What piston?

[fasterz]

Im putting a new piston in my 450 next week so i need to order one asap. Im leaning towards the JE, but now im not totallt sure what i need after reading abotu a thermal coating, what is this and how much? I looked into the hammerheads and they just seem too skeptical and way over priced for just a freakin piston. If they start to prove them selves then mabey ill get one. is any one running the JE? what compression ratios do they offer? Do i need this thermal coating? Any other companies i should look at before I order the JE? Did you notice any power increase? I am puttin in a cam and an FCR Carb also so the piston should help these out. I ran the stock motor fine at all the races last year, just with all these new 450s im thinking i could use a little more pep. Thanks...

[WhiteZee]

what cc piston are you getting?

[jeepnrocks]

I noticed a huge difference going from a 13:1 Je to a HH style piston at 13.75:1, the difference was night and day

[culookn]

weren't the HH smoking or having some sort of malfucntion? dont hold me to that but i think i read that somewhere

[chad502ex]

JE makes solid reliable pistons. Personally, I'm not totally convinced that coating pistons is really worth it. Never coat the deck of a piston cause it inhibits thermal expansion of the piston to the walls. The coating of sideskirts can also prevent efficient thermal transfer from the forged piston to the sleeve. Yea, may be little less friction when the side skirts rub on side loading, but most like more power is lost from the piston inability to transfer the heat to the cooling of the cylinder.

[TWISTED]

Originally posted by chad502ex
JE makes solid reliable pistons. Personally, I'm not totally convinced that coating pistons is really worth it. Never coat the deck of a piston casue it prevents thermal expansion. The coating of sideskirts can also prevent efficient thermal transfer from the forged piston to the sleeve. Yea, may be little less friction when the side skirts rub on side loading, but most like more power is lost from the piston inability to transfer the heat to the cooling of the cylinder.

YEAH!!!!! What he says.....

[WhiteZee]

Originally posted by culookn
weren't the HH smoking or having some sort of malfucntion? dont hold me to that but i think i read that somewhere
the only people who have oil problems are the ones who did not have there piston to cylinder clearance set at .001 and did not have there rings gapped correctly.

[chad502ex]

Originally posted by WhiteZee
the only people who have oil problems are the ones who did not have there piston to cylinder clearance set at .001 and did not have there rings gapped correctly.

WhiteZee, please advise:

on typical shelf pistons- piston to wall clearance run about .003-.004, how is it that the HH doesn't expand more than the shelf pistons? how is it that the 96mm HH doesn't expand more than 0.001" after heated?

Originally posted by chad502ex
WhiteZee, please advise:

on typical shelf pistons- piston to wall clearance run about .003-.004, how is it that the HH doesn't expand more than the shelf pistons? how is it that the 96mm HH doesn't expand more than 0.001" after heated?

good question...:confused:

[Bad Habit]

Originally posted by chad502ex
WhiteZee, please advise:

on typical shelf pistons- piston to wall clearance run about .003-.004, how is it that the HH doesn't expand more than the shelf pistons? how is it that the 96mm HH doesn't expand more than 0.001" after heated?
It has nothing to do with piston expansion from heat. Shelf pistons can run larger p-c clearance because they use high tension rings to make up for variations due to cylinder wear. The HH uses low tension rings to reduce friction, which aids power production. This makes p-c clearance, ring gap, and gap clocking critical. The larger bore HH are being mated to cylinders that are bored and plated specifically for the piston size, just like any overbore. The stock bore HH have been installed in cylinders with varying amounts of wear and more than likely were not checked for proper p-c clearance before installation.

[chad502ex]

Originally posted by Bad Habit
It has nothing to do with piston expansion from heat.

i wanted to hear WZ explanation not yours.

But since you seem interested in providing details on the HH smoking issues, which i wasn't asking, answer my original expansion question- with a clearance of 0.001 p-c how is it that the smaller mass of the piston doesn't catch up with the expansion rate of the hardened water cooled sleeve with 0.001 clearance?

[fasterz]

Will i be able to run 94 pump gas with the JE 13:1? the 11.8:1 is a little lower than i would like. Also what are all the available compression ratios? where should i buy it from? thanks

[chad502ex]

Originally posted by fasterz
Will i be able to run 94 pump gas with the JE 13:1? the 11.8:1 is a little lower than i would like. Also what are all the available compression ratios? where should i buy it from? thanks

running pump fuel has everything to do with dynamic compression not static compression. In other words, if you have a high overlap top end cam like Web 208, Megacycle, HRC, or such, the valves during overlap are open longer causing static compression ratio to drop. 13:1 with large overlap cam is ok near ~100 octane but 94 only if you had to get back to the truck after riding the trails.

hope this helps.

[fasterz]

Originally posted by chad502ex
running pump fuel has everything to do with dynamic compression not static compression. In other words, if you have a high overlap top end cam like Web 208, Megacycle, HRC, or such, the valves during overlap are open longer causing static compression ratio to drop. 13:1 with large overlap cam is ok near ~100 octane but 94 only if you had to get back to the truck after riding the trails.

hope this helps.
What about with a stock cam? I may have to run it with a stock cam for a ride or 2, is that going to change things? will the compression be lower with an aftermarket cam? also what kind of compression check readings should i be wanting with a 13:1 piston? Right now with stock its about 94 which is a tad low but the motor is a season old.

[chad502ex]

Originally posted by fasterz
What about with a stock cam? I may have to run it with a stock cam for a ride or 2, is that going to change things? will the compression be lower with an aftermarket cam? also what kind of compression check readings should i be wanting with a 13:1 piston? Right now with stock its about 94 which is a tad low but the motor is a season old.

i wouldn't on stock cam with that compression on pump. with hrc cam but never stock cam. dynamic compression is when the engine is running and is different than static compression when the engine isn't. the 13:1 will drop more into the safe pump fuel zone with higher overlap top end cam

[homer]

I am also interested to know about the thermal expansion with the hammerhedz. I have a HH 480 kit and I am having problems with it (I won't go into it here). But thermal expansion is something that my machine shop inquired about when examining my 480 kit. As of yet no one has been able to explain it to me.

[chad502ex]

Originally posted by homer
I am also interested to know about the thermal expansion with the hammerhedz. I have a HH 480 kit and I am having problems with it (I won't go into it here). But thermal expansion is something that my machine shop inquired about when examining my 480 kit. As of yet no one has been able to explain it to me.

the thernal expansion of the piston and the ring pack are crutial in te design of the kits success. hope you find your answers or they offer you help.

[homer]

I know the thermal expansion is cruitial but what I don't know is how they have any room to expand without trying to seize up with less than .001" clearance.

[chad502ex]

Originally posted by homer
I know the thermal expansion is cruitial but what I don't know is how they have any room to expand without trying to seize up with less than .001" clearance.

yes i know. that was what i was asking but the Bad Habit could not answer that question when asked about expansion of the piston and not the ring pack or smoking issues.

I know that forged aluminum expands at a faster rate than hardened cylinder NiCaSil so my question really is that how 0.001" is enough. I understand the ring pack that the HH uses isn't as tensile as typical shelf ring pack kits to reduce friction, but i wanted the theory that the 96mm HH piston isn't going to expand any more than the cylinders expansion and therefore bwyond the 0.001" tolerance.

Like i said thermal dynamics is mechanical engineering and i specialilze in electrical engineering so i wonder about the mechanical engineering side of thermals too; however, i've always known that two dis-similiar metals expand at a different rate when heated with the same temperature, and that typical "shelf pistons" are somewhat oval in design and squeezed in the front and rear of the piston because as the "shelf piston" front and rear side squirt loads cause increase friction it causes greater heat compared to the left/right side skirts of the "shelf piston" which causes to expand the cooled oval piston into circular cylinder fashion. I do not believe the HH has any oval uniqueness into their design- i could be mistaken.

[wvspeedfreak]

Chad 502ex,ck your pm's please.

[homer]

does anyone have an answer for this? My machine shop has inspected my 480 HH kit and the answer about the thermal expansion and the marks on my piston/cylinder are not very good.

[chad502ex]

you should call VCP for explanations then. It's their product and they are the ones who should back it.

[450ar]

The less mass of the hh collellates to less matrial. The less matrial you have to begin with the smaller amount the object can expand. Plus your head is made of the same matrial. And the bore will get bigger as it heats up. And since its the same matrial as the piston. The piston will expand at the same rate, but just a little more, cause it is hotter.

You dont have to take my word for it, you can open up a book and read it. Ill will qoute some spec form the honda service manual bottum of the table, on page 10-3
"Cylinder to piston clearance_ .0004" min and .0022" Yes thats inches

[chad502ex]

ahhhh, finally an explanation sheding some light.

maybe since the HH doesn't have the mass to expand in the first place its expansion rate isn't as great as stock and the less tensile HH ring pack can not expand with as much tensile as the stock ring pack thereby producing more blow-by.

There sure is a lot of angry consumer though...

[Bad Habit]

Originally posted by chad502ex
maybe since the HH doesn't have the mass to expand in the first place its expansion rate isn't as great as stock

Virtually every aftermarket piston made does not have as much mass as the stock piston.

Keep on taking your digs.

[chad502ex]

Originally posted by Bad Habit
Virtually every aftermarket piston made does not have as much mass as the stock piston.


Dan, if your going to quote me, try quoting my complete statement and not the fragment you frequently extract.

What i'm saying is that maybe the stock ring pack, as you suggest, does have more tensile strength than HH, and the stock ring pack is more able to make up the cylinder expansion distance than the HH ring pack. I'm not trying to dig, just encourage technical dialog as to offer some explanation- more than I can see from anyone else thus far.

[cals400ex]

i am running the HH 12.25:1 piston. i had the dome and the skirt thermal coated by www.swaintech.com

i am not have issues with anything. it uses a little bit of oil, but not much. it uses less than my stock 400ex did when i ran similar weight oils. i do not consider that bad considering the 400ex piston had an extra ring. i can't state facts for others. just telling my experience....

[HUNTSALOT]

My sparks 13:5.1 pust be a piece of crap it uses very little oil & for some damn reason it wont smoke what am i doing wrong??

Originally posted by HUNTSALOT
My sparks 13:5.1 pust be a piece of crap it uses very little oil & for some damn reason it wont smoke what am i doing wrong??

lmao :devil:

[Martin Blair]

I went with 13:1 je and stage 2 hotcam, and I love it, havent had a chance to eally ride it, but i can tell its gona be good, good bottom end, and pulls hard up top, I was cacthing my friend on hsi yfz on top end. Its a good combo, and I love it.

I just went with standard piston, not the coated one, didnt see any need for it. and i went with JE because they have a long reputation for making good, reliable products, maybe a little less power, but I can count on the je piston. And I persoanly dont like VCP for a few reason, that I would rather no get into.

[desratt]

I won't run anything but je

[chad502ex]

Originally posted by HN400exracer
I just went with standard piston, not the coated one, didnt see any need for it. and i went with JE because they have a long reputation for making good, reliable products, maybe a little less power, but I can count on the je piston. And I persoanly dont like VCP for a few reason, that I would rather no get into.