Loooooow compression cam conundrum

[IQ52]

No one here saying aluminum heads will not work at lower compressions has tested this........am I right or wrong? Which one of you has any emperical data, in an internal combusion engine test, that substantiates your assumptions? Hmm? Anyone? Where is the test?

 

[ga66mopar]

Personally, I'd keep the cam you have (same one that mopar muscle used with the e-street heads) and change your gears and converter and see how that works. Than if you feel you need more power put the 75cc heads on.

I agree with Banzaii67 I would keep what you have. I'm running the xe274 in my 10.5 compression 440 and it have a lot of bottom end torque and it pulls real hard to about 6000. If it is low on low end torque I would advance the cam a few degrees

 

[MikeyT]

No one here saying aluminum heads will not work at lower compressions has tested this........am I right or wrong? Which one of you has any emperical data, in an internal combusion engine test, that substantiates your assumptions? Hmm? Anyone? Where is the test?

I haven't, but don't need too... plenty of real life racers here doing the same things as OP is saying. However out of all those builds how many are running aluminum heads?

here is a great article by Hughes engine explaining which is right for you.

http://www.hughesengines.com/TechArticles/7choosingheadsaluminumvsironwhichonesdoyouneed.php

Also, here are some real life experience for OP too
build ideas:
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=4656289&an=0&page=0


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Also, this wasn't meant to poop in your cornflakes IQ52, just posting an opinion and where I got my data from to support it.
Mikey

 

[HT413]

This is great input, guys, I really appreciate it. My take away here is those cams are not slam dunks, so thanks for setting me straight.

Regarding the negative affects of aluminum, well you guys got me there. I'll tell you what, I'll go with whoever wins the argument lol.

Now, regarding my budget - I have about $4k this winter / spring for the whole car. Anything I don't spend gets saved for next year's budget:

$700 gears (figuring I'd sell my setup)
$0 converter (I have a 2800-3000 stall ready to put in)
$200 used rpm intake (or other decent dual plane)
$0 ductile iron rockers (already have the setup)
$200 or so for pushrods and incidentals
-----------
$1100 that should dramatically improve performance and drivability.

That leaves me with about $3k to work with.

Again, thanks for the input. Without it, I'm sure I'd just build another mismatched pig.

 

[HT413]

Also, here are some real life experience for OP too build ideas:
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=4656289&an=0&page=0

Thanks, mikey, I found that thread a while ago and just rereading it tells me I'm on the right track. 12 seconds with an 8:1 motor, dang. I constantly look out for some nice prepped 915's but deals on 915's are pretty hard to find and they quickly start approaching aluminum head prices, further confusing the issue. :thinker:

 

[Sweet5ltr]

I will be doing a turbo very shortly... with 3k, you could do an easy turbo setup making 500-600rwhp and run a modest 3.23 gear and pig low compression.

 

[IQ52]

I haven't, but don't need too... plenty of real life racers here doing the same things as OP is saying. However out of all those builds how many are running aluminum heads?

here is a great article by Hughes engine explaining which is right for you.

http://www.hughesengines.com/TechArticles/7choosingheadsaluminumvsironwhichonesdoyouneed.php

Also, here are some real life experience for OP too
build ideas:
http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=4656289&an=0&page=0


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Also, this wasn't meant to poop in your cornflakes IQ52, just posting an opinion and where I got my data from to support it.
Mikey

Nobody has to prove to me you can make power with low compression.

And I see no defilement of my cornflakes.

And Huges is repeating the same ol' crap that has been pronounced for years ever since the aluminum head came out..........without any test that shows the compression must be increased to maintain the same horsepower. I have seen the tests that show that notion IS FALSE.

 

[Meep-Meep]

I'm figuring this stuff out as I go so I will try to explain why I believe IQ52 is correct in saying that the aluminum head makes no difference. It is said that you need more compression when using the aluminum head vs. the iron because aluminum is a better heat conductor than iron. One might conclude from that statement that aluminum tends to suck the heat out of the combustion resulting in less power. My take is that while the amount of heat during combustion is very high there isn't enough time for that heat to get sucked out of the chamber. Think about it. The temperature during combustion is in the order of 1500 degrees and is on a duty cycle if you will (once every four strokes). If the cylinder head material was so efficient that it can transfer heat that quickly, you would have a lot more to worry about. How about the aluminum pistons? The oil film on the walls? The only thing that might happen with the use of the aluminum head is a slightly quicker warm up time.

 

[99ss]

Agreed ^^^ Maybe what they meant to say was that you can RUN more compression with aluminum heads. Iron heads just like iron intakes are vulnerable to heat soak as well. There isn't an issue with all aluminum engines making power these days as well... in fact a lot is done to avoid heat soak. Yes there is a minimum temp for efficiency but you aint getting below it with a set of aluminum heads. If that were the case boosting would be a hell of a lot cheaper and easier


Heads make the power and its all about air flow ... which encompasses a bunch of little things about the head.

 

[HT413]

Well, I'm officially out of the aluminum vs iron debate. Just picked up some 915 HP heads last week. Petty psyched about em. They have the big exhaust valve and look like they may have had some bowl and port work done. Bonus, they even came with valves. I had em checked over by the guy doing my gears (old school mopar guy) and he said they look pretty good.

While I was there, we made a nice deal on some steel shim gaskets and a oem timing cover (can't stand the chrome one I have). He threw in the valve covers you see there, which look pretty neat.

Now I gotta save some cash for an RPM intake. Anyone have one lying around? Maybe trade for my Torker2?

(Not sure why the picture posted upside down?)

 

[HT413]

Got my gears!

My buddy Ken set up my new gears for me. Took my 489 case, installed the crush sleeve eliminator and some 4.10's.

Bad news is i needed a new auburn unit, as the other one was trashed. Amazing that the trashed unit could still lay 2 strips with my 30"x12.5" ET street radials.

Next up is the converter. Should start it up tomorrow if i'm lucky.