LeftySS

iTrader: (17)

Recently installed some PRC stage 1 ls6 heads that were milled to 62cc and used a .045 head gasket. When I went to the track this last weekend my car ran the same MPH as when it was cam only. The weather conditions were pretty much the same as before. Since running cam only car received a k-member and I went back to 3.23 gears from 3.73? I was hoping the car would run at least 116mph. I do all of my own tuning and feel the tune is pretty good. I can post it up if someone wants to look.

EDIT: Final Dyno pull attached.

LilJayV10

iTrader: (39)

Did you recheck your pushrods length with the new heads? Did you run at the same track? DA the same, temp?

I take it you had 241 heads before?

I know you said you tuned it but has it been on a dyno? What's your AFR and spark look like?

Black 99 Bird

iTrader: (31)

You changed the gear from 3.73s to 3.23s? You said the weather was pretty much the same, how different was it?

LeftySS

iTrader: (17)

I did check the PR length and got 7.325. Oh I forgot to mention I replaced the lifters with the LS7s. Same track, roughly the same DA if not better this time. It was less humid and a little cooler.

No I had the 853s. No dyno tune just a street tune. As far as spark goes I am not sure if I am getting false knock or real knock. But don't see anymore than 2 deg pulled a WOT, that puts me at about 24 deg total. Is that too high for 11:2 CR with 91 octane?

LeftySS

iTrader: (17)

Yes. I broke a ring gear tooth and decided to go back to 3.23s.

Darkman

iTrader: (2)

So the "before and after" comparison involved two different sets of gears?

LeftySS

iTrader: (17)

Yes. Will gears make that much of a difference? Lets say I still had the 3.73 gear what should the car run? Just trying to figure out if the car is down on power, bad tune, or it is where it should be with the 3.23 gear.

Johnnystock

iTrader: (6)

Well, with the 3:23, you should get slower trap since youre passing the finish line not in your power band like with the 3:73...so I'd say your car is faster!

Darkman

iTrader: (2)

Gears make a significant difference and render the before/after comparison meaningless other than to indicate the gear change is roughly equal to the head change.

LeftySS

iTrader: (17)

Ok, feeling a little better i guess. I didnt think about it being lower in the rpms at higher speeds and not being able to pull quite as hard. What kind of mph could i expect with 373s?

LilJayV10

iTrader: (39)

I would also look into your knock. IMO I would think you still would be closer to 26-27 degrees even on 91 octane. I'm not a tuner so take its for what its worth.

NC98Z

iTrader: (1)

You should of picked up 45-50 rwhp from thoses Stage 1s. I agree somethings not right. There isn't that much difference between thoses 2 gear sets.

LeftySS

iTrader: (17)

It is a little hard for me to swallow a gear set being worth the same gain as a nice set of heads. I mean $1500 for no gain??

SOMbitch

iTrader: (8)

Something is not quite right somewhere. Those heads should be worth 30hp so even with the gear swap you should be .2-.3 quicker IMO....

LeftySS

iTrader: (17)

I feel the same way. I will post up my tune and a log i took yesterday, when i get home from work. Hopefully someone can point me in the right direction.

getusumws6

iTrader: (9)

what was your 60' before and after the gear swap ?

LeftySS

iTrader: (17)

The same 1.8.

LS6427

iTrader: (2)

Of course something is wrong............why use the same cam with a new set of heads? They have to be matched together if you want to get that ~40 RWHP out of them thats still on the table. Heads that breath more need a cam to allow it......

You obviously gained a little through simply having better flowing heads, lost a LITTLE bit with the gear change. But you should have seen a big difference....with a new cam.

.

thunderstruck507

iTrader: (18)

Well a 228R shouldn't be that far out of line with ported 243s.

Gears should not make enough difference to negate the gain from ls1 heads to ported 243s, especially not on an automatic car.

If you find out what it was be sure to post up!

01ssreda4

iTrader: (96)

No, no, and no. No yesterday, no today, no tomorrow. Absolutely not.

They do not make much difference in the autos, especially since he only back-tracked to a 3.23.

OP, something is wrong. Your 60 should be better, you ET should be better, and your mph should be better.