HorsePower Help

[Annivette]

I just recently purchased a 78 anniversary stingray and i would like to make some hp modifications. What would be the first thing that i should consider looking at?

 

[78SilvAnniv]

Welcome Annivette!

Welcome to Corvette Action Center.

It all depends on how much power you want and what you want it for.
There will be different combinations that will give you more speed at the top end with less low end torque, or a different configuration could give you more torque at take-off with a slower top end speed.

I don't have any experience with mod-ing an engine, but from reading here at CAC, you can gain some hp by changing your exhaust and/or using headers. (I prefer to stay away from headers unless you have monster hp) Overall, I think you would be better served to re-do your block with a cam, heads, intake and exhaust manifolds that match and a bigger carburator.
(get better/detailed info from someone who knows what they're talking about, unlike me...who doesn't understand the specifics)

You may even prefer to buy a crate motor where almost everything is done for you and it is ready to go right in, saving the original engine for a later build or resale value.

Good luck with your project!
Heidi

 

[80vette_ca]

Raw Power

I agree with 78SilvAnniv here. You may also want to bore and stroke your engine and put in some high performance pistons, but you may not want to do that to the original engine in a beautiful car like that. If you really want to get crazy and go all out I read that chevy has a new 572cid engine that pumps out around 750hp and with some minor mods you can get it over 1000hp with out nitrious. That is a little on the crazy side involving so much modifing of the car, but hey I can dream can't I?

 

[LEEJANDZ]

My vote is for headers. If you plan on just increasing the power of your 350 without doing any major modifications, then headers are the way to go. Headers are something that will follow your engine no matter what the buildup you plan for later. But I suggest you address the entire exhaust system as well. Then work on the Intake manifold, carb, etc. If you feel you need more power after this... Skys the limit!!!

But there are so many schools of thought on this subject.

 

[page62]

Do NOTHING for the first 6 months! (Except necessary repairs, of course.) There's a lot for you to learn about Corvette culture -- not to mention the quirks these car have.

You may find you have a numbers-matching car that you want to preserve. Or smog regulations where you live may prevent you from doing certain things. You haven't even told us if the engine is an L48 or an L82.

By the way, the last thing you want to do is install those silly underdrive pulleys. You wouldn't even notice the difference. And these cars need all the fan cooling and water pump speed they can get.

 

[Bob Chadwick]

Re: Welcome Annivette!

I don't have any experience with mod-ing an engine, but from reading here at CAC, you can gain some hp by changing your exhaust and/or using headers. (I prefer to stay away from headers unless you have monster hp) Overall, I think you would be better served to re-do your block with a cam, heads, intake and exhaust manifolds that match and a bigger carburator.

Heidi's comments follow the general train of thought you will see here. The smogged cars need better breathing and compression, which equates to intake, cam, better flowing exhaust and better heads. There is some disagreement on the headers. Some swear by them, others feel that the heat and other issues make them more trouble than they are worth.

Good luck.

Bob

 

[80vette_ca]

Do NOTHING for the first 6 months! (Except necessary repairs, of course.) There's a lot for you to learn about Corvette culture -- not to mention the quirks these car have.

This is another good idea. You should learn the car and how it handles before you do anything major. Remember, once you start you won't be able to stop, you'll make mods and then drive for a bit, then that won't be enough and you'll have to do more and more. Speed is an adiction, a lovely adiction, but an adiction nevertheless.

 

[Jack]

Do NOTHING for the first 6 months! (Except necessary repairs, of course.) There's a lot for you to learn about Corvette culture -- not to mention the quirks these car have.

You may find you have a numbers-matching car that you want to preserve. Or smog regulations where you live may prevent you from doing certain things. You haven't even told us if the engine is an L48 or an L82.

By the way, the last thing you want to do is install those silly underdrive pulleys. You wouldn't even notice the difference. And these cars need all the fan cooling and water pump speed they can get.

Agreed! But once you're beyond that & do want more ... One of the first things to do for more power AND economy is the easiest & cheapest (also unnoticeable impact on originality/appearance). Go through the distributor. Make sure everything is in good condition ... then pay close attention to Lar's papers on vacuum & mechanical advance curves ... make recommended changes to the curve. Lighting the fire at precisely the optimum moment is as important as anything on anyone's list of add-ons. I recall Lar's papers are archived here through knowledgebase ... and other sites. An $8 vacuum can & a $5 mech advance spring kit ... carefully dialed-in ... does wonders for cars from early days of anti-smog era (ie 71-81 C3).
JACK

 

[LEEJANDZ]

Jack --- Go through the distributor. Make sure everything is in good condition ... then pay close attention to Lar's papers on vacuum & mechanical advance curves ... make recommended changes to the curve. Lighting the fire at precisely the optimum moment is as important as anything on anyone's list of add-ons. I recall Lar's papers are archived here through knowledgebase ... and other sites. An $8 vacuum can & a $5 mech advance spring kit ... carefully dialed-in ... does wonders for cars from early days of anti-smog era (ie 71-81 C3).

This a new idea... where can I find this LAR's papers???

79 L-82 just waiting for those new ideas.

 

[page62]

www.corvettefaq.com

Lots of goodies on that site. Also check out Lars QJet tuning paper (the man is a genius).

 

[Ganey]

Ex. is first if your ex. is stock single. See Why Exhaust is problem for HP on 75-81
what many refer to as my Exhaust topic.
http://www.corvettefaq.com/c3/ganeyexhaust.htm

Depends on yr., for example the BB LS-4 or common SB L-48 w/ duals, then cam is first. Some may want to do headers first or maybe not at all- i.e. no headers for stock appearance.
Of course tuning is important, a part of any setup, but not the primary way to HP. Just standard operating procedure.

 

[vettepilot]

The very first thing that should be done is open a checking account that your wife doesn't know about, that way you get to spend money on mods without expaining why you need them.....
:L :L

The best way to go about modding is to first sit down and figure out just where you want to go ... high HP/TQ, street driven, track, low RPM TQ or high RPM HP. From there make a "road map" as to how to achieve your goals, what parts and machine shop work is required if any. Then determine if you want to do this in stages, or all at once... That previously mentioned bank account may be the driver for all of this.
If it's in stages, then you have to decide where you want to begin... bolt on parts such as headers, or tear down replacement such as heads, cam, etc.
If money is no option, then get the whole enchilada done at once.

vettepilot

 

[Jack]

Of course tuning is important, a part of any setup, but not the primary way to HP. Just standard operating procedure. /QUOTE]

Your info on exhausts ... particularly the restrictions of 2-1 is very good, grounded in reality and info I'd encourage others to consider ... even follow up on. True duals is sop for me ... but not so for other folks. Hence, the good info from you.

You're essentially right that distributor stuff is sop ... it is sop for you & I. But too many folks overlook recurve or are unaware of its importance as they get caught up in excitement of cams & headers etc. IMHO, a proper recurve (as opposed to factory settings) is probably the best bang for the buck a smog era C3'er will find. Applies to most other GM V8s from same era as well.

I tend to agree vettepilot's item # 1 !

JACK:gap

 

[LIRacer]

ok my turn.....

Free flow exhaust will give the bigest bang for the buck. I wouldnt do headers on a CAT car. After that find a shop with a Dyno and tune it. Unless you are going to go full dual exhaust route, I wouldnt do much else other then enjoy a great ride.

 

[lg78VETTE]

I recently just finished my 78.My neighbor and I did all the work.New performer manifold ;comps cam268h;true dual exhaust mid americastainless steel with dynomax ultra flo mufflers.Its just awesome I love the increase in hp and torg and the sound is just music to muscle carheads.True duals is the best and its not hard todo yourself and you can save some bucksMy silver aniversary has just9000milesand was top flighted scored98.Now I did what I wantedtodo next.Its your babyenjoy and do what makes you happy!