The guy that ground my cam recommended a 246/246 .621 .621 112lsa for my turbo 418. Its straight up since I will be spraying nitrous, large duration sicne I had low end problems already(too much tq) and didnt mind having the power band moved up some. What really gets me is the lsa. This cam has like 22*s of overlap, that seems like too much to me. His thinking was the extra cylinder pressure that will be bled off will still be spinning the turbo, but when the wastegate is open a little bleeding off boost Im going to be bleeding off power since the cylinder pressure is reduced. Am I right in my thinking. This is the first I have messed with FI, I've always been N/A and nitrous kinda guy.

The setup is ecsb Z71 418, gt-67for now(will be a 76 or 88 soon), 3K stall, 2step, soon to be 80e and transbrake, nitrous, full bolt ons, vic jr and about 5400# streetweight.

 

While that cam would probably be good in a low 8 or faster turbo car, it's really not necessary in something that weighs 5400lbs.

We use our 225/225 113lsa cam in many turbo applications and it would have great driveability and response with your setup.

 

My setup will be 3bar SD tuned by Allen Nelson himself so driceability really isnt going to be an issue. I also told him with the bigger turbo Ill be spraying a 150 shot out of the hole and backing it down as the boost comes on. Im going to run this cam for a while and see what it does then go to something else. The recommendation just struck me as a bit odd and wondered what everyone else thought. What ya'll run is more along the lines of what I was thinking maybe something in the low 230s.

 

im using 220/220 .565/.565 114+3 for my turbo lt4...should me good 2 6200rpm

 

That's a lot of cam...

I've got a Lunati 236/236 .580 112LSA on a TT f-body weighing maybe 3700 lbs tops. The cam is a monster under boost screaming up top. In fact I'm out of fuel up top. I'm hooking up a volt blaster/fuel harness upgrade to my Walbro 340 tomorrow.

Personally, I'm going to a smaller cam soon. I had this cam when it was N/A making 421rwhp, but switching the gears from 4.11 to 3.42 (for the turbos) has made the lower rpm drivability not as polite as it could be.


If I were you I wouldn't go much into the 230's unless it's a track *****.

 

I dont drive the truck unless I want to. I guess Ill throw it in and see how it does, if I dont like it then Ill call him up and tell him he needs to grind me another one thats a bit tamer. I wonder if he could grind me a new cam out of the current one since it owuld be smaller then the current one?

 

Overlap doesn't bleed off cylinder pressure - a late IVC does.

 

Aaaah, all generalized statements. Too many variables to justify the simple responses. But then again, what do I know.

 

I wont battle you on cam specs and what they do, I know that overlap is what causes "lope" and lope is a product of the intake and exhaust valve being open at the same time, for the most part. When talking about the size cam and motor that we are this is generally what it is from. Im sure there are other ways to do it but Im no cam expert by far thats why I posted this thread, I dont know **** about turbo cams except they are generally reverse split and lower in duration thats why I posted this thread. Ill have dyno numbers in a month and we will se what it does.

 

All the things you said here are correct, but don't have anything to do with bleeding off cylinder pressure.

Mike

 

Thats a big cam!!

 

I've got an old turbo cam laying around that is along the lines of that one. 254/254/690/690 on a 114. This came from a very knowledgeable guy, but it is 10 years old. My current is a split dur/lift cam. I can't recall the specs though..lol.

 

Keep us posted on how the combo does, always interesting to see what a different cam does. I'd think the truck will be totally different on spray vs. not... Would like to hear if the bottom end power w/o nitrous is strong or laggy.

 

i have a 228/236 .585 .585 116LSA that LME custom ground for me when i got my 370. Its a monster on the big end, and driveability is great with a good tune. The best part is the sound at idle. its the favorite part i put on the car

 

I dont think it is going to lack low end judging how it reacted with my old Lunati 237/242 .595 .595 112lsa cam. Spinning all four wasnt a problem on the street. Ill be getting some dyno numbers after I get the vic jr on. Also boost is going to be pretty much instant since its only a 67mm on a 418. Late December Ill be upgrading to a 74 then in the summer an s78 or 88.

 

I had an NA 422ci iron block, and I ran a 242/242/114 Lunati for a while and then a 244/244/112. The latter loped like crazy and liked to idle at 1100. Keep us posted.