I think I'm just waiting on my paintjob to be completed and my break in miles to be done before I get my car back. I let Stephen know what I wanted in terms of drive-ability and longevity, and we ended up going with a low 9.2:1 CR on a 402 + ported AFR 225s + ETMC stg 2 blower cam + A&A S/C + meth. I was previously making about 570rwhp with the A&A kit, running on 325 Goodyear Eagle F1s. Was plenty enough power for me, not looking for any additional.. really just wanted to overbuild so it could handle a lot more than we'll be asking of it. Running 345 NT05Rs out back and NT05 up front, should easily handle all the power.

<you can ignore below this, it's not really a question and probably a waste of your time to read>
They say 1 compression point is worth ~4%hp, so that's about 7% loss since we are going from 10.9:1 (stock CR) to 9.2:1, all other things equal on a completely stock. I don't know specifically how the 1.7points of compression will play into total power lost, given that we're going from 6.0L to 6.6L and new heads, meth and of course it's supercharged. What I'm saying is, if being 1.7points down means always having 7% less power, then if I make 600rwhp (easy number to work with) then a 10.9:1 would've made about 650rwhp. But as I said I don't know if when you start going up in power, does the CR start to mean less, the same, or more vs. stock engine with no mods. i.e. Does making 600rwhp with 9.2:1 equate to 10% loss instead of 7%, or does the gap narrow to 5%? Not that it matters to me because, again, I'd be happy to hit 550rwhp and just have my car back

Anyway, I didn't ask for any numbers prior to them putting the A&A kit on because I'm not going to be running it without the kit anyway.. though I guess for the sake of this thread it would've been interesting to see what AFR 225s + 402 and a mild blower cam (though again without the S/C the cam choice wouldn't be optimal) would make.

 

I never saw much that would make me want to use anyone's ported LS3 heads on a stock cubed motor. Always thought those huge hogged out ports might do better on a stroker motor. Not the case?

 

Your losses from lowering the compression are higher. While N/A losses at peak only are equated to about 4% per point in compression, the losses are far greater with boost compression. Where you lost big time was at all TQ values under the TQ peak. As Powerlabs will tell you with his build, the TQ losses were staggering as was fuel economy.

I never understand why someone would lower compression like that given the staggering number of cars running 600rwhp on stock compression with the stock cam and no meth. I mention the cam because any cam you choose after stock closes the intake valve later lowering dynamic compression which you compensate for by raising static compression. I can think of no build that would require 9.2:1 with meth even at 900rwhp. If you're at higher altitude, all that goes out the window from lower cylinder pressures.

Meth is 115 octane. 600rwhp on pump gas is fine at 11:1. At 115 octane, its past overkill. You can run it way leaner at least making it cleaner.

Aintqik's car was 768rwhp at 11PSI/403/ETP 225 heads, 236 cam......10.5:1. JT head unit (1450cfm) on 93+meth. Without boost he was in the 520rwhp range. That same car would hit 550rwhp retuned for N/A with meth activated by MAF frequency. It had a really smooth idle on the 11 degree overlap cam which is typical of strokers.

I wouldn't lower compression for any car under 650rwhp with meth.

 

I had seen a before/after dyno result showing gains of 20/20 on stroker motors but that was the porter selling his product. LS1 tech is full of strokers making 480rwhp with ported heads.

I have a 416 stroker with advanced induction heads getting ready to be tuned soon. It will tell me the whole story because its an N/A build and I'm doing the tune and the stock LS3 head swap for comparison.

Seeing the limited gains (or losses) ported LS3 heads make, it makes you wonder why no one is willing to try a Trick Flow 235 on the LS3 6.2L. You can sell the stock LS3 heads to offset the cost some.

 

I'm printing that for the shop wall. Its perfect.

 

To be honest, most of the numbers I've seen on decent built strokers in the 402-416 range are right around the 500whp mark and slightly over. I think its easier for a stock LS7 to hit the bigger numbers b/c of the bore stroke relationship (bigger bore) and less rotational inertia (titaneum rods.)

 

Quite a bit of dyno numbers are being thrown around, does anyone have trap speeds for these setups mentioned? I think this would tell the story better than peak rwhp figures that certainly can be manipulated. A lot of people mention the trick flow heads over the AFR's. Any reason? I'm sure I'll be in the market for a set of heads during winter downtime, so I will have quite a bit of research time before I make a purchase.

 

As have I. I can see ls7 cars pulling these numbers, but they are also working with a decent amount more CI. There are a few stroker c5's for sale on this site and there numbers may seem low to some. They also are equipped with Trick Flow Heads.

 

I wonder how the big (235+) catty port heads compare with ported LS7 stockers?

 

The reason is the same one you quote here: track results. The dyno numbers for the most part agree with the track results. The fastest cars on the 1/4 mile challenge are LS2's powered by Trick flow 225's runing 10.5's (the 235's fit the LS3 bore). The power they make on the dyno are 520rw while the next closest LS3 head cammed LS3's run 500rwhp and run 10.62-10.66 for the fastest ones.

While your post is a valid point, altitude, track prep and driver will be cited as reasons to not be able to compare track results.

If you're going to dismiss dyno results, there isnt much you can go by. People like myself are selling nothing. If I post dyno results of cars I tuned (for free) only an azz would cry foul stating the results are manipulated if I'm not picking the parts and the comparo is on the same dyno. Now track results at Bandimere raceway with its 7000' average DA would mean nothing if I posted them.....I have plenty if you're interested. A cammed Z06 with nitrous running 134 trap speeds isnt going to show you what it will do at Atco in NJ with a neg DA.

Dyno's are corrected and the same dyno for a head swap or motor swap is valid only to compare those specif parts to each other and give a data point. Anyone saying otherwise, please contribute something yourself to get scrutinized before bashing (last sentence not intended for njgreg). I share this info based on factual installs and tuning on two dynos (Dynocomp and dynojet 248 with current software). I dont get paid for this and most people who have come to me can say, I'm not in it for money. Most of what I do is free and heads back out for a cause.

 

Yea, this was kind of a general response to a lot of speculation ongoing in this thread from several posters, as there are a lot of factors at play. Reading back through there are some comparisons to the LS7 with stock heads and a cam making such and such numbers so a stroker with w cubes should be making... But it doesn't necessarily work that way.

 

I have given H/C parts/specs for a Katech based 427 using a 427 with TRK FLOW 235's and a 236/242 cam and through an auto its abot 600/580. The LS7 heads cost the same and make a very good result more geared to top end while the TF's are better low end. I've seen 630/590 on an LS7 based build with a huge cam.

Keep in mind TF has much bigger heads with LS7 ports....255 and 265 cc LS7 port heads.

The TF 235's fit the LS3 and LS3 stroker, the LS7 heads dont.....they are for a 4.125 min bore.

 

A 3.905 bore will never match a 4.005 or 4.065 bore for power. The LS3 heads on the LS3 make up to 500rwhp. I've never seen better than 480 with them on an LS2.

It follows that the 383 strokers will never match a 403 with the same heads, cam, builder, ect. Its displacement but its also shrouding. As 99BlancoSS said, its the combo, not just one part that makes a build. The LS3 heads are shrouded on the 4" bore.

 

Spin, could you post the results of the AI heads (are they 243's?) vs. the stock LS3 heads? I have CNC'd 243's by AI and am curious if they can match the ability of the stock heads. I understand that this is on a 416 stroker (I have the stock LS2), but I'm still curious.

Also, I go on the dyno again Monday, 8/8. I'll give you results as soon as I get them.

Sean

 

Holy.....what a nice turn around in this thread, some very good information that is very difficult to gather other than hands on

Some clarity regarding less than stellar output from the stroker builds!

I really believe mine is over cammed & I will deal & dealt with it accordingly, this thread & the last several posts have helped confirmed my thoughts.

To those who have had cam spec'd as I have the suggestion's & recommendations are that only. We/I still have the responsibility in the end to educate ourselves & make sure the end result is where we want to be.

 

That above doesn't seem accurate.

 

This thread has been so far off track, is this relavant....I'm very respectful of who you are. Maybe explain how your post & the original topic relate?

 

Well, in all fairness it is quite relevant as Cartek actually had two 10.5x (and a few other 10.6x, 10.7x and 10.9x ones as well) NA heads & cam 5.7L cars way back in the day...robz happens to have been one of them.

But Spin is not entirely mistaken there as the cams used in some of the other 10 (and 11) second Cartek NA 346 heads/cam cars might've been in the 224 range but the 10.5x cars likely used one a little bigger (not ridiculously huge, just bigger).

 

Maybe consider the extra info a little "bonus". I sure didn't mind it a bit

 

Hey Spin, let me start my response by saying your posts are always informative and you are one of the few members that actively tries to contribute to the forum with useful information and hands on experience. Without posts by you and other smart guys, this forum would be a lot less useful. What I wrote below may sound like I'm playing Devil's Advocate, and the internet doesn't let you convey emotion, so I'm not trying to call you out or one-up you in any way - I'm just throwing my thoughts out there and kind of "thinking out loud". I'm often wrong on subjects I know little about, but I've been on a learning spree for the past couple of years so I've just about scratched the surface at learning the basics Again thanks for your helpful posts.

Figures that it wouldn't be a static % loss across the board. All other things being equal, going from a stock bottom end LS2 with stock heads to a 9.2:1 402 with AFR 225s, should the longer stroke and better flowing heads end up making more power with F/I over the stock setup, at a meager 6~8psi? I've not seen or heard anything as of yet for my dyno numbers, so not sure how the TQ curve looks compared to what I had.

Not quite apples to apples there, because he did not go with a stroker, he did not swap heads, and his engine had some serious issues.
Link to thread
He pullied down, lowered compression a point and installed a blower cam, and lost ~20/20 across the board (before he added meth I believe) - but he also had a ton of oil build up and he ended up having LME build him a different engine. Here's a post from Doug@ECS in that thread:
PowerLabs' unfortunate and terrible results that he had fixed, doesn't really correlate in my mind for how a properly running engine would run. In fact, he did not rebuild at 9.8:1, but at 10.5:1 which is still under stock CR.
Link to the second engine swap thread
After the rebuild and tune at 10.5:1, he made 684rwhp vs. 620 with the "problem ridden" engine mentioned above (with meth) at 9.8:1. If it had been built correctly who knows how much smaller that gap would have been. I just find it hard to believe that 0.7CR loss would account for a 10% power loss. That would mean at 9.2:1, which is over his CR loss, he would have been making >20% less power... so 550rwhp@15PSI? I think that's insane and simply don't see that happening. But I'm not an engine builder and I'm just using your example, if I'm wrong please correct it

My reason is because I do not care to make a certain amount of power, I just want the engine to last a long time. If I'm leaving 250HP on the table, I don't care. I've been making my monthly payments for 10 months now, on a car that I cannot even drive because it's in the shop. I'm ready to get my car back and never be without this long ever again. I tried to convey that to Stephen and let him know I want a solution that will provide a compromise between longevity, reliability, and an increase in power (over stock).

Well I'm in Dallas and don't take road trips to Denver, so I don't have to worry about altitude I'm not running 100% meth, it's 50/50, and it will only come on at 3 or 4psi - again I had Stephen set it up for safety, not to make more power or increase my dyno numbers.

For argument's sake that's actually a better comparison to PowerLabs car because he has 10.5:1 as well. 684vs.768:
84rwhp more from a 403+225, with 11PSI vs. 15PSI and JT vs. T. Both are gas+meth.

I'd be curious if the only thing that changed on Aintqik's car was reducing to 9.2:1, how much power would he lose. There might not be a 100% sure way to answer that, but if PowerLab's results at the top of this post were any indicator (which again I think are flawed because the engine wasn't running right), he would be making ~18% less power, or 629rwhp.. just seems super low for 11PSI. Maybe that's right though