aklim

Fair enough. I usually use a known good plug and test for a blue flame.

Highlander1732

Foundation is actually really solid. The car has 28,000+ miles and the PO had new plugs and wires installed not too long ago. The car is actually (dare I say it...) almost pristine. PO owned for 17 years and only put 10K on the car, so it is really factory fresh. Back to the cats, what codes or enige management issues might pop up if I swap straight pipe in? I don't have to get safety or emissions inspection where I'm located...

aklim

None. O2 sensor is in the exhaust manifold. Definitely gain more noise but since the choke point is further up in the exhaust manifold, the gains will be in your head. If you want something solid, change the manifolds to long tube headers

ClaudioC4

Underdrive pulley kit was on of the best upgrades from SOP perspective.

aklim

Theory is nice but I suspect that it is likely to be like you said, imaginary gains

Tom400CFI

One thing that the OP could do is give us an idea as to his mechanical abilities. There is really NO WAY, that anyone can give "best mod/least money" w/o knowing his ability to work on the car. For example, for a savvy person, hands down, the best bang for the buck would be headers/dual exhaust and a cam. How? For less than $999, he could buy Hooker headers and the cam, do that installs, then buy piping and bends and fab up a nice flowing dual exhaust system. Those two mods would make for a significant improvement; both SOTP and with the timer.

On the other hand, if the OP is farming work out, a custom exhaust and a cam would be (as Trumpy might say), "a complete and total disaster", financially! In that case, he should go the route of the tune up, TB foil, filter lid and maybe some UD pulleys. -Or something slightly better than worthless, like that.

So really, in order for the forum to offer great advice, the OP needs to help us, help him.


.

ddahlgren

All smoke and mirrors and makes all the accessories run slower.

aklim

But the stickers add HP. Everyone knows that. Of course it is smoke and mirrors. You don't pay much so that is what you get.

RF1

Bolt on a 150 horse shot of spray.

aklim

I wouldn't be able to afford it. I'd be on the bottle too often

Gibbles

I have a couple gallons of pure nitro methane in the garage... Not really "cheap" but it can sure make a difference!
i have been mixing it into the fuel for my chain saw, allows me to run a very aggressive chain and really plow through some logs that should require a much more expensive saw...

​​​​​​​I keep stroking the bottle while i stare at the vette...

aklim

No flames out the exhaust?

Oh, it has been a long time since by bottle had to be stroked by my own hands I probably forgot how.

johno504

best mod / least money = best gas you can purchase local .

coupeguy2001

proper air in your tires................well you said cheapest....................
Next cheapest, drive alone.........every 100 lbs you shave off is a 1/10 second down the quarter.

Never fill up more than half tank
If you don;t drive it all that much, keeps you filling it all the time, but you have fresh gas all the time.

Get rid of those heads.
Put better heads on it and open up the factory exhaust manifolds at each head port and you will think you have headers.

Go from 58cc heads to 62 cc or 64 cc heads, and advance the timing.

get 91 factory convertible mufflers.
both pipes work, and still relatively quiet with no drone
use a 160 degree thermostat....won't make it run cooler, but will circulate water sooner
go 2 steps cooler spark plugs
check the gaps on your plugs
Change your rockers to 1.6 and shave the drippers off your rocker covers inside them

take the water hose off your throttle body
add an oil cooler and make sure you have a power steering cooler.
Less heat under the hood makes it go faster.
make sure the air filter duct clamps are tight
use a low restriction air filter.
Use a truck oil filter. they hold more oil and more oil is cooler oil
use synthetic oil
put synthetic fluid in the trans and the rear end.
you will be surprised at the power you recover after you do some of this stuff

gallaau

Cheap upgrades, hmm
I am going to say exhaust, don't destroy what you have, just cut it and replace with pipe, keep the old stuff for a while in case you need to put it back on for some unforeseen reason
If it were me I would start putting money into reliability stuff
Like U joints
wheel bearings
tie rod ends
brake rotors and pads
The L98 is not a good motor to try to modify its pretty weak on torque and HP, but that is by design. It was designed to produce all it power at low RPM so it would feel awesome to drive on the street.
If you go to messing with the heads or cam its gonna suck
the 170 cc intake runners are there to keep intake velocity high for low end torque
Maybe 1.52 or 1.55 or 1.6 rocker arms that would be another good choice
putting 3.73 gears would be a bad idea cause its suppose to run at lower RPM where the power is
Sound proofing ! yeah that's it, I would definitely work on that
just remembered what I thought of mine when i first got it
work on the back area first that did the most good for me
Whatever you do just make sure you have a good time with it
I still love mine, especially when i see it setting next to that 500 HP 383 that's about to go in it
https://www.corvetteforum.com/forums...ies/yesnod.gif

aklim

Check with the scanner to see if the gas is causing detonation. If not you won't be able to know if the gas is good.

aklim

How fresh is the gas going to need to be? Fresh from 6 months ago, have you noticed much difference? Now a couple years, sure.

Or for the time you will have to spend hogging out the boat anchors, you can get a set of LT headers that will help so you will have headers and not have to think you have them.

And the ECM will pull timing out if you start to have pinging that it can hear.

At stock level, are you sure that circulating the water will do much?

The danger of that is that it can foul out easier.

To clean up the engine area so you can get the throttle body off easier, sure. Otherwise have you seen it reported to get anything really?

What exactly will that accomplish?

How does more oil keep it cooler? It takes longer to heat up but it will accomplish the same temperature sooner or later.

You are right. I will be surprised if it nets even 2 HP with all of this other than the timing and that is provided it doesn't ping and the ECM retards the timing.

86Pacecar

Don't touch a thing other than basic maintenance. Once you start modding and going down that road it's a money pit as it's never enough. A pristine 89 with 28K miles is a gem, you will regret the day you modded it.
I may get bashed for this but I got the mod bug with my 86 years ago and now I wish I'd left it stock. I'm slowly going the other direction, pulling the mods and going back towards stock. Wish I still had a lot of the parts I sold. I had my car running like a beast for an 86 and it would do low 13's but it was no longer an enjoyable car to daily drive and going our for an evening cruise with my wife stopped happening. Too loud, too smelly, rough running, too whatever, just not an enjoyable car to jump into and just go. Because of the mods it was just more difficult to drive for a non motor head and my wife just stopped enjoying the car. Now it gets maybe 400 miles a year and it's non use is starting to have an affect on the car. Everytime I do drive it I notice another thing that needs attention from lack of getting used. It's going to cost me more to get the car back to where it should be than I ever spent on mods.
But it sure was fun back in the day.

sprink94

This is a guess...but if there is a compatible manifold available for the TPI...bolt on a set of Vortec heads. Every Gen I SBC I have done this on runs like a "Raped Ape" !! LOL

They will give you the advantages of the LT-1 set up without worrying about the reverse flow cooling. You're basically bolting on 50~100 HP with the heads only.

aklim

I'd agree with that with a caveat. If you want to do mods, figure out your budget, plan for twice that number before you are done with that phase. If you can't swing it, don't start.