Bad06vette

How normal is this? I posted about my timing problems in a previous post...

Day was hot, but not much hotter than when I previously dynoed. High 90s.

My previous dyno #s 367/357 STD
Mods: Ported tb/intake, halltech cai, exhaust, tune.

New dyno #s 374/364 STD
Mods: Same + Kooks 1 3/4 headers, catless x pipe/mid, retuned.

A total gain of 7rwhp/7rwtq. Besides loudness, I did not feel much SOTP gain... nor did the dyno show much gain either.

I am pulling 3-4 degrees of timing every pull and my hp/tq curves drop off at 5k rpm, almost hitting a wall so to speak, and then trying to recover but its too late to recover much. You can hear/feel when the power kind of drops off a bit and trys to come back.

My previous dyno also pulled 3-4degrees of timing and we used torco and it seemed to solve the timing problem and I gained about 5hp/tq total and thats where my 367/357 number came from. Unfortunately, we did not have any torco for the new dyno #s.

What could possibly be the problem? I mean, even solving the timing problem would lead me to expect maybe 6-7 more hp/tq. But, even added with my gain so far that means I would have gained less than 15hp/tq from headers and xpipe... Something seems a miss to me.

My tuner told me that it was more than likely just bad gas and that everything else was fine.

Any suggestions? Should I have another tuner look at it? What else could be wrong?

Let me know guys, thanks!

PowerLabs

My dyno: Before: Kooks 1 3/4 JetHot Coated, Catted X-Pipe, GHL Exhaust, VaraRam Intake.
After: Same setup same day same dyno, but tuned:



Clearly something is wrong with your setup. The only thing that comes to mind is that I would take a look at the plugs and see if the plugs are fouled or if you have excessive carbon accumulation that could be leading to hotspots...

oneblackvette

I agree start with the plugs.

Maybe poor fuel.

I beat my head for 1/2 the day one time before the guys who car a was getting tuned told me he was running 89 octane.

Bad06vette

See, yeah, I would def expect to be around 390ish if not more... especially since my numbers are STD and not even SAE.

I don't understand what the deal is... I am taking my car to a new shop on saturday to get an unrelated issue solved and I think I might talk to them about what they think might be the problem and what can be done to solve it.

Bad06vette

I only run 93... period. Never will run anything buy 93.

The plugs I have are NGK TR55s and they are 2 months old. I don't see what would be wrong with the plugs? They are gap to 42.

PowerLabs

The numbers on my graph above were with California 91 octane oxygenated crap gas and stock plugs.
How many miles on your car?

Bad06vette

Just over 17k miles. Its an 06. I drive it daily, but most miles come from highway, driving to and from school.

PowerLabs

Mine is an 06 daily driver too, but 2 trips across the country coast to coast and several 1000+ mile weekends have me at 33000M, 22K of which during the last 4 months!
Well, if you can't advance timing it has to be either poor fuel or a hotspot in the combustion chamber. Or clogged cats?

Fore58

Melrose headers 1 7/8" , VaraRam, ported intake/tb and tune....378/366SAE. With headers, VaraRam and tune..... 360/356. Just with the Melrose headers and VaraRam no tune...343/340. The dyno was done in Florida's summer heat around 90 degrees. I did not expect anymore than that. And, I'm not disappointed with the numbers above. Also, this was a very conservative tune. I do not have a stock baseline. Unfortunately, I did not feel any difference by adding the headers with VaraRam and no tune....the numbers show it. My car is probably just as strong if not stronger than a 385-395 car on the street. For example, I had an 02 Z06 only with Halltech, Borla stingers and tune that dyno'ed at 375/359 also tuned in Florida. When your talking about SOTP both cars felt about even to me, with the exception that the C6 felt stronger on top end. Just my .02

Bad06vette

The new set up is catless. So, I don't see any reason for that.

What do you mean hotspot? They only thing I can think of is maybe the porting of my manifold was not done properly and because of that I am running leaner in a cylinder or two... even tho my A/F seems to be okay. But, I dunno if that is even plausable.

Bad06vette

My biggest problem and biggest fear is the fact that it was nearly the same conditions and I only increased dyno numbers by 7/7.

There has to be something wrong to go from 367 and add 1 3/4 headers, with catless x pipe and mids, and get retuned and only get a total gain of 7rwhp/7rwtq. Something is a miss to me...

ProgGod

You do realize you gained power by leaning out your A/F?

LSCHLEM

Can you post your dynograph. The dynograph should be useful in determining what may be wrong. You should at least be runnin
mid 380's on average and 390's if you have a good tune.

Wallacefl

Both this and the ZO6 forum had an apples to apples discussion about real header horsepower gains awhile back ...headers do add HP...problem is tuning is the key to getting the midrange bump they can give you. I remember when Kateck did the original bolt ons article on the new LS2 at the time..headers gave 20hp/tq in the middle but very little to no hp increase at the top! ...use search: ZO6 EXHAUST MANIFOLD...all sorts of interesting reading on this site...now if some tuner could come up with a package of stock ZO6 exhaust manifolds plus ZO6 headpipes with cats installed for about maybe $1000.00...sign me up

03 Z-oh-6

I gained 16 PEAK HP/TQ from Headers, X pipe w/CATS, re-tune. This is on an LS3, though. My final numbers are right where they're supposed to be with my mods, though. I guess my car breathed pretty well with intake, stock manifolds, and tune.

BOB EAGAN

Headers normally put out 25 HP, exaust 10 HP, headers and exaust 25-30 HP. Typically your header addition should add 15-18 more HP. Appears you are about 10 HP short. My 07 m6 dyno'd at 365 with Halltec, Corsa Sports and a tune. Your ported intake/tb should give 10 HP more. Don't know why your 20 + HP short, my guess is the tune. Good luck.

Ragtop 99

The fact that adding Torco solved your problem the first time and you didn't add this time means your 15 HP figure is a better measure of the gain. Was the 3* being pulled the timing that is pulled from high IAT temps or additional timing beyond that? (Ignore if the LS2 doesn't pull timing at 90* IAT like the LS3)

Do you have a 160 T-Stat and matching fan settings?

Powerlabs: Your graph is tiny, don't you have a bigger version?

PowerLabs

Well that is the only way to gain power: you either lean out the fuelling table or you advance timing
Stock tune as pig rich anyways; 12.6:1 is very conservative; I hear that most tuners tuning for 93 octane will do close to 13:1!

Braciole

Actually most tuners will also leave your car RICH because they dont want you to blow your motor from being too lean and coming back to them stating that the tuner blew up my car!!
Mike

AU N EGL

Or the new LS3s are just much better engines then the older LS6s.

So bolts on dont really help that much.

A tune is were the gains well be seen