[72pontiac]

how much horse power can be gained by nothing other than a change from cast to aluminum heads.

[66bonne]

Can't tell you the HP gain but when we changed from mildly ported 6X-8 to out-of-the-box KREs we dropped nearly .5 seconds off the ET.

Jim

[72pontiac]

based on 30hp for a tenth then 5 tenths would be 150 hp gain.

[bdrac]

I bought a set 87cc edelbrocks right after they came in the mid 90s , just bolted them on , no other changes and picked up .5 seconds on my 64 with a 455.

[Ron H]

First the weight savings is going to give some gain. Next it depends on how much more the aluminum head flows over the iron and if the parts compliment the aluminum heads correctly.

You could swap to a set of 330 cfm KRE D Ports and run the same intake and choke the new heads and gain very little. The combo has to work no matter what.

Also the aluminum heads will need nearly another point of CR to equalize. So you could end up losing with just a head swap too.

[72pontiac]

yes I fully understand that. was just looking for generalization. was told that 30 hp was worth a tenth and a mild porting on cast heads at a cost of $350 would gain 30 hp for a $11.66 per hp cost. now with 2 reports of 1/2 sec increases with aluminum heads that equates to 150 hp increase for $2200 or $14.66 per hp so dollar for dollar porting cast heads is more affordable way to increase hp. im just farting around with my own theories. keeping my brain working.

[1971WARBIRD]

find a set of already ported heads and you could save some money. i have bought more than one set here with flow sheets for under 800.00. 2 were in the 260 @.550 lift, complete with stainless valves, going to use my own springs because of going from solid to roller cams.

[Ron H]

You can remove weight for only the cost of your time and run quicker.

What intake are you running?

If you order the heads with a good bump in CR then you will gain there.

You can buy lighter rims and gain there plus you have cool looking rims.

Everything is relative. One thing is certain. Sinking money into iron heads will bring nothing back on the resale value, in fact could hurt depending on the heads. However buying a set of aluminum heads will have more resale value.

[72pontiac]

I want to switch from a performer rpm to a torker II. for now I would like to port my cast heads to accommodate the increased flow of the torker II then use these heads on a different build not crying for aluminum heads and finally get some aluminum heads later when money allows it. I have done a side job that will pay for a mild porting and fresh valve job but nowhere near enough for aluminum heads much less some round port headers if I went with round ports and not d's.

[Ron H]

Do you have documentation that shows a T 2 outflowing an RPM intake? I wouldn't be so sure about that.

Switching from a dual plane to a single plane can have a negative affect.

Can you list your combo? Be as specific as possible.

Also post run times if you have a slip.

[72pontiac]

here we go on the great intake debate. I appreciate any and all info given. I cant reveal my secrets though. just kidding. 1970 455 .030 over, trw forged flat tops, #15 heads with 2.11 1.77 stainless valves, hardened seats, bronze guides, Harland Sharp 1:50rockers. 9.6:1 compression. engle hyd. flat tappet cam .483 lift 230 duration @.050 112 lobe centers. performer rpm intake, holley 850 dp or pro form 950, have tried both. zex perimeter spray nitrous plate with nos solenoids 150 hp jetting. msd billet distributer msd 6a ignition box. three tube headers maybe a weak link. frank lupes dynamic 9" converter in a built t350. 4:10 rear gear.

[66bonne]

From my own experience: Switched from RPM to T2 and picked up .14 in the quarter. Your results may vary.

Jim

[Ron H]

Humm, I would start with headers first. Especially with nitrous. You need to scavenge that exhaust quickly.

Stock stroke?

What is the exhaust duration on the cam?

Maybe a 1.65 rocker can help your combo too.

The thing that you may find is some bottom end is gone and you might rpm higher. But posting a slip will help know where you are on the track.

What rpms are you shifting and trapping at?

[72pontiac]

yes stock stroke. shifting at 5800 with shift light. tried 5600 but I like shifting by ear and I always go past the 5600 light. I cant remember trap rpm. I took last year off due to losing my grandson to sids so my mind is a little foggy. i think 5600. is exhaust duration, running duration. that is 274. was going to get some 1:65's off this sight but they sold fast. so 4 tube headers can make a big difference eh. what tube size should be considered. ive heard not to go big. are you not so into the torker II. im just bored and want something different but by all means not slower.

[screamingchief]

For nitrous use,I'd always opt for a single plane intake over a dual plane intake.

And I'm a TII fan,ask me,it's a pretty good intake for what it is,could it be better,sure,but that would be splitting hairs IMO.

One thing though,I'd lose the Zex perimeter plate and get a crossbar style plate instead.

Seems pretty clear to me that the crossbar plates win the "even distribution" contest hands down.

I'd want a different cam too,and yeah probably some better headers as well.

Just curious here,have those #15 heads have been converted to screw in studs?

That's another one I'd hafta do too.

I dunno,I can see a few areas I'd wanna fine tune before I'd plan on dropping the coin for aluminum heads.

But by the same logic,I also would'nt put much more $$ into the current iron heads either.

For right now,I'd probably work on improving areas that would help with either set of heads.

FWIW

Bret P.

[72pontiac]

yes they have screw in studs. I think I will stick with the zex plate I like it and switched to it from the nos plate. have you ever seen the zex video and write up. quite impressive. have I track tested the difference. no. just use it for a little fun I use it on the last one or two runs and go home with a smile on my face.

http://www.google.com/url?sa=t&rct=j...48705608,d.aWc

[72pontiac]

got a good craigslist score within 10 miles of my house. some ceramic coated dougs headers. real happy with how they cleaned up.

[Ron H]

Nice, they will help a fair bit. Fatten up your tune and see what gains you find. One thing at a time!

[thadeal4real]

One ? With the 15s shouldn't the compression be closer to 10 .5 to 1?

[72pontiac]

I think the pistons are down. In the hole