Heads

Author Topic: Heads  (Read 5823 times)

Offline 74 340 4speed

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Re: Heads
« Reply #30 on: November 03, 2008 - 11:20:02 PM »
Have you considered Brodix Heads?  http://www.brodix.com/heads/b1.html
Andy
1967 Camaro SS: 406 sbc 505 hp/506 ft lbs|4 speed|Posi|3.73s
1969 C/10  350|Turbo 350
1969 Dodge D300 318|4 speed|Dana|4.88s
1972Nova: 350|Turbo 350
1974 'Cuda: 340|4 speed|Dana 60|4.10s|posi
1999 Camaro SS: Auto|Longtube Headers|True Duals|TT2s
2013 Challenger R/T: 6 speed|Hurst with pistol grip|mopar performance exhaust|super track pak




Offline 71chally416

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Re: Heads
« Reply #31 on: November 04, 2008 - 12:07:54 AM »
According to Shadydell flow figures the big port Commandos are about 5% better on the Intakes (using smaller valves) and 21% better on the exhausts ported at .500" lift. Unported it's still 5% in favor of the Commandos on the Intake side and about equal flow on the exhaust. Both need special valve gear.       
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Offline CannTankerous

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Re: Heads
« Reply #32 on: November 04, 2008 - 05:09:39 PM »
[quote author=71chally416
Just that the bigger a motor is, the "bigger" the cam you can use and still be streetable. That should be the LAST thing you pick for a motor, not the first, because all the other motor parts will dictate what you should use. Picking the wrong cam is probably the most common mistake people make with a performance motor. Do that last

Yes, exactly. L, I was also thinking about you talking about the possibility of a Victor, and some of the bigger heads you all discussed. The thing is, I figured your hp peak would probably be below 6000 with your original parts choices, 5800-5900 as I remember. The Victor probably wont pass the RPM Air Gap in power production till fairly high in the rpm range. The Victor would keep pulling way higher than that cam we talked about. So, it's not that long after your Victor and big carb start to pull that your cam will run out of breath. The Victor will kinda torpedo the torque of the semi conservative stick, and then the cam will torpedo the big intakes ability to breathe up high. All about combination. So, just thinking if you go up a step or two on all the supporting airflow pieces you might consider going up a step or two on the cam too. Man, I better go introduce myself if I'm gonna be blabbing on here. L8R

Offline 71chally416

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Re: Heads
« Reply #33 on: November 04, 2008 - 05:51:38 PM »
The Victor that replaced my RPM Airgap crushed it up top by I think 40+hp, but I'll check the dyno sheet again. Mostly because the RPM just doesn't have much extra metal on it to port, so you're strapped to a smaller volume in the runners. The truth is on a stroker motor you can afford to lose some TQ to gain a bunch of top end HP. I'd rather have a motor that still makes good HP at 6K than one that throws out the anchor at 5,400. The worse of both worlds on a street car is to have a short winded tire burner. You lose ET with tire spin and also lose MPH because it's gasping for air going through the traps.  :2cents:
 
« Last Edit: November 04, 2008 - 05:58:44 PM by 71chally416 »
Once we had Ronald Reagan, Bob Hope & Johnny Cash. Now we have Obama, No Hope and No Cash!

Offline lemming303

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Re: Heads
« Reply #34 on: November 04, 2008 - 06:25:03 PM »
Well I just talked to the machine shop today and found out how much its gonna be to get the block inspected and cleaned. So when I get paid again I'm gonna take it there and have that done, then I'll know if I can still use it.
I haven't bought any parts yet, not one. I've been asking around trying to decide what I want to go with.
If I understand right:
The longer stroke of the crank restricts the engine to a lower rpm right? Or can I go with a range above 6000?
If I get a single plane intake it will give more HP and torgue at a higher rpm, but be lacking below 3000 (subject to the cam also)
A dual plane will help with lower rpm torque, but limit the revs to a lower range, around 5500?

So now I'm confused. I thought I had a good combo to go with. I need to get some books, but I'm having a hard time trying to decide which one to buy.

Another question: how do you determine what lift and duration to use, according to your rpm and intake choice?

I know thats a lot. Thanks everyone.
Kevin

73 Challenger Rallye - first project

Offline Chryco Psycho

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Re: Heads
« Reply #35 on: November 04, 2008 - 08:56:56 PM »
a stroker trims maybe 500 RPM off the peak but generally is good to 6500 rpm
 singlke planes are not all th ewsame some have lower powerbands & work well , the Eddy RPM or the old LD 340 are 2 of the best intake for midrange power
 Duration & overlap controls the rpm range of the cam generally lift makes no difference to the RPM so get as much as you can at the duration you need , most of the cams I use with a 2200-6200 powerband have .530-.550 lift if hyd & closer to .580 lift with solid grinds

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Offline lemming303

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Re: Heads
« Reply #36 on: November 04, 2008 - 10:15:16 PM »
I understand about overlap and duration. I'm gonna use solid lifters, not hydraulic. I found a couple books that I'm gonna buy and hopefully after I read those I will have a better understanding. I also got a subscription to Mopar Muscle Mag and I'm waiting for my first issue. Thanks for the help yall.
Kevin

73 Challenger Rallye - first project

Offline Chryco Psycho

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Re: Heads
« Reply #37 on: November 05, 2008 - 01:30:18 AM »
Beware of the mags , MCG is better than most though , usually the tech articles are sponsored by manufacturers that want to sell parts & info can be incomplete or erroneous pump up products that do not do what is claimed
 there are 2 articles I put together in the archives that cover a lot on cam design & choice as well

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Offline moper

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Re: Heads
« Reply #38 on: November 05, 2008 - 06:17:40 PM »
The stroke of an engine does not gain or lose power. It simply moves the peaks in the rpm range. Longer strokes will generate the sam epower at lower rpms. This means they need MORE air to rev higher. The  typical 280cfm ported Edelbrocks are enough to make 560hp at 6800pm with a medium sized (280°@.050, .630 lift) solid roller. A set of Indys or done W5s will make power well beyond 6K. But, a typical street car that races say, 4-5 times a summer, doesnt need to make power that high. And to make power up high, you have to sacrifice some torque. I'll take 500 pound feet at 2500 any time before 500 pound feet at 4K in a car with street gearing and street convertor. A car that goes 115 (in the 11s) with a street 3.55 or 3.91 gear should'nt rev past 5700 anyway. It takes about 475hp at the crank to push 3400lbs to 115. That's a head that flows 240ish and a medium sized hydraulic cam with a 4" arm.