Cam recommendations? Twin Turbo

I have been off this board for some time now, but starting to make progress again. .

I am finally building the motor for my "street" car superbird and I was hoping to get advise on cam and lifters for it.

I have a mega block from a 500" 505hp crate motor. (4.15 x 4.380), and a set of Indy CNC 325 heads. It comes out to a 8.8 compression ratio with the rods and pistons I have for it.

The plan is twin 74mm turbos, keeping the boost around 15-18 max.

This will be street driven more than raced.

The heads came with 1.5 rockers, springs have 534# @ .500 and 597# @ .600, 256# seat. 2" installed.

I seem to recall that the mega block needs a particular lifter to clear the boss.

Thanks in advance!

Scott

When I was looking for a cam this year I went to the Howard's Cams web site and plugged in all my specs to their order form and I couldn't believe how good my car runs with their recommendations. I don't know what software they use but it just flat out work awesome.
Gus

Your first cam should be a wide-ish lsa. 112-116 range
Duration in the mid 230-240 range.
The reason I say first cam, is the cam timing is heavily dependent on intake / exhaust pressure ratios. It isn’t really a calculable figure without trying it to get a base line. Any cam will function. But getting one that works great is only found through trial and error. Instead of just getting cam and converter correct, you throw in a 3rd variable with the turbos. The nice thing is, even a bad turbo combination will be way better than any well thought out N/A combo.

What fuel? Intercooler?

This advice s right on the money. With the back pressure in the exhaust due to drive pressure, the exhaust closing @ .050 should be before or at TDC but not after. Typically will put the cam durations in the low to mid 230's and maybe higher with a modern aggressive lobe profile. LSA typically as mentioned in the 112-116 but leaning toward 114. Cams like this will make power well into the 30 psi range. If the cam gets any bigger and a lot of overlap the drive pressure at the higher boost levels will truncate the power.
AG.

I got mine from Little John Motorsports. It's aBullet s.f.t. cam. 247@.050 .546 In., 251@.050 .540 Ex. 115 lobe sep. It was speced.for a 470 with twin 69m.m. ebay "Hong Kong Hurricanes" Lookex up the lobes online. In. is a ford lobe and the ex. is a chevy lobe. Working great so far. Give them a call.