TheTech91RS

Just out of curiosity, why don't you just do a M/T swap? Lighter, more acurate "If you know how to drive".....

And also, did you ever stop to think it might be the way your pushing the car, and not just the setup? Good launches etc. (Im not trying to critizize you at all)

Im the proud owner of a 83 Z28, hard top, 4BBL, 5spd. 305 (Yes nothing super special but i want to build it for fun)

Im currently in the process of putting Holley flowtech's equal headers, and this is a question i have for everyone here, IS there a possible way to make it a true dual exaust? Is there enough room under the car to push 2 pipes side by side? Im totally against the single side exaust =D WHERES THE REAL POWER? And shame on chevy for the horrible design IMO.

The headers im putting on, already require to me to modify the stock Y pipe, so if theres a better way to pull some power out of this thirdgen, let me know!

roughskinjrz

i had true dual exhaust. i used hedman long tubes, s-bends, summit h-pipe, 2 moroso spiral mufflers, and turn downs.

cubemaniac

Got a pass out of it today, couldn't get in anymore cause apparently I have an oil leak somewhere. Only changes are instead of that 670 now I have an 800DP. I also had a pro comp distributor to go with it, but that burnt up with less than an hour on it. I'll have to see what kind of warranties it has.

Reaction: .315
60 foot: 2.251
330: 6.185
1/8: 9.329
1000: 11.994
1/4: 14.257
MPH: 99.44

cubemaniac

Could the low gear be hurting me much?

86 IROC

iTrader: (3)

What is the rest of your combination? What do you run for tires? Also, what track do you run at? Do you know the altitude? Too many factors involved and not enough info.

IMO - yes, the 4.56's are a bit much. I would go with a 28" tall tire if you aren't running that size already. As everyone else has stated, your car seems down on power, but it is definately lacking in the launch department.

mcbchild

iTrader: (1)

EvilCartman, what bunch of little changes did you make to get your max power output to the ground? This is what people are really looking to get answers on. I am in the same boat with only running low 13s at 105 mph. Can see my details in my sig.

cronsformula350

I think you should do lower control arm relocators, lower control arms and a panhard bar, maybe some drag shocks. But I didn't do any rear suspension to my 87 iroc with 156K miles on it, and I was at a 13.81 at 99 mph with nitto drag radials, then when I had the rear suspension, after two runs, I broke the transmissions 3-4 clutch pack, with street tires. Check out what I did, and you'll be surprised what a little know how and experience do.

www.cardomain.com/ride/471099/8

EvilCartman

iTrader: (1)

Lets see... stepped up from the edelbrock shorties and single 3" exhaust to 1 3/4" hooker long tubes with dual 3 inch. Went from a 3500 stall to a 4000 stall converter. Switched to weld pro-stars all around. 28x9 Hoosier slick instead of some old crusty quick time pros and Moroso DS2 front runners. Switched from a 750 Speed Demon to a 850 Mighty Demon and then quicky back down to a 750 Mighty Demon, still tuning on it. Relocation brackets for the lower control arms, also boxed them. Subframe connectors, polly bushings in the rear control arms made a difference in the feel of the car. No front swaybar, rear one is still used. Haven't weighed the car yet but I'm guessing it's still around the 3500 mark with me in it. No A/C or heater box, hardly anything left behind the dash. Used to have lower compression but bumped it up to 10.5:1.

Think that's the bigger changes I've made since first running this engine in the car and turning mid 13's.

cronsformula350

That dual 3" exhaust is way over kill, your losing hp and torque through it, and its too loud, my dads 68 GTO is making 650 hp on the dyno, and he has 3" duals. Also what are you turning your motor to? Because a 750 is still a little big, a 850 is good for a motor making a tad over 800 hp. You should go back to that 650 you had. Your car should be around 3000 lbs, my iroc with a full interior, and a few missing parts under the hood, weighed in at 2940 with a half a tank of gas.

Codename 47

iTrader: (4)

I agree. Everyone here was blurting out "jump to the 750". Carb has nothing to do with this problem. Someone said it before, but the motor should still run 12s even with the 670. I think you'd be best with a 700 DP. 800 is too big. It's just a mild 350.

Greg

EvilCartman

iTrader: (1)

IMO It's not way overkill and I seem to be doing just fine. A friends car went from dual 2 1/2 to dual 3, guess what, it went quicker. 750 is running great, plugs look good and it drives great. I shift right around 6900-7000 rpm, any more than that and it'll start to die off. I have never had a 650 on this motor and don't plan on it. Not about to spend more money on something people said," Oh it'll work better with that!" Screw that. I've got a brand new 550 dollar paperweight sitting on the shelf from the last time I tried listening to others. Others that have been messing with cars a lot longer than me.

cronsformula350

Thats fine what you think is correct or isn't. I didn' tell you to buy a 650, your the fool that made that mistake, but you also didn't mention whether the car is more a street car or not, a 650 is better for street use, and you didn't mention before u were shifting at 7grand! At that point a 750 is probably about just right. But theres big blocks pushing over 550hp and run great with 2.5" duals, 3" is more for a top end, 600+ hp motor, if you only drop .1 or .2 from your times, and its mostly a street car, I'd stick with the 2.5" duals, because its torque, and area under the curve that your driving with. DO you drive with your foot in the gas all the time? Then you could use your 3" exhaust.

cubemaniac

squeeezer

i have a 91 camaro
and an 84 trans am
my 84 t/a is my budget racer

im sure you will find some sililarities with my t/a
it has only a 355
i have gmpp fastburn heads light cleanup on the bowls and shortside
xe 288 hydraulic roller cam
its only 9.77 to 1 comp
profesional products hurricane intake a holley 750 dbl pump modded by me
factory hei with msd ign module
long tube hooker super comps=homemade mufflers 12" long i take off at the track
my motor on the dyno made 452 h.p @6100 rpm and 430 tq @4800 rpm
nothing fancy here
i also have a 700r4
a cheapie dayco advertised2700 to 3200 rpm stall
tci full manual valve body with corvette2-4 servo
stock rear end outa my 91 i added 3.73 gears and a locker
micky tompson 26'' tall et streets

i ran a 12.29@112 mph
ive never raced in less than 90 degree heat and heavy humidity
running out of fuel pressure at the top of the track down to 3 psi (im currently fixing that cause i have a 125 shot ready to go)
from my trap speed i may se high high 11's with this package
suspension wise i have
welded frame ties
8pt cage
lca's
relocation brackets
air bag @right rear
panhard bar

just added and not yet tested

90/10 front struts
moroso front trick springs
50/50 rear shocks

i wana get a adjustable torque arm soon

my best 60 foot is only a 1.77 1.8 is typical for me
id like to see 1.6's
anyway enough about me

pm me if you want actual help
im not much into pissing contests like some people

cronsformula350

whats a pissing contest? Lmao

327_TPI_77_Maro

iTrader: (8)

Something is extremely wrong. A STOCK TPI 350 will run your time. The fact that you are mph'ing slower than a stock TPI car tells you you are not making any HP.You need to get back to basics w/ your combo. A holley 750 might run 1 or 2 tenths faster than an eddy but there is no excuse for the performance you are seeing, that is simply not quite optimal parts. Is the car cutting out or does it seem to run okay, just really soft on power?

cubemaniac

Everyone that hears it says it sounds good. I've even had some older guys tell me it sounds about right. And it runs great just doesn't seem like the power is there.

cronsformula350

This is just a 355 right? Over carbing, can take 30 or more hp off your motor, make it lazy and not come alive at all + having bigger headers than you may need, and a too large of exhaust, that all hurts the motor, its the area under the curve that makes a street car powerful, not all top end!

Thats also like, putting a huge cam in a motor that doesn't need it, that used to happen all the time in the '60s, so maybe you should reconsult someone else if you don't want to listen to anyone here. I'll get my formula in the 12's with a stock cam, you'll see next year, just wait.

Go to my site, www.cardomain.com/id/cronsformula and check out the videos of my dads GTO and my formula.

Codename 47

iTrader: (4)

Is the motor timed correctly? What is the timing?

Have you gotten a stall converter yet?

squeeezer

is it getting too much fuel????
not enough fuel?????
both jet wise and pump wise????

Batass

Something is still terribly wrong. Sound isn't reliable. I had a healthy sounding 305 but it only made like 180hp. Combined with a poor transmission, it was real doggy. 15 psi of boost was another story.

Who put the motor together? Did you check the plugs after WOT shutdown?

Et has almost an infinite number of variables, but mph is usually pretty consistent from a poor et to a good one. Mph is basically all power and correct rpms.

I don't think you ever answered the transmission question, whats your rpm crossing the traps?

cubemaniac

Its a 383 not a 355. The timing is set to 32 degrees@3000rpm. The car is at about 4800rpm through the finish line. Haven't checked the plugs after a WOT shutdown and the engine was put together by someone who knows what they're doing, and me.

Batass

Is that in fourth gear? So the cam was degreed? Could you maybe post a video of your car launching?

cronsformula350

ok, 3" duals on a 383 is over kill unless your making over 550hp, you'll lose torque and hp, because like I said, its the area under the curve that makes the difference. There is a ton of 5hundred cube big blocks running 2 1/2" duals, and a lot of nasty motors running smaller exhaust, with one single 3" pipe, good for up to 450hp, or even a single 4" mufflex setup. Also, your converter may be too loose, you may not be launching it right. You should be running closer to 34-36* of timing and you should make sure your throttle is opening fully, people overlook the small things, that make a huge difference.
You may also be shifting way too high in the RPM causing valve float, try shifting at 5500 rpm, your motor might not be making power that high in the r's as you think, shifting too high.

cubemaniac

It was a while ago when I went racing but I'm pretty sure it was only 3rd gear. I've been shifting it at 6000rpm.

Codename 47

iTrader: (4)

I'd go throw the car on a dyno and get it tuned. There's not much we can really do for you. It appears that the car should be running correctly?