ok guys heres what i have 89 drop top i bought from a dealer, it had one owner since new and appears to be absolutely as chev made it. now the beginner questions. i would like it to run better, what can i do as far as mostly bolt on stuff . what works & what dosen't? i think i would like to replace the exhaust, to get air out & sound a little better. how can i get more air in? I live at 5500 ft. alt. i need all the air i can get. the car starts instantly when cold. when hot it has to crank a little longer & flutters a little bit after it starts but soon clears up. the car just turned to 90,000 miles. as allways thanks for the info & your time.

 

I would definately start with the exhaust, as most engine mods wouldnt come out unless the exhaust is there to compliment it. There are many different brands out there depending on how much $ you can spend and what sound you want. Delete the precats, get a nice free flow cat in there...headers are great!

As far as getting more air in, you can start by cutting the air filter lid. There are many different intake options you can go with, depending on what you want your power curve to look like, you'll have to decide that for yourself. Keep in mind that everything stock on this engine is restrictive as hell. If you point at something under the hood, you can generally say that it can be made better. Heads, AIR, Pullies, water pump, exhaust, intake. roller rockers are the best bang for your buck. Let us know on your intentions and we can better help you decide on what would be best.

 

Hi, I am also a new C4 owner and new to the site. My new toy is a 1989 6 speed coupe and I will be looking at some power mods as well. Mine is a one owner with 47K miles and as you might imagine mostlty sat in a garage for the last five years (only 3K in the last 5 years). The car is bone stock and has just had oil changes. What suggestions would you have before I start air flow mods? Thanks, Badd

 

thanks for the reply raisinbran. my first mod will be exhaust, from the stock headers back. I would like to get rid of the cats, but don't know what that does to computer controls? I am also interested in ratio rockers. what ratio does what & what to expect. do you have to re-tune the computer, and how??? also does anybody know about a throttle body air foil??? does it work or is it just made to sell. how about a k&n filter, does it make a noticable differance? as always thanks for the help.

 

Here is one example of a true dual exhaust system that i found:

http://www.madvet.com/shop?frame=3.36.6752

I would also recommend you contact a local muffler shop and see if they can custom make you an exhaust system....it is, afterall, just straight pipes all the way back.
It should not effect your computer controls, as long as you keep the O2 sensor

As far as roller rockers go, stock your car has 1.5 rockers. I would suggest going with 1.6. This will increase the lift, but more importantly it will greatly reduce friction in your engine allowing for better throttle response, probably good for about a max of 10 hp. The wimpy cam really doesnt let other mods come out.

No dont have to retune for any of those mods, though it never hurts. To get a tune, you can either get it dynoed or send in your Pcm. pcmforless.com has an excellent reputation, good price. talk to them if they decide you would benifit from a tune, you can get you will get a great tune.

Dont waste your money on the air foil. A K&N filter will perform equal to a brand new stock air filter.....but after a couple thousand miles, a regular air filter will really deteriorate whereas a K&N will perform great for long after....and they are rechargable, never have to buy a new one.

 

for those intersted in air mods, check out this article. This is one of my favorites. It breaks down all of the major air intake systems available for the L98. Dont pay attention so much to the numbers, but the effect one has on the power curve, peak tourque and hp numbers.

http://www.compcams.com/Community/Ar...?ID=1737510521

MY favorite is the Big Mouth manifold and large runners to compliment... I would love to have a tourque monster like that, yet still be able to make that kind of hp too. But others may want a high rev hp screamer, and the superram may be what you need....decide for yourself.

 

wow thanks raisinbran i just read the website you sent at compcams. that is a bunch of info.i agree with you i would rather have a torque monster than a screamer. have you ever heard of anybody porting the stock stuff with good results? it looks kind of square & boxey behind that throttle body.

 

Yes people have done it, and they do get results. Porting the runners is tricky because there is not much excess metal to begin with. Just deicde if its worth it (especially if you're paying someone to do it) to port them or if you should just go with an aftermarket set up.