Posted By: Labratt
HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 01:03 PM
I asked this question in my "Horsepower Post" but didn't get any feedback at all.
I had my Edelbrock RPM's cnc-ported..and milled .060,by Jeff at Modern,last Fall. Still have to finish re-assembly of the 440 they're going on. With approx. 35 cfm more flow on the intake..and a bump-up of compression,from 10:1 to 11:1...what can I expect to see in horsepower gains? Thanks!
Randy B
Posted By: tboomer
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 01:34 PM
Interesting question,Randy! If I get back to racing next year,I will replace my MP aluminum heads that flow 299 cfm with Edelbrock Victors that go around 350 cfm...
Posted By: gregsdart
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 01:51 PM
I bet the reason you didn't get feedback was the real answer is "it depends" There are so many variables that it is impossible to give a ball park figure without someone having the virtually identical combo.
First off, how much NET valve lift do you have? Take away lash, and another .020 for flex, and you may be close to what flow the motor can access. Don't forget that the valves are not at peak lift very long, so the numbers that mean the most are below the peak. Compression increase is fairly consistant I believe, but other areas may not be.
My WAG would be based on a very well matched exhaust ,intake, carb and cam setup that is making close to max hp for the flow you had before, which should fall in the range of 2 hp per cfm. Now take a look at the AVERAGE flow increase from say .100 to max net valve lift and see what you have. You might see 2 hp per cfm gain, maybe not.
Case in point. If you had installed those heads on my old 535 cube stroker, going from the iron ported 906 s that were on it to the new ported heads would show some very serious gains in deed. The motor is choked to death by the heads. Do the same trade on a 383 with a stock cam, and you might not see any improvement.
I increased the flow on my 440-1 heads by an average of 5 percent. But I got ZERO gains. Part of the problem may be that there is a spot right in the mid lift area where the gains go down to very little. The other is the cam may not be the right grind for what I now have, or other components don't match and restrict the increase in Hp. I may not be running the motor up high enough either. Lots to think about.
Posted By: gregsdart
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 02:18 PM
After thinking on it for a bit, I would think you may dip into the tens on a good day.
Posted By: BradH
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 02:33 PM
I'd want to see 60-70 HP for those changes.
Posted By: Thumperdart
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 04:16 PM
No one can nail a definate number for you but I would hope a 2-3 tenth increase IF everything else is up to snuff. In my case I fully ported my heads plus my intake was opened WAY up to kill any restriction or choke point that some intakes have. I picked up just shy of .02 but I know there`s a bit mre there............either way, you should feel/see a nice difference as long as you hook.
Posted By: ZIPPY
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 04:22 PM
I would hope to see 70 to 80 HP better than it was, and I think it should have about 500 at the wheels at that point when it's done.
Edit, to be more detailed about it....
60 to 70 from the head work
9 to 13 from the CR increase
And though it is an oversimplification, I am talking about adding that to the 425-ballpark number that was observed earlier, which should put it pretty close to 500rwhp at the end I would think. Maybe more.
Posted By: Streetwize
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 04:35 PM
General rule of thumb an old NASCAR Guru (who probably forgot more than I'll ever know) for normally aspirated conditions is around 4-4.1 cfm per hp per cylinder is your OPTIMUM full-race potential, so you're looking at roughly another 68hp or so of Maximum potential. The one point bump in CR is "generally" ~3-4%, but....your CR bump may only help in that it keeps the pumping pressures adequate to use the extra airflow....so it's sorta complicated. If you have the ability to get the extra air in and out.
And then who is to say either your old combo was optimized or your new one will be?
I generally shoot for 80% of optimum as a realistic guestimate for a Mopar Wedge motor bracket car....so I would wager with what I know of your BB wedge to look for around 50-55 hp max.
Hemi's and some of the better Canted Valve combos (Like a Yates Ford) generally get closer to the optimum for the same % increase...but that's just from my xperience.
Another trick and to me the most accurate measurement for this type of thing is to look more at the AVERAGE CFM increase that occurs between 1/3 and 2/3 of your valve lift....if you look at your flow as a Window you realize that your valve spends much more total duration time between 1/3 and 2/3 open that it does at the peak (where everybody seems to fixate on peak flow.)
Posted By: Dodgem
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 06:32 PM
I would say you'll pick up .3 minimum and .5 to .6 on the high end!
as said above looks like at 120 on 11.19 your 60 foot was not optimized or you had a 40 MPH tail wind??
so there is probably another .1 to .2 in optimizing your 60 foot!
Posted By: jafr
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 07:39 PM
I was being a little sarcastic when I wrote that.
Posted By: oldtimer5151
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 07:58 PM
I had a set done here in Texas and asked the porter to port mine with about 20 extra cfm on int and ex. It picked up from 7.oo to 6.89. Yours should pick up even more.
Posted By: Streetwize
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 08:46 PM
Last set of -1's I saw out of the box were ~310-315-ish but they can reach 335-340 without a ton of work. Well Ported the ones I've had were close to 360 by .650-.700 and ~380 by.800. I'm sure there are sets approaching (or just over) 400 in Max wedge PLUS form. Interestingly, OOTB the Cast Iron -1's always seemed to flow a little better than the Aluminums; As-cast I suspect they might be slightly thinner (less meat) around the guides I suppose but I've never had them side by side
It's been about 7 years or more since I've run them and I'm sure the state of the art CNC programs today are even better.
Posted By: jyrki
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 09:25 PM
Depends of what your engine is lacking. You may even loose something if your combo isn't right to the right direction. Head flow is not a key factor. Otherwise everyone would be running hemis.
Posted By: deaks
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/22/12 10:20 PM
I think you will see around 3 to 4/10.
I run the exact same heads as you, also milled .050 and i changed from mild port 452's with big valves and a torker man, to my present heads and a victor man and picked up nearly 7/10 and 6 mph.
Mick
Posted By: firefighter3931
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/23/12 04:29 AM
Randy, that SQ Cam will respond favorably to the increased compression and head flow. Expect a nice improvement in torque and horsepower and the midrange should be significantly improved. The stall speed will increase so the short times will improve and it will launch harder. Hopefully it'll hook and if it does that will translate to better ET's and higher trap speeds.
A reasonable expectation would be 50hp based on the bump in comp and port work. How much that improves the ET/MPH remains to be seen but like I predicted in the other thread ; it will run into the 10's
I'll go out on a limb and predict
10.85@124...hopefully better !
Ron
Posted By: deaks
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/23/12 08:15 AM
HI Don
The motor i'm refering to, is my old motor but the short block i got off you is still going good thanks.
Sorry about the hijack Randy, as you were.
Mick
Posted By: Labratt
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/23/12 01:53 PM
Greg..thanks for your well-thought-out,and detailed info!
To answer a couple of your questions..the ACTUAL lift of the SQ cam..after deducting .040 for lash,and "flex" is .574 on the intake....580 on the exhaust. Also..some mid-lift numbers,157/120 @ .200..221/159 @ .300...266/189 @ .400....298/204 @ .500...and 310/210 @ .550. How good are these numbers?
I'm assuming they're pretty good.
Thanks,again!
Randy
Posted By: roadhazard
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/23/12 04:42 PM
Randy those numbers are a little better than mine
Posted By: Labratt
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/23/12 10:16 PM
Hi,Greg! What heads do you have...and who ported them? Thanks!
Posted By: gregsdart
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/24/12 01:28 AM
R&J out of Iowa did my heads originally, and they ran the fastest that way. I tried some bigger valves, but they didn't help dispite showing flow gains. I have 440-1 heads.
Posted By: tboomer
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/24/12 12:24 PM
Randy....I hope to see you gain about .4..I think that will make ya smile!! My heads are at the same place that did Gregsdart..He said mine will pick up at least .5 over the small ones I have now...Good luck,buddy!
Posted By: 5spdcuda
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/24/12 12:52 PM
I tend to be conservative in my power estimates. My best guess and thats all it is would be 30-40 on the port work and 20 on the compression increase. A lot will depend on whether or not the rest of the combo can take advantage of the port work. The law of diminishing returns has never been repealed. Increasing compression from 8:1 to 9:1 will result in X amount of increased power. Going from 9:1 to 10:1 will result in something less than X and so on as the ratio increases the results diminish. Just see what your trap speed changes by. The old rule of thumb is 1 mph = 10 hp. Of course as speed goes up areodynamic drag enters into this since drag increases at the square of speed. As speed increases the power required for each increase also goes up.
Posted By: Labratt
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/24/12 04:00 PM
Greg..what gasket did you use to open up your intake port window?
They look nice to me!
Do you have any flow numbers on them? Thanks!
BTW..it'll be great to finally meet you..in Norwalk!
Posted By: roadhazard
Re: HORSEPOWER GAINS FROM HEAD WORK??? - 08/24/12 11:21 PM
Randy.....I didn't use a gasket to open them up, I relied on my extensive air flow knowledge
.
Just figured what they needed/I wanted to do and had at them
Don't know what size they are, just trim the gasket to fit.
Put them on Compu-Flow's 1020 bench and was told his bench is actually 15 cfm shy of any bench he's compared with so this has been added into the numbers below.
.100- 80.8
.200- 155.6
.300- 217.1
.400- 255.2
.500- 290.8
.600- 291.9
.700- 300.1
Don't know what the deal is with the flow between .500 and .600
I'm willing to bet if that motor had my 262/266 @ .050 duration cam..he would have been seeing a bit more than a 46 horsepower increase! 
Randy B. 
