New Manic Mechanic High Comp Billet Head

[210061741]

Here is the new high compression head from Jim at Creative Engineering.
Currently there are only 2 of them and i have 1.
These will be available at Pirate Cycles only.
Very Very soon.

THE FIRS PICTURE IS A VIDEO IF YOU CLICK ON IT.

IMG]http://i887.photobucket.com/albums/ac72/RidingRich/latest%20work/SDC11042.jpg[/IMG]

IMG]http://i887.photobucket.com/albums/ac72/RidingRich/latest%20work/arianna2.jpg[/IMG]

Heres a video of how it sounds.
Notice i am running an 18mm Dellorto Carb now too.

http://www.youtube.com/watch?v=zQRDSwtc4KE

 

[AussieSteve]

Looks different. It's very tall.
Again, what's the compression in psi?
That's more important than the sound, which is really the carb & pipe, not the head.
Also, what is the clearance, head/plug to piston?
And, does it bolt straight on with standard 107-108mm studs?

... Steve

 

[210061741]

Yes it bolts right on.
It's for the PK motors only at this point.

I will have to figure out the psi and get a compression tester.
However my PSI will be slightly lower than on a stock motor due to my porting arrangement.

I will get both measurements soon as i have some time.

The chamber with the dome piston is cut down to 4cc.

You have to set the clearence to exactlly .020 inches.

The squish is perfect.

 

[AussieSteve]

This is another one that's quickly losing me.
You guys are designing a high-compression head, but you don't even have a compression tester?
I'm a beginner backyard mechanic and it was one of the first things I bought.
You say high compression, but then say combustion chamber pressure will be lower than a stock engine?
20 thou clearance, with lower psi than a stock engine?
Mine is a measured 142psi, (17psi higher than stock), and has 0.044", (1.1mm) clearance, measured and not from spec.
And why so tall? My RSE billet head is plenty cool enough, with much more meat than a stock head.
Maybe I'm off track, but I'm not quite keeping up with this. something doesn't add up with the 'hi-comp' head. Maybe I'm misunderstanding what you're saying.

...Steve

 

[swifty]

steve,when you do a compression test you are measuring dynamic compression.from where the piston seals the exhaust port to the top. if you port & raise the exhaust port you will have less dynamic compression.this is not to be confused with static compression ratio which takes into account the total swept volume.you could have an engine with low cranking pressure yet still have hi comp ratio if it has a very high exhaust port. hope this helps.

 

[AussieSteve]

Swifty, I follow what you're saying, but isn't the aim of a high compression head to raise the gas pressure at the point of firing, regardless of compression ratio.
If the measured gas pressure is lower than that of a standard head, isn't that a low compression head?

... Steve

 

[swifty]

as the engine revs higher the percentage of loss becomes less & less to a point where with a properly tuned expansion chamber it will start to increase.this is when a 2 stroke comes "on the pipe".the engine with low cranking pressure, due to port timing will out perform the std port engine in the mid & hi rpm.given that the static comp ratios are the same. you dont ride your bike at cranking speed.

 

[AussieSteve]

I was only originally trying to find a way to compare the Manic Mechanic head with my Rock Solid Engines one, in some useful fashion. I guess it's not that easy.
Also, originally I thought the new MM head was a bolt-on performance accessory for a standard HT engine, rather than being specifically for a ported PK.

I've avoided porting, apart from a tiny bit of widening, to keep my bottom end.
(I'd love to be able to ride my bike at cranking speed, although that's less important now, with a shift kit.)

Compression ratio measurement always had me wondering, on a 2-stroke, since it's not just a matter of the swept volume : compressed volume. As you say, it's dependent on the position of the (top of the) port.
I thought that psi measurement at cranking speed was a fair comparison, but obviously not.
And therefore it follows that measuring psi has been a waste of time, except for future comparisons to see if I've lost any.

Not that I was planning to change, but from the sound of things the head I have suits my purpose best.

... Steve

 

[210061741]

Steve

I am not the only person working on this project.
I am not the one who designed the head.
It was done by Manic Mechanic and BRENDON POWERS.....
Brendon powers builds F1 Racing Engines professionally.
So i don't allways have all the figures at my fingertips.

I do things mathematically and then verify it all in the cad system.

Obviously Rock Solid didn't tell you what the PSI of there head is or you guys wouldnt be testing with compression gages.

The high performance engine is much higher than stock.
greater than 9:1.

Now to clarify things.

The high compression billet head will produce higher PSI on a stock PK.
Much higher.
It also produces higher psi on my engine.
All i was saying is due to my porting the PSI reading i get will be slightly lower than what you will get.

I will model everything in CAD and tell you the exact compression ratio and the exact psi of the head.

Also we will be producing an even higher compression head for the ported Performance Motors.

I'm sure Jim at Creative Engineering can tell you what the Exact PSI is as well.

The stock cc chamber is 8cc.

The billet chamber is 7cc.

The piston also consumes around 3cc.

1 more thing as well.

Engines with different strokes and different porting will have different Readings.

Hope this helps.

I will post the data soon.

 

[210061741]

Steve

The head is currently being produced for stock unported motors.

A new one will be produced for the ported motors.

Also my porting and the addition of the Dellorto drastically increased the bottom end as well as the top end.

It pulls hard and fast.

You just wouldn't believe it.

I allmost fell over when i got it ported spot on.