308 cam question for boost

Research the 208 turbo. Those cam specs shoukd get you in the ball park. Are you intending to keep the CIS injection?

 

I dont know on a Ferrari but theory should be the same. I have been racing 1/4mile for 30 years. For a Roots blower and strickly full out race we use cams with 114+ ls. but were trying to build as much boost as possible for a very short time. If you plan on running on the street or endurance then running 110-112 is going to be more street friendly. Your going to need some of that overlap to cool the exhaust. I built a 308 once 20 years ago and if memory serves me correctly Im going to say the 308 was right at 108 degrees LS.

 

Either way your going to have to buy a degree wheel and dial indicator to measure lobe lift and find out what your motor is. Cams, belts, pulleys all have a tolerance. I bet you may see +/- 1 or 2 degree's between the same motors. A better question is going to be what is your piston to valve clearance going to look like when moving the cams to a 110-112 ls. Time to steal the kids playdoh and clay the pistons. If they even make playdoh anymore, hmmm wonder if there is a playdoh app for the phone, lol

 

What type of forced induction?

 

I have cam specs for 308s, which 308 are you looking for?
308 Euro specs have an LSA of 109 & with US specs it is 107.

 

Let me see what I can find.

 

I am fitting a new set of Catcam cams.

I thought the playdoh method a lot of work, so I made up a jig to measure piston-to-valve clearance.
I cut a plate to fit across the cam bucket, and weld on a 8mm nut centrally and in line with the bucket bore.
By turning the engine to any desired degree setting and winding it down until it contacts the bucket, and then measure how many turns are required to contact the piston, if at all, the clearance can be established. As the thread spacing is 1.25mm the total number of turns + 1/6 turns will give the figure required.

 

P6 cam specs:
Int. open, 48 close, 62. Centerline, 97. 9.25mm lift
Ex. open, 64 close, 44. Centerline, 100. 9.25mm lift
LSA, 98.5
Overlap is 92

If I were doing a turbo 308 I would consult a cam company and have cams made for it. I use Dynomation 6 engine simulation and it helps quite a bit in "seeing" what the difference can be with a given change.
On doing my 2.0 Type 4 for my Rail Buggy, I found the best header configuration was actually the step headers I had fabbed already out of what I had hanging around. Sometimes a blind squirrel finds a nut.

 

So how do you find what position the cam is in at its closest point of piston? The critical time is at the end of the exhaust stroke/start of intake. That changes with cam timing adjustments.

Also, the playdoh method will let you see how well the valve fits the cut out in the piston. I have had to make more adjustments for that then I have for total lift impact.

 

I would call Nick up at Nicks Forza he's already done this many times and a sponsor here I believe.
http://www.nicksforzaferrari.com/

 

Catcams specify setting up their cams based on lift at TDC. So the crankshaft is set at TDC, and the clearances measured. As the exhaust will be more open approaching TDC, and the inlet will be more open after TDC, additional measurements at ,say 5 and 10 degs before and after TDC should give the clearance curve.

From scaling up Catcams valve lift curves, the clearances can also be calculated using piston /crankshaft degree position.