Lumpy idle with a supercharger not possible??
 

Hey guys I have the want for a lumpy idle but my engine tuner is saying that's not going to happen with my setup.....

I have a B15 GM crate LSX with a 2.9l Whipple super charger. His recommendation is to leave the cam that's in the engine alone or to change it out for a Lingenfelter GT9 LS9 cam which in the description states it has a smooth idle. I understand that to much overlap is not good on a boosted application but I have head other supercharged cars with great sounding lumpy cams. Whats your guys thoughts on this???


Thanks!
Corey

You can play with timing correction values in the idle overspeed/underspeed tables to roughen up the idle a bit.

Listen to a BTR Stage 3 PD Cam on youtube. They have a pretty healthy idle and make good power.

^^^^^this^^^^^
You can manipulate idle characteristics with the tune. Don’t shoot your self in the foot chasing sound and give up performance. Some overlap is compensatable with a really good tuner, but blower cams are designed to operate differently than n/a cams for a reason.

I will mention this to my tuner. Thanks!

Thats the plan then! I wonder if swapping the cam out for the other makes any sense at this point then? Thanks for your advice!


Corey.

I would definitely swap that cam out if you are looking to make good power with that engine.

The cam that comes in the B15 crate engine is an off the shelf LS7 cam. Nothing that is designed for boost, or even the displacement or style of cylinder heads that are on it.

I would call a company like BTR or Cam Motion and tell them what you are building and have them spec a cam to your wants and needs. There is a lot of power to be gained in that engine from a cam swap.

There is no reason you can't have an aggressive idle with a supercharger, but you don't want hardly any overlap, so you have to go about it in other ways, like has already been stated in this thread.

Thank you! I appreciate you taking the time to give me some good advice. One thing that concerns me is building a combo that my tuner has no base line for. Hes already recommended the cam I mentioned earlier but it seems there is no love for that one thus far. Where in NorCal are you?


Corey

You should definitely talk to Matt @ GP tuning. He is the premiere tuner in the CTS V world, is an expert on PD blower setups, and specs all his own cams.

[email protected]

Good luck
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This might sound harsh, but if your tuner can't tune something like this from scratch, you should find a new tuner. Really though, the cam that you put in the engine is all going to be dependent on your goals and the rest of the setup on the car.

I am in the San Jose area. Feel free to PM me and I'd be happy to help you out.