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912 Views 7 Replies 6 Participants Last post by  theghosttanker
I could not find the info I was looking for on the search engine. I wanted to know with cam/copression/bigger exhaust mods done on a 78 otherwise pretty much stock l28, would I see fair power gains by getting a better breathing intake manifold, or is it better to go with MS? And would any potential intake performance gains not be seen if headwork is not done?
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Headwork is where horsepower is made. intake an exhaust just release the potential of headwork. Depending on the cam and compression, the stock intake will be ok for small gains. Big gains the stock efi intake is too restrictive. If you are building a wildly modified race car, go with a log intake.
Just went from dish to flat top pistons, aboout 10-2 comp with MSA stage 3 cam 270-280 460 lift. Im not doing wildly fast just trying to see what I can get with these mods, or just most eficient for the money.
if you port your head and intake you'll have the potential for larger power gains, but you need the megasquirt to match the increased air flow with fuel. There is no way to adjust fuel on the stock ECU so the porting won't do nearly as much as it could with a programmable ECU.

your stageIII cam needs two things to perform, high compression (which the flattops give you)... and less restriction on the intake side (which the porting does). Personally I'd port the head and intake at the same time, cause just porting the intake just moves the restriction farther down the line (to the head).

for the money I'd megasquirt (which will give you a fair amount of performance and an increase in fuel economy most likely) first and then port your head and intake.

you won't find any numbers on hp/torque gains because there are still a lot of variables at play...but I wouldn't expect to see too much without porting the head. You've moved your power band up about 1500 rpm and at the top of the house...you'll be needing more fuel. Results will be tough to quantify
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Ok, well that sure answers my questions. Thankyou guys for your input on this.
I'm building a similar engine and will be using Megasquirt. However, I'd like to go with a "log" manifold but have yet to find a source for one. Does anyone know where I can find one. I'd prefer several choices if possible. Any help will be greatly appretiated.
Lonewolf performance has the log style intakes, of course they are not cheap...
lonewolfperformance.com makes performance intake manifolds. Or you can use the manifold from a carbed z-car, using two throttle bodies from efi cars, and injector bungs from summit racing welded into the runners. However...with either of these methods, you will need to use megasquirt.
It's kind of hard to say whether a megasquirt or a better manifold will improve your performance when you evaluate them singly. With a megasquirt on the stock manifold, you will be able to remove the air flow meter on the intake system. If I were you, I would either do everything at once, or if I couldn't afford it, do the megasquirt first, because doing the other mods (headwork, cams, manifolds, etc etc) will be much easier if you already have a megasquirt system in place to support them. You really can't modify the stock motor too much without changing the EFI.
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