help, 81 performance tips

[bandit]

hi i'm new to this site but been reading the threads since i bought my baby this fall. right now its all stock but i have some equipment i would like to put on, right now i have a edelbrock performer intake, edelbrock 600 cfm manual choke carb, and breather. from the threads seems as this would perform nicly. here is the Q. if i went with 2.02 64cc heads what kind of cam would i need to match? i was also looking at putting in a set of 3.73 gears, can i get a set out of a doner vehicle ie. old blazer, jeep, etc.? gears come first cause i'm not gonig to get imbarased by some import! but im still debating on missin with the motor as she pers like a kitten. any imput would be great.

 

[LanceB]

I think 3.73 gears will make your rpms wind out quite a bit at 65 mph...I would consider something a little lower if you are just driving on the street and racing it every once in awhile. I thought the stock gears on my 81 make for a pretty good takeoff. I adjusted timing to 14 (pretty sure that was the mark, been a little while), removed the cats and put true duals (perhaps the most noticeable difference), and I removed a lot of the emissions equipment. Save everything you take off in a box. I put a chip in mine but didn't notice anything different. Not sure on the carb, I think when tuned right the stock carb performs just as well although there is a lot of emissions stuff added to the 81 carbs that you don't necessarily need, but I don't think removing them will give a performance boost, it will definitely simplify the carb. Mine was missing the A.I.R. tubes and smog pump when I bought it years ago; a lot of people remove those too. Enjoy your 81, I still think it is one of the best looking models.

 

[bandit]

what would you recomend as she is stock now but like said gears are first. she does pull good but i would really like to get shove in the seat feel. maybe 3.54, or 3.36 ? she is really an around town kinda girl once in awhile i hit the highway thanx

 

[GTR1999]

373 gears with a 1:1 final trans ratio and 225-70x15 tires will be about 3400 RPM @ 65 mph. With an OD about 2200 RPM depending on the OD.
The 80-82 differentials are not the best, they are weak if you start to build power and push the car. There are some that run 400hp and street tires and don't have a problem but there are also guys with the stock engines that broke the bearing caps. Keep this in mind if you really start to build power. If you keep it under 400 hp and want a stronger diff then stock you can add in a steel bearing cap. This will add stregth to the unit but it's not going to be anywhere near as strong as converting to a correctly built & blueprinted iron unit. This would cost you a lot more then the stock with steel cap so you really have to be honest with yourself on your usage. I don't touch the 80-82 diff's as they just don't offer any performance benefit or long life. If you want an iron unit check out my threads on how to build them strong. If you want the steel cap fit to yours then contact Mike Dyer, he'll build you one.
Good luck with the car.

 

[Rodney Gold]

With my stock vette , I got beaten by 2 20something chicks in a golf GTI...they gave me the finger after humiliating me to boot - I vowed...NEVER AGAIN!!!!

I have modded my 80 to run mid/high 12's on its street tyres and still be capable as a daily driver and a weekend warrior.. I can anhilate a merc SL55 amg and just about any import and have even taken on superbikes from robots and surprised em or even beaten em (they cant get the traction so they wheely the first couple 100 feet - then they streak past me....with a dumbstruck expression

I run 3.55 gears and a 2000+ rpm stall in my 80 , good for street and strip.
Remember an engine is an air pump , the more air you pump the more fuel you burn , the more power you make.
Your incremental approach will not really get you anywhere, the intake and carb , without headers and a decent set of heads is wasting money for the HP increase you will get.
A set of ally edelbrock heads and matching cam will get you the performance you want. Rather buy the whole Edelbrock performer package. (I run edelbrock ally heads but a a Holley 770 street demon ---the Edelbrock 600 wasnt that great for the mods... I also run a 270H cam , good for street and strip) I limit RPM at 6000 - at that rpm , the motor should live a long time.
Get a decent seat of headers to match all that
Be a bit more conservative when you read cam or power package specs , most owners want more cam and carb than the car does.. something that only delivers power at 3500 up will be a dog to ride on the street.
Apart from that , a shift kit in the tranny will be a good idea. A tranny swap like a beefed up 700r4 or a 4l60e would be ideal. A MSD 6al is alsoa nice addition , as is a decent MSD distributor. I dont particularily like points ignitions.
The biggest "kick" from my power upgrade came from the stall and the rear end -- once again , match the power delivery to the rest of the car.
I dont think my 80 is particularily rare or desireable , so have somewhat bastardised it by deleting the aircon , fitting decent racing seats and harness and fitting a hurst promatic shifter and made myself a decent gauge set using autometers
I still run the stock 15" rims with 235/60/15's
Gearing is 35 km/1000 and top speed is 210 kph
in miles that is 22miles per 100 rpm and a top speed of 130 or so....Im not into high speeds with the car at all , 130 is just fine for me.

 

[bandit]

well i'm not rollin in the doe, so this wont happen to quick. i did the hard part and got the car now its the little things. like i said i dont want nothing to agressive {ya right} but for now maybe just the intake, i hear thats a nice improvement and i have it anyway. and maybe i will just go with the 3.55's as i would like to somwhat cruise she is old, but still a looker. it does have an exhaust on it, i have the targo mufflers on it now, and thought about getting a test pipe for it. reviews??? i bought her with matching #'s and kinda would like to keep it that way, for the most part anyway. i just want want a nice street machine, and hold up the corvette heritage.

 

[LanceB]

Are they true dual exhaust pipes all the way back from the engine and the single cat eliminated (not just new mufflers)? That was the cheapest, most noticeable difference on hp with mine but check your local emissions requirements. It also made it sound like I think a Corvette should. There is no end to the quest for more power!

 

[Peer81]

Try looking for a nice 200R4, direct bolt on and you have a shorter first gear for more off the line speed and an overdrive to keep the rpm low at high speed. Or at least compare the first gear endratios with a 3.55 of 3.73.

Groeten Peter

 

[Evolution1980]

Hey Bandit...welcome to the site! (nice email addy BTW...)

You're kinda like me when I first got my car. A cruiser but you don't want to get embarrassed by the local tuner crowd. For now, you're gonna have to pick your battles carefully. (The mid 70's through mid 80's weren't much for speed.) Best bet is to learn to enjoy cooly and casually declining any invites for a race, unless you are a fun racer and don't mind winner nor losing.

As you've figured, gearing is gonna give you most immediate increase in performance. 3.73 is pretty tall and you'll notice it. Especially if it's mated to a (beefed up) 200R4 trans as Peer81 said. However, as LanceB and GTR1999 said, you're highway RPM's are gonna be up there.

As to your question of matching heads and cams, that's well outside my technical knowledge. Though there are definitely some engineers on this site though that could point you in the proper direction if they happen across this thread.
What you might want to do in the meantime is read up on some of the specs of the crate engines out there and see what combos builders are using, be it GM crate engines or the numerous engines built by the various Hot Rod mags. There's so much more to building a solid engine than just try to mate up heads and cam, but it is a good start nonetheless.
And as you probably know, ricer math doesn't work. Power numbers are not cumulative from a vendor's specs of individual pieces. :eyerole

My 2¢ is this...rear-end gearing if you are mostly burbling around town and occasionally red-light racing. Next move on to the exhaust if you don't have to worry about emissions. The factory exhaust was very restrictive and quieted down the car quite a bit. A nice set of ceramic coated headers and some freer flowing exhaust go a long way to making the car "sound the way it should". It might only be a little faster, but the sound will definitely have you (and others!) believing it's a lot faster!

There's tons of threads on the site here about what constitutes "true dual" exhaust. If you do a lot of high RPM driving, then just go each side, straight back. That will also be the loudest.
If you are mostly burbling around with occasional full throttles, a Y-pipe configuration like you have now isn't that bad. Or go "true duals" but toss in an H- or X-pipe.

It all comes down to this...You're young(er) and likely/hopefully going to have the car for many years. Most of us that get our cars at an early age (re: pre-marriage, pre-parenthood, etc :L) tend to not have tons of money to throw at it all at one time. My car took me about 10 years to get it to where it is now. And of course, I'm not done with it. But I'm satisfied at this point. I'm not the fastest guy on my block (no one ever is), but I'm certainly not the slowest.
Take your time. Make wise investments in your car. But most of all, Enjoy it! because it's YOUR car. :cool

 

[LanceB]

Good reading Evolution! I have had mine since 1998. I treated myself when I got my first real job (you know enough money to pay the rent, a car payment, and the job actually had health insurance, what little money was left went to the local pubs those first couple of years). I started out wanting more performance but then I started getting picky about the details like paint, new interior, tires, stereo and mostly...unscheduled maintenance (it is about a 30 year old car, things just get old) so learn the car a little bit I think.

For quick and relatively cheap performance just start with exhaust and the right gear/trans combo and you'll surprise those imports. These cars still have some good torque as is. If you feel like getting in that engine, weigh the costs of a crate vs rebuild. The numbers will surprise you. I am sure the crate can give you all the hp you can ask for. The crate always seems to be the final answer to the maximizing performance question.

 

[Vette79]

hi i'm new to this site but been reading the threads since i bought my baby this fall. right now its all stock but i have some equipment i would like to put on, right now i have a edelbrock performer intake, edelbrock 600 cfm manual choke carb, and breather. from the threads seems as this would perform nicly. here is the Q. if i went with 2.02 64cc heads what kind of cam would i need to match? i was also looking at putting in a set of 3.73 gears, can i get a set out of a doner vehicle ie. old blazer, jeep, etc.? gears come first cause i'm not gonig to get imbarased by some import! but im still debating on missin with the motor as she pers like a kitten. any imput would be great.

What are your goals? How much money do you have to spend? Will you be doing the work yourself? These are important questions in determining where you want to go with this. If you are going to do little by little then be sure you have all the parts in mind that you need because these parts need to match up. For example: the head, cam and intake need to work with one another. I would start with headers and dual exhaust first and then decide from there. After this I started modifying the motor. I think prioritizing and being patient is the key.

 

[bandit]

thanx for all the feed back, i geuss i'll be leaving her alone for now. got a new thread on side pipe guts but i think the rearend and exhaust. paint is also first on the list as she is still orig. she has a few spider vains along the rear luv humps, lol! i'll have to get a pic up when the snow melts so i can get to her.

 

[Rodney Gold]

If you going to do the rearend...spend the few $'s on an aftermarket stall...600-900 rpm over stock really makes a big big difference. The rear end gears wont cost a fortune , but find the right guy to set up the diff...it's not as simple as just bolting them in.

 

[Vette79]

If you going to do the rearend...spend the few $'s on an aftermarket stall...600-900 rpm over stock really makes a big big difference. The rear end gears wont cost a fortune , but find the right guy to set up the diff...it's not as simple as just bolting them in.

Rodney, did you swap out your rearend after installing a new stall converter?

 

[bandit]

ya i know the right guy for the gear job, as for the the car the guy i picked her up from took really good care of it espesally when it came to replacin parts and tuning. i do like the trans swap idea cause i wouldnt really mind a od gear. with the 200r wouldnt i have to shorten the drive shaft? as for the exhaust on it now is orig. it only has the targa free flow mufflers, looking into a high flow cat or test pipe. but i think i may pull it all off and go for the hooker side pipes, they really make the car, just not to sure on the length baffles i should run.

 

[Evolution1980]

ya i know the right guy for the gear job, as for the the car the guy i picked her up from took really good care of it espesally when it came to replacin parts and tuning. i do like the trans swap idea cause i wouldnt really mind a od gear. with the 200r wouldnt i have to shorten the drive shaft? as for the exhaust on it now is orig. it only has the targa free flow mufflers, looking into a high flow cat or test pipe. but i think i may pull it all off and go for the hooker side pipes, they really make the car, just not to sure on the length baffles i should run.

Couple of things for you..
1) the 200R4 is a direct bolt in. The 700R4 requires a shortened drive shaft.

2) The stall rating of your Tq. converter ("TC") should be matched to the approximate average RPM range of your normal driving. Thus, if you spend a lot of time at 2000 RPM, which if I recall is about the approx RPM range for burbling around town and on highway in OD, you'd want your TC stall to be around 2000. If you are doing a lot of drag racing or high RPM driving in general, you want a higher stall TC, say closer to 3000
If you need "TC stall speed" and whatnot explained to you, feel free to look it up or ask.

3) Cats, mufflers, side exhaust, etc... If you don't need to deal with emissions and aren't overly concerned about a little more-than-normal pollution, you don't need to bother with cats.
If you want your car to have that old hotrod sound, I'd suggest glasspacks (Thrush, Cherry Bombs, etc) and not regular mufflers.
If you are thinking about side pipes, yes, they are very cool looking on our cars. I had wanted them for a long time. But you will have to consider the "consequences" (for lack of a better word). One, they are NOT girl friendly, even with heat shields. They WILL burn their leg on them. And that doesn't make for a happy girl. It's not 'if' they will, it's 'when' they will. :eyerole And just in general, it takes some getting used to not being able to hang your legs out right over the door sill when getting out of the car or just lounging around in it for whatever reason. (And side pipe burns can leave nasty scars. Again, that doesn't make for a happy girl...or driver...or whomever gets the treat.) Two, you are going to possibly lose clearance for getting a jack under the side of the car. I'm not 100% on this, but Dark Shark could probably give better insight. And Three, they do sound great, but unless you get 'em baffled or something, your performance is going to suffer on the relatively stock engine. Side pipes are essentially an open-exhaust system which is great for high RPM engines, but not so great for low RPM stuff. Four, they are quite a bit more expensive (ya gotta get chrome or ceramic coated) relative to a standard front-to-back exhaust setup. ...They do look awesome though! :cool

 

[Rodney Gold]

I swapped out the rear end first ...and didnt get the performance increase or driveability improvement I wanted , then did the stall and the combo of both was just right.
I used and grenaded 2 TCI stalls - their 1800 RPM one (maybe the sat night special?)--- I was extremely p---sed off that my stock stall was fine but an aftermarket one with all manner of improvements bust the sprags both times after 100kms (and no drag racing) - they sent me a 3rd one , one they use for oval track evidently - 2400 stall and it has survived well.
A rear end swap is not always the answer--- I have a El Camino (actually a Holden Ute not the Yank elky) with a 425hp 454 and a ford 9" rear end , swapping from a 3.75 to a 3:00 lost me 0.1 sec on the quarter --- but gained me a huge amount of fuel economy and a much more relaxed cruising speed. 0.1 isnt a huge gain and it isnt seat of the pants either.
If I had the choice of which to do first again on my vette - the stall would be first ...if you can't get the motor up in its powerband when launching or accelerating or even overtaking .. it doesnt matter what your diff ratio is - you are still in "bogland"
The 2400 RPM stall is essentially "invisible" when driving normnally , its not like you got a clutch that slips to 2400 , the car still creeps at idle , doesnt feel like you need to give huge amounts of gas when going up an incline etc. I dont even stall the car when launching , I just mash the pedal cos stalling winds up the suspension and you get less traction. Where the stall really comes into its own is whacking the pedal at cruising speed , the shift kit and the looser stall make that downshift "explosive" and the car feels far more violent then than without the stall.

One other very worthwhile and cheap mod was a B&M governor kit for the box , albeit I have a Hurst promatic shifter , the box in auto was short shifting 2-3 and not shifting high enough 1-2 , I set the governor so that WOT shifts are now 5500 rpm..the kit was cheap and the performance increase very tangible.

 

[bandit]

ya i like that idea just got to find me a tranny now i geuss {not that kind perverts....lol} and about the stall how would i go about this. ive got a pretty good machanics backround but never been in that situation so teach me wise men. i think a new stall and small gear change will give me what i need, for now that is. could i use the 2000 stall in my stock trans or should i wait and do the trans swap and stall the same time?

Goal: get her a new paint job, and give her a little more pep while still stayin relitivly stock. gettin side pipes, ol lady will have to just spread her legs a little wider..lol. watch ill be the one gettin burnt! tiss the price you pay for style. as for the baffles in them i hear the spirral ones are the ones to get, now what ones do you think 12 inch hot rod style or should i go with the full length baffle.? these improvements should give her the wake up call she needs. oh and gotta get the stinger style hood before she gets painted . god dont they look sick. as for the motor everything works the way it should so ill keep it that way , for now , untill i win the mega bucks! then its 383 all the way.{it is nice to dream!}

 

[Rodney Gold]

You can swap out the stall right now , you got to take out the box and it should be a bolt in.

 

[Evolution1980]

could i use the 2000 stall in my stock trans or should i wait and do the trans swap and stall the same time?

If you are getting a new trans, get a new TC with it. I probably wouldn't go higher than 2400 stall speed.

Give more consideration to your time frame for doing the paint. It's going to be the most expensive thing you do to the car. For most people, a full show quality paint job is going to be at least $5000-$7500. (Would you really want anything less than show quality???) And that price doesn't include the cost of the new (stinger) hood.
Given that, if you plan on doing a lot of work under the hood, you really don't want to be having to work over a brand new paint job. You're leaning on it / over it, working with tools, power cords / air hoses draped over it, fluids being passed over it... It's not the kinda of careful stress you want to endure while working under the hood.
I would suggest making paint one of the last things you do to your car. Get it mechanically sound/safe and do all the upgrades you want. Even a ratty looking car still gets props if it's fast. But take a showy car to a race and then lose? The taunting is even greater. "All show and no go."

Someone else is gonna have to chime in on the baffles. I've heard plenty good things about the spiral type, but that's about the extent of my knowledge. You might try doing a search of the C3 forums. A few years ago there was a pretty lengthy discussion about 'em with input from people that had 'em.