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Old 08-24-2007, 02:32 AM   #1
raceman
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How to get more HP out of an L48

Im just an owner of a 350 corvettw -74 350 (L48 I guess)with 4 speed gearbox. Standard engine less than 200 horsepower, it is not good enough. My knowledge have to be improved about V8 engines. I want 375-400. I got when I bought the car some new parts: Cam Erson E110421 (296 IN 228 IN .472" IN 108. 0 .000" IN. 5750. Hi-Flow IH) Edelbrock intake, Edelbrock carb 650 Thunder AVS , and headers. Next step have to be something with the heads and comp I guess. What ? Can anybody give me some support?

Thanks

Last edited by raceman; 08-24-2007 at 03:27 AM.
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Old 08-26-2007, 04:55 PM   #2
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Old 08-26-2007, 05:09 PM   #3
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Quote:
Originally Posted by raceman View Post
Im just an owner of a 350 corvettw -74 350 (L48 I guess)with 4 speed gearbox. Standard engine less than 200 horsepower, it is not good enough. My knowledge have to be improved about V8 engines. I want 375-400. I got when I bought the car some new parts: Cam Erson E110421 (296 IN 228 IN .472" IN 108. 0 .000" IN. 5750. Hi-Flow IH) Edelbrock intake, Edelbrock carb 650 Thunder AVS , and headers. Next step have to be something with the heads and comp I guess. What ? Can anybody give me some support?

Thanks
New heads..................Higher compression.
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Old 08-26-2007, 06:00 PM   #4
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New heads..................Higher compression.
L-98 heads are probably the best choice.
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Old 08-27-2007, 01:50 AM   #5
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some decent-performing heads. a zillion choices out there, anything with Vortec, Fast-burn, and/or the current swirl technology (Edelbrock, Dart, Brodix, AFR). I think high-perf current-technology heads will make a difference (ASSUMING you have the intake and exhaust side sorted out).

you didn't say which Edelbrock manifold. if it's the basic "Performer", then you might consider the Performer RPM Airgap. or a single-plane like the Victor Jr, Strip Dominator.

if you already have headers, hopefully your exhaust is 2.5" with mandrel bends. and you have Flowmasters or some similar new-technology muffler.

and you're running a 14"x3" open-element K&N-type air filter, of course.
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Old 09-20-2007, 02:57 PM   #6
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thanks all for your answer
The intake I have is Performer 2101
I have a guy who whant to sell one pair of heads
Cast iron GM 333882 with 2,02 / 1,60 valves and slighly open ports The heads are after overhaul not used. Good chose?

morgan
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Old 09-20-2007, 07:43 PM   #7
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This thread is likely very helpful :


http://www.digitalcorvettes.com/foru...ad.php?t=82139


In a nutshell: moderate performance increase is easy and not too expensive. Most restrictive are your heads and exhaust. The cam isn't all that great either....

With decent aluminum heads that raise the compression to 9.5:1 or 10:1 (aluminum heads with 64 or smaller 58cc chamber), better cam (don't overcam the engine, 214/220 i/e dur with .500" lift at the valve should be sufficient) and free flowing exhaust it will run good
With your manual trans you can get away with a little more cam.... trade off is a little less low end power...

Resist the urge to buy the "hottest" parts you can find.... when I bought my '79 it had a bone stock L48 with 64cc edelbrock heads, a performer intake and a 750cfm Holley... and a Performer RPM cam (234-244 and high lift)... hardened pushrods and solid lifters..... all expensive parts but the engine ran like crap with the low compression.... even with flat tops it was only about 9.7:1 and too low for the hot cam....
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Old 09-22-2007, 08:48 PM   #8
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Quote:
Originally Posted by rpol98 View Post
some decent-performing heads. a zillion choices out there, anything with Vortec, Fast-burn, and/or the current swirl technology (Edelbrock, Dart, Brodix, AFR). I think high-perf current-technology heads will make a difference (ASSUMING you have the intake and exhaust side sorted out).

you didn't say which Edelbrock manifold. if it's the basic "Performer", then you might consider the Performer RPM Airgap. or a single-plane like the Victor Jr, Strip Dominator.

if you already have headers, hopefully your exhaust is 2.5" with mandrel bends. and you have Flowmasters or some similar new-technology muffler.

and you're running a 14"x3" open-element K&N-type air filter, of course.
Yes, don't forget the K&N!! Will give you up to 25-50 HP, as reported on the Internet!
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Old 09-22-2007, 09:18 PM   #9
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Quote:
Originally Posted by raceman View Post
thanks all for your answer
The intake I have is Performer 2101
I have a guy who whant to sell one pair of heads
Cast iron GM 333882 with 2,02 / 1,60 valves and slighly open ports The heads are after overhaul not used. Good chose?

morgan
any heads ending in ...882 are smog heads. Stay away from them.

I like my "upgraded" vortec heads.

Good Luck!!!
Chris
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