Engine upgrades
Le Mans Master
Joined: Oct 2007
Posts: 7,474
Likes: 990
From: RI, Now Franklin/Nashville TN
You wouldnt by chance have dyno'd yours since the upgrade have you? I put the same heads(58cc instead) and a little but smaller cam in mine. Air gap intake, side pipes and all pollution crap deleted. Just curious as I have dyno'd her. About 8 years ago prior to heads & cam, it dyno'd at like 230 to the tires...was a little disappointed. I want to get it re-dyno'd but dont wanna be disappointed again...
With that said the OEM L-82 with no emissions, shorty headers/2.5 Duals, Holley 4175 650 CFM spreadbore carb, 882 heads, L-82 flat tappet cam .450/.460 with poor compression (very weak Cylinder #6) did 233 RWHP on the dyno.
I can tell you this much..the new L-82 355 has a ton MORE power than the OEM L-82 and pulls VERY hard from 3,000-6,000 RPM and is still pulling strong at 6K. Based on the comparison to the OEM L-82 (233 RWHP), my 2010 Z06 (450-460 RWHP) and my Lexus IS 350 F Sport (306 net HP versus IS250's I have driven with 204 Net HP-same car, same transmission, same weight), I would guess an easy 100-125 MORE RWHP for the new L-82 355. As it stands right now, I would guess about 400-425 Gross HP/315-325 RWHP. AR LTH headers with the tune should be good for another 30-40 HP..
There is zero comparison between the OE L-82 and the new L-82...its VERY apparent throughout the whole RPM range..
As reelav8r stated the stock L-48 has VERY low compression and even with those 58 CC heads assuming a good bottom end compression at best is around 9.2:1, probably less. The flat tappet cam at .470 is only very slightly better than the L-82 and a ton less than a roller (much better ramp profile) with .525-.560 lift...thats a big difference in compression and cam lift not to mention a flat tappet profile.
Last edited by jb78L-82; May 26, 2015 at 12:46 PM.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
What do you mean something seems wrong?
AFR eliminator heads(58 cc), comp cam(270 dur/470 lift), comp 1.6 roller rockers, edelbrock air gap, k&n breather, smog/egr/etc all deleted, march underdrives, holley 650, dewitts dual electric fans, msd distributor w/ msd wires and hooker headers.
AFR eliminator heads(58 cc), comp cam(270 dur/470 lift), comp 1.6 roller rockers, edelbrock air gap, k&n breather, smog/egr/etc all deleted, march underdrives, holley 650, dewitts dual electric fans, msd distributor w/ msd wires and hooker headers.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
I think bluedawg thinks that you should be making more power. I would tend to agree with him.
Could be that cam duration and lift are a bit low, carb or intake (depending on what you got for intake) possibly restricting it.
I'm running Dart SHP 180's with a 270 duration and .549 lift roller cam with side pipes through a TH350 and 3.08 rear, Q-jet carb, dynoed 262HP at the rear tires.
Biggest difference I see is your flat tappet cam. You have better heads than mine.
OP, if you have the mechanical ability, a complete rebuild is really the way to get the power you want. If you put on small chamber heads on the current bottom end you will get more but it might not be as good as you want and it may burn oil due to poor ring seal.
The stock compression on a L48 is 7.66:1. I cc'd the pistons and the heads.
So if you plan on going smaller combustion chamber heads use 18 cc's for the piston volume. Post #31
https://www.corvetteforum.com/forums...er-size-2.html
Could be that cam duration and lift are a bit low, carb or intake (depending on what you got for intake) possibly restricting it.
I'm running Dart SHP 180's with a 270 duration and .549 lift roller cam with side pipes through a TH350 and 3.08 rear, Q-jet carb, dynoed 262HP at the rear tires.
Biggest difference I see is your flat tappet cam. You have better heads than mine.
OP, if you have the mechanical ability, a complete rebuild is really the way to get the power you want. If you put on small chamber heads on the current bottom end you will get more but it might not be as good as you want and it may burn oil due to poor ring seal.
The stock compression on a L48 is 7.66:1. I cc'd the pistons and the heads.
So if you plan on going smaller combustion chamber heads use 18 cc's for the piston volume. Post #31
https://www.corvetteforum.com/forums...er-size-2.html
