Piston Boost Port

That first piston picture, it definitely has a "hot spot" right in the middle. Was it lean?

looks good id like to know how mutch more power it makes

sicivicdude said:

That first piston picture, it definitely has a "hot spot" right in the middle. Was it lean?

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That was just alittle oil.

Great stuff as always! Watch someone doesn't steal your idea and make it there own!! I know it's for all! Shaweet!

best said:

Actually James, I think that was a drip of something as we took it apart.

You can see it is a wet drop, and the smudge line is from a sloppy finger.

Here is the bottom of the piston, a bit of carbon, it has been hot but it has also been run long and hard.

Steve

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Ok, at that angle it's much clearer. It looked in the first picture series to be aluminum spalling off almost dead in the middle of the piston (like it was seriously hot and starting to melt though).

The carbon on the bottom of the crown concerns me a tiny bit but real bad. If that's an older piston, it's kinda to be expected.

I can't wait to hear the "True reality" behind a piston boost port on a blaster!

Looks like there's not going to be any more "Obi-Wan Kenobi",talking in riddles stuff any more.
Bring forth the TRUTH!

Damn Steve,you beat me to it by at least a week!
I can't wait to see the outcome!

I have the milling machine warmed up and ready to go!
I see you run one of them there
"cheap cast pistons" too!

I also see that as hard as Neil runs that engine,and as hot as he sometimes gets it ,that "Cheap Cast Piston" lacks the usual...
"mighty wiseco forged piston" four corner seizure marks,and the "Got too hot an swelled up in the bore" scuff marks. Hmmm... must be something to that "cheap cast piston" after all. Imagine that!

Great pictures by the way. Thank you. Cant wait for the out come. At least now when someone googles ...
"Does a piston boost port increase power in a blaster" they will actually get an answer. Good or bad.

I predict an increase in power output that you will be able to feel in the "seat of your pants" and across the entire rpm range,with more near the top. Thats my prediction.

I see you run good oil. Must be that Ipone?

joeak47 said:

]I also see that as hard as Neil runs that engine,and as hot as he sometimes gets it ,that "Cheap Cast Piston" lacks the usual...
"mighty wiseco forged piston" four corner seizure marks,and the "Got too hot an swelled up in the bore" scuff marks. Hmmm... must be something to that "cheap cast piston" after all. Imagine that!

Great pictures by the way. Thank you. Cant wait for the out come. At least now when someone googles ...
"Does a piston boost port increase power in a blaster" they will actually get an answer. Good or bad.

I predict an increase in power output that you will be able to feel in the "seat of your pants" and across the entire rpm range,with more near the top. Thats my prediction.

I see you run good oil. Must be that Ipone?

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No, it'll just explode in the bore and take out the cases and crank. MUCCCHHHHHHH better. 8-| 8-|

sicivicdude said:

No, it'll just explode in the bore and take out the cases and crank. MUCCCHHHHHHH better. 8-| 8-|

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We'll just have to wait and see about that,now won't we? Its funny that I've been running cast pistons for many years with ZERO issues,and so has many other people "including" the manufacture of our atv's (along with many other manufactures). Perhaps your not boring or honing your cylinders correctly? No big deal. It happens. Now aside from all that,I can't wait to see the out come to the test. Aren't you interested too? I know you dig this stuff at least as much as I do.
Besides,remember...its only a test. "Best" (Steve) is only doing a "quick and dirty" slot in the piston to see the effects it will have on over all power increase,and where in the power band it will play a part,if any,BEFORE he installs the heads that I machined and the cylinder that I ported. This is only a test on a well worn cylinder. No harm done.

If this was going to be in the cylinder for any length of time,I'm sure he would have smoothed his work to remove all the stress risers,and gave that slot a very small radius inside and out.
I look at this three ways...
#1...We will NOW know the effects of a "piston boost port on" a blaster engine. (good to know)

#2 There will be an actual answer to the question when people ask it.

#3 He beat me to it by about a week.

If it works,I'll be applying it to my porting and testing it too. Less output? Perhaps. More output or some form of improvement? Most likely,but I don't really know until I test it.

Right now I'm working on building a "boysen port drilling jig". This is becoming a fun project. It will take away the guess work and mistakes when drilling the boysens. I might make it with different adapters ,so I can progressively increase the boysen sizes as I see fit. Pretty cool huh? That way I can test,test,test,and then share the results.
No more guessing,guessing,guessing. Its for the greater good of learning.
I'm even going to show how I make it and how to use it. I might even offer them for sale. Who knows?

Now about that radius tool.....

I don't use cast pistons or recommend them to anyone else. It's how I get my case repair jobs, actually... so please continue to recommend them.

My thoughts on piston boost ports without any other modifications:

You won't feel much of a difference if any at all.

You're not increasing volume transfer to the bottom end significantly because the boost port is blocked by the "T" that makes up most of the intake window (piston down) or straight covered up by the sleeve (piston up) most of the time during the stroke.

Any increase in flow to the bottom end, without changes to the transfer ports won't be any more likely to actually make it to the top end to improve power output any.

You may be lubricating the bottom of the piston crown and the wrist pin better than before but neither of those are major weak/failure points to begin with so any change in the amount of cooling or oil they may receive isn't going to significantly affect engine life.

Thers is the distinct possibility that the incoming fuel may "wash" the wrist pin clean of oil that may have been slung up there during high rpm operation. It could actually shorten the lifespan of the wrist pin/small end of the rod. This is obviously not an issue with the engines I HAVE seen piston boost ports cut into (drag and hill shooter motors). However, those engines are generally an extreme case of a trade-off for maximum power output versus longevity anyway. They can't speak to how many hours the wrist pin bearing lasted.... they tear the engine apart every few hours of operation anyway.

I'm all for testing and trials but for someone who speaks to testing and critical thinking, these principles should be relatively clear from the onset. Now, let's hear some results.

Be careful and check periodically for cracks. I had one of mine crack but I caught it in time. Yours is not as extreme as mine but it doesn't hurt to check on it every now and then.

Thanks for the "Heads up"! I always inspect. Thank you.

Now I've got to ask...What,how much,and where did you notice the improvement in the power band with the boost port?

I see thats a "wiseco" piston. Did you ever try it before the wiseco with a stock piston,and what was it like compared to now?? Lots of scuff marks on that piston too...what do you think contributed to that?

It almost looks like the bore was worn which allowed the wiseco piston to expand too far (the wiseco's do that when they get hot),and something had to give,which in this case was the bridge in the boost port.

This seems like an interesting modification.

sicivicdude said:

I HAVE seen piston boost ports cut into (drag and hill shooter motors).

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What hillshooters have you seen this on? Have you worked on any of those hill shooters? They sound like a blast to build. Where in North Carolina can you run hill shooters?

joeak47 said:

Thanks for the "Heads up"! I always inspect. Thank you.

Now I've got to ask...What,how much,and where did you notice the improvement in the power band with the boost port?

I see thats a "wiseco" piston. Did you ever try it before the wiseco with a stock piston,and what was it like compared to now?? Lots of scuff marks on that piston too...what do you think contributed to that?

It almost looks like the bore was worn which allowed the wiseco piston to expand too far (the wiseco's do that when they get hot),and something had to give,which in this case was the bridge in the boost port.

This seems like an interesting modification.

Click to expand...

I'm fairly sure that's not a boost port, that's just a piston for a YZ400.

I've never worked on a hillshooter (or seen a successful blaster hillshooter). I have seen banshee engines disassembled that were used for that purpose and had piston boost ports cut into them (added to stock style pistons, not a completely different piston design).

My wossner forged piston has a "boost port" in it. It's actually centered basically at the top corners of the two intake windows on a "standard" blaster piston.

sicivicdude said:

I'm fairly sure that's not a boost port, that's just a piston for a YZ400.

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No...it is without question a yz400 piston. I use to own one.


Looks like you've got a bit of "four corner" scuffing...at least from what I can see. Not terrible.