I have an 87 Z with a TPI 305, 700R4,2.73 posi. Only mods so far are full MSD and a 125 wet kit.I have limited track time and the best so far was an 8.95 @86.14. I need help to get that down to a mid 7.

 

well, your mph is there for some 7.8's or so. there are two possible reasons why you're not already there. either the car is bogging due to a tight stock converter and highway/gas mileage gears, or the car is spinning the **** off the tires. what is your 60' times?

here's what i'd do if i were you:

SUSPENSION!
-rear lca relocation brackets, lca's set on lowest hole
-a set of 275/50/15 mt et street radials on a 15x10 wheel. if you wanna stick with the 16" wheel, a 255/50/16 will work nearly as well, but the larger sidewall of the 15" tire will help absorb some drivetrain shock. both are 26" in diameter
-subframe connectors if you don't already have them.
-a set of 3.73's
-2800-3200 stall speed converter. get a good one too, not some junk TCI or B&M. i'd give my money to someone like EDGE, Yank, Fuddle, ATI, BTE, or the like. i've run the ATI converter in my 700r4 and that thing is bad.
-headers and full exhaust, along with all the other bolt ons you can think of won't hurt, but since nitrous is the key power adder, i suppose once you optimize the rest of the car, then you can start adding even more power.

 

my 60' is 2.21. i think it is gear and converter. I would like to get on the jug sooner, it takes too long to get to 3500 rpm. I love the way the lil 305 runs,I just want more. Also what about intake and cam to get more useable rpm?

 

i understand, lol! definitely do the suspension stuff i said though as well as converter/gear. cause once you add the converter/gear, traction will be a major issue.

my 305 runs 7.9's n/a, and i'd like to hone that down to about a 7.5

 

Yea the quest for speed is never ending. Thank you for your help.I have a set of 17x9's to put on, go dr's on them of stay w/ 15".

thanks, Jason

 

put the dr's on some 15's. the 17" wheels don't allow a large enough sidewall to absorb the shock of a good launch. and when you do buy tires, get the mickey thompson ET Street Radials.

 

3200-3600ish converter and some 26x11.5x16 et streets. or 15s if you are running those.
i think those 2 mods will make the biggest difference.

 

if you're going to the track and have a set of track only rims then get some hoosier slicks or the ET drags, if your suspension isn't setup properly the drag radials are just going to spin and spin. You'll be happier with the slicks and I agree with diggler too

 

I dont mind track only wheels. Only thing is can I use my 15x7's? And why so high on the converter? It is a TPI car with no top end.

 

Being a TPI...

Suspension/Wheel & tire mods Matt and others have suggested
3.42 gears
2600-2800 Stall (being 305)

 

you want stall speed to be at peak torque production, so I'd imagine 2800-3200 to be close on a tpi engine. Only a dyno sheet would know for sure.

 

True say. Brain fart on my part.

 

i said 3.73's instead because of the 1/8mile racing. if he's wanting low 7's out of a small motor like that, even with n2o, he's gonna need a car setup for it.

 

Not use to the whole 1/8th thing. Makes sense though. Whatever.

 

prob. right on that, i was thinking LT1 cars when i said 3200-3600.
i do know you can HAUL in a juiced LS1 car with a converter and 2.73's. with 17" dr's, a buddy of mine ran 7.10's with a 150 shot. full weight.

 

I’m curious, why do you NEED low 7’s?

In a pinch you could get a 275/60 or 28x9 drag tire on a stock 15x7, not perfect but it will work and it’s enough to run the time (my brother runs about that on a 26x9 on 15x8). You’ll need one healthy 305 build up to go that fast with a 150 shot, I’d probably instead go with some careful tuning, either a progressive controller or 2 stages with a 200 or 250hp total shot.

 

Not tryig to threadjack but my next motor combo should make peak tq at 5000rpms. Does that mean I should have a 5000 stall converter?

 

i know full well that a 235/60/15 mt drag radial will fit on a 15x7 wheel with no issues and still stick you to the ground with the suspension setup like i said. a 26x8.5 slick will work as well. they just aren't that wide or menacing looking. i'm a huge advocate for the drag radial, you can ask xpndbl3 or any of the other guys, that's why i suggested them. but i suppose that if all you wanted was cheap and fast, a drag slick will do everything you want it to...but saying you did it on "radials" is just cool.
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possibly. you really need to call a reputable converter company and have them build on for you if your talking about building a serious performer though.

 

Well I dont plan on racing it 100% of the time but it should put out some good numbers.



Some DR's will help tremendously. I'm following a very similar setup for suspension as mw66nova. Almost exactly to be honest.

 

if it makes it at 2000 rpms or 5000 rpms, that's what you want the stall at. Now it gets more technical when the converter flashes a little higher then settles back down and that's where the $$$$ converters come into play. Coan, vig, etc.

 

Ahh ok thank you for clarifiying that. No clue on what converter I'm going with or even the tranny at the moment but the motor is supposed to get 635flywheel HP @6500rpm and 580lb/tq @ 5000 rpm

 

what size motor is this? thats pretty stout at just 6500rpms...

 

[quote=83 Crossfire TA;3584084]I’m curious, why do you NEED low 7’s?

the simple answer is everyone says i can't. And the guy i got the car from spent 3600 on the 305 20k miles ago. it seams dumb to just take it out.

 

It's a 406 with forged internals, 13:1 compression, AFR 210cc heads, Lunati cam #60133, Vic jr. intake and a 750hp series carb.

 

I have ran 7.50s with my old 305 with 160shot. It had ported s/r torquer heads, 1.6 rr, lpe 211 cam, tpis big mouth base, edelbrock runners, vigilante converter, 3.73 gear, lcar's, 275/60,15 MT drs. The car was heavy over 3600 with driver. You will need to spray it right out of the hole. I was getting mid 1.5 60's with a best of 1.53 If I would have got into the tuning I t could have gone faster.