I just purchased a 85 vert. I have about $1500 and I was wondering what would be the best mods, most cost-effective, for my car. I should tell you right now I am definitly a novice with cars. I am currently looking into exhaust/header systems and maybe gearing in the rear. What I know now, is that I only plan on the exhaust work, the gears, and maybe a camshaft. What header and exhaust sizes would be best? and what gearing would be best for a daily driver, but still have more kick at the track? Any help is great


[Modified by 1985vette, 4:05 PM 8/18/2003]

 

Automatic or stick? A full exhaust will help her out a lot. If its an automatic the combination of exhaust and a new torque convertor REALLY livens up L98s.

 

They made a convertable in 1985???????? :eek:

 

No, but there were companies that would convert them for a price.

 

That makes it a TRUE convertible. :cool:

 

Hmmmmmmm I have a sawzall.....two good batteries......... :smash:

 

Oh by the way: From one Stephen to Another.....Welcome to the Forum :party:

 

Welcome to the Forum and congrats on your new Vette.

Indeed you will get good gain from exhaust mods. Since you live in Smog **** country, foreget about LT headers; instead just port your stock shortie headers. Then gut the two pre-cats (if '85 Vettes had them), install a hi-flow Catco (Summit Racing) cat and finish off exhaust with some hi-flow mufflers. You should be able to bring these in for around $500-$700.

Install a 160 deg stat & fan switch to reduce engine coolant temps, install the TB bypass to lower intake temps and install an SLP ram-air setup to bring in cool intake air. These should run about $200.

As Scorp mentioned, if you have an A4 tranny, install a TransGo shift kit for nice firm shifts. You already have a 2,000rpm TC, so I would stay with that for mostly street use and mild engine mods.

A March Power & Amp underdrive pulley set will free up a few HP too. Cost is about $160.

Consider upgrading the ignition system with a HyperTech coil/cap/rotor, TPIS wires and cut-back (see my site) AC Delco plugs for a HP gain. Cost is under $200.

A nice flat-tappet cam with 1.6:1 full roller rockers will add some good power; since the heads have to come off for the RRs, pocket port the heads at that time. Since these two mods go well together and will cost some bigger $$, you may want to do them later.

Enjoy your new Vette and save the wave.

(Oops, sorry but I foregot about the AFPR and fuel pressure gauge to dial in more fuel with air flow increases).


[Modified by 65Z01, 1:12 PM 8/18/2003]

 

Welcome to the forum. I too have an '85 so ... 'Hi' :D

You have to find out what gearing you have first of all. Do you have a Z51 car or other/ DO you have 3.07 gears in the rear or other? I fyou have 3.07's already DO NOT even think of going with lower gears. Your TPI setup is only good for low rpm, high Torque, so the higher the gearing, the faster your engine runs out of breath. It has been said that with a TPI system 3.07's are as good as it's gonan get..

On an otherwise stock intake/engine setup, I would also drop the idea of headers.. Yes they do add proven gains (I have them too), but unless you open your intake up for more breathing, opening your exhaust up for more flow is bad. You will lose too much Low-End torque and not gain the HP back to make up for it..

What I would do for under $1500..

Here are the 'simple' mods..

Get a set of good mufflers to replace your stock restrictive ones. I wouldn't bother with a full exhaust as those can get very expensive.

Get a K&N Airfilter and modify/cut open the airfilter housing cover.

Get a Coil upgrade like an HEI Accel or Hypertech or MSD one, and either do the SPark Plug electrode cut-back modification, or gap your stock plugs to .045 from the stock .035.

Get a set of Pulleys. This will reduce drag on your engine, btu also reduce your votlage output at idle. I've been using a set of Power Amp March Pulleys for 3 years without any problems.

Get an Adjustable Fuel Pressure Regulator. With this you can dial in your perfect fuel requirements and richen up the engine a bit..
Advance your timing and add a little extra fuel and see how far you can go on pump gas (93 octane) without detonation.

Here are the more complex mods. Up to you how far you want to take it.

Get a set of Long Tube Runners from Lingenfelter, or AS&M or TPIS, or a set of SLP Siamesed runners. Beofre putting those on, port out your upper Plenum, and maybe port a little of your lower plenum.

ALL this should be able to be had for quite less than $1500.

You might even have money left over to buy a set of good sticky street tires and have fun learnign how to launch with minimal wheelspin.

Just FYI, with all the above mods I ran 1.82 60foot and 13.597-13.749@98.5.99.86Mph at the track in hot and humid weather last year.

 

Dont touch the rear gearing, if you have an automatic you dont need a new TC.

Do all the free mods suggested, check 65Z01s site for info/directions, pick up some headers and whatever catback you like. The popular catbacks will be in the MidAmerica and Ecklers catalogs, or you can contact the manuf. directly on some of them.

I would do the Hooker headers, probably in 1 5/8" size if you arent going to heavily mod it, but 1.75" if you will.

Dont mess with the cam/heads/intake (other than porting) until you drive the car for 6-8mos so you know what you want out of it.

 

Thanks for all the good information guys. And thanks for making me feel welcome!

And Nuke, seeing your times has triggered another question. What is normal for a stock 85'. I took mine up to the palmdale/lancaster LACR raceway and my best times were in the 15.2-15.3 range. Is that abnormally high???


[Modified by 1985vette, 8:40 PM 8/18/2003]

 

I am not sure of the adjustments that have to be done to the times at your raceway, but when the car was stock with KYB Targa Mufflers and a K&N the car ran between 14.0-14.2@94mph.. that was a long time ago with 50 or so miles..

 

15sec is abnormally high, unless your track is high elevation, you probably need a tune-up.
plugs, wires, cap, rotor, fuel filter

 

Anyone know what kind of horsepower potential the iron heads have?

 

Stock you should be in the 14.0-14.5 range. I ran a 14.1 in my '86 when it was stock except for a K&N and Dynomax mufflers. Here's what I would do with $1500.

$550, 1-5/8 longtube headers and y-pipe(1-3/4 if you plan on future intake mods)

$355, Flowmaster catback exhaust system

$60, Adjustable Fuel Pressure regulator

$400, Accel HiFlow runner (Might as well change the stock runners since you'll have them out while changing the fuel regulator)

$0, all free mods (plenum porting, MAF screens, TB bypass, ect.

And then use the rest on a good tune up (plugs, wires, ect.)

With all the mods above minus the Hi flow runners, I was running 13.5-13.6's at the track! :cheers:

 

I think they max out at just around 300HP.. That's where I am now.. Maybe with porting/larger valves you can get 20+ out of them. but they aren't worth it.

I already have a set of almost new ZZ4 aluminum dports sittiing in my garage that will be cnc ported and larger valves put in to offset my new cam and other little things during a winter teardown.. :D

The aluminum heads will shave off 60+ lbs of weight just by that, raise my compression from the 9.5, and be prone to less detonation than the irons..
WOOHOO!!


[Modified by MrNuke, 11:02 PM 8/18/2003]

 

:iagree: I figure they wont make much more than 300hp.
The irons weigh like 44lbs each, whereas the D-port AL heads weigh 19-20lbs each. So you see the weight savings potential.

 

The lancaster track is at about 4,000 ft elevation, and the temp that day was definitly 85+. Is 15.2 still insanely high for a stock 85' auto?

 

I too have a 85 with a stick. When I first did all the free mods and a good tune-up including new injectors, my best time was 14.6. After Headers, free flowing cat and powere effects exhaust and drag radials my best time was 13.98 at 99mph.

A good tune-up will help and many of the free and low cost updates will definately help. Be patient and read/search alot in this forum and you will find an unbelievable amount of info.

Enjoy and don't forget to wave :cheers:

PS: You are beginning a journey that can become very addicting but enjoyable - Upgrade mania!!!!