i just finished my t5 swap in my 85 iroc z. the thing performs amazing.even in first if i start going then stump the gas it burns rubber, chirps when i slam into second. so what am i missing then. i don't plan on running drag radials. i kknow i'd shred my t5 then.

 

well what size motor .I have a 1984 z with 273s in the rear with a t5trans and a cammed 305 and i go's good but takes a while to make it to the next bust of power in the next gear

 

305 tpi with thermo-master chip, complete accel ignition system, screens cut off maf sensor, bottoms cut out air box, regular filters. poly,:trans mount, torsion bar , crossmeber bushing. headers but to regular exhaust.

 

For a car that sees more highway use than anything else 2.73s are fine,any gears lower than that gives you better acceleration,that's why most prefer lower gears.

 

well whats the difference between 3.08's and 3.23's? and an 84 z with 273's? i didnt think z's came with those, i thought they came with like 3.23's?

 

2.73 gears are fine, but the fact remains they are not performance gears. I ran 13.8 with my 2.77's and could smoke the tires no problem. I upgraded to 3.45's and I run 13.5's all day long with a best of 13.3 at 100. I can now completely destroy the tires if I wanted to. BIG difference between 2.77 gears and 3.45's. Since you have a 5-speed you could even give 3.73's a go.

 

2.73, 3.08, 3.23, 3.42, 3.73 are 10 bolt gears
2.77,3.27,3.45,3.70 are 9 bolt

Not sure if that is what your looking for?

 

If you think 2.77s are good enough then 3.73s will shock you. There is nothing "wrong" with econo gear ratios, except that you WILL get better acceleration, up to a point, w/ steeper gears.

Just because you can spin the tires does not mean you have the optimum gear ratio.

 

2.77's are not bad on a TPI car because the engine makes so much low end torque and the 700r4 has a very low first gear, but they SUCK on a TBI 5 speed car for performance.

 

the tbi t5 has a lower first gear (like a ford t5)than a tpi t5
look it up
a tbi and tpi 305 third gen no mods will be a dead heat in a race

 

True but 2.7X gears dont help much with only 170 horsepower and 255 lb ft??

 

I've gone from 3.73 down to 3.23 and noticed a substantial difference, and I'm sure the 2.73 I'll be putting in the car in the next few weeks will suck even more lol.

 

i originally had a 91 rs 305 tbi (now a 406 carbed)
it had 3.08 gears i could race almost any tpi car neck and neck

 

Hows the Camaro?

-- Joe

 

Why are you doing that? To save gas or something lol

 

Me? It's fine. I haven't driven it in probably a year. After converting the HSR'd 327 to aftermarket heads and roller cam, I found some rear subframe rot that has me concerned. I have donor parts but have not found the time or motivation to start cutting and welding. Its pretty minor for a 2nd gen but its going to be time consuming nonetheless

 

Oh. So you really have not got a chance to beat on the converter huh?

I ended up with a ZF6.

-- Joe

 

Maybe I am reading this wrong but a tbi car is a low 16 second car stock. An L98 is usually a mid 14 second car, and the 89-92 LB9 5 speed w/g92 packages were high 14's How could you be neck and neck?

 

im just sayin ive done it
i dont EVER see a high 14 outa stock cars either

tell me there is a 1 to 1.5 second difference between a 305 tpi and 305 tbi
torque values very close
only low rpm motors to boot

id say ur off ur rocker
170 hp vs 220 hp= all im sayin is gearing here will make a difference!!!!!!!!!!!!!

 

50-75 horsepower is a HUGE difference. Just look at the specs below. A 1990 L98Iroc Z ran 14.4 bone stock with 3.23's [Motor Trend]. The LB9 ran 14.7. I have never seen a stock TBI run under 16.0 stock. While at the track I saw one run consistant 16.4's. Bottom line is no stock TBI should be able to hang with a good running L98 or 5-speed LB9.

90 RS
Firebird M5,A4 LO3 V8 9.3:1 5.0 (305) 170@4000 255@2400 TBI 3.08 ---- 2.73 ----
90 IROC-Z

90 IROC-Z
Formula
Trans Am M5 LB9 V8 9.3:1 5.0 (305) 230@4400 300@3200 TPI ---- 3.42 ---- ----
90 IROC-Z
Formula
Trans Am
GTA A4 L98 V8 9.7:1 5.7 (350) 245@4400 345@3200 TPI ---- ---- ---- 3.23

 

At that low power level, the difference between a tbi and tpi car is roughly 25%!! That is huge

 

I hit a 15.7 with a mostly stock L03/700-r4 car and felt pretty good about it. I had a friend with a same year LB9/700-r4 car that could hit 14.8s-15.0s all day with similar mods. Both cars had computer tuning and exhaust, that's about it. In factory form, the TPI motors are better, don't know how else to put it.

The 5 speed TPI cars with the better cam and the L98 cars had between a 45-60 hp advantage depending on model year, and the L98 has almost 100 lb-ft more torque. There's plenty of people on here running low 14s and high 13s with minor mods on cars with those drivetrains.

Are we really off our rocker?

You can touch low 15s with a L03/5 speed setup, but that's really closer to the LB9/auto cars, not the LB9/5 speed cars.

 

15.7 is about where id expect a very lightly modded L03 to be. Seems like a better engine to compare the L03 to would be the LG4 motor. The LB9 is a step up, and the L98 is just no comparision. I owned an LG4 car. Trust me, they are dogs. Ive seen a 1992 L98 run 14.2 at 98 bone stock. NO stock L03/LG4 could touch that.

 

Yeah, I'm agreeing with you.

 

I keep breaking them, and I never end up finding a 'matching' rear to replace what I broke, its always one or two 'sizes' smaller lol... oh well, maybe upgrade to a 12-bolt later and call it good ... it should be soon, I'm running out of gear ratios to try!

 

Yeah I know.

Wasnt trying to dis the L03/LG4, just telling it like it is. I know there are many LS1's that will tool on my car.


Air_Adam- I wouldnt keep getting higher gears. I think new 12 bolts go for around 2,500, kind of steep. If you cant afford that you can always call the junk yards, or look in the TGO parts section. I found a 9 bolt 3.45 rear on craigs list for 200 bucks in mint condition... Maybe this time you could give 4.11's a go. Get some nasty low end.

 

No offense taken. I was talking about an L03 Camaro I used to have, not my current car. The 310 in my Cutlass used to be a truck equivalent of an LG4 (it was swapped in) but it now has Heads/cam/intake and forged internals, all the goodies. I won't speak too boldly till I get to the track, but I would imagine I could handle an L98.

To defend my sanity, I didn't personally build the 305. I just bought it from some guy who did (for $400) after his car burned to the ground.

 

I had a '91 RS LO3 auto 2.73 with exhaust,chip, open element air cleaner and some advanced timing and I would easily pull my friends low mileage IROC with a 305 TPI in it, However one of my other friends had a '84 Z28 with the 305 H.O. t-5 and that car was wicked fast, it was bone stock and would run its best with a lot of cars, I remember him beating a IROC with a 350 tpi auto in it, it was a close race but he got him along with plenty if 5.0 Mustains, I just chalked this up to be one of those factory "mystery" cars that was just faster than its siblings. As far as gears go I swithced from a 2.73 to a 3.42 and it was a night and day difference!

 

A stock 83-86 HO L69 has 190 hp and runs 15.5's at around 90 mph. Sorry but that isnt going to match L98's or 5.0 mustangs. BUT, I am not saying I dont believe you. Anything can happen on the street. A good driver can make all the difference. I am just stating the facts above and I provided information to back up everything I said. I have beaten LS1 cars before, but for all I know the car could have been out of tune, or had someone driving who couldnt drive stick. We are also talking about 20+ year old cars, so yes I believe a 305 L03 or L69 car COULD take a 350 L98 or 5.0 GT/LX car. However if both cars are running properly the L03 or L69 wont have a snow ***** chance in hell.

 

15s is wicked fast?? hrmm..

I got my friends GTA in the high 13s with tuning, headers + exhaust. It's still a slow turd though. (13.80ish).

-- Joe

 

I know man. These noobs are killing me.

 

I'd buy a 12-bolt right now if I wasn't going to be a broke schoolboy in September so it will have to wait untill next summer I guess. I don't drive the '83 much anymore, mostly only on race days and cruise nights. The times I do drive the car, I am pretty hard on it, so I'll continue to go through rear ends like the fat guy at the dessert bar untill I get something strong enough to hold up to what I do to the car, like a 12-bolt or a 9" or something. I'll get a good gear ratio when I get a good rear end, like something between 3.70 and 4.11, depending on which rear I go with. Probably something like a 3.70 or 3.73 would be good for me.

 

I agree with you an the driver playing a huge roll. I knew a guy with a 30th anniversary Trans Am 6speed with 411's and on the bottle who at best could pull low 14's. I retract my "wicked fast", I was just refering to what the car was and how it ran for what it was simply amazed me, and for the most part annoyed me.

 

when i had tbi and 2.73 gears the best i could get was 16.4 @ 84
i put 3.23s and get 16.1 @ 81 but i also spun on take off with the 3.23s

the 2.73 open chould spin the "right rear tire for blocks" and never could chirp the tires hitting 2nd and was much slower overall driving

but the 3.23 with posi i could only spin them off the line but only for about 5 feet they would hook then a chirp from 1-2 shift

then i put Tpi on and i can roast the tires all of 1st and it kicks out sideways on the 1-2 shift
with tbi and the 3.23s i could only run with poorly running or out of tune tpi cars but could easily smoke crossfire and lg4 cars i took l69 cars off the line but they had me after i hit 2nd

oh and btw Tbi Came with a 2.73 open rear
do a burn out and you will only see 1 tire mark

 

plzzz.......stock Lo3 auto low 16<stock auto 305 tpi car mid 15