head flow numbers vs power gains question

[Guest zfan]

I currently have a 385 sbc 6" rod motor. The heads I am using are Canfield 200cc heads with 65cc chambers and minor bowl work. The heads flow very close to what canfield advertises.

 

I am currently looking at ways to make more power n/a, no power adders. I am currently running a Comp cams hydraulic roller xr288hr-10, 236/242 duration and 520-540 lift with 110 lobe seperation, I am using 1.60 roller rockers so the lift is more approx 553/577 I believe.

 

I am seriously considering a more aggressive cam, maybe solid roller and a swap to the AFR 210 heads. I guess my question to the Horsepower Guru's is will it be worth it?

 

Here are the flow numbers from Canfield and AFR to compare, do the flow numbers make that big a difference?

 

Canfield heads AFR heads

 

145/107 135/112 200 lift

 

201/143 197/145 300 lift

 

247/175 245/185 400 lift

 

258/190 273/205 500 lift

 

258/200 282/215 600 lift

 

Obviously the canfields hold there own on the low to mid numbers but are clearly lacking on the big end. The AFR exhaust numbers also excel as well.

 

One cam I have been looking at is the Crane PowerMax hydraulic roller part number crn119841 Its advertised numbers are 296/304 duration and 539/558 lift.

 

I have also given some thought to porting my existing heads as well. Any imput or suggestions would be greatly appreciated.

 

Thanks,

Mike

[jt1]

Mike, how much power are you making now? The canfields are probably good to about 520hp as they are.

 

AFR's are good heads, but way overpriced IMO. Consider the canfield 220's, they outflow the AFR 210's but are a lot cheaper. One downside is the 220's require offset intake rockers, I don't know if the AFRs do or not.

 

What kind of exhaust are you running? That's a big problem on high hp Z's.

 

And, unrelated, with a 3.75 stroke/6" rod, were your wrist pins up in the oil ring grooves?

 

jt

[dr_hunt]

IMO if you stick with a hydraulic roller, your going to net at most a 20 to 30HP gain with existing heads over what you've got now. If you switch to AFR's, then you'll pick up an additional 20 to 30HP max. The 220's are probably a better choice if the rpm range is up there. If your going to stay HR then look at AFR rev kit for HR cams, it works, I've used them before.

 

A solid roller will necessitate a spring/retainer/keeper change and IMO a valve change as well unless your running manley race valves or ferrea's, so your looking at valve job and resurfacing the head at a min, maybe guides, so If your contemplating that then you should seriously look at buying some new heads vs. dumping more cash into what you've got.

 

But it's the total package that counts, what CR, what headers, what intake, what carb/EFI, what spark generator, stall converter, trans and rear gear.

[grumpyvette]

what are your current engine specs(cpr,intake,carb,header specs,ETC.) and dyno results????

where in the RPM range are you lacking the desired power increase?

whats your gearing,trans,and tires?

whats the current combos best times?

you can,t expect to make meaningful improvements without having a good idea EXACTLY where your current combo needs improvement

[Guest zfan]

A little info to start with. It's a 1971 240z and weighs 2850 with me and a full tank of gas in her. Combo is as follows: 385 6" h-beam rod motor, fully forged with JE flat top large 2 vlave relief pistons netting 11.1 compression. Block is a zero decked 010/020 4 bolt block, line honed and bored.

 

Intake/carb and Ignition are as follows: Port matched Victor Jr. intake with a Proform 750 dp and 1/2" phanallic spacer. Ignition is a all MSD set up with 34 degrees of timing and all timing in by 2700 rpm's.

 

Transmission is a built 700r4 with a 3500rpm Edge racing converter, tires are 235/60-15 Mickey Thompson drag radials with a 3.70 gear LSD rear end. The last time on the dyno the numbers were pretty low: Peak Tq was 436 at 3800 rpm's and peak hp was 363.8 at 5700 rpm's.

 

The car has run a best 10.81 at 125 mph. And ran 3 more 10.8X-10.9X passes at 123-125 mph. It also has run a best of 6.81 at 101 mph in the 1/8th.

[Guest zfan]

Forgot to mention the exhaust system: Hooker super comb long tube headers 1 5/8" primaries with 2.5" collectors. H pipe with dual 2.5" exhaust all the way out. Muffler is a performance single muffler with dual 2.75" inlets and outlets.

 

Thanks Guys!

[dr_hunt]

That's about a 450HP motor at the flywheel! More of a midrange motor, you could extract some more HP but it's going to be at higher rpm. If you want more HP at the same rpm, your going to have to add cubic inches. If you want more HP out of that combo, your going to need more cylinder head, more cam and more carb. HR cams start to fall off at 6K maybe 6300, so the rev kit is necessary to go much higher than that IMO.