but it may or may not help.

I ran my 58mm BBK TB when my car had a 4.3L L99 motor in it (from a Caprice). I have a feeling that it did lose a touch of low end torque on that small of a motor (as the timeslips were an extremely consistent 15.6x @ 90.x mph), but other than that, there was no ill effect at all.

But the throttle body would be one of the last mods I'd do to the motor. I'd do headers, exhaust, cold air intake, cam, heads, rockers, etc. first.

HBHRacing

It will not help in the least, you simply will be able to flow MAX air at a lower percentage of throttle. It will do absolutely nothing for you, except help burn up your tranny if your an auto, and waste your money.

buffman

iTrader: (9)

well it will only burn up your trans if you dont get it tuned.

Nonetheless as mentioned you dont really need a big TB until you start making power, but there are some that will argue that the stock 48mm one becomes an intake restriction above 5000rpm

LT1BRN

iTrader: (1)

well, I have a 58mm TB, i can't say I gained anything but it didnt hurt the performance.

94 F-body

iTrader: (1)

As far as factory stock, do not do it, get some headers or more, I have seen no gain on a bone stock set up,(LT-1), you can lose 1 or more tenths per 1/4 mi. MENTAL NOTE, AN ENGINE IS AN AIR PUMP/ THE MORE YOU INTAKE THE MORE YOU NEED TO EXAUST.

GIZMO

iTrader: (8)

The GM Performance Parts Ram Jet 502CI / 502 HP motor uses a 48mm throttle body!

buffman

iTrader: (9)

it's GM. If you already had a TB sitting around that would make the power needed on a motor, why would they design a new bigger TB, if they've already got one sitting in the parts bin. I'll have to dig up the dyno results, but one of the impy guys who has a ram jet 502 gained some horses going to a 58mm TB.

Remember anything over 2" of vacuum at WOT indicates a intake restriction...

speed_demon24

iTrader: (6)

Just because you make a certain amount of power with something doesn't mean its not a restriction.

radioren

iTrader: (2)

but, is that just slapping on a bigger TB or will it give you a lil more if you port your intake as well? Always keeping the more in the out rule in mind.

Schweet97Z

iTrader: (35)

why will a bigger throttle body destroy a transmission if untuned?

LT1MAN

iTrader: (6)

the intake bores are 48mm in my 94, they are 52mm on the lt4 intake. i bought one of those ported (52mm) factory tb's for $160 and ported the intake to 52mm and picked up a few, smoothed out acceleration some. 58mm is too big.

TurboZ28

I was wondering that too.

buffman

iTrader: (9)

Incorrect. The TB bores on the intake are 54mm on any LTX intake...


Yes you can destroy an auto trans with a larger TB if untuned. You car is seeing more air movement at lower throttle positions so there's going to be lower line pressure. It wont just automatically make it go boom when you drive it around, but extended untuned use, will reduce the life of your trans

TWS

iTrader: (63)

Yep. 58mm for your application is overkill. I didn't get a 58mm (ASM) until the 385 stroker motor. Ran around with a BBK 52mm for years, even on my H/C 355 and it was enough.