Hey all, I will start simply listing the current mods

2005 Ls2 408 stroker (eagles bottom end)
243 livernoise ported heads. (12+ years old heads)
kooks 1 7/8
Custom 2.5 dual catback
pat G custom spec cam 234/242 .629”/.615” 112 LSA +4 advance (ran when engine was stock cubes)
​​​TR6 plugs (.040 gap)
Fast 102mm manifold
nw 103mm tb
100mm ls3 style maf
3.90 Gears

Dyno on stock cubes with stock correction:

Dyno using STD correction smoothing 5 Stock cubes 6.0 same exact bolt ons.


Dyno using SAE correction smoothing 5 On the 408 stroker setup. Same bolts on and cam as 6.0 setup just more cubes.

A/F R and ignition system look perfect according to 3 different tuners.

Pretty lost on what else it could be. Spark plugs look perfect after 2k miles

 

6 speed I'm guessing.
Old heads
Cam for stock sized motor
1 7/8 headers 3" collector I'll assume-down to a 2 1/2" exhaust
HP falling off before 6k
I'm not sure what you were expecting but new cam and exhaust at the very least for improvement.
Nice smooth graph-motor is giving you what it has based on what you put in it and behind it.
You have long tube headers which lets motor make more power at higher rpm and then you choke it down with 2.5" pipe out back.
All imo obviously, I don't think there's anything wrong with the set up as far as looking for something in the ignition or the tune etc. You just have some parts that aren't maximized for the bottom end you now have. You can't compare your 408 to another 408 with better heads, better matched cam and better exhaust.
450 at the wheels is a nice number for what you have in it imo.

How's it feel driving around? Throttle response good? What's the compression ratio now?

 

Was going to say get a fast102 as the LS2 intakes royally suck but you already have that covered.

With that being said, that cam is too small for a 408.

I would sell heads/intake, swap for ls3 heads/intake and re cam.
​​​

 

What's your CR? heads were ported, but were they milled? ME 2006 LS2 fast 102 for cathedral ports, 90mm TB 100mm LS3 MAF body, 13/4 kooks into ZO6 mufflers, Trick flow "fast as cast" 220's, Comp cams 231-239 .617 lift intake, .624 exhaust, lsa 113 109 cl, First time on the dyno same thing disappointing numbers, actually lost HP from previous version. Then some people who knew of which they spoke, convinced me to pull the heads and have them milled, between 0.0025 off the heads and 0.005 off the head gaskets a total of 0.030 mill. IT WOKE IT UP! Back on the dyno and 495 rwhp and 489 TQ.. My guess your heads need to be milled and a combo of your gaskets too, I'm some where around 11.65 to 1 CR, don't go smaller then 0.0040 on your head gasket, you don't want to ruin your "quench" if you go this route you will have to figure out how much you can go, but my guess would be you have at least 0.030 you could lose. use a GOOD head gasket like a Cometic blower gasket and you will have no problems, remember your combustion chamber will get smaller so you what to keep the inside diameter of the head gasket as tight to the bore as possible, your local machine shop should be able to do this, LS heads need a dam near mirror finish, should be very very smooth after milling.

 

Here's what I did 3.5 years ago. TxSpeed heads and mild cam build - CorvetteForum - Chevrolet Corvette Forum Discussion

Substitute a bigger cam like the guys mentioned above. The above build is effective and not terribly expensive either. I have about 35K miles on the build. Still makes me grin every time I'm able to drive it. The Livernois heads are an upgrade over stock 243's but nowhere near as potent as CNC ported and milled LS3 heads. The ported and rod modded LS3 intake manifold is a good bang for the buck too. Don't know where you are CR wise, but 11.5:1 will make power everywhere along the curve compared to lower static CR's. Assuming 93 octane available. It will also help tame a bigger camshaft.

 

That's seems low from what my friend dynoed with similar build, Just go to another dyno shop tell them what your problem is and they'll fix up.

 

Hey guys thanks for tuning in. I've decided to change a few things. Come to find out my static compression is actually some where around 10:2.1 which would explain a lot. I just ordered an M311 Frankenstein head for this setup and possibly swapping the -15cc dish pistons from some flat tops to boost my CR. Waiting for Pat-G's custom spec cam for the next setup. I will keep updating on results. The person who built the 408 now has an in-house dyno and will run current setup first to see how much power he is able to squeeze out before changing Heads/cam. Might possibly even leave the pistons just to see what it makes although with 68CC chambered heads compared to the 64cc 243's it will considerably lower compression even more.

 

There's always a reason.

And you had dish pistons to boot.

 

I had a 416 that was an absolute dud, fancy everything. Spec'd by LS guru that everyone admires, it was a slug @ 518rwhp. Besides no power it was the worst running POS I ever owned. Get to a different dyno the LS guru said.

Staring @ the car wondering what to do next as I had tried everything I decided it had to be the cylinder heads. The heads were supposed the latest greatest thing with special hand porting for those last precious power numbers.

I started calling various cylinder head guys & finally talked to Chris Frank @ Frankenstein. He was not familiar with that particular head, offered to flow bench them & check over. When he called the heads would never flow to my power expectation, the hand finish porting was not done. The combustion chambers had been polished to look pretty. Basically I had been stroked Ha!

Not wanting to screw around anymore I asked for his recommendations & ordered his cylinder heads.

This was the only change to the car, nothing else. I drove it on the street & recalibrated the AFR, the power difference was major.

Back to the dyno, first pull was 596rwhp. It ended up @ 604rwhp. This is cylinder heads only, no cam change, no intake change & no header change.

 

Those are amazing numbers. Just trying to clarify. Are you saying you also had livernoise ported heads and went with M311's?

 

No, they are a rough cast cnc TF 235, Frankenstein finish's the porting to their spec retaining the 235 port. Then he had to weld the combustion chamber to get the compression back. I had the wrong pistons for that cylinder head, the original build with the POS heads was a smaller combustion chamber.

The power numbers are reasonable, 427's are easily in the low to mid 600rwhp these days. Mine was not a budget build, I did not cut any corners & not likely I would ever do it again. It's hard to find the guys that can walk the talk, I believe Chris Frank is one.

This is with a very streetable 4.5* overlap cam, anyone can drive this car without a drivers meeting or any pedalling of the clutch.

 

Driver's meeting? That's just rich

 

I've just re read your thread, I'm confused with your comments stock correction & STD correction. Dyno reports are either corrected or uncorrected, weather & elevation have significant impact on what is displayed regarding power. Repeatable & consistent numbers are difficult on dyno as many factors are involved, corrected numbers removes one variable.

It is difficult to get the same manufacture & model of a dyno to report the same nevermind different shops, when tuning you chase gains & losses more so than peak numbers. Weather, elevation, tires, air pressure, tie down procedure all become factors......they need to be consistent.

You are showing different dyno's in your thread then the stock vs STD correction, smoothing won't have a significant impact. Looking @ your list of mods for the LS2 including gear ratio, on a dyno jet I'm suspicious the accuracy of what is being displayed....as in possibly flattering.

Then I look @ the stroker, different dyno. I think of all the variables I mention. Did you go back to the shop that dyno'd the LS2? If so do you have those results?

Cam timing, I do not see any mention if it was degreed or not? That is a major known or unknown when chasing power. Peaking earlier than the LS2 brings that question to mind.

Chasing a low power issue myself I learned about the cylinder heads air flow. I did make marginally better power with my POS heads same dyno, so there was a small improvement. Just not what I was looking for, when you have a bigger motor it needs more air that's not hard to understand. I believe that choke point becomes even worse from peak torque when you want to carry that number as long as you can for peak HP.

My original stroker was spec'd, built & dyno'd by big names. That shop claimed 535rwhp on a Mustang in ground dyno. Not bad I thought, 550rwhp was my target. So I made arrangement's to visit a Dyno Jet shop on my return trip home after picking up the car. I will never be able to express my disappointment how badly the car ran when I picked it up. Worst running POS I ever owned & it was tuned by the big name pro. Adding to my grief & misery was the Dyno Jet reporting 518rwhp. My BS flaps were already on hi alert & this just pegged the meter. Dyno Jet reporting less than a Mustang dyno, that was confirmation how badly I had been stroked.

Here are my cam spec's for you to compare 231/243 .637/.627 116+3. This is full roller rockers with a good wipe pattern & morel drop in lifters, correct pushrod length after shiming pedestals for wipe pattern.

 

Those pistons were a fair part of the recipe, no doubt. Ill re-read the thread again, but I suspect the heads are also part of it........

 

After reading again, I feel the cam is not terrible, but if the OP is looking for even 600 crank, the cam and heads he has will never get him there. I don't know if that FAST intake would match up with AFR 245s, but if it does, it would save a grand towards another intake. I'm not knocking the ported LS6 heads OR Livernois. But those heads are nearly a 25 year old design, and won't match the 245 AFRs OR the LS3 heads. If it was me, I'd go for the ported LS3 heads, and MSD intake. See how easy we can spend YOUR $$$!! Anyway, if you had the above setup, 11:1 compression, a 240° intake/248° exhaust duration, or maybe a bit less duration, say 236°/244°, with around .630" lift on a 112°-114° LSA, and ported LS3 heads, it may not be a grocery getter, but it sure would be an *** hauler!!! My opinion, YMMV

 

I have pretty much a whole new top end ordered now just looking at camshaft options. I have gotten a custom spec'd sheet from pat g but undecided between 3 camshaft options ATM. My power goal is to shoot for atleast 550whp. Drivability is not a major concern for me.

3 options:
Pat G spec: 245/252 .629"/.615" 111LSA +4
Cam motion stroker:244/256 .621"/.604 112LSA +4
CM raceday stroker: 252/264 .646"/.629 112LSA +4

 

Old thread but i Want to update you guys nonetheless.
still on the same exact short block that was built for boost. What i had my mechanic/tuner do was to deck the heads to increase static compression to about 12:1. I upgraded the heads to some frankenstein M311 (rectangular) and BTR recommended their Stroker V2 camshaft. Running a stock Ls3 Manifold and stock 92mm TB. The car made 530whp and 503 TQ on a dyno jet. Will swap to a BTR trinity manifold along with a Nick williams 103mm in a few months. So far it seems the compression and camshaft change with more lift did some magic on this build.

 

interesting, I have a 408 being built as well and it'll have a big cam 246/266 looking to go with btr trinity and nw 103 trying to spin it until it can't as I will Johnson lifters . . . I was hoping for closer to 600 maybe but it looks like I need to readjust my expectation i'll follow for the update. what clutch did you go with?