LT1 ANDY

intake just cleaned up, heads flow 260/200, CC306 cam, 11:1 compression. Still running the stock 48mm TB. Car isnt trapping for crap for as light as the car is and how much power the car SHOULD be making. 111.69.

car trapped 107.80-108.50 on STOCK heads cam+intake and 200+#'s heavier.

Dont want to waste my money on something that isnt gonna do anything for me, but im sure that thing has to be a restriction.


Andy
Transbraked T400

Somnambulist

i dont think you need a 52mm TB yet, but no hurt in stepping it up and seeing what it does for ya. that way you wont have to worry about it later if you do anything else...

ibanez6rg

48mm TB will get ya in the 10s.

LT1 ANDY

well yeah but at some point it does restrict flow.......i have some big dollars in the car, this isnt project cheap street or anything like that.

All tubular front suspension
BMR, madman Rear Suspension
Maual Rack
T400 w/ transbrake
No accesorys

Ill spend the money if i can pick up a 1mph or so.......just dont want to WASTE money as we all have in building one of these cars.

Andy
X-6speed driver

1racerdude

It won't hurt to go to a 58MM,but it may not help either.You need to look at everything in the CAI including the filter.The K&N is the best I have found with their 7" long tapered filter flows about 780CFM.The K&N tubing will flow over 1300CFM,then get some ends for your MAF that have been ported.Think of it as needing to flow 750CFM from the filter to the piston and adjust accordingly.

CoUnTryMuZiCZ28

Arazona speed and marine make a 54mm TB that i really like.. its shown on thunderracing.com.. Some have told me on my old stock bottom end that a 58mm might hurt, some say get a 52... Check out that TB.. It flows killer too!!

1racerdude

A 58MM flows 1000CFM and it would be good for the future mod's.Don't know about the 52 probably flows in the 800CFM range.You don't figure TB's like you figure carbs though.

formula383

You will hear several different opinions on this. But the only way to really tell will be to change the tb out. I say if you are going to buy one you might as well go ahead and get the 58mm.

LT1 ANDY

Very true........yeah, everyone said (around here locally) that i couldnt go 12's with a stock motor....and after some time and work i went 12.84 on the stock internals, so if it was easy everyone would be fast.


Thanks for the imput.

Andy
Pulling the wheels on the footbrake

RealQuick

i would look into the tuning being the restriction and not the TB I think that is why you are trapping so low. When I was making 368rwhp/336rwtq i trapped 114.5mph with an M6 tranny. I should hope your close to that powerwise and should run pretty similar.

However, if your just wondering about the TB only, then i dont see it hurting you stepping up to something bigger.

LT1 ANDY

yeah, the tuning needs some work. for sure its nowhere near perfect, little rich at idle still, and major split BLMs. Yeah its a TH400 with a pretty loose converter so thats killing a bit of MPH but as light as the car is and how well it hooks and runs in the low gears i was hoping for 115MPH, hoping for more actually but gotta be realistic the T400 isnt taking up 7-8 MPH, shortblock is brandnew soooo.

Yeah my hack'd up LT1edit tuning probaby isnt the greatest, soooo some dyno time and a 52MM TB and a new opti/coil is probably in the car's future...or i could just part it out and start over with a LSx


Andy

RealQuick

Another thing, I was trapping just under 106mph with bolt-ons. First time i went to the track with combo i ran consistent 111mph. I was pissed. I went back 2 weeks later without changing a thing and was trapping consistent 114's. Weather and track prep play a role too.

LT1 ANDY

car is deadhooking and pulling the wheels(VERY consistant 60's) and have had 70* weather and 95 with 100% humidity, ive been going to the track for a long time, i know when its good and bad, but thanks for the help,


Im gonna change a couple things in the tune
move the limiter up to 7000 (from 6500)
shift at 6700-6800 (from 6300)
and get a 52mm tb


Should net some gains...we shall see, plus im just waiting to put a few more miles on the motor... so i can put the nitrous kit on it.


Andy

sleepy_z28

Hey Andy, it's Will. Were you ever able to verify whether or not you were tapping the rev limmiter? And what about just having the stock TB ported out to 52mm, or are people having problems with the TB port jobs? I really haven't talked to anyone who has ported out the stock TB so I don't know. Just a thought.

LT1 ANDY

No, Randy's adament (if thats spelled right) it was jus getting into the limiter (whatever). and adjusting the limiter right now is much easier than putting an opti or coil on at this point. Plus if it is missing it will be eaiser to tell if it misses for 300-500 RPM rather than 100 (cause of the higher shiftpoint the miss maybe more pronounced) If i buy a TB, it will be a ported stock TB, i got a price of 130 from some people/place that do it in KY.


Thanks


Andy
(edit: plus i have an extra stock throttle body laying around)