New 81 owner and Forum Member

[PMartin]

I've been reading the forum for sometime now and I just recently purchased an 81 with a 4sp and 88,000 original miles. I just finished installing new interior and now I'm wondering how to get more power out of this L81. Any ideas??? What would you guys recommend without breaking the bank??? FYI everthing is orginal on this car...

 

[big2bird]

I've been reading the forum for sometime now and I just recently purchased an 81 with a 4sp and 88,000 original miles. I just finished installing new interior and now I'm wondering how to get more power out of this L81. Any ideas??? What would you guys recommend without breaking the bank??? FYI everthing is orginal on this car...

If you do not have smog inspections, pull that crap off. Cheapest bang for the buck, change rear gearing. It probably needs going thru anyhow. After that, change the cam.,then...........................

 

[Sensei]

Unless you want to keep it looking stock under the hood or have to pass state inspections, the single best performance mod is to replace the exhaust. You will feel headers and 2.5" duals with high flow mufflers in the seat of your pants, no ifs, ands or buts. I actually did mine a few years ago for around $300. Biggest performance difference to date (including heads, cam and intake combined). Best of all, I'm pretty sure it has payed for itself by now with fuel savings! God bless, Sensei

 

[KANE]

I've been reading the forum for sometime now and I just recently purchased an 81 with a 4sp and 88,000 original miles. I just finished installing new interior and now I'm wondering how to get more power out of this L81. Any ideas??? What would you guys recommend without breaking the bank??? FYI everything is original on this car...

Welcome to the CAC! If you are looking for cost effective horsepower, then a new intake, Vortec heads, and 1.6 roller rockers may get you more with less money. Another option is to pull and store your L81 and purchase a crate motor. Jegs has a 385hp SBC motor for around 3k.

Unfortunately, "original", "more power", and "inexpensive" aren't always together. I wish there was a $5 solution that unlocked 100hp- I'd patent it and be rich! Until then, you'll have to balance originality, power, and expense with what you are willing to trade off between the three.

 

[PMartin]

After I pull the smog crap...Will that have any effect on the ECM? This is my first 81..

 

[PMartin]

Did you do it your self of use someone in Jacksonville?

 

[Sensei]

You can pull the AIR and EGR with no problems, as well as the heat stuff on the air cleaner box, but you won't notice much, if any performance benefit. You will want to leave the O2 sensor, and Evap canister and don't mess with the carb or distributor. God bless, Sensei

 

[Sensei]

I do pretty much everything myself.

 

[big2bird]

don't mess with the carb or distributor. God bless, Sensei

That's a point we will never agree on. If you change to an earlier quadrajet, and put a proper curved vacuum HEI in there, Big difference. Cam? GM 181. Gears? 3.73..
This puts them back to where they were before. 3.08 and 2.79 coupled with ECM is about MILAGEand EMISSIONS, not PERFORMANCE.

 

[Sensei]

Sorry Bird, a $120 performance chip will give your distributor a performance curve that will not change with temperature, spring wear, vacuum leaks etc. I've hooked up my car to an analizer and my E4ME carb keeps my A/F ratio at 14.7:1 (ideal efficiency) at all times except WOT, at which it runs around 13:1. How could any other carb or distributor improve on performance from there? God bless, Sensei

 

[big2bird]

Sorry Bird, a $120 performance chip will give your distributor a performance curve that will not change with temperature, spring wear, vacuum leaks etc. I've hooked up my car to an analizer and my E4ME carb keeps my A/F ratio at 14.7:1 (ideal efficiency) at all times except WOT, at which it runs around 13:1. How could any other carb or distributor improve on performance from there? God bless, Sensei

Okay Cris. Do me a favor. Do you have a dial back timing light? Chart the curve for me sometime. Then I can make an edified decision.
Idle
500
1,000
1,500
2,000
2,500
3,000

Fair enough?
(P.S. Name one performance/race car with an 81 computerised carb)

 

[Daryllawman]

Hello and welcome to the Corvette Action Center

 

[GerryLP]

Sorry Bird, a $120 performance chip will give your distributor a performance curve that will not change with temperature, spring wear, vacuum leaks etc. I've hooked up my car to an analizer and my E4ME carb keeps my A/F ratio at 14.7:1 (ideal efficiency) at all times except WOT, at which it runs around 13:1. How could any other carb or distributor improve on performance from there? God bless, Sensei

Chris has a valid point which I have experienced first hand. For a while I ran nothing but a Holley carb, springs in the distributor, MSD 6AL, headers, same cam as now (XE268H) and an open intake. Made for a very fun time while at the 1/4 mile track and following the adjustments with gained speed or faster slip times. It was rewarding to see what many books teach on tuning a car. It was alright by me to twice a year change the jets or re-time the ignition due to the seasonal changes (colder air is great, but if you're not careful, you'll end-up with the effects of running an engine in a lean mixture :ugh).

But what a PITA it was for just traveling around the country. Case in point -I had to change the carb jets at Auburn and re-time the ignition. Then on the way back, I had to change them back outside of Amarillo, TX for my climb back to 5k feet of altitude.

That convinced me to return as close to stock as possible (with a true 9.5 CR no less, and a quench of 0.045" ). But everything else, to include the smog equipment, went right back inside. And I am happy with my 19 MPG .

I still have to breakdown for one of those HP chips, but once I get everything else done, I'll be swapping the chip as well.

p.s. Welcome aboard, PMartin. Definitely you'll find this forum informative and a great place to "hang-out". Plus, The entire website has gobs of information on just about any subject related to Corvettes.

 

[Vette79]

I've been reading the forum for sometime now and I just recently purchased an 81 with a 4sp and 88,000 original miles. I just finished installing new interior and now I'm wondering how to get more power out of this L81. Any ideas??? What would you guys recommend without breaking the bank??? FYI everthing is orginal on this car...

Without breaking the bank and attempting to conform with some originality of your Vette, install headers and dual exhaust. Then a cam (Cam Kit from Summit) and roller rockers. Intake manifold might be necessary as well. Anything you remove from the Vette that is original keep for future reference and later install if needed. You can gain more tq and hp from these upgrades and others but it is minimal. I am currently taking this route as I want to remain with the originality of my Vette besides it is for cruising anyway. Not for the track. You can always just stick with what you have and enjoy the ride...

 

[KANE]

.... It was alright by me to twice a year change the jets or re-time the ignition due to the seasonal changes (colder air is great, but if you're not careful, you'll end-up with the effects of running an engine in a lean mixture :ugh).

But what a PITA it was for just traveling around the country. Case in point -I had to change the carb jets at Auburn and re-time the ignition. Then on the way back, I had to change them back outside of Amarillo, TX for my climb back to 5k feet of altitude....

Gerry- the constant hunt for the right setting led me to fuel injection. I got so sick of setting and resetting timing, swapping jets, and the over all fumbling with the carb a couple times a year. I've been much happier with EFI because I get great performance and gas mileage.

Although the initial post was asking about cost effective mods for more power, a discussion of alternative fuel/air delivery seems a natural progression.

However- the initial start-up costs for EFI aren't for the faint of heart. A pieced together TPI system will run between $700-$1,000. Other than efficiency, gas mileage, emission quality (I've passed smog tests easier), ease of maintenance (trouble shooting is easy if you have the right books!) and the gee whiz look... its not worth it to most people.

For a "stock" look... I'd say go with Holley's Commander series. Essentially, it is a 4bbl TBI with software that makes tuning a breeze. You could run the OEM air bonnet and aside from the extra wires, I doubt most people would recognize the difference in looks.

 

[big2bird]

I ran an HEI on my 76 pick-up for 20 years without touching the timing.
GM engines are designed to run at 36* advance at 2,500RPM, period. When running under light load, they can take up to 52*. a 16* vacuum unit automatically controls this.

 

[pbcanney]

I'd really like to put Hooker side pipes on my 81, but, quite honestly, all the ones I've heard are just to frikkin loud and harsh. I like a nice growl, but side pipes seem to be barking always

 

[SIXFOOTER]

I got to agree with some of the guys. Change the exhaust forst and see what that gets you. For any other performance mods you will need upgraded exhaust anyway, so do it first.
If you don't have to deal with Smog peel off the air pump and maybe the egr, I don't it really robs much power at all, it only does its thing at cruise, not at idle or with your foot in it.
The evep canister should stay too it sucks up all the gas fumes and doesn't cost any power either as long as the hoses are good.
Farming out the exhaust will cost you upwards of $700. I built all of mine myself for about $400 including ceramic headers and exhaust wrap.

 

[PMartin]

Thanks for the Advice

I'm going to cruise and enjoy it for now and worry about the HP later Like the old saying goes "If it isn't broke don't fix it" How can I go about registering my 81 with the vette registry?

 

[big2bird]

I'm going to cruise and enjoy it for now and worry about the HP later Like the old saying goes "If it isn't broke don't fix it" How can I go about registering my 81 with the vette registry?

Click on the 81 registry link above.