Scott C

I posted my 350TPI dyno results a few days ago and I've been doing alot of research since then. I was very pleased with the torque numbers, but not thrilled with the hp numbers. Here are the results:

260rwhp @ 4700rpm
340rwtq @ 3500rpm

The mods are in my sig and the roller cam I used for the dyno is a Crane 2031 (264/270 - 208/214 - .438/.452 - 112). The lift is actually .467/.482" with my 1.6 roller rockers. I know this cam is not optimum for my current setup and I plan on swapping it out next weekend.

I'd like opinions on the replacement cam I'm leaning towards. It's a CompCams XR264HR-12 (264/269 - 212/218 - .488/.495 - 112).

From my research about a 350 long tube runner TPI, I think this cam has the best all around specs for making the most power out of my setup. I've learned to look for low advertised duration, less than 220* duration at .050, and a 112* lobe separation. The XR264 covers all of the concerns pretty well, don't you guys think? I'm also using 1.6 roller rockers, so the lift will be closer to .520/.528". I've not read alot about the role that lift plays with a TPI, but I see that most people are running a minimum of .500" lift.

I'm looking to pick up around 25-30rwhp...Will I achieve this goal with the XR264 cam or should I go with the XR269? Opinions, please!

91L98Z28

Hmm - I'm thinking 4 degrees of duration and a tad bit of lift isn't worth your time.

You've got a bit of stall, you've got decent heads, you've got headers, exhaust, gears....everything is set up to make some decent upper RPM power. don't choke it with another tiny cam. I'd go for a LPE219, or the LT4 HOT cam, or something in that neighborhood. However one thing to keep in mind is the cam is the "brain" of the engine, and as such will have quite a bit of affect on the volumetric efficieny of the engine. In english: you'll need more tuning in the PROM to make it work right.

Oh yeah, here's a quote from traxion to help out too, hope trax doesn't mind me quoting him:

Scott C

The XR269 I listed as my next choice is the same cam that Traxion refers to. My Edelbrock heads don't flow quite as well as AFRs, but I hear ya about going with another "too mild" cam. I would've expected the XR264 to produce a good amount more power than my current cam simply due to the fact that it does only have 4* more duration at .050, but at the same advertised duration (quicker intake valve opening). Also, going from a .467/.482 lift to a .520/.528 lift is a 10% increase. I wouldn't want much more lift than that anyway and was also told that to error on the "small" side is better than on the "too big" side as far as a cam goes. What do I know?

Can more people give opinions on the XR264 vs. XR269 for my 350 setup? I only want to change the cam and tune the prom, not have to port the heads, get better runners, etc...I'm looking to maximze the efficiency of the current setup without losing my Phat low end torque. The engine runs very strong right now, but I just want more upper rpm (3500-5000) power.

Anyone else have the technical answers?

91L98Z28

about the lift. You should check and see if you can find the flow numbers for your heads at various valve lift heights. Often times, heads reach a "limit" of where they will flow no better regardless of how much lift you're running, which then makes it kind of a moot point to lift the valves more (and maybe a detriment, given that it's harder on the entire valvetrain).

Also I didn't realize that the XR269 is the same one trax used.

I'll let someone else reply now so that you can get more than one opinion but I'd say that it's not worth doing the cam unless you go straight to the XR269. Just my opinion though....

You might realize the same amount of gain by doing some serious siamese work on your SLP runners to shorten up the runner length - from what i've heard/seen, SLP only siameses them about 1/2" in, instead of half the length like the AS&M SemiSiamese runners. Just another thought. If you'd like to see a picture of the AS&M semi siamese runners let me know.

Good Luck!

ViciousZ

iTrader: (1)

Personally I think the cam you selected is a good choice, considering your intake setup. You're running a LTR setup, so it's important to keep the cam's powerband in the same range as your intake's powerband. Meaning, lower duration, nothing higher than 220*. Acutally, an article in CHP that I read a while back recommends 210/220 as the optimal duration for a long tube runner setup.

HiTech5

iTrader: (4)

My first choice of cam for your application would be the LPE 74219 cam or the 219/219. Another that will work well is the LPE 74211 or 211/219. Both of these cams offer more aggressive profiles and increased lift which equates into more power.

From past experience, the stock springs that come on the Edelbrock heads are mediocre. If you decide to go with one of the LPE cams, get yourself a set of Comp Cam 987-16 springs and enjoy your new found power!

www.geocities.com/dzperf

Scott C

Well, I just ordered the XR269HR-12 (218/224 - .528/.537 (w/1.6) - 112*).

I plan on installing it this weekend. I decided to go on the larger side in case I want to upgrade the intake later on. I'll post results of how it runs next week...