How much horsepower and or torque does it require for a 3rd gen to run a high 13 in the quarter mile. Im looking for a general answer because obviously there are many factors.

Basically whats the least you could get by with a 13 in 1/4 with an automatic transmission? With some good Gears if you must

 

I would guess probably about 300 horsepower or so. And maybe 3.55 gears with an auto would be a good choice.

 

not about the power its about mostly the performance of your vehicle. my buddys 01 gt with 97 markv swap pushes just 287 rwhp and runs high 12s all motor

 

Thats why i was asking in general... for the 3rd gen what power am i looking to put out in order to run 13s w/ a small block if i must say that and without having a bunch of weight mods. Stock Weight w/ gears auto tranny and v8 what am i looking at. 300 sounds like what i was looking for .

is that gt auto or stick?

 

I bet right around 285-290 horses can put a thirdgen into the high 13's.

 

L98 350 with headers/catback/air intake mods and mild converter should do it on street tires alone regardless of gear. I went 13.89 on street tires with 2800 stall and those exhaust mods with 2.77 gear. Iroc with full leather/power everything interior. No weight reduction.

With few more bolt ons, 254whp and slicks, i went high 12's.

venture to say a stock L98 in good condition with slicks/3.23 or better gears/2500-2800 stall or better will go high 13's, thats 220's whp.

NOTE: assuming sealevel to 2500 ft density altitude. My times above were at 1200 ft altitude in various weather conditions with DA ranging from 188 ft to over 2500 ft. 12's with the lower DA, 13.89 was in summer air with DA in the 2500-3000 range.

 

Probably 260hp would be plenty. Stall and tires, and you might hit that with stock numbers.

I had a couple of friends that had 87 and 88 5.7 IROC's. Both ran 14.3 and 14.2 when they were bone stock back when they were both new. That was when the Gatorbacks still had bite as they were still new. Drag radials and a stall would have put them in the 13's for sure.

 

well to give u an idea of what i have that im putting in my car to compare.

l98 with 58mm throttle body, ported plenum, slp runners , ported stock intake, stock heads with 1.5 rockers, msd wires and coil, 1 5/8 inch edelbrock headers, 3 inch exhaust and 342 gears , rebuilt tranny with 2400 stall, ls1 drveshaft and some suspension stuff ( LCA's and brackets, panhard rod)

I figured in going to get 275ish or so from the motor with decent traction.

I better hit mid 13's with this setup in a 91 RS for sure. one thing to consider as well is the weight factor. the lighter u make your car the less power u need to get into he 13s. easy stuff to do in getting rid of ac and egr crap for sure.

 

Mods in the sig, I'm basically running LS1 times at the track. Probably right around 330ish flywheel hp... I'm going to guess. I ran a 13.5@ 105 last time i was at the track. And that's rolling into the clutch and on street tires.(with a bog out of the hole also) lol i can't launch the car.... but i weighed my car in at 3680lbs with me in her.

I know she's got a lot more in her, i need DR's, better rear gears, and tuning. Yea i think the timing is close(not familiar with carbs).... Then after the gears and DR's i'll need a 9 or 12 bolt also... haha

 

Check out the latest issue of Super Chevy. They build up an LG4 roller block, from 170 hp to 360 hp. Trick flow heads for 305, long-tube headers, 1.5 roller rockers, mild street cam (around .425-.450 range, heads had a max lift of .540), aluminum riser intake w/ Holley 750 carb (600-650 would work just fine). Given it wasn't run with accessories and an electric water pump on the engine dyno. All for around $2,000 (heads are around $1,200). That's around $10 per hp.

They will be making a tech article for TBI soon. So don't toss out your 305 yet. They have plenty of potential many people over look.

 

287 whp is close to 360 hp at the crank. That's LS1 category. It better run 12s. Power and putting the power to the ground is the performance of the vehicle + the driver mod.

 

Magazine is Super Chevy not GMHT. My bad

 

With a full tune up, optimum gears, nice stall, drag radials, and you'll be there with stock hp.

 

not when you are starting out with a 305 tbi! first of all you dont have enough rpm range. plus by the time u built up a 305 you can have a 350 for about the same.

when i had my 305 tbi with 323's 2400 stall and lcas aftermarket intake and headers the best i got on a hot day was in the high 15's with decent 60ft times.

 

I run a 14.2@96 in the 1/4 with 235 WHP and 318 WTQ. That's with 3.23 gears, street tires and getting lose off the starting line for about 10 ft. too.

 

the speed is there u prob just need better 60 ft times...

 

Roughly 280hp at the crank.

I run 13.5 @ 102, with my race weight the car is estimated to make 330hp at the crank. Mods are in sig.

But I got something you may want thats even better.

A excel spread sheet that can do both. Its a sheet that can estimate HP from ET and Trap speed, as well as trap speed and ET from known HP and weight variables.

http://home.comcast.net/~thirdgen89g..._formulas.xlsx

Need Office 2007 viewers installed, Office 2007, or OpenOffice 3 to view the sheet.

 

Agreed. I need to adjust my tire pressures down some in the rear and work on my launch. My best 60' time was 2.05 and I know I should be able to hit a 1.9 at the least.
I should be in the 13's a little easier pretty soon anyway once I install my headers and Y pipe, delete my cats and AIR pump, and get my chip retuned.

 

Headers will make a huge difference in these cars no matter the engine. i would invest in some better lower control arms prob about 100 dollars and those will greatly help with traction..

 

I will look into those down the road as money allows, but my first big chassis mod is going to be SFC's I think before I move onto anything else chassis wise.
Thanks for the suggestion.

 

My old l98 when it had 240wrh it ran 13.9 with 2.77 gears. Got much better times when I threw in the 3.45's with a set of radials.

 

I think a well maintained L98 should be able to pull off high 13's with a few bolt ons. We've got an 92 Z28 L98/Auto with just headers, exhaust, intake, and 275's running 8.9 in the 1/8th mile with a crappy 60ft , which is high 13's in the 1/4.

 

Is the OP wanting to hit 13s, or are you just asking a general question to get different build ideas?

Are you sticking with your 305? Or getting a different 3rd gen/motor?


I plan on making my Firebird hit the 12.xxs. So this thread will help me some.

 

i think hes generally looking to hit the 13's and was looking for some power estimates personally. the best i can recommend is to get your ideas thru some basic engine software so you know what to expect. The other thing to consider is the type of fuel injection you are running. I had tbi and its great but TPI supplies the fuel so much better and evenly that i would be curios to see what that swap alone does on a dyno.


i can def say that it will cost less to build a 350 no matter the injection to get to the 13's.. a stock l98 auto TPI as started with a few mods should def be a high13 low 14s for sure pretty much no matter the driver. ALso for tbi the biggest problem is the heads. boy do they suck!

there is no replacement for displacement!!!

 

The Weight of my car is a little under 3400lbs. I hit 14.2@96mph last week with 206WHP and 286WTQ, with quite a bit of spin at first. What helped me was definitely the tranny rebuild. I just replaced my bald tires with Firestone Firehawk Indy 500 Wide Oval Tires so that should put me in the high 13's I hope!