The "Right" Cam

[FAST3V]

LSA is lobe sep I believe. So yes, 115....those might work fairly well for you Mike.

 

[TexasBlownV8]

LSA is lobe sep I believe. So yes, 115....those might work fairly well for you Mike.

Well I hope so

 

[BruceH]

I got mine from Comp and they are basically the 127500 but on 115° lobe separation. l like them a lot. I would give the guys at Bullet a call and they will go through your whole combination and recommend a grind for you. They don't cost any more then the Comps, from what I hear.

Mine are basically 127500 with a 113 lsa and 108 icl. I also like them a lot. They worked great na and are working just as great with the M122. Very driveable and a little "non stock" sound.

FYI the Livernois cams are basically Comp grinds with a different lsa.

 

[RED09GT]

Can someone explain how backpressure can be affected by the duration changes? Is it because the exhaust is open longer, to make the engine breathe better under other f/i operations, but with turbo, you want a shorter duration to get better spooling?

If going back to stock cams, would springs need to be changed as well? What about VCT?

(yeah the "shop" doing the install has no "experience with spec'ing out cams"..only putting them in.)

I should have worded it a bit better, overlap was what I should have said. If you have excessive overlap (can come from either a tight LSA or duration) you basically pressurize the exhaust from your boost going out the exhaust valve. This isn't much of a problem with headers and a decent exhaust system on a blower motor but with a turbo you are already dealing with removing the exhaust from a boosted motor and then have to spin a turbine which is a lot more restrictive than a set of headers and a crossover pipe that can scavenge the gasses for you.

 

[tigerhonaker]

Tiger, I do all of my own work.

Thanks guys.

Leo,

I did not know that .........

That now makes sense as why you were asking the question.

Terry

 

[FAST3V]

Mark at Bullet Racing Cams is recommending to me a duration of 222-230 with a 115.5 LSA....and switching from the COMP 20* limiters to the Livernois 10* limiters.

It won't Lope at all..but it will make all the power

 

[retfr8flyr]

It sounds like a good cam for you and I recommend the Livernois limiters over the Comp Cams limiters. I had a very bad experience with the Comp limiters.

 

[TexasBlownV8]

..leave the limiters alone!.. we don't need MORE work!!!
Interesting recommendations for sure

 

[retfr8flyr]

I really recommend not using the Comp limiters. http://www.s197forum.com/forum/showthread.php?t=92049

 

[toorbeenee]

Here is mine

Intake-274 - Lift .548
Exhaust-278- Lift .548

LSA-114

Duation @ .050
Intake 226
Exhaust 230

Lobe Lift:
Intake .274
Exhaust .274

 

[lito]

I just tuned a turbo 298 3V with Michael's custom cams, 778@6800@13psi, just saying

 

[FAST3V]

Really don't want to switch my Limiters if I don't absolutely have to. What do you think Lito?

 

[lito]

Well, I can't speak for them as I don't know the exact reasoning in their mind.

If you want me to guess, I see the change fit by a single reason, no VCT control.

Most of the cams I've got to tune with high lift and strong springs have zero VCT control, I've played with PID stuff in the calibration but it is something caused by hardware that have no software hack that could help. Having a shorter limiter helps on using them as a two position camshaft, which still works.

 

[BruceH]

I've used both and prefer the Livernois 20 degree limiters. Not sure if they still make the 10 degree.

Part of my testing has indicated that with the same cams and springs the livernois limiter equipped phasers were faster to the commanded vct angle. The Comp limiters also got there but they just weren't as quick. I'd imagine it had to do with more resistance.

IIRC you are going twin turbo and custom cams. Just have the cams ground with a 108 icl and lock them out. I doubt you will notice any difference in the low end.

No matter which set you use be absolutely certain to apply the proper fastener torques to the screws that hold the phasers together.

 

[FAST3V]

I thought about lock outs as well..but hell, I don't want to pull my motor.

 

[lito]

You plan to just drop them in?

 

[FAST3V]

id like to just drop them in, yes.

 

[lito]

You can replace limiters without losing the cam timing if you mark everything good and lock the chain with the tool firmly.

 

[FAST3V]

"with the tool"

Is there a special tool for this?

 

[lito]

There is a Ford tool to lock the chains against the guides, some people use a hose, others a vise grip, I won't get into the discussion of what is best because I think is an already beat path in this forum. But yes, there is a tool used for cam swaps.