just a quick question. was wondering if swaping to a higher lift cam would achieve real good resaults with my AFR 195 lt4 heads.
heads flow 280@.650 lift. i made 399rwhp with the xe236/242 shelf cam (.565 lift) my overall goal is to go 10s NA. do you think this would be possible with 450rwhp and would this cam get me closer?

230/236 duration @ .050", .622"/.624" lift with 1.6 rockers.
or
236/244 duration @ .050", .608"/.613" lift with 1.6 rockers.

how much would streetabilty change if any with these 2 cams? how hard on the valvetrain would these cams be? deff need awesome springs..

 

Funny, I just spoke with Joe Overton on the phone about cam lift today. (9sec Naturally aspirated TA) He runs AFR 227s and a cam that has a peak lift of about .550.

He was saying that the valve hardly sees peak lift so its not as important to get such high lift numbers, even if your heads flow at that lift. From what I got talking to him there is no need for over .600 lift.

 

377 ci engine, AFR 194 LT4 heads, and a big cam..........and youre only getting 399 rwhp?!?!?!

id be trying to figure out whats holding you back before worrying about more lift.



btw, someone correct me if im wrong, but isnt 280 @650 a bit low for ported afr 195 lt4s?

 

10s NA on a hydrolic roller is QUIET a goal

Like you will find in almost any cam thread that Rich has replied to-

Lift is your friend. Even if you left beyond where your heads stop increasing flow... thats still a lot of air your getting in there, more than you will with at low lift numbers.

I went with that cam on a hydro roller as well. My head #'s should be similar. I hope for 425rwhp. expect 400. I'm going through a stalled A4 though.

I think you should concider a solid roller. Seems to be the way to go NA

 

treys spellcheck must be broken

 

i think it commited suicide

just overloaded and self destruct right next to that bar of deoderant ohh wait nevermind....

 

I agree.

Thoughts and opinions:

96Z (Matt) made 433 rwhp with his budget 383 with ported GM LT4 heads and a cam a couple of yards shorter than yours.

http://web.camaross.com/forums/showt...hreadid=134698

If your car is over 3000 lbs with your aboard, 10's are gonna be very expensive, and IMO, your heads ain't gonna make it.

Less is sometimes more when choosing cams.

My $.02

 

J-
you get my email?

 

not to mention that phils (advanced induction) guys are making 400 rwhp with just ported LT1 castings, and moderate cams, and boltons on the stock bottom end.

 

Ported LT1/LT4 heads and moderate cams...maybe they're onto something.

 

from phils customers

EconoPort LT1 Head Package, a GM847 Hydraulic Roller, and a mail-order program on a stock 72,000 mile LT1 shortblock. SAE corrected, the numbers were 405rwhp & 365rwtq.

Full port Heads, 411rwhp and 370rwtq through 1-5/8" shorties and a full SLP catback from a stock LT1 shortblock with 98,000 miles, 91 octane MTBE fuel, and a 230/238-112 Hydraulic cam

 

We shall see what my Phil-headed car makes soon. Very soon....425 rwhp shouldnt be much of a prob.

 

There is no such thing as a free lunch when it comes to cams. An advantage in one area usually has a downside to go along with it. The downside to big lift is that it's tough on springs. You need more spring to support the same rpm with steeper/taller lobes. This places more stress and requires upgades to all the other valvetrain parts (rockers, pushrods, etc.). Anything over ~.600" lift is not for 99.9% of us. If you put any miles on a a valvetrain with that kind of lift, you are going to be changing your springs pretty regularly.

That said, as Trey suggested, I would rather see higher lift/shorter duration for a street car, up to a point. The steeper the lobe, the longer the dwell at intermediate lift and the more area under the lift curve and therefore more hp. Obviously, the cam has to be tailored to the heads, the CR, and the desired rpm range.

Bret knows this stuff. You might want to "buy" his expertise and get a cam from him selected for your particular combo. It's part science and part art, as each of these combos is slightly different.

Rich Krause

 

I thought I was on my own on this one and there's Joe... a guy we could all learn from if he'd just post a bit more.

Lots of lift and lots of acceleration in the valvetrain is cool.... you get more lift area per degree of crank rotation that way but guess what..... it's not the holy grail of engine power. It is however harder on springs.
Look at the guy who won the PHR Engine Masters Challenge last year. Not to take anything away from the other contestents, but the fact is that the winner used an old Isky grind with 234* @.050 and .565 total lift on the intake, .530 on the exhaust. Not exactly spectacular AUC compared to the high tech cams I can assure you that many of the other guys were running..... Comp's 236 (3100 lobe) for instance...... .624" of lift with a 1.6 rocker.

So, is it all about the most lift per degree? Is that the magic element? You decide.

-Mindgame

 

Mindgame: your post reminds me of something I have wondered about for a time. Would the "ideal" valve lift graph out to a "square wave" kind of shape? Just in terms of engine operating characteristics, ignoring the mechanical effects on the rest of the valve train, is more valve acceleration always better? What do you think? I do think that within the limits of imposed by practical spring pressure, etc. that steeper lobes are better, but is there a limit to this concept other than mechanical?

Over the years, the trend in street performance (my area of primary interest) is certainly toward steeper and steeper lobes.

Rich Krause