Author Topic: M8 Flow Testing 2.0  (Read 925 times)

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Offline HD Street Performance

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M8 Flow Testing 2.0
« on: November 26, 2020, 07:53:32 AM »
I have a set of the SE CNC M8 heads in the shop and I decided to test them vs my ported heads and stock base line. The CNC heads are not the "Extreme" version

Online Hossamania

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Re: M8 Flow Testing 2.0
« Reply #1 on: November 26, 2020, 08:24:21 AM »
Thanks for that comparison, looks like yours really flow nicely.
Now for some Dyno testing!
Does this rag smell like chloroform?

Offline sfmichael

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Re: M8 Flow Testing 2.0
« Reply #2 on: November 26, 2020, 11:02:25 PM »
 :up:
Colorado Springs, CO.

Offline Admiral Akbar

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Re: M8 Flow Testing 2.0
« Reply #3 on: November 27, 2020, 07:50:42 AM »
Now the question is,,, Do you really need that much flow?  If the motor is 160 ci? maybe.  Will the SE CNC stuff perform just as well but give a better power band due to higher port velocity?  (IIRC the SE ports are smaller)

Offline sfmichael

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Re: M8 Flow Testing 2.0
« Reply #4 on: November 27, 2020, 08:21:15 AM »
Now the question is,,, Do you really need that much flow?  If the motor is 160 ci? maybe.  Will the SE CNC stuff perform just as well but give a better power band due to higher port velocity?  (IIRC the SE ports are smaller)

good point  :idea:
Colorado Springs, CO.

Offline HD Street Performance

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Re: M8 Flow Testing 2.0
« Reply #5 on: November 27, 2020, 08:38:20 AM »
Good question Bruce, and I track this line of thinking. Opening the barn door too wide? These are ~130" motors and in the V8 world that is a 520". We are asking for 6500 rpm. Reality is dynos are abundant with the SE 1.0 heads and they are not much, if any, better than the stock heads with similar builds. What I didn't mention is testing at 28" WC these SE heads howled like a banshee at all higher lifts and the pressure gauge was wandering wildly as well. Ear plugs mandatory. I did find the source and it will take removing some of the touted added material to get the port to be stable. Localized hot spots are not any better than low velocity, and probably worse. Like a lot of Harleys offerings "HD" half done. Keeps guys like me in business. The springs appear and measure to be the same as stock, same pressure and coil bind as stock. If I was a consumer looking at and evaluating the value of $1200 heads the dynos and specs would send me looking elsewhere. Valve sizes are stock, chamber untouched, and the hidden issues.

I will get a chance to look at the SE Extreme CNC heads and I expect a very different picture. Those heads use the same casting to start with but have opened up the throats and other features like +1mm valves and in real world work pretty well.

Here is a typical dyno with my ported heads. This build has been repeated several times and on other dynos has not made less than 155 hp and a few have over 20K miles without issue. Owners report fantastic manners and driveability and no pinging.
« Last Edit: November 27, 2020, 09:18:28 AM by HD Street Performance »

Offline Admiral Akbar

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Re: M8 Flow Testing 2.0
« Reply #6 on: November 27, 2020, 10:01:05 AM »
Thanks for the info.  I do think some of it has to do with cam selection but noisy ports as you say can lead to issues.

Offline sfmichael

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Re: M8 Flow Testing 2.0
« Reply #7 on: November 29, 2020, 08:31:01 PM »
looks like a very impressive combination Don - well done  :up: :up:

what clutch?
Colorado Springs, CO.

Offline HD Street Performance

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Re: M8 Flow Testing 2.0
« Reply #8 on: November 30, 2020, 06:18:25 AM »
Rekluse RMS-285, Thanks

Offline scotman623

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Re: M8 Flow Testing 2.0
« Reply #9 on: December 09, 2020, 02:42:41 PM »
Very impressive.. Is that Dyno from Dave’s bike? 😎💪💪💪💪
Always look forward...

Offline HD Street Performance

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Re: M8 Flow Testing 2.0
« Reply #10 on: December 09, 2020, 04:01:59 PM »
Yes Dave's  bike

Offline Durwood

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Re: M8 Flow Testing 2.0
« Reply #11 on: December 11, 2020, 07:02:10 AM »
Stock heads make more power than the early SE CNC heads. Nice work Don.