i have an 85 trans am with a 305 that is basically stock except for a ported plentum and i ran a 15.1 at 90mph. but i want to go faster so im going to put on some aluminum heads a bigger cam full exhaust and a cold air intake. i was wondering what my times will be with this set up and if u have any other ideas for me i would like to hear them my goal is to hit high 13s then im going to superchage it and hope for 12s is this possible

 

Not with a 305 TPI. Your dreaming with those times. Mayby with a highly modified one.

 

A best of 15.1 @ 90... hmmm.
Well, lets assume this is your damn best time and you cant go any faster than this right now.

I'd say with cold air 2 tenths, but its got to be good cold air - you gotta put the effort in, maybe do the ram thru the fog light nostril.

Full exhaust - this is good. If you mean headers with a cat-back I'd say another 3 tenths. (A similar 305 gained 2 tenths in chevy hi tech with JUST a catback, and then maintained its best time in altitude 1600 feet more on the next track run with headers)

Aluminum heads (L98?) and a better cam - these are your money makers (not to mention money takers) =D - and In all my guessing splendor I'd guess another 3 tenths.

These are all guesses, and im trying to be reserved here. I have no idea how well your car is running, if it has any tranny problems etc. But for the most part i think these are fair estimates. And if I am anywhere close to right - you'll be running a 14.2 - 14.4.

Superchargers are expensivo dude... I would nill the blower and get myself a transgo shift kit with a torque converter (half the price of a blower and very substantial gain) Youd have cash left for roller rockers or some other goody.


Just my two pennies.

 

Do a search for 13 sec 305 TPI, very possible especially if you are cutting 2.1 60' already. Unless you are going to do "some" amount of porting to those heads I'd probably save your money and keep the stock ones. You should be able to get high 13s from the stock heads.
I ran 96 mph with the stock cam/heads/TPI with a 3600lb race weight.

 

305's are underrated, those numbers are most definatly possible. I run a 14.4 @ 97 w/ a 2.2 60ft. Look at my sig. for mods. I don't have a cam and I don't have heads yet. Makes me wonder what I would be putting out if I did...

And don't let people tell you that you can't use corvette aluminum heads on our 305's because there for a 350 and compression blah blah blah. A certain year corvette came with 58cc L98 heads. Same cc as our 305's so they are a direct bolt on . Now if I could just remember what year they came on. I'll be getting these soon, that or Vortec heads.

if a 15.1 if the damn best time you can pull out of your car, is there anything wrong with it?

 

5SIZ, your car is also a 5-speed, which put out more than the autos. so based on tpitransam85's times i'd guess he's running an auto

 

I have a 305 TPI auto and I ran a best of 15.36 bone stock. I dont know if I am going to mod the 305 this spring on anti up for a 350 or 383. The only problem with the 305 is that the block is only a 3.74 bore while a good 305 such as the ones in mustangs use 4.00 bores, The same as the 350 TPI. I dont know why GM did such as dumb thing. Good luck with ur mods

 

willie on the history board runs 12's with that setup

 

Simple enough. 86 convertible, 87-up (to 92 I do believe) had those heads. Use a 350 gasket, for aluminum heads. The newer ones (88 up IIRC) are better.

 

I have those heads on my 305 and like them a lot.

The 'Vette had those heads until the 1992 model year when they switched over to the LT1.

 

When I first ripped my motor apart, I had a lot of choices. I wanted to stay 305 and have mucho bragging rights pulling as much horse as I could from it.

Here's some ideas to think about:

First, decide... do you wanna go mildly fast street(high 13s) or knock down the times and build a monster?

Now a cold air intake... a must. I relocated my battery, took out the tray, and made a PVC pipe custom dual K&N intake.

I considered stroking it to a 335. This would help because 305 are a bit wussy on the torque. Consider it and 13s will be no problem.

Transmission. I hadda auto. Im swapping for a stick now. I drove a friends car and g-teched it. I pulled him nearing mid 14s just from how I drive. If you know how to handle a manual, the engine will easily bring you into 13s.

Full exhaust - I got a 2¾in mid pipe and 2½in exits from a flowmaster. Mine is also Stainless steel. Dont waste the money on it... trust me. Stay Y-Pipe and remember, you will need all the low end you can get outta that motor. 2-2½in Pipes are MORE than enough for that motor. TOO good of breathing wont help you unless you are going radical on the cam and port those heads out till they look like origami(like mine... paper thin)

Aluminum heads - Well... good for heat, but not really nesscessary with a 305. Your stock heads ported and polished with a compitition valve job will be plenty fine to take you into the 13s. Bore out the block and open up them heads and intake.

I am assuming you have a TPI. Get the 52mm throttle body, and make sure the intake is lettin as much as possible in.

Get suspension upgrades. Believe it or not... suspension is just as important as the driver ability and the motor. Control arms, bushings, lift bars, d/r (if you wanna easy boost), and if you wanna get a little more radical shoot for 90/10 struts and take them damn sway bars off. All that could help ya nail off a half second easy if you know how to launch it.

I personally ended up going 350 block with my 305 heads(worked to p!ss) with the flat dish pistons pulling a nice 11:1 compression. I had mine worked pretty extensively and it shows too. I am expecting easy 12's outta my motor and am told I should hit 11's. Over 500 horse and all that suspension.. I damn well better.

Sorry its a long post but I hope I may have helped.... I remember getting ridiculed about staying 305. Trust me, with the right setup, you can pull 12's without the blower. And dont forget a chip. Learn to make them or get one from somebody. All that work wont help if the computer isn't told to push more.

Hypertech = junk

~Cory

 

They were used to the 91 model Corvette. The 92 Vette had the LT1. Mid year 86 hardtop Vettes got the heads too.

You're correct about the better heads, they are 88-up.

 

With a TPI 305 low 14s can be had with the usual bolt on stuff and some decent driving. If you have an '85 TPI from factory chances are your cam is beefier than usual check the tech data pages for the facts you might be surprised.

To make low 14s or high 13s the 305 needs help with ignition, CAI and gears. This is in addition to a cam, exhaust and TPI work. If you have an auto a torque converter is a must. I've seen quite a few 350 autos run alot slower than they should be because of poor T/Cs and a 305 will just magnify the problem.

IMHO,
RP.