A tale of 2 327s

G

guru

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Mar 25, 2008
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Hey guys,
I have been pouring over the dyno mania article on the 2007 engine masters challenge and I have come up with the following tale of 2 327s.

1 is a ported stock casting head with a mild solid cam, and the other is an AFR headed 327 with a larger solid cam. I dont really care about the variation in camshafts because different heads should have different cams. Different heads have different strengths and weaknesses. In any case lets continue.

Ataleof2327s.jpg


As we can see the ported stock head combo was dramatically superior to the AFR head under 5000 rpm and at a noticable disadvantage above 5000rpm.

I will let you draw your own conclusions. Mine are as follows:

The AFR headed 327 is a really good high RPM combo and would tear it up if it was never forced to compete below 5000rpm. Probably given our M21s close ratio probably wouldnt spend to much time below 5000 rpm anyway down a 1/4 mile track. If I were a drag racer it would be my engine of choice. The other 327 would probably be a better street engine, and maybe better in other forms of racing like road racing or autocrossing. The ported stockers also scored better on the 2007 Jegs engine masters challenge.

So the major lesson to take away - the best combo is the one that meets your intended purpose. Before you pick up a catalog and buy the most expensive shiniest part with all the right brand names, and be lauded by the interweb fanbois ask yourself is it right for your intended application? Who knows maybe some ported stockers IS right for what you are doing.

An AFR 195 CNC ported head was in the top 5 on a 302, and made a ridiculous amount of power and torque. The winners used some raised runner racer pro heads from australia.

Well matched components are well matched components no matter what. But well matched to what?
 
Another brilliant post. I love reading your stuff.

Anyway, what was the stock head that was started with? 113s or old double humps? Was the AFR head a Comp Port fully CNC'd?

And at the end of the day, looks only like about 30 HP difference up top...is my eyesight treating me right?
 
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By the same token the AFR motor was at one point down 73 ft lbs of torque.

They didnt say which AFR heads or which Edelbrock intake but the intake valve was HUGE for a 327. It wouldnt suprise me if the AFR motor kept making power after 6500 rpm. If it doesnt then well given that its making peak torque around 5200 rpm it has a narrow power band and will feel peaky. The ported head motor was a nice broad power band.
 
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guru said:
By the same token the AFR motor was at one point down 73 ft lbs of torque.

They didnt say which AFR heads or which Edelbrock intake but the intake valve was HUGE for a 327. It wouldnt suprise me if the AFR motor kept making power after 6500 rpm. If it doesnt then well given that its making peak torque around 5200 rpm it has a narrow power band and will feel peaky. The ported head motor was a nice broad power band.
Click to expand...

Who runs their car to 6500 rpms on the regular basis that it's all that important?
 
Jsup said:
guru said:
By the same token the AFR motor was at one point down 73 ft lbs of torque.

They didnt say which AFR heads or which Edelbrock intake but the intake valve was HUGE for a 327. It wouldnt suprise me if the AFR motor kept making power after 6500 rpm. If it doesnt then well given that its making peak torque around 5200 rpm it has a narrow power band and will feel peaky. The ported head motor was a nice broad power band.
Click to expand...

Who runs their car to 6500 rpms on the regular basis that it's all that important?
Click to expand...

In ALL my years of messing with engine, I have NEVER seen one blow at speeds below 5000 rpm....YMMV......

gimme torque enough to break axels at 1500 rpm.....

:1st:
 
I'm willing to bet the AFR's were 195's...IMO way too big for a 327. I think the torque numbers down low would be much better on the AFR 327 had AFR's 180 cc intake runner head was used. Too many variables, IMO. The combustion chambers suck on the old GM heads, along with the port design. I do believe the runner volumes are almost optimum for a 327 though.
 
big_G said:
I'm willing to bet the AFR's were 195's...IMO way too big for a 327. I think the torque numbers down low would be much better on the AFR 327 had AFR's 180 cc intake runner head was used. Too many variables, IMO. The combustion chambers suck on the old GM heads, along with the port design. I do believe the runner volumes are almost optimum for a 327 though.
Click to expand...

Oh, it's the 195s, that's all they ever test, they put them on everything.
 
TQ at lower rpm's can be compensated somewhat by using a higher numerical rear gear. If you can pull enough rpm's and fuel efficiency doesn't matter you can make a real strong engine with a short ratio trans. If you don't like the high rpm's on high way cruising, you can always go with a 5 or 6 speed.

I think alot of the hp numbers have something to do with the big valves versus cubic inches.
 
There is something to the big valve arguement. Each motor requires a certian amount of valve area to get the job done. Larger diameter valves need less lift. But you can only get so big before causing other problems.
 
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