69TPI383

I will be building a 383 for a 87 TPI unit. I'm not quite sure which heads I'll end up with but hopefully some Trick Flows. I am now porting and removing the dividers on my SLP runners, stock base and plenum. How big a differance will a 110* LSA and 112* LSA be? I have a Comp 270 HR with 110 (218*/224* .495"/.502" 110*) hyd roller. I have a chance to buy a cam that has the same dur., lift, both hyd rollers. Only diff is mine is 110* and the other one is 112*. I do know the 112* will have more vaccuum, and a broader power band but I'd like a little lope too whcih the 110 cam will have more of. How much noticable differance? Anybody experimented with cams of the same specs with diff LSA's?

88 IROC BOB

I'm no expert but from what I've read, I think you may have some problems with the 110*. I think not enough vacuum and the ECM will say .
Hopefully someone else will either confirm or deny.

Bob

Grim Reaper

If you are planning on getting into eprom burning so you can "cusomize" the eprom with "hands on" tuning, you should be able to make the 110* LSA run okay. If you are just going to "buy" and eprom, then I'd go with the 112* since the person that is going to write the eprom is not going to be able to "tweak" it - which they often require with long duration cams or narrow LSA cams.

David 91RS/Z28

I'm running the next up 224/230 Extreme cam on a 110 and like Glenn mentioned....you better have the ability to tune the computer yourself. It's taking lots of tuning, but it seems to be working quite well. 12.0's so far! I've never taken a vacuum reading but I have no problem with brakes so i figure it's pretty good. Be sure to have good valve springs for the Extrmem cam. I'm getting valve float at 5800rpms with the installed springs from AFR. Got some Comp 987's and Ti retainers going in soon. Good luck!

Matt87GTA

FYI, a 112 LSA will lope pretty good. Here is a sound bite of my GTA with the LT4 Hot Cam:

http://www.mnfbody.com/memberpages/m...ndQuickRev.wav

Sound quality is kinda poopey, but eh..........

88 IROC BOB

That sounds SWEEEEET!!

Bob

Matt87GTA

Thanks! Me likes too ......

tpi_roc

That seems pretty lopey for the hot cam unless the specs are different than I remember them....

Either way sounds good

Matt87GTA

Thanks!

Duration @ .050" lift: 218* intake, 228* exhaust
Lift with 1.6:1 rockers: .525" intake, .525" exhaust
112* LSA.

It pretty much sounds like that except the mic on my laptop is a bit of a POS and I think the air from the exhaust moving over it is what caused the distortion and all that low end bass sound (I set the laptop on the ground about two feet behind the tailpipes for that recording)..... I have a clip of it just idleing from about 10 feet away too, but it is pretty quiet and really doesn't do it justice.... I really need to get a decent recording with a regular mic instead of the one that is integral with my laptop. But she does lope nicely and I have gotten quite a few 'What the hell cam IS that????' questions from people when they hear it....

GTA1327

From what I understand, a lower lobe seperation cam will run lower vaccuum pressure and the computer will think something is wrong and spit out a code. I also under the impression that it will idle like ***. You might be able to get away with 110 degrees, but 112 is would be the safe route. By the way, Matt, you are crazy for saying that your bite sounds crappy, because I listened to it and now I am extremely jealous. LOL. She sounds beautiful, and I wish my car sounded remotely like that.

Matt87GTA

Thanks .

anesthes

iTrader: (12)

112 is a really good number to stick with.. The exhaust valve closes sooner into the intake stroke, giving you a lil more vacume, but more important better if you get a blower down the road.

-- Joe

69TPI383

Well.....after listening to Matt's LT4 Hot Cam idle for about 30 minutes (and wiping the drool off my chin ) I think I'll go with the 112* cam. My cam *should* sound about the same as the specs are almost identical.

LT4...218* 228* 112*

XE270HR....218* 224* 112*

Ok....I'm convinced! 112 it is! Thanks guys!

PS....That GTA sounds awesome Matt! Thanks for the sound byte....now if I can just quite listening to it

Matt87GTA

Thanks again for the compliments!!

Here is that other clip of it idleing from about 10 feet away:

http://www.mnfbody.com/memberpages/matt87gta/Idle.wav

Laterzzzzz,
Matt

Guest

David, could you tell me more about your setup? Like induction, exhaust, launch rpm, compression?


Posting sound files eh? Open headers 224/230 112LSA (the mic was not as close to the car as it sounds... I was at least 50 feet away if not more):

http://home.earthlink.net/~madmax0/GP2.wav
http://home.earthlink.net/~wtomfoster/GP5.wav

HiTech5

iTrader: (4)

The added cubic inch of a 383 will handle a 110 lsa cam without a problem. The key will be to get the compression ratio in the 10-10.5 range. The 110 cam will lope more than the 112.

www.geocities.com/dzperf