That_Z28_Camaro

I'm about to do a new setup built forged 402 CID and i'll be doing a nitrous application (300 shot). The cam is a custom grind and is 242/250 .624/.624 and I can't decide if i'm going to go with the 112LSA or 114LSA...i know i'll probably lose roughly 20-30hp (spraying) if I go from the 114LSA to the 112LSA. I'm mainly worried about the idle between the two. Right now I have the 228r 112LSA and don't want to idle to be any quieter. The exhaust setup is 1 7/8 header to a X pipe then dumps about a foot after that so whatever I do it'll be loud lol. Below I attached an idle video of the 228r on the second page of the thread.
https://ls1tech.com/forums/generatio...8r-241s-2.html

KW Baraka

iTrader: (7)

A 242* cam, even with a 114* LSA is still gonna have a pretty rough idle (18* to 20* of valve overlap). So.....there's that.

Since either cam is gonna be a bit rough around the edges, you may as well go with the one that figures to be most likely to reach your most important power goals.

KW

CAMSTER

iTrader: (10)

A 112 is not for that big a shot even what you should go with will lope like craze at that kind of duration and do all you need it to.

In fact if you really want to lock in all the power at a duration that high I would best advise to have the cam spec by an expert. You'll be glad you did.

http://www.guerragroup.com/#!camshaft-help/c1mq5

ctd

iTrader: (1)

Your 228 cam with 4* of overlap should have near perfect manners on the street, mine did in a 346 with AFR 205's. When that puked we did a 416 with AFR 230's & 17* of overlap, that was the most miserable POS I've ever owned. Then we reduced the overlap to 10.5* with much better manners & no loss in power. A cylinder head change & a substantial increase in power, same 10.5* of overlap in the cam.

It still did not drive as well as the 346 with 4* of overlap, tolerable & many would probably be happy with the manners. So I've reduced the overlap a further 5* & have started the retune process, the difference in manners from the 10.5* is significant. I will get back to the dyno for some comparison number once I've got it dialed back in on the street. SOP the pants dyno suggests the power numbers are still going to be good.

My experience with both motors is overlap is overlap, supposedly the bigger CI sucks up the overlap........not my experience. Better heads worked for me.

HOHN

I think it's the wrong question. LSA should be result of the valve timing events, not a driver of them.

Personally I think it's a good idea to make EVO a little earlier with spray, as it takes more time to vent all the gas.

Wider LSA reduces overlap, but spreads IVC and EVO-- IVC is later and EVO is earlier.

Keep in mind that for cams and spray you are having to choose between making power with and without the spray. A cam the makes more power on spray is weaker without it and vice versa.

On the spray, reduced pumping loss is major consideration, hence the earlier EVO.

Your current 242/250 cam on 112 LSA would have the following events straight up:
IVO: -9
IVC: 53
EVO:-57
EVC: 13

22 degrees of overlap at .050" is going to lope for sure in a 408.

If you dropped down to 239 on intake lobe and went to a 114.75 LSA, you could drop your overlap from 22 to 15 degrees which would help idle a ton and give you these valve events:
IVO:-5
IVC:54
EVO:-60
EVC: 10

Note we've closed the intake valve one degree later, opened the EV three degrees earlier, and closed the overlap up a bit on both sides.

The reduced overlap here will cost you some NA power but not much. IVC at about the same timing helps the bottom end not go totally limp even with the wider LSA.

IMO, spray needs bigger disparity between intake and exhaust lobes.-JH

fastazzls1

why so tight on the LSA I understand people like chop but on a nitrous car its not beneficial especially hosing the car with a big hit

fastazzls1

my 2 cents have a nitrous cam spec'd out I did and sure its not an animal with out the bottle but one turn of a valve behind my drivers seat it becomes another force to be reckoned with. I had a 228r and sprayed that car all the time put a nitrous cam in and what a difference.

That_Z28_Camaro

Thanks everyone for the help I really appreciate it. I never really looked into all of this info when I picked out the 228r but that wasn't a high dollar setup. Ordered the 402 a little over a week ago from Texas Speed and I ended up going with a 112LSA.