my car is a 91 GTA with a 305 auto. exhaust, k&n, headers,megashifter, and some other small stuff. what do you think it would run? i had guessed a high 14 or low 15 before. but i just checked out some cars like mine on cardomain. here are some times(each time is a different car) of 91 GTAs with 305s.

16.62@83(and this was a 5-speed!!)
16.2@88(a convertable)
16.1@85(at 3500 feet..so whats that at a normal height?)
15.9@83.6

those all sound high to me?

another guy with a 91 GTA 305 with slp runners, fpr, exhaust, chip, headers, removed ac and smog ran a 14.5. rule of thumb is 10hp per .1 s. so that means he gained about 150hp from those few mods?

so wht do you think i would run. if its in the 16's(and i will find out in june/july) then i am going to be pissed/sad. help me clarify something here..there has to be something i'm missing?

 

dont get upset if u run a 16. i know i was there with my 305. if u look at the mods in my sig those have only gotten me a 15.6 at 88.88 mph so far, i gotta change things around like suspention wise to get some better times, but hey if you get a 16 it gives you a good excuse to tell you to mod your car some more.

also one major thing is get a set of sfc. this kid at work that had a 87 camaro put a set on his friends GTA and they took off .2 in the 1/4

 

That's the trouble with the 305. It was never designed for any kind of performance in mind. Sure there are a few Stock Eliminator racers who use the engine to put them into a limited class but anyone who wants to go fast easier will build a 350 or larger.

The 305's small bore and tiny heads/valves really limit the amount of power that can be produced compared to using the same aftermarket components on a 350.

Any relatively stock 305 that can get into the 14's is actually very good.

Engine size/HP isn't the only factor in how fast it will run. Most third gens are around 3500 pounds. With a massive weight reduction it's possible to get it down closer to 3000 pounds and still keep it relatively street legal. That alone will gain you another 1/2 second.

 

yea, our stock times suck, i used to run 17.4, my weight has always been pretty low (3050 w/me), but i shaved a few seconds off since then.

 

a 17.4! was that a tpi? man o man this sucks...i though the car was good for at least mid 15''s stock. ****ty. oh well, i've known since i got the car that its 305 wouldn't be there to long. anyway....i am looking for a 400SBC to build up. i should be getting SFC's soon to. i want to run low 13-high 12s when its done, and be able to use it easily on the street without ridiculously bad gas millage and stuff.

 

Estimating about 3300 pounds race ready (driver, fuel etc), you're going to need to get at least 300hp to the rear wheels to break into the 12's. A heavier car will need more hp and a lighter car will need less.

Now that's rear wheel hp. As a general rule, you're going to lose about 30% through the driveline but it's not exact. That means the engine will need to produce around 400hp at the flywheel. Since we don't race engines, rear wheel hp is all that matters.

A 3500 pound car running 16.0 is only getting 169hp to the rear wheels.

HP will also change as the weather conditions change. The amount of HP an engine produces will also decrease the higher in elevation you go. A 16 second car in Denver is actually faster than a similar 16 second car in Florida since it's running 16 seconds with less hp.

 

I think those times are crap. I ran a 16.3@82 mph completely stock in my 92 305 tbi. Your car comes with about 35 more hp or so. You should be a solid 15 second car. It has little to do with the 305 though, as you have a cam the size of a pencil and 2.73 gears probably, not to mention tpi that doesn't breath worth a crap.

 

well my car came with 2.73's but the owner before me swaped un some 3.23's...not a big change, but a change none the less. and i may look into the cam problem in the spring.

 

I had a 1991 Z-28 w/230 HP 305, 5 Speed and performance axle ratio that ran 14.8 stock. If it had an automatic, it would have had a 350 and I remember them being about as quick stock.

 

I don't want to rain on your parade but don't waste your money on the 305. if your heart is set on it then buy the best set of cylinder heads that you can afford, keep in mind that about the largest size valve you can out in there is a 1.94/1.5. This alone will give the biggest gains. But then to compliment the heads you should install flat top pistons for a better burn characteristic and better part throttle fuel economy.
you should put your money into a 350, nothing exotic. you can run a stock crank and rods, hyperutetic flat top pistons, Vortech heads, RPM intake, vacuum secondary carb, mild cam around 218*-224* at .050" and you'd be in the ball park of around 380-410 HP. if you shop wisly for used or discounted parts it could be had for $1500 or less.

 

NO NO NO...don't get the idea that i like the 305 or want to keep it. as soon as i find a 400 sbc to build, its gone!

but for the time being, like this coming summer, i will still have to rely on the old 305 on the street. and when i seen 16 sec times, i lost the confidence to challenge civics and stuff, cause some with a few mods should be able to run around 15's, and probably get beat!

 

race weight, 3600lbs.
2.73 open rear
91 TBI 305
700r4 trans

mods:
no catback. just open cat at the track
open element.
new shocks/struts (went from a 2.0 60' to a inconsistant 2.2-2.6 60')


i dont have the slips infront of me to give you exact times, but i run:

60' 2.2 - 2.6
1/8th 10.0 - 10.5 @ about 67mph.
1/4 16.0-16.5 @ 80ish mph.... to be honest i dont recall exact 1/4mph. im bad at recalling numbers.



dyno sheets are here: http://josh.swoca.net/board/mrdude/dyno/


dont worry, you arnt the only slow one here.
most people on this board wont admit it, but 95% of the thirdgens are slow... only a few people actually have them going fast, but they're the ones everyone likes to talk about. every car group is like that.... for example, you hear of the LS1 guys talk about 12sec bone stock cars, yet they never talk about the high 13 dog ones........




heh, looking in my wallet at work i just found a 1/8th mile timeslip.. not too proud of it, wasnt a good run, but here it is anyway:

tree is @ .500 btw
reaction: .692
60' 2.362
330 6.836
MPH 66.37
1320 10.541

def one of my slower runs...

 

heh, on the back of the slip is the 60 to 0 braking numbers i got from a Gtech that night....

to account for the road, they flop directions.... direction one has no star, back the other direction has a star

60 to zero braking in feet for disc/drum 16" tire 91 camaro vert.

153*
165
163*
135
155*
149
146*
138
140*
139
152*
170
138*
142*


im ruling out the 135 and 170 as a fluke and saying the avg distance is 148 ft.

 

well here's some pointers for the 305: put 1.6 ratio rockers on the intake only. use a cold air kit or the dual snorkle air cleaner from the L69 option. DO NOT use OPEN element under the hood, yes you'll gain flow but its ALL hot air. If you don't drive the car intemps colder than 40* , then pull the intake and install heat riser block off plates.
i just reread your post and was going to delete some of this but figured it could help out some other people too.
do the rocker thing and keep the air as cool as posible, even use heat reflective tape on the duct work. For every 10* drop in intake temp you gain 1% HP increase which can add up to alot real fast for a cost to power average. If you have "cheap" headers on the car take them off and wrap them with header wrap, this will do wonders for keeping under hood temps down, also wrap the y pipe just until its under the body. it also starts a scavanging effect, not alot but every little bit helps. in stall a 160* thermostat if you don't care about gas milage, the cooler stat will tell the computer to richen the mixture, or you can install a 180 stat to get the best of both worlds.
you could install a cloyes timming chain and advance the cam 4*, you will gain everywhere in the RPM range of this engine, i don't care what the DeskTop dyno says. this is worth 10-15 lbs of torque, which is what you feel when you step on the GO pedal.
install a shift kit!!!! its pretty easy but messy. get a MSD 6A box you can reuse this for the next engine. it will give a little more top end but not much where you have TPI. shift at 5200 RPMs
I saved the best for last: go to sears and buy one of those Super Duper leaf blowers and plum it into the air cleaner assembly. dont forget to buy the cigaret lighter addapter (or a very long extension cord). you'll have no way of controlling the boost level so once you turn it on hang on tight!!!!! this will make you "blow by" the ricers!
disregaurd last idea, i can't garantee the results

 

tpi is worthless IMHO, but anyway, no, my car was a carbed LG4 85 Sport Coupe with the f41 package (before it became standard)...thats all gone now though

 

if you're smart enough to keep your engine cool, a open element has no effect on your ET at the strip.

it will have a mild effect on the street though.

 

i changed to 3.73's as well. i forgot to mention that.. how much difference will that make?

 

These numbers are crap IMO (for a decent low altitude track anyway), a decent running bone stock 305 TPI auto should do no worse than a high 15, some better depending on year and such. A 91 should be pretty good as far as 305 TPI autos go, there is some evidence that they got the hotter cam. With headers and decent gears and such that you have I wouldn't be surprised at all if you hit a high 14...

 

I'd have to disagree. ANY 305TPI auto besides an 85, is gonna be slow as hell. I just sold an 85 305 TPI auto, and that was the only year that the 305tpi auto could be had with the L98 cam (I'm 99% sure but do'nt quote me on that ), other than that, only the 87 5 speed 305 tpi and 90s 5 speed 305 tpi's got the better cam. I'd say those times are about on par.

Btw ray, I haven't talked to you in YEARS man. How's it goin?

 

My 305 is really slow, only 85.5 MPH in 1/8th mile w/ Best ET of 8.07 w/1.79 60' . It is also a TH-350 w/Torsen posi and 4.10 gears. If it was not allready rebuilt and in car I would have had a 350+.

 

AIM91 on the V6 board has gotten a 15.31 out of a modded 3.1 V6. Best of 9.61 1/8 mile.

Eric

 

I have data gathered last season in back-to-back runs to the contrary.

 

Yeah the 85 Irocz were good weren't they? LoL only casue I have one.
Mine hit a 14.8@94mph with the mods in my sig. Corrected it should be in the low 14's high 13's. Pretty much all the mods Blue Thunder has except I have a cam but they have the runners.

 

I've ran a best of 15.4 with the mods in my sig. After reading some of other people's times with a 305, I'm wondering if my car still has the original engine (L69) or if I have a crappy 350. OR if the difference in elevation from their's and here in Alabama is so different that it just looks like I'm running faster. Either way, I still have to go faster. :lala:

 

check out my new website @ http://www.zerotactic.net/

you can get some good comparisons their!

also see my sig, my best is a 16.668

 

crap, forgot to show siggy, here it is

 

Well, I was going to chime in, but forgot about the differences with the '85 TPI. When I had the 305 TPI/Auto, the only thing I had was a Hooker Cat-Back, Smog Delete, and custom CAI, and ran 15.15 in the quarter, so I was thinking that you should run faster than that, but alas, only '85's got the nice cam.

 

Several people have claimed to have pulled the cams out of their 91-92 305 TPI auto cars (and 5spd non-G92 cars which are rated at the same 205hp and also supposedly had the small cam) and spec'd the cam out to indeed be the better cam. Just for what it's worth...

 

what elevation track? DAMn lol... my 86 lg4 bone stock with an open element ran a 15.8... with 273 gears...

i dunno, those sound like some high alt. times....

 

i just read my post and i made an error, i ment 15.668 not 16.668

this is at 500 feet

 

wel 15.6 is more like it... with some finess and good launch technique you could get it down to a 14.9- the reality is tho, that 305 has the peanut cam in it...

 

i know

but soon im getting my 3.73's in it, that should help some eh?

 

Well, maybe, maybe not.... it will be stronger off the line, but your gonna run out of rpm at the end of the track with a tpi setup... or out of cam with both a tbi and a tpi...

However, put those gears in, upgrade that cam, and do some nice bolt ons and you will be able to take care of them nicely with those gears...

 

well i have a TBI setup, and when i pass that finish line, im in deep third like 4500-5000 rpm, so i think the 3.73 will help me get into fourth

 

TraviZ, I don't believe a gear swap is going to help- if you go into fourth (Overdrive) it is a BIG gear ratio drop, and it takes more horsepower to pull the car.

Basically if you are at your redline in 3rd through the traps you are ideal on your gear selection for the 1/4 mile. What you need are engine mods to let it breathe and make more power (broaden the powerband)

If your engine made it's max power at say 6000 and you were at 4800 in third through the traps then going to a lower gear would help.

Eric

 

i have the manual 5 speed, not the auto 4 speed, so my fourth gear is the 1:1

and i will pull into fourth gear right before the finish line, so i still haev another full gear to go!

 

Ahh- that clears things up on my end! Yes, swap to something lower- what do you have? 3.08's?

Eric

 

yes, stock 3.08's

something lower? liek 3.42?

 

Nah, i think that you might be ok, but going not going across theline in 4th doesnt mean anything- going across the line right at the peak o fyour power band is what you want...

 

peak powerband in my 1:1 ratio (aka 4th)

 

Glad to see that there are other "slow" 305's out there.....lol
I have a 91 Trans Am with a 305/700r4/2.73's.The car is stock apart from a Dynomax Super turbo exhaust.I'm from Calgary AB and elevation here is just crazy.Apparently my time corrected would be a 15.2???

Here is my best slip to date
Weight 3416 w/o me---3556 with me

R/T... .426
60'... 2.474
330... 6.823
1/8... 10.398
MPH... 70.87
1000... 13.445
1/4... 16.014
MPH... 88.55

 

Secret Street "should" be starting up on April 14. If it does, don't expect great track conditions. Our first track day is on May 14 with a T&T and King of the hill race. I don't expect track conditions to be any better by then.

You can come and run in Street class. You don't need a fast car to win but you'll need to improve those reaction times. As the yellow lights are coming down, launch as soon as you see the last yellow light come on. Racing in brackets, anyone has a fair chance of winning. During the King of the Hill race, your 16 second car could still beat an 8 second dragster. You can even win a trophy plus cash if you make it into the final round. All you get from the Friday night Secret Street race is a timeslip.

I haven't been checking our density altitude lately but during the heat of the summer, it doesn't get below 5000 feet during the day very often.

 

Thanks for all those tips Steven, I appreciate it.
I also need to work on my 60' times as well lol!
I've only been down the track about 20 times or so and my best 60' was 2.444 and my worst was 2.566(spin spin spin)
I bet a gear swap would improve that.I just may go with 3.42's.

I'll be sure to look for your car this year...and you look for mine.Be nice to introduce ourselves!