Sitting Bull

I am going to choose between these two cams but want to know which one will give a smoother idle for my 305. The engine specifics are in my sig at the bottom. Here are the specs of the cams:

Crane PowerMax 266

Duration @ .050 intake 210 exhaust 216

Lift intake .440 exhaust .454

LSA 114*



Comp Cams XE 256H

Duration @ .050 intake 212 exhaust 218

Lift intake .447 exhaust .454

LSA 110*

iroc22

The Crane cam will definitely give you the smoother idle because of the higher LSA.

Pony Killer

The Crane will idle smoother... but i'd still go with the Comp Cam.

Crane has had a problem with their Hydraulic cams shedding lobes, I wouldn't use one.

Sitting Bull

I've never heard of Crane having a bad reputation for lobe quality! They brag that their lobes are actually the best, iso 9001 or something quality control.

Here is the DD2000 of the two cams on identical 305s. Which do you think would win in the quarter mile?

iroc22

If I'm reading the graph correctly, the Crane seems to have more power up top, which will probably win more races.

I've never heard of bad lobes on Crane Cams. I know that Comp's cams can't be beat in the quality department though.

Sitting Bull

It almost seems like a toss up to me. The Comp has it over the Crane until about 5000 rpm. Thereafter the Crane should catch up.

But it would seem to depend whether the Comp has managed enough of a lead to compensate for the Crane's top end rush.

It would be very interesting in the 1320.

But most of my driving is in the Comp's juicey area, so the XE 256 seems best to me.

F-BIRD'88

I ran both cams and a few others through a little more suffisticated program than Desk Top Dyno.
(Performance Trends Engine Analyser)

The crane powermax 266 was the better of the two
in both torque and hp.

The stock heads really hold back these cams potential
I got 263 hp with the stock heads and 315 with "my ported
305" heads.

Please note that because of "my ported heads" larger
port volume, There was a small loss of torque below
2500 rpm. This is typical of ported heads on small motors.
Some benefit could be realized by epoxying up the floor on these heads to both improve flow and increase volosity.
A torque converter with a actual stall of 2800/3000
behind a 305 is called for / for max performance. The converter should be swapped for the "corvette/ s10 converter" as a minimum. If you're stuck with a tight (1400stall) factory converter
a smaller cam may be the wiser choise overall. like crane's H260-HMV
These cams also responded to increased compression ratio
over the stock factory motor. The available octane gas
would be the limiting factor.

Also note that I modeled your 305 using SAE net "As installed"
conditions using your exhaust system specs, to better simulate real world in the car results.
Dyno 2000 can't do this.
So based on this simulation, The crane cam was a clear winner
over all and the motor is crying for better heads and a little more compression..

In my experience, Both these companies' products are real good.
Both companies have there fair share of failures especially when customers "pop a lil' cam" in a used motor. I include my self here.
The culprit is bad lifter bores. Either glazed or scored.
If the lifter cannot spin freely in the bore while running, the
cam (anybrand) will fail. A small brake hone, quickly run through
the lifter bores to clean ,em up during a cam swap makes all the difference in the world.

Dyno 2000 always assumes a perfect exhaust design.
So choosing "Small tube headers and mufflers" may not best model *your* small tube headers. According to the instructions, your shorty headers are better modeled by choosing "high perf manifolds and mufflers." You get a more realistic result. Try it.
The truth, typically falls some-where in the middle. I like
to interpolate between the two choices here.

F-BIRD'88

I estimate that with your 305 tweeked to true 9.9cr
with the above mods, a good 9.5 in 3000 stall converter
3.73's and short sticky tires like BFG's P225/50/15 drag radials
you should run 14.10@97 with stock 305 heads and
13.65@102 with my fully ported 305 heads.

So how fast would that be "In the snow"????

88GTAinRI

I shopped both of those cams also. Decided on the SLP 51006. That DYNO 2000 program is cool! Where do I get one? Could you plug in some spec for me and show readings? Here are my projected mods.

88 GTA stock 350 bottom end (for now)
SLP cam dur@.50 218/224, .495/.502lft, 114 centerline
Dart pro1 heads 72cc combustion chamber 200cc intake runner 2.02/1.60 valves
roller rockers 1.5
Accel superram and base manifold
52mm throttle body with air foil
remove screens from MAF
Adjustable fuel pres. regulater
MSD ignition, coil, distributor, and wires
24lb injectors
SLP 1 3/4 headers
ProCharger 8-10 lbs boost with intercooler
2500 stall speed converter
3:73 gears

Sitting Bull

That's mighty fast in the prairie snow! Thanks Russel

Can you model how fast it will be with my 2.73 gears and stock 1200-1400 converter? That's what I'm stuck with for this year, at any rate.

Sitting Bull

OK, this is the best I could do, given I don't know every last spec of info and the fact that this is, at best, a program with a 5% fudge factor.

For instance, I don't have the SLP cam file but substituted a Comp one with the same lift. I assumed it was a roller cam.

Nevertheless, this should give you a fairly good idea. This is one smokin' 350!

Sitting Bull

Russel,

Does your dyno program show the Crane 266 with an advantage in torque and hp all through the rpm range, or just above 4000 rpm, or where might it be?

F-BIRD'88

In this simulation the Crane 266 had a clear advantage
all the way through. Except below 2500rpm. The comp cam was designed for a 350 with its 110* LCA.

If I was stuck with a 1400stall and 2.73's I'd probabily select a smaller cam either way. The loss of torque near 2500
is too important because you spent so much time at or near there while driveing with that set up.
Even the factory 305HO with a 203/207-.404/.415 on 115 LCA
used a special 3000 converter and high gear in the monte SS.

The simulation slowed to 14.85@100 with the 1400stall/2.73's
on the ported head motor. Sorry
Maybe you could ask for members to post there real world car with simular mods and real timeslips and see what to expect.

It seems that the rear gear/ converter/compression ratio
mods are real critical when you put a longer duration cam in a 305.
This is typical of small motors. I remember when a friend put a Comp cams 260H high energy cam 212/212-.440" 110
in an other wise stock 267. It was a dog. Lots of rpm but no
torque.

Sitting Bull

Well, 14.85 is better than what I'm getting now! (I think--everyone seems surprised that I have "just a 305" in the Camaro right now. They think it responds more like a 350 but it ain't. We checked the serial on the block and it ended with a "301", which I believe proves it to be a 305.)

I do plan on a 2000 rpm TC when I can afford it, so I think the Crane 266 will be the sensible long term purchase.

What do you think of the high bleed lifters? Are they durable? Will their bleed down at low rpms restore some torque below 2500 rpm?

88GTAinRI

Sitting Bull,
Thanks a ton. Been doing alot of the figuring with a pen and paper and that chart is the exact redline I was looking for. I was hoping for a little more power, but who isn't. I am going to keep the compression under 9.0 also so there will be even less than that. That program is awesome! You should check out the cams that SLP has for sale. The only complaint is the time it takes to ship. 10 days and still counting. I think I've received 3 Summit orders already and heard nothing from SLP yet. Good luck on your mods and thanks again.

Hank O.:rockon:

Sitting Bull

You're welcome!

If your intercooler is more efficient than the 30% I assigned it, then it will produce even more hp and torque. I don't know much about them and the program only listed Paxtons. There were no Prochargers, though I suppose they are fairly similar.

F-BIRD'88

I would only use Crane hi-bleed lifters with a crane cam
and comp hi bleed lifters with a comp cam.

They have the potential to restore some of the lost low end torque but they also make more noise.
Might drive you crazy.
Even a smaller cam, say with 204/214 .420/.442 -112
would be a real step up from stock and have more low end torque
then either of the crane 266 or the comp 256XE. without the special noisy lifters.
I can't comment on their reliability but the factories have never used them in any motors.

You really have to watch not to over-cam your motor.
with low # gears like 2.73's you're always going to like the
smaller cam better.

This cam would respond nicely to 1.6 rockers on the intake side.
Not on the exhaust.

Sitting Bull

Alright, I dynoed my engine with the Crane PowerMax 266 and the Crane PowerMax 260 (the next step down in the line) but their graphs are almost identical.

Does it look different on your program, Russel?

F-BIRD'88

Yes

Sitting Bull

Hmm, OK.

Is it safe to assume that the Crane 260 had more low rpm torque but the same high rpm hp as the 266? Or did its hp fall behind the Crane 266?

F-BIRD'88

Yes but you'll still be better off with the smaller cam.
Because you'll never get to the spot where the 266 pulls ahead a little. Because you don't have/ won't put in the required gear.

Sitting Bull

Yeah, can't afford gears anytime soon

So, the Crane PM260 it is