Crowhater

I am in the process of changing some things on my set up and I am looking for some advise. When I had the engine put together last year I felt pretty quick that they had over cammed the engine. After talking to several shops and friends I have ended up with all kinds of suggested cams, been told my heads are the problem, you name it. I had a leak down done on Monday and my lowest cylinder is 12% so I know the engine is still good. My specs are in my sig and my compression is 11.1. The car had a 2.77 rear diff and I changed it to a 3.42. It has a 5 point cage, belts, Hoosier drag slicks, m&H skinnies up front. I drive the car a couple times a week but not everyday. My in town MPG is 6-7 and my hwy is 15-18. It was built with nitrous rings and filed a little lose so she drinks about 1/2 a quart of oil every 1500 miles. I have HPtuner and I scan my runs, I also have a wide band A/F. It runs speed density down low and goes to MAF about mid way up the rpm. This is not a 100% drag car, I like to drive it on the street and I want to keep an aggressive cam lope at idle.

Right now the shop is changing my engine mounts, adding two B&M fan Trans cooler, and a Trans/diff brace.

Any inputs would be greatly appreciated

DietCoke

iTrader: (18)

i have a similar cam (251/259, same lobes) thats a little bigger, except im using ls7 rockers so mine is .670 lift or so... and i get ~9mpg town an 15/16 hwy on e85 with a 4400 stall and a 4l80 in a much heavier car with 3.91 gears.

I dont think the cam is your issue... and there is no reason for you to be on speed density at all, ever. MAF everything... the e38 is 1,000,000 times better then the old ls1 pcms.

Crowhater

We had a real nasty random lean spike that we chased for months. It just showed up one day and I had the world look at my tune and scans. We changed everything electronic, including the engine wiring harness and still could not get rid of it. For some reason the 80th time we purged the tune and uploaded the new tune the spike was gone. It also destroyed three 6L80 transmissions in those 3 months. This car has alway been a tuning pain in the butt.


Back to the problem at hand, I want to find some more power. SDPC made some big claims on the heads I have so where is my 550rwhp?

Crowhater

The auto c6 Corvette comes with a 2.73 rear diff and I changed to a 3.42. The 3.42 ration with the gear set up in the 6l80 makes a good combo. If I went any lower 1st gear would be worthless.
Gear ratios:
First:
4.02
Second:
2.36
Third:
1.53
Fourth:
1.15
Fifth:
0.85
Sixth
0.67


I know I need to do something but I am not 100% sure what I need to do the car should make another 40rwhp. As the car sits it is 505-510rwhp.


Video

egod

iTrader: (1)

you could lighten up the valve train, run an under drive pulley, electric water pump, basically everything to reduce parasitic loss. Without seeing your tune I'm sure but can you run a higher octane and add some more advance.

WKMCD

iTrader: (2)

You could paint it bright red and put wings on it...or you could put the right cam in it.

Crowhater

I think the cam I have is incorrect but I have people telling me it is fine. Others are telling me the heads are the problem. I don't not plan on buying anything until I get the issue nailed down for sure. This is why I am asking for advise.

I did not do the underdrive pully because the car already runs hot and will over heat in traffic. I have the biggest radiator and dual fans. They are installing twin B&M Trans coolers with therm controlled fans right now. When it gets out of the shop I am getting the hood vented also.

My Hinson front motor mounts split so they are replacing those and installing a Trans/rear diff brace I had made in CA. For some reason you can only buy them for standards.

egod

iTrader: (1)

most of the time a cam is trial an error because there are so many factors involved. If I were you I would contact a cam manufacturer and get their expert option based on your set. They have millions of dollars in R&D to know what works best. Its better than buying cams at $400 a pop and since you don't plan on doing that I would start there. I was under the impression that the 40 HP you were looking for was with that cam.

Crowhater

I have contacted Comp and several shops but everyone keeps telling me conflicting things. " my cams to big, it's not big enough, I need new heads, I need to get my heads hand ported ". From what I was told and the reading I have done on the site it looks like a bunch of you guys know this stuff foward and backwards. Who would be the Expert I need to talk to so I can figure out what cam I really need.

My camshaft knowledge is basic, I have no idea about ramp rates and things like that.

egod

iTrader: (1)

The biggest factor or a cam, or the one that has the biggest impact is duration. That is probably what they are referring too when they say too big or small. I would not tell them what you have, I would ask them for a recommendation. Get a few recommendations and see how they compare. Changing the LSA can fine tune a set up once you have the lift and duration that you want. The other two recommendations that I have are to find people with similar set ups and see what cams they are running. Lastly grab some dyno simulations software and plug in the different cam profiles that you like on the market. Reach out to the techs on at summit, jegs, and of course all of our awesome sponsors here.

DietCoke

iTrader: (18)

Dyno #s dont mean much unless its locked up, then you can get some idea of where you're at. What is it running at the track

Crowhater

I agree, I have never cared for dyno numbers, Track numbers never lie.

The car runs the 1/8th in 6.6-6.7 @ 101-103mph with a 60' of 1.42-1.46 with the old 3000rpm vigilante stall

I have only made a few passes with the new stall 3800rpm circle -D triple disc. It is going to take some adjustments to get my traction back and I need to figure out the best rpm to load it. My 275/45-17 Hoosiers are giving me traction at 16psi cold but the car is rebounding and blowing that traction away