unioncarpenter84

iTrader: (22)

i know ive had threads of this build



but anyone think my 48mm throttle body can be holding me back or should i do a 52mm or a 58mm




Lt1 350 bored to a 355
Heads ported and polished (flows: intake 278, exhaust 197)
CC Cam 230/242, .510 lift,113 lobe separation
Comp Cams Pro Magnum 1.6 roller rockers w/7/16" studs
Comp Cams 987 Dual Valve Springs
SI Silverline Series Valves,(2.00" intake and 1.57 Exhaust)
Eagle H beem connecting rods
JE Forged Nitrous Pistons
Crane Hardened Push Rods

Hooker Headers Long tubes.
3" Custom Made Y Pipe
Borla 3" exhaust

FMS 30lbs. Injectors (38 psi at idle never checked at wot)

3500 stall
410 gears

unioncarpenter84

iTrader: (22)

any gains or is it gunna be a waste of money

duh

iTrader: (16)

I would go up to a 52mm. If nothing else, it will make sure there is no restriction. It definitely won't hurt anything.

unioncarpenter84

iTrader: (22)

i was going to do 58mm but alot of ppl on here say its to much sometimes

im was getting the intake ported to

TAEnvy

iTrader: (2)

I would run it. Ive never heard of them being too big, as in hurting performance. I think the debate comes to whether or not they are worth it.

Chris96ws6 (founder of ls1lt1.com) tested it on his H/C 350. He said he saw a higher kpa in the manifold with the 58mm vs stock.

93M6Formula

A ported stock TB (52MM) would be the way i'd go.

ahritchie

iTrader: (1)

^What he said. Cheaper and less problems than aftermarket TBs.

unioncarpenter84

iTrader: (22)

Would a throttle body make me trap more speed

KW Baraka

iTrader: (7)

Almost certainly!

BTW......if you have a 4L60E tranny, you'll need to get the PCM tuned for the bigger TB.

KW

Ed Wright

iTrader: (1)

My testing on a stock '95 Z28 did not show that. Nothing on the dyno either.
A modified engine may pick up a little. My Super Stock 350" only pulls about 2" of vacuum at 7500, I doubt a 52mm would help much. Sure doesn't need a 58mm.
If you can borrow one for a couple of passes, that might be a good idea.

unioncarpenter84

iTrader: (22)

so ur saying just save my money ed?? no need for either ??

Ed Wright

iTrader: (1)

I don't think you will see much. As I said, a stock engine saw nothing. My 355" saw damn near nothing from a 52mm. To test it correctly go to the track and what most racers do: A-B-A testing. Make two or three identical runs, put the new one on and make a couple. If it picks up, put the old one back on for a couple. Average runs both ways. Let us know.

HellTeeOne

I don't think you stand to gain anything from a 52 or 58. If you want to do something, just put a $30 airfoil in the stocker and run it. Spend the $300-$400 an aftermarket tb costs on something else.

quik95lt1

iTrader: (7)

this is one area I don't really buy into the smaller is better thing........I ran a 58mm on my 355 with TFS heads and a 234/242 cam and the thing ran its *** off, ran with heads cam ls1 Camaros all day trapped 120+ at 3450 lbs....not saying that's all that did it lol but just saying I think it helped my situation....I have never done back to back tests on them however

Ed Wright

iTrader: (1)

Only way you can know is go to the track and back-to-back-to-back test it! Saying "I think my car is fast, and I had one, so it must be good" is bogus.
If you want to look at it that way my NA 350" has gone nines at 3300 lbs with a stock TB, and pulls almost no vacuum. Means nothing.

Only way for you to find out is go test it. Not make a pass, change and make another and call that the results. Any change will be within what your runs vary anyway. It's called A-B-A testing, but most guys are too lazy to do it. All the top, actual racers do that. Guys that can't figure out why somebody else is faster do not. Or, in their little world they don't encounter the faster guys, so think they have it figured out.

Will it slow your car down? Of course not.
Will it make your car faster ? Probably not.

96capricemgr

iTrader: (1)

Are you saying he saw higher pressure or vacuum?


A lot of folks chase KPA on LT1s but given the MAP location I believe Bernoulli effect begins to sway the readings.

Ed Wright

iTrader: (1)

I explained this in another thread. I don't think many get it. Look where the MAP is mounted. You would think that would turn on a light. It has been discussed before. "Chasing KPA" like that is a dumb- assed deal. Think about it.

96capricemgr

iTrader: (1)

I have mentioned my Bernoulli effect theory before, probably in the same threads.

What I was saying in mentioning Bernoulli effect is I don't believe the stock MAP in the stock location accurate enough to gauge this.

Ed Wright

iTrader: (1)

You are correct. It is not. Vacuum should be checked at the rear of the plenum.
I put a baffle over mine in the back of my sheet metal manifold.

Jason94z

iTrader: (3)

I had a stock TB trapped 115mph (in my sig)
Put on a big mono-blade - idles sucked, part throttle sucked no gains.
I have a 52mm now just because it was the same price when I was shopping ... but am 100% sure a 350 is fine with a 48mm. They flow a lot of CFM.

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