formularpm

Comp grounds all the standard XR-series cams on a 110LSA, but you can get a custom 112LSA ground for virtually the same price through several distributors. You may sacrifice a bit of upper RPM power by going with the wider LSA, but the midrange pull should be slightly better, the car will idle better, the brakes will probably be more responsive and it will be easier to tune. This is really a preference type of thing, though, the two angles arent radically different enough to provide a completely different powerband, its more of a fine-tuning thing. If you choose to go with the XR276, you may be able to get away with the 110*, but if the XR282 is used you Id definitely recommend the 112*. That is the exact cam Im using in my setup.

stealthramman

Actually the comp cams catalogue shows the XR276HR with a 112* lobe separation (# 08-503-8) under the 'Extreme' series of cams designed to work with computer controlled vehicles from 1987-1997 (except LT1-LT4).

This cam might just be the ticket for me.


Looking at the catalogue I noticed the 280HR Magnum cam (# 08-430-8)with 224* duration lobe has more lift (.525") than the 'Extreme' cam with 224* lobe duration (.502").

It seems that the magnum uses a more agressive lobe? But it's a narrower RPM range advertised.... Camshaft science!

mrr23

you can also post this over at www.stealthram.com i'll be using a crane cams 119831. according to DD2003 pulls more above 4500 than the comp cams 305

hp compare

tq compare
will find out in about 2 weeks.

formularpm

Odd. Ive never seen that cam in the PDF online catalog. Do you happen to know if there is an XR282HR in that catalog with a 112LSA?

stealthramman

Check page 144 on the pdf catalogue. It looks like the 276 is the biggest they recommend for computer controlled cams.

aklim

Why should the computer controlled cars be any different from a carb? The only thing I can think of is they mean that if you go further than their recommendations, the ECM will not be able to adjust for it with it's current programming. All of which means that if you are hoping to install and forget, you will need to stick to their recommendations. If you are going to change the program in the EPROM, which you will want to do anyway for max benifits irrespective of the cam, I would think it does not matter.

formularpm

aklim is exactly right. In fact, with the corrrect programming, you can actually streetably run more cam duration with EFI than a carb setup. This is due to better fuel distribution to the cylinders and increased control over air/fuel parameters at different engine states. (idle, cruise, WOT, etc)

stealthramman

Well i'm looking to produce about 400 hp with a nice broad torque curve. I'm thinking that a 270-276 adv. duration hydraulic roller with some nice (over .500) lift will get me there with a hp. peak around 6000rpm.
Probably not much need to go bigger than that.

Agree or disagree??

91Z-28

I have an HSR as well and want to run the XR282HR on a 112 LSA. Formularpm, how is your vacuum at idle? I know this is old as dirt, but hopefully you guys are still around.