During a cam removal, we noticed the cam bearings were bad, so I will have the motor rebuilt with some forged parts, including valve relief pistons. I will be using a G5x3 cam, with Absolute Speed stage 2 5.7 heads that have been milled 5 thousenths, but will eventualy add AFR heads on it. I am not sure how much compression would be good. I dont realy want to mill the heads to do that, since new pistons can determine the compression. The car is a daily driver, and will be sprayed once in a while in the future, but not any time soon, and not that often. Any ideas? thanks

 

I think something close to an 11:1 compression ratio would be a good compromise between performance and trouble-free motoring.

 

 

Thanks 11:1 it is. thanks

 

that would be optimal for max power/driveabilty/effeciency

 

Hi, I have an 04 GTO. I just got the GM Lingerfelter cnc'd ZO6 heads installed (Gm part # 88958622) with a Lunati 55004 221/221 cam (the installing shop's recommendation). I think the static compression of the heads is 11.1. The car also has a K&N CAI and Stainless Works LT headers and 3" catback system, with no cats, and a 160 thermostat. I only use Shell 93 octane, which is what is was tuned on.

The car pulled 386 hp on their Mustang Dyno during the tune. After driving it for a few days, I noticed it was consistently stronger until the car ran for 10-15 minutes (the engine bay gets really hot now with the SW uncoated LT headers). After the car gets hot, it is easy to tell it loses power. So I took the car to a local shop with a DynoJet (the shop I used for the installation is a couple of hours away). It pulled 410 hp on the 1st pull (which I think is about right for the Mustang Dyno to DynoJet difference). On the second pull when it was hot it was around 360 and on the third pull in the low 350s. It was pulling a lot of timing because of the knocking and the shop tech thought the underhood temp was crazy hot even though the watertemp looked normal.

It had six "DTC NotRan" codes. Besides knock sensors P0327 & PO0332, I got a two P0601 Internal Cont. Module Check Sum Errors, and a P1539 & P1546 (AC high & low voltage).

I am taking the car back to the shop that did the install next week but I would appreciate any thoughts from people that know more than me, which is probably all of you. Here is what I am wondering: If the cam may not be the best one for the heads considering the already high static compression ratio of the heads? Would changing the LT headers to ones that are coated keep the temp down in the engine compartment to a point it would be worth the cost? What is the P0601 error? And, what else should I suggest to the shop? They are nice people but are not really answering my questions at this point although they seem to be interested in correcting the tune.

Thanks for any thoughts.

Tim

 

well if u don't drive the car in the rain get some header wrap they will bring the temp down more than coating, the coating is a thin layer that doesn't do alot for heat retention it's just there to prevent the headers from rusting.

edit that lunati is pretty small so it's up to u.