LunaticTA

I see a lot of people talking about specific grinds for FI cars as opposed to NA cars..

At the end of my list of mods I want to do to my car is a vortec, and a friend of mine wants to do twin turbos..

Now since neither one of us has the dough to throw down for a vortec or a set of twins yet, we are doing the mods in stages, and the next thing I would like to do is a cam.

So here is the question.

What differences are there in cams that are ground for an FI car and for an NA car? If I purchased a cam for an FI car, and didn't buy my supercharger for a year, how would that cam affect the performance of the car while it stayed NA?

TIA

Chuck

2000 Camaro SS

FI cams tend to have a longer duration and tend to have more lift. Not always so. FI cams also have either (or both) a longer duration and or higher lift on the exhaust side. If you get one of these cams and run NA it would most likely affect your low to mid range HP. But it would not brake anything.

Doug Tschantz

Any supercharger or nitrous applications would like a cam that has more duration and lift on the exhuast side. From what I've seen in the past I don't beleive that a FI cam would be a hindorence to performance. Maybe a dropoff of torque but nothing major. Some people actually like and run the split duration cams without a supercharger or nitrous. Not me......

Doug
00 Pontiac

LunaticTA

Great, so a split patern cam is needed when we go FI with a higher lift and longer duration on the exhaust..

I was under the impression that the older motors had a tendancy to run better with a split patern, and the LS1 was best with a single patern cam.. I guess in this situation that is when a good old split patern cam does the trick.

Thanks for your answer Richard..

anyone else have any thoughts??? Has anyone tried a split patern <other than stock> and then a single patern in an FI car?

If so which do you think performed better??

How about a single patern smaller lift cam and then maybe a steeper ratio rocker on the exhaust ports when the turbo kit is installed? What would that do the the valve train having 2 different ratios on the rockers, and other than clearence issues, can these motors handle it? Would it be worth it without the extended duration?

I know a few old school engine builders that used to do it on the old GM motors, couldn't tell you if it caused an improvement on performance.

Thanks,

Chuck

XLR8NSS

iTrader: (4)

Hey LunaticTA

Check out this thread from a few days ago. It has a little info about blower cams in it.

https://ls1tech.com/ubb/cgi-bin/ulti...c&f=1&t=000141

XLR8NSS

LunaticTA

[quote]Originally posted by XLR8NSS:
<strong>Hey LunaticTA

Check out this thread from a few days ago. It has a little info about blower cams in it.

https://ls1tech.com/ubb/cgi-bin/ulti...c&f=1&t=000141

XLR8NSS</strong><hr></blockquote>


Thanks XLR8NSS,, I read it, but it just kinda left me hanging with a few questions..

I saw you asked the same question about the rockers,, Great minds think alike!! <img src="images/icons/grin.gif" border="0">

Chuck

XLR8NSS

iTrader: (4)

[quote]Originally posted by LunaticTA:
<strong>


Thanks XLR8NSS,, I read it, but it just kinda left me hanging with a few questions..

I saw you asked the same question about the rockers,, Great minds think alike!! <img src="images/icons/grin.gif" border="0">

Chuck</strong><hr></blockquote>

<img src="images/icons/grin.gif" border="0">

When the time comes I'm going to leave my cam up to Chris at SpeedDemonMotorsports. He answered all my questions. Maybe he'll look in here and help ya out. <img src="images/icons/smile.gif" border="0">

I'm outta here for the night. <img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

Johnnie

kick_*ss

iTrader: (1)

I am the other person lunaticTA is talking about, I am leaning more towards the incon 550HP twin turbo setup, as Chuck said, we would like to drop in a cam now and upgrade later without having to pull out or swap out cams.

<img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

LunaticTA

Ok, to recap, for an FI motor, cam should have higher lift and longer duration on the exhaust side of things..

so, I am thinking for an ls1 with M6, I could get away with the hotcams 218/227//.525/.525//112lsa which gives good power with out too much sacrifice, but even better the longer duration on the exhaust side will help out when I go FI.

================================================
Now to achieve a higher lift on the exhaust when the twins are installed, could I get away with a 1.8 rocker ratio on the exhaust side to open it up more, or is it too steep of a lift for the quick ratio rockers?
<<found the answer to this, the 1.8 rockers would put me at a whopping .556 on the lift for the exhaust, just a little less than the B1 cam..>> Thanks again XLR8NSS, next time I will pay a little more attention to you past posts..
================================================


To add to this, does anyone know what is the maximum lift you can push on a stock motor before you start knocking holes in pistons?

thanks again for your responses.

This site rocks!!!

Chuck

[ November 25, 2001: Message edited by: LunaticTA ]</p>

Rpm2800

Just a note. You really can't ask for just a FI cam.

Turbo and supercharger cams are NOT the same.

Camaroholic

iTrader: (1)

[quote]Originally posted by Rpm2800:
<strong>Just a note. You really can't ask for just a FI cam.

Turbo and supercharger cams are NOT the same.</strong><hr></blockquote>

I agree. Turbo cams keep the exhaust gas velocity high, and help prevent lagging.

Superchargers depend on higher RPMs to build boost, so it's usually a little closer to an NA cam.

As for the hotcam, if it were ground on a 114 or higher lobe separation, then it would probably be OK. But it's a 112, which is a little tight for a FI app (IMHO). <img src="images/icons/wink.gif" border="0">

Me, I stuck a B1 (221/221 .558/.558 114LS) in my car, and am going ATI D1-SC on top of it next year. I think it will do quite nicely. <img src="images/icons/grin.gif" border="0">

-Andrew

CHRISPY

In general blower cars do favor more exhaust duration. However a more important element in my opinion is lobe seperation. You want to maintain a Lobe sep of 114LSA or higher. If you go with a narrow lobe sep (Like 112) you risk pushing the combustion charge out past the exhaust valve and can cause problems with exhaust valve damage or header damage. This is due to the increased overlap of the 112LSA cam. In my opinion for a near stock displacement LS1 the best cam to go with is a 221/224 .55x lift 114LSA cam. This will give great power NA and provide REALLY good power under FI. When you are doing heads, emphasize exhaust port work as well and smoothing the CC. Any rough spots or edges will cause detonation under boost. A good NGK TR6 plug gapped at .030 and a GREAT fuel system with big injectors and custom regulator and you are all set.
Cheers,
Chris

LunaticTA

Great!!

Thanks guys, I now have the info I need to make an informed decision on what cam goes with what setup, and hey, it only took a couple of posts.. <img src="images/icons/smile.gif" border="0">

Chuck