desi

Here is the DD200 results for the two cams. I am looking for low end power, will try not to rev past 5500 rpm. 256S seems like the better choice. But operating range sounds low at 1000rpm?? Anyone running any of these cams?

Cam XE256S XE262H
Duration 218 / 224 218 / 224
Lift (1.6 rocker) 0.496 / 0.509 0.493 / 0.500
Range 1000-5600 1300-5600

RPM HP HP
2000 157 148
2500 201 189
3000 245 231
3500 289 274
4000 329 313
4500 364 346
5000 384 366
5500 385 369
6000 369 357

RPM Torque Torque
2000 413 388
2500 423 397
3000 429 405
3500 434 412
4000 432 411
4500 424 404
5000 403 385
5500 368 352
6000 323 312


Here is my setup:

350 cid, TH400, 3.08, stock convertor. 9:1 CR
Sportsman II heads, 64cc, 200 runners, 1.6 stamped rockers
Performer intake, dual plane, Q-jet by lars
Hooker comp headers, 2.5" true duals, chambered pipes, no cats

Need your opinions please. Good or bad

71coupe

The hyd cam looks to be about the right specs (Hyd cam wise) for a stock autmatic & 3.08. For the solid, you could probably & should step-up to the next size XS262S. That's the cam I would use

desi

No can do. 0.477/0.488 ===> 0.509/0.521 with 1.6 rockers is too much. Springs are rated for 0.500".

What is the ideal operating range for my set up? Is 1000 rpm too low? or just right? Car is doggish off the start now, will a lower range help overcome that?

71coupe

Edit: Try this in DD...
http://www.compcams.com/Technical/Se...umber=12-222-4
Comp S270 solid - .499" lift, 270 deg adv dur & 224 deg @ .050"

I just ran the #'s in DD, & the solid XE 256 does look better. BTW, your HP & TQ numbers are about 10% higher than the numbers I got. Do you have good head flow data? If not, I have good flow #'s I can send you.

desi

Yeah. I was about to buy the Magnum270S last week, until the comp cam tech guy told me to use the XE series as they ramp up faster. 270S makes more power at higher (5500+) rpm range. That range is not practical for me due to stock bottom end.

So for driving please under 5000rpm, I think XE256S is the most aggressive I can go with.

The head flow files that I got had 4 different heads, called Sportman II. Send me the one you used. Regardless of the head files, XE256S made more power than the 270S.

Anyone using this cam??

Glensgages

desi:

I have run neither cam, nor tinker with DD2000, but the numbers seem obvious that for low-end throttle response and off-idle TQ, the 256S is what you'd like the best:
it even appears to make more HP across your intended RPM range, too.

With 3.08 gears and the stock 'tight' converter, this would make a much-quicker accelerating car, I'd think.

gkull

First of all you need to rethink your springs. Solids require a good 20 pounds more seat pressure. Typical H-flats run 90 - 120# closed seat pressure. I would not run an aggressive ramped solid without 120- 150# springs

Springs are cheap insurance against engine damage. Buy the cam lifter and spring package. I'd even recommend a next step up over the light springs that usually are the base.

If you have a L-82 bottom end. I had my original stock doing 7000 rpm before it even had 1000 miles on the car.

bobs77vet

specifically where did you get the dyno results from the comp cams web site? i found it once for my XE268 and then it slipped into cyber oblivion and i could never find it again thks bob

71coupe

The website just has the cam card. The dyno #'s are simulated on the Desktop Dyno 2000 computer program.

bobs77vet

thks i did find the dyno results once on the cc website but never was able to find it again....

79VetteMike

I have a 256XE on a stock GM Goodwrench bottom end with Vortec heads. The toruqe is there!!!!! If you just want a good light to light car, that cam is pretty stout. I'm going to bigger heads and it seems that I've gotten exact opposite stories from different cam companies. Sometimes, I think it's just a crap shoot.

MotorHead

I have found that in the real world things are not as they are on paper alot of the time. Don't get me wrong I use DD and I like it for comparisons etc. But trying different combinations on a chassis dyno is where you find some of the things you thought would happen don't

Here is a dyno printout of my L48, basically the same as yours, with those same Sportsman II heads. The first was is 10:1 CR with Comp Cams 270H cam, 1.6:1 rockers, RPM Air Gap and 750 Holley DP. I don't see any lack of torque here and the HP is pretty good for a L48.



Now here is the second printout, same motor now the cam is changed to Comp Cams 282S with 1.5 rockers, Victor Jr. intake and 750 Holley DP. Now according to everything you hear you are supposed to gain HP and lose torque because of the cam and single plane intake, but as you can see I gained HP and torque across the board.



My recommendation for that motor is still the 270H because it will be OK with stock coverter, give you the most HP and torque and the single pattern cam is going to be OK with your open chambered exhaust.

chewy

I have the XE- 256 H in a Vortec headed mild 350 with a 4spd and 3.08s. It works super, power to 5700 and will work well at 1000 rpm in high gear.

desi

Thanks for the info guys.
MotorHead, I agree about the 270H cam making lots of power on the dyno. I saw that in person. But, when I run the comparison on the DD, here is what I get:

Cam XE256S Mag270H
Duration 218 / 224 224 / 224
Lift (1.6 rocker) 0.496 / 0.509 0.501 / 0.501
Range 1000-5600 1800-5600

XE256S Mag270H
RPM HP HP
2000 157 141
2500 201 179
3000 245 220
3500 289 264
4000 329 306
4500 364 343
5000 384 369
5500 385 384
6000 369 378

Up until 5500 rpm, 256 makes more power by 16-25 hp throughout. I think this may be the one for me. Unless of course, there are too many problems found on the forum.

desi

Here is a camparison of whole bunch of cams I did. Again, keeping all other parameters same.

XE256S Mag270S XE268S XE262H Mag270H XE274H
RPM
2000 157 146 146 148 141 135
2500 201 186 189 189 179 175
3000 245 228 233 231 220 216
3500 289 274 280 274 264 262
4000 329 320 324 313 306 306
4500 364 359 365 346 343 345
5000 384 388 396 366 369 377
5500 385 405 408 369 384 391
6000 369 401 408 357 378 392

comp

Torque is what you need to look at first with those gear's and a tight converter

nastee383

The XE262 is an excellent "all around" cam. I had t in my 383 for several years until it wiped. Drove the car 4-6000 miles per year, long hauled the Power Tour and turned 8 oh's in the eighth mile.(low 7's with N20) Mileage was good with my Q-Jet, about 15 mixed and 20 hwy cruising. Vaccuum was 15 with 1.6 rockers.

75 Stingray!

I thought you already had the XE262 H
Buying springs would be cheaper then another cam and lifter kit!

desi

I have the HE260H (high energy)....basically stock setup.

I know changing springs is cheap and easy, but there's only so much you can push a 30 yr old engine....even if it's a chevy

75 Stingray!

http://www.compcams.com/Technical/DynoSheets/