gasporting OEM pistons for a street motor. - Honda-Tech

mike_belben@yahoo.com · 10-15-2006, 12:48 PM

im going over it in my head and cant think of any reason why not to, the fixture is set up and when i come back from walking the dogs in a few hours im gonna get started unless someone brings up a consideration ive overlooked between now and then.

anyone had bad experience with gas ported pistons?

bluedlude · 10-15-2006, 01:07 PM

yeah, its a good idea on a race motor, but a daily driver

. it puts more wear on the rings and more pressure on ring lands. not a good idea unless you dont mind inspecting and changing rings fairly periodically. theres reasons there not readily available.

mike_belben@yahoo.com · 10-15-2006, 04:00 PM

Quote:

Originally Posted by bluedlude

...it puts more wear on the rings and more pressure on ring lands...

the first part (more ring wear) i will not dispute because i have no data against it.. do you have any in support of it or is that just some reasoning? all rings require cylinder pressure behind them to seal against the bore, their own tension is not enough. during cylinder pressure their bottom face seats on the bottom of the ring groove, during vacuum it shifts to the top.

the second part i have to flat out reject. how can there be additional pressure on the ring lands? the cylinder pressure is the same whether i help it get BEHIND the ring or not. an unported piston will see the exact same downward force on the ringland. the only difference i can imagine now is how much pressure is helping to force the ring outward. im thinking the more the better for the sake of ring to cylinder sealing.

anyone else?

b19coupe · 10-15-2006, 05:08 PM

After 10k hard miles my gas ported pistons and rings were still near perfect; I see no reason not to try it on OEM pistons.

d16dcoe45 · 10-15-2006, 05:09 PM

I am pretty sure TBone had gasports on his pistons and when he tore it down (don't know exact numbers--maybe 10,000 miles?) he said they were not plugged up as many claim will happen on a street motor--as far as wear "they" say it increases wear, but I do not know for sure.

Dyno Dave · 10-15-2006, 06:01 PM

Its not something that had ever crossed my mind to do to OEM pistons

Regards Dyno Dave

mike_belben@yahoo.com · 10-15-2006, 06:07 PM

now that you mention it, i got to take a pretty close look at tom's IB super dupers when it was apart. i think there was even crosshatch left after some ridiculous amount of abuse/pulls.

Supernatural · 10-15-2006, 06:18 PM

the only question now is will the pistons structural integrity be weaked by the modification....

mike_belben@yahoo.com · 10-15-2006, 06:21 PM

yes, which is the point DonF mentioned. im contemplating that and all the ringlands ive seen pinched/blown off over the years. they all had taco's rod bearings too which shows how much cylinder pressure a heavy dose of nitrous detonation has to offer. im thinking this motor wont be seeing anything like that. ...hmm.

Combustion Contraption · 10-15-2006, 06:27 PM

In speaking with some pretty knowledgable engine builders and piston manufacturer reps, they claim that gas ported pistons actually increase ring and piston longevity due the fact that the rings and bore are in constant contact, less flutter.

I think the misconception of them being a race only peice comes from the fact that so many members are severly stressed on a race engine. It could have all started after someone with the gas ports tore his engine down to see cracked lands, and blamed it on the gas ports. Maybe they would have cracked anyway. It was a race motor, right?

I think when a piston is designed with gas porting in mind, its structural integrity shouldnt be an issue, modding a set of OEM's is hit or miss.

DJ_NeX · 10-15-2006, 06:32 PM

I almost bought gas ported rollerwaves once for my motor from Larry Widmer of ENDYN. He talked me out of it, He said it would increase wear on the rings and would only be a good idea, if I planned on rebuilding the motor once a year.

mike_belben@yahoo.com · 10-15-2006, 06:50 PM

i just sawed a cast piston in half. im definately doing it now. ill update some other time.

mike_belben@yahoo.com · 10-15-2006, 11:37 PM

i ended up converting them to forced pin oiling since the squirters have been deleted. also machined a bunch of other tricks in there and set back up to do the gas ports tomorrow when i get up. im going with 8 holes at .032" diameter. still have to move the exhaust reliefs back a hair since i milled the quench pads off a b16 head, which took about .090" and reduced the radial clearance on the exh margins. intakes just barely squeek by.

anyways. about cylinder wear and gas ports, im really starting to expect less ring/cylinder wear with the porting done. the ring grooves have such a tiny little bit of clearance for cylinder pressure to seep by that i cant imagine much of it really getting behind the ring to expand it. if it isnt pressed against the cylinder wall i envision it doing a lot more fluttering and rocking (so that the upper and lower sharp corners of the ring are biting into the cylinder wall.) with cylinder pressure always instantly behind the ring and in an even fashion, i think the ring will be prone to remain much more square against the bore. if so, the crosshatch would last a lot longer i think.

when the cylinder sees vaccuum i suppose the rings will want to collapse? which could be good for power but bad for blowby?

GSRCRXsi · 10-16-2006, 08:07 AM

what block are you doing this to? id love to see some pictures

mike_belben@yahoo.com · 10-16-2006, 02:23 PM

this particular engine is a gsr bottom end with itr rods/pistons and a b16 head milled till it looked like a gsr.

NJIN BUILDR · 10-16-2006, 04:54 PM

I've had good luck with lateral gas ports.These appear as eight or so half circles above the top ring.They are nearly unaffected by carbon buildup.The piston companies claim it is just as effective as vertical gas porting.You can see them on JE's website.They are standard on some small block Chevy pistons as an example.They can do it as an option on almost any piston.

mike_belben@yahoo.com · 10-16-2006, 05:36 PM

hey thanks for the tip,, i suppose those are significantly more shielded from combustion crapola loading up in them. and theyd be easier to do if i can find an end mill that tiny..

decisions decisions.

drift4jesus · 10-16-2006, 06:04 PM

What cams are you going to run in this combo? Are you having to take alot out of the valve reliefs to compensate for the amount taken off the head?

mike_belben@yahoo.com · 10-16-2006, 06:32 PM

hey rico, the stock intake actually is acceptable for radial clearance. its only running ITR cams now, maybe bc3+ or some other moderate cam later. exhaust needs to shift back about .030" only because of the fillet/radius in the casting. if it were a forged piston with a square machined relief it would fit, no matter how far i had the cams in either direction, i was surprised actually.

i just vertical ported a pr4 piston with about 8 .040" holes bunched together on one side and hammered the snot out of the whole compression height edge. i couldnt break off the top corner and the ring still slides freely all the way around the piston. that pretty much answers my questions.

couldnt find an end mill small/rigid enough to do the lateral ports or i would.

Runnerdown · 10-16-2006, 07:00 PM

Props for trying something different.

mike_belben@yahoo.com · 10-16-2006, 07:22 PM

thanks man.. still have the same goal as everyone else though

lohatch · 10-16-2006, 07:22 PM

nobody in here has subscribed to the theory that the gas ports release the tension on the ring as it glides down the bore due to the pressure differentials??
reducing the frictional HP figure

jweller · 10-17-2006, 08:42 PM

Ok I read this the other night, realized I didn't know a whole lot about gas porting, tried to read up on it as much as I could, and came up with a question or 2. excuse me if I sound like a moron, but here goes, just trying to learn.......

I can picture vertical ports no problem, but I'm having some trouble either finding pics of or visualizing in my mind exactly what a horizontal port looks like

From what I have read, gas porting lets you run a tighter ring side clearance. this helps reduce the "fluttering" of the ring. if you run a stock piston with a stock ring groove, will you run a thicker than stock ring to end up with a smaller side clearance?this seems to be one of the big advantages of doing it, so just running a stock piston you have gas ported, with a stock ring seems to be missing out on one of the big advantages.

87sivtec · 10-17-2006, 09:25 PM

Bump for the creative thinking.
Show pics of the piston and combustion chamber if you can.
What headgasket are you using and what compression ratio are you aiming for?

10-15-2006, 12:48 PM	#1
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	gasporting OEM pistons for a street motor. im going over it in my head and cant think of any reason why not to, the fixture is set up and when i come back from walking the dogs in a few hours im gonna get started unless someone brings up a consideration ive overlooked between now and then. anyone had bad experience with gas ported pistons? __________________ Gone Fishin'

10-15-2006, 05:08 PM	#4
b19coupe Senior Member Join Date: Mar 2002 Location: Southern, California, U.S.A. Posts: 9,299	Re: gasporting OEM pistons for a street motor. (mike_belben@yahoo.com) After 10k hard miles my gas ported pistons and rings were still near perfect; I see no reason not to try it on OEM pistons. __________________ C.A.T.

10-15-2006, 05:09 PM	#5
d16dcoe45 Senior Member Join Date: Jul 2005 Location: Armonk, NY, USA Posts: 3,729	Re: gasporting OEM pistons for a street motor. (mike_belben@yahoo.com) I am pretty sure TBone had gasports on his pistons and when he tore it down (don't know exact numbers--maybe 10,000 miles?) he said they were not plugged up as many claim will happen on a street motor--as far as wear "they" say it increases wear, but I do not know for sure. __________________ Cusco EF master cylinder brace-- brand new, unopened, still in package $75 shipped obo (RHD ONLY!!!) WTB: 88-89 Civic hatch driver side door w/ glass and regulator. Losi xxx4 G+ Associated Rc10 t4 FT Losi xxx BK2 JConcepts BJ4 WE

10-15-2006, 06:01 PM	#6
Dyno Dave Join Date: Jan 2004 Location: Sydney, NSW, Australia Posts: 151	Re: gasporting OEM pistons for a street motor. (mike_belben@yahoo.com) Its not something that had ever crossed my mind to do to OEM pistons Regards Dyno Dave __________________ Bel Garage Sydney Australia Many thanks to Rocket Motorsports for his help and support.

10-15-2006, 06:07 PM	#7
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	now that you mention it, i got to take a pretty close look at tom's IB super dupers when it was apart. i think there was even crosshatch left after some ridiculous amount of abuse/pulls. __________________ Gone Fishin'

10-15-2006, 06:18 PM	#8
Supernatural Senior Member Join Date: Mar 2003 Location: East Bumfuckville, Wisconsin Posts: 1,383	Re: (mike_belben@yahoo.com) the only question now is will the pistons structural integrity be weaked by the modification....

10-15-2006, 06:21 PM	#9
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	yes, which is the point DonF mentioned. im contemplating that and all the ringlands ive seen pinched/blown off over the years. they all had taco's rod bearings too which shows how much cylinder pressure a heavy dose of nitrous detonation has to offer. im thinking this motor wont be seeing anything like that. ...hmm. __________________ Gone Fishin'

10-15-2006, 06:27 PM	#10
Combustion Contraption Senior Member Join Date: Jan 2003 Location: So Cal Posts: 8,534	In speaking with some pretty knowledgable engine builders and piston manufacturer reps, they claim that gas ported pistons actually increase ring and piston longevity due the fact that the rings and bore are in constant contact, less flutter. I think the misconception of them being a race only peice comes from the fact that so many members are severly stressed on a race engine. It could have all started after someone with the gas ports tore his engine down to see cracked lands, and blamed it on the gas ports. Maybe they would have cracked anyway. It was a race motor, right? I think when a piston is designed with gas porting in mind, its structural integrity shouldnt be an issue, modding a set of OEM's is hit or miss. __________________ EARL LASKEY, YOU WILL BE MISSED CCCylinderheads.com Check out the INDUCTION SPECIAL Matco Doublebay Toolbox FOR SALE Click Here!

10-15-2006, 06:32 PM	#11
DJ_NeX Join Date: Feb 2004 Location: AZ, USA Posts: 323	Re: (Combustion Contraption) I almost bought gas ported rollerwaves once for my motor from Larry Widmer of ENDYN. He talked me out of it, He said it would increase wear on the rings and would only be a good idea, if I planned on rebuilding the motor once a year. __________________ Low Profile - High Performance

10-15-2006, 06:50 PM	#12
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	i just sawed a cast piston in half. im definately doing it now. ill update some other time. __________________ Gone Fishin'

10-15-2006, 11:37 PM	#13
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	i ended up converting them to forced pin oiling since the squirters have been deleted. also machined a bunch of other tricks in there and set back up to do the gas ports tomorrow when i get up. im going with 8 holes at .032" diameter. still have to move the exhaust reliefs back a hair since i milled the quench pads off a b16 head, which took about .090" and reduced the radial clearance on the exh margins. intakes just barely squeek by. anyways. about cylinder wear and gas ports, im really starting to expect less ring/cylinder wear with the porting done. the ring grooves have such a tiny little bit of clearance for cylinder pressure to seep by that i cant imagine much of it really getting behind the ring to expand it. if it isnt pressed against the cylinder wall i envision it doing a lot more fluttering and rocking (so that the upper and lower sharp corners of the ring are biting into the cylinder wall.) with cylinder pressure always instantly behind the ring and in an even fashion, i think the ring will be prone to remain much more square against the bore. if so, the crosshatch would last a lot longer i think. when the cylinder sees vaccuum i suppose the rings will want to collapse? which could be good for power but bad for blowby? __________________ Gone Fishin'

10-16-2006, 08:07 AM	#14
GSRCRXsi Join Date: Jan 2004 Location: Baltimore, MD Posts: 2,658	Re: (mike_belben@yahoo.com) what block are you doing this to? id love to see some pictures __________________ WTB: clean crx shell http://hondamarketplace.com/zerothread?id=1490544 Please give what you can to the Tom Cote Medical Fund http://honda-tech.com/zerothread/1828476

10-16-2006, 02:23 PM	#15
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	this particular engine is a gsr bottom end with itr rods/pistons and a b16 head milled till it looked like a gsr. __________________ Gone Fishin'

10-16-2006, 04:54 PM	#16
NJIN BUILDR Senior Member Join Date: Mar 2003 Location: Hudson, NH, 03051 Posts: 3,159	Re: (mike_belben@yahoo.com) I've had good luck with lateral gas ports.These appear as eight or so half circles above the top ring.They are nearly unaffected by carbon buildup.The piston companies claim it is just as effective as vertical gas porting.You can see them on JE's website.They are standard on some small block Chevy pistons as an example.They can do it as an option on almost any piston. __________________ http://www.rrcycles.com Yah,my day job is building 2.5L TWO cylinder engines.

10-16-2006, 05:36 PM	#17
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	hey thanks for the tip,, i suppose those are significantly more shielded from combustion crapola loading up in them. and theyd be easier to do if i can find an end mill that tiny.. decisions decisions. __________________ Gone Fishin'

10-16-2006, 06:04 PM	#18
drift4jesus Senior Member Join Date: Jun 2005 Location: East of Cleveland, oHIo Posts: 373	Re: (mike_belben@yahoo.com) What cams are you going to run in this combo? Are you having to take alot out of the valve reliefs to compensate for the amount taken off the head? __________________ http://www.thehorsepowerfarm.com http://www.myspace.com/thehorsepowerfarm competition clutch http://images.honda-tech.com/set1/smile/emthup.gif JHott Imports http://images.honda-tech.com/set1/smile/emthup.gif WTB:GSR moroso oil pan- cage for an EG- Blown or damaged cyl heads: F20/22,B,D,H,K,L 452whp 340wtq 92octane 32mpg sleeper

10-16-2006, 06:32 PM	#19
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	hey rico, the stock intake actually is acceptable for radial clearance. its only running ITR cams now, maybe bc3+ or some other moderate cam later. exhaust needs to shift back about .030" only because of the fillet/radius in the casting. if it were a forged piston with a square machined relief it would fit, no matter how far i had the cams in either direction, i was surprised actually. i just vertical ported a pr4 piston with about 8 .040" holes bunched together on one side and hammered the snot out of the whole compression height edge. i couldnt break off the top corner and the ring still slides freely all the way around the piston. that pretty much answers my questions. couldnt find an end mill small/rigid enough to do the lateral ports or i would. __________________ Gone Fishin'

10-16-2006, 07:00 PM	#20
Runnerdown Join Date: Aug 2003 Location: Albany, NY Posts: 2,356	Re: (mike_belben@yahoo.com) Props for trying something different. __________________ http://www.synapsemotorsport.com 12.4@109 all motor street car w/stock cams. Curiosity is the mother of creativity.

10-16-2006, 07:22 PM	#21
mike_belben@yahoo.com Join Date: Feb 2004 Location: not riding any bandwagons in, massachusetts, usa Posts: 1,565	thanks man.. still have the same goal as everyone else though __________________ Gone Fishin'

10-16-2006, 07:22 PM	#22
lohatch Senior Member Join Date: Jan 2003 Location: the backwoods, usa Posts: 2,605	Re: (Runnerdown) nobody in here has subscribed to the theory that the gas ports release the tension on the ring as it glides down the bore due to the pressure differentials?? reducing the frictional HP figure __________________ RDR 12.009@113, 11.53@121 ....all motor streetcars Modern Automotive Performance (763)545-3800 http://images.honda-tech.com/set1/smile/emthup.gif

10-17-2006, 08:42 PM	#23
jweller Senior Member Join Date: Aug 2001 Location: Crofton, MD Posts: 2,422	Re: (lohatch) Ok I read this the other night, realized I didn't know a whole lot about gas porting, tried to read up on it as much as I could, and came up with a question or 2. excuse me if I sound like a moron, but here goes, just trying to learn....... I can picture vertical ports no problem, but I'm having some trouble either finding pics of or visualizing in my mind exactly what a horizontal port looks like From what I have read, gas porting lets you run a tighter ring side clearance. this helps reduce the "fluttering" of the ring. if you run a stock piston with a stock ring groove, will you run a thicker than stock ring to end up with a smaller side clearance?this seems to be one of the big advantages of doing it, so just running a stock piston you have gas ported, with a stock ring seems to be missing out on one of the big advantages. __________________ 99 accord coupe I4 5-spd 08.5 Mazdaspeed3 GT

10-17-2006, 09:25 PM	#24
87sivtec Join Date: Sep 2002 Location: 604, Canada Posts: 321	Bump for the creative thinking. Show pics of the piston and combustion chamber if you can. What headgasket are you using and what compression ratio are you aiming for? __________________ 13.16 VIDEO HERE! Drag Compilation VIDEO HERE! 87 CRX N/A B16 Update: 13.029@101.75mph Sept. 29/06