06SCGT

Any one running these cams? I have been fighting what I think is a tuning issue. Cams are in time with TDC of #1, but the new DSS PRO MOD 5.0 (stroked 4.6 3V) is down about 150 HP. I run an I/C KB 2.6 with 12PSI and GT500 Fuel pump on my stock heads. compression ratio is 8.6:1.The fuel and timing appear to be within its perameters. I have had the S/C checked by KB and all is ok! I am not sure with the new phasers that come with the cam kit are my issues. Getting frustrated and about to go back to the stock cams and phasers to try and eliminate problems. Would love to talk to anyone that has tuning experience with these cams.

GT Bob

What exactly is going on? Describe the problem as precisely as you can, as well as your setup both before and after the cam install.

8cd03gro

talk to comp. In any case, you shouldn't lose THAT much power. I don't know as much about the 4.6 as the 4.0, but what kind of power were you pushing before. Valve float maybe? who's your tuner?

06SCGT

I had the stock 4.6 that I had installed the 2.6 KB with 9psi and it broke a connecting rod. I then had DSS build me a bullit proof stroked 4.6 that I put my stock heads on. (I had them checked out and repaired the 1 valve that kissed a piston) At that time I deceided to go with the compcams blower grind to help make more power and to get the lopey idle. I did the phasers,springs and retainers that comp said was required along with a 3000 rpm stall conv. I changed out the KB BAP for a GT500 pump to make sure I didnt starve this new monster of fuel. It started right up the first time and I broke it in before taking it to the dyno (I broke it in on KB 92 oct. tune) once I got to the dyno the tuner installed his tune after we spoke about the changes I had made to the engine. The first pull it made 330 RWHP @ 9 psi and I thought wow what a POS!! We then installed the 12psi pulley and it made 10 Less RWHP!!! asked the tuners what they thought and they said the blower wasnt effeicent (although the dyno showed 8.99psi and 11.93psi) They had me check the engine out for a restriction in the intake system ( look for a rag he says...lmao, I am a little better than that, but I looked and yeah, no restrictions) Fuel curve and timing are within a safe perameter. I sent the Blower back to KB and after a week and half it checked out fine!
while waiting on the blower I checked cam timing 2 times on 2 different days and it is in time with #1 at TDC. The car starts fine but runs like poop! it acts as if it is a 2 stroke engine (runs decent on the upper rpm) but still only 320 RWHP. it also sounds as if it is loading up at lower rpm. I can hear the Phasers more now than before. I am at the point where I am about to put the stock cams and phasers back in the engine to see if that could be the issue being its the only real thing that has changed since it broke on 4-1-08
any help would be greatly appreciated!

GT Bob

shooting from the hip here, because to really give you a solid answer I would need to plug into the car.. but I don't think the problem is the tune.as long as your AFR's are in the 11.0 range at WOT. timing should be low 20's to start, and add as it will tolerate. I know that you said you checked the cam timing twice, but have someone else check it for you. I know many times I saw what I thought, instead of what really was and had issues.. one of the cams may be like one tooth off or something. next I would check the ignition parts... in fact, I would double checkl all my sensor connections too. make sure all your connections are good, and every coil is getting juice. After that, my next stop would be a compression test.

Last suggestion.. switch shops. Anyone who tries to pawn off a serious problem like that as a blower inefficiency is trying to sell you something that stinks. I would get everyone involved too... DSS, Comp, and Kenne Bell. maybe one of them has seen a similar issue,

forgive any typos.. typing while holding a 3 month old wiggle-monster.

zkiller

Isnt that compression a little low there? 8.6 to 1 seems low to me. If I was to build a motor for forced induction I would be 9.5 to 1 myself.

06SCGT

I went with their suggestions on the CR. I have read on another site that possible the valve springs supplied by CompCams may be to weak and I am having valve float. I am not sure that changing shops at this time is the answer, they are really concerned and willing to help out. I didnt realize that the cams are as new as they are and possibly Comp needs to re look at what springs they are suppling?

GT Bob

Valve float would account for those symptoms, tho having it at low RPM's is unusual unless they are completely incorrectly sized. Might be a place to start tho. The shop... well, if you trust them, and they seem to be looking past their initial statement at this time, then thats your call. From what you said at first tho, sounded like they were just trying to pass the buck. If they have stepped up, then thats cool!

Give Comp a call and see what they say about the springs. Maybe they will be a stand up company (and they are usually one of the better ones) and try swapping out your springs for better ones at no charge to you, besides labor.


AS for CR.. mid 8's for a supercharger, especially if your looking for anything over 12 psi is about perfect. I would tend towards the low 9's for a turbo, only to help put a bit more heat into the exhaust and help the spool up.

Hufenstang

I have a forged 4.6 liter with these same cams, I recently had it tuned in summer texas heat and humidity at 101 degrees and pushed well into 500rwhp at 14psi. Something definately isnt right somewhere, im not sure when you bought your cams, but when these first came out they recommended a spring with the cams that was way too weak and they had to switch it up to a stiffer spring. If you have one of those weak springs it could definately be causing your problem.

06SCGT

That is what I am finding out, they sent me part# 26113-24 and I have been told they are to weak (seat pressure) and I may be experiencing valve float. I bought the Cams, Springs, Retainers and Phasers the first week in July (08) with my DSS Super Mod short block and I have been dealing with this since. I have made an appointment to have the stock cams and phasers reinstalled. Now I hope that my converter stall isnt way out of range with the stock cams, just another item that was changed because of the cams!!
If I knew for sure that new springs would fix my issues I would change them, but I am not certain and I am tired of throwing money at it.