cams?
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
cams?
hey everyone, what is the largest emissions legal cam available for an lt1/4? i was thinking of a cc306 or the gm847 but i am pretty sure that neither are emissions legal and that a cc305 is kinda small. i have done the lid mod with a k&n and high flow maf ends and a catback and am planning on getting tpis LT headers too. any info will help. thanks
josh
[Modified by pr0zac, 4:50 PM 4/4/2004]
josh
[Modified by pr0zac, 4:50 PM 4/4/2004]
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: cams? (pr0zac)
Define emissions legal.... because neither on of the cams you mentioned have an EO sticker on them. A CC306 or the GM 847 cams are very difficult to get to pass emissions. A 305 is much easier to pass if your tuner is good. I am running a custom ground cam from Comp with a 224/236 ground on a 112, at my present idle speed it don't quite make it, but with a different tune and a little higher idle speed it will pass. A LT4 hot cam can be made to pass with ease as is a LPE 219 cam. Once you go past the 224 duration number it is going to get increasingly harder to pass smog. And if you dump your cats its very difficult to say the least to get passed smog.
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
Re: cams? (tjwong)
i am stationed in oklahoma and don't have to worry about passing emissions at the time but i want to be able to pass if i get stationed where it is going to need to pass it won't take much to do it and be able to have the most performance out of it now. all of my emissions equiptment is still in tact and i don't plan on ditching the cats. if a temp retune is all that it will need to make it pass should i go with the gm 847?
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Re: cams? (pr0zac)
My best advice for you if your engine is basically a stock LT4 is to use the LT4 hot cam. It is a proven power adder that works well, reasonably priced and will pass emissions with a good tune. Both the GM847 and the Comp 306 will be nearly impossible to get to pass. The other alternative is the Comp 305 or a cam similar to what I am using. Doing a cam is one thing where bigger is not always better. And that is especially true on a basically stock engine.
Burning Brakes
Joined: Jan 2004
Posts: 933
Likes: 0
From: Inland Empire CA
Re: cams? (tjwong)
:iagree: You don't want to totally kill low speed torque either... especially with a really lumpy cam that'll scream best between 5000 - 6500+.
That's why L98s can get into the 12s fairly easy they don't have a good top end... but they have tractor like low and midrange torque. Low speed torque is good thing :yesnod:
That's why L98s can get into the 12s fairly easy they don't have a good top end... but they have tractor like low and midrange torque. Low speed torque is good thing :yesnod:
