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BiGANG
19-08-2005, 10:58 AM
Hey guys,

I was wondering that if forged Hi-comp pistons are strong enough for FI applications, I am asking this because in most cases Hi-comp pistons are used for NA and i was thinking maybe they might not be made as strong because of this. Would regular forged hi comp pistons be good enough or would some sort of customs have to be made?

EGB16A
19-08-2005, 11:09 AM
hi comp meaning 12.5:1 (or there abouts)??

BiGANG
19-08-2005, 11:32 AM
hi comp being higher than a forged turbo piston CR would be, maybe 10.5:1 and higher probably.

BLKCRX
19-08-2005, 12:09 PM
Your question is way to ambiguous, what brand piston, what size, what compression. Every piston is designed differently some pistons have more “meat” on the crown of the piston, some pistons are designed to be ultra light thus have minimal meat, less material generally = a weaker pistons although in most cases I can not see this being a problem. Its all about using the correct parts, the correct quality.

Regards James

saxman
19-08-2005, 04:20 PM
there are some high comp forged pistons that are meant for turbo applications... most aren't though. best bet is to talk to the seller/manufacturer

alta'd n13
19-08-2005, 08:59 PM
not the best idea to be running high comp with a turbo set up no matter whether the pistons are forged or not unless you are going to run very low boost for a bit of extra torque.

the two methods of boost are basically high comp/low boost or low comp/high boost. basically this will put boost into two categories. even if the pistons are forged the remainder of the engine will more than likely give way on a high compression load + boost.

Weq
19-08-2005, 10:53 PM
this is ozhonda not pulsar.org alatd ;) we run highcomp everything, cause our engines are engineered well.. lol..

your best bet when looking at a high-comp setup is either going custom, or getting pistons suited for a different engine and running them. all b18's and b16's have different squench area'sclearences, and differnt combinations will come to different static cr's

BLKCRX
19-08-2005, 10:57 PM
not the best idea to be running high comp with a turbo set up no matter whether the pistons are forged or not unless you are going to run very low boost for a bit of extra torque.
.
Well that’s just a lie ;)



ignore that; ) go high comp hi boost ;) we don't live in the 1950's !



Regards James

saxman
20-08-2005, 04:14 AM
so much misinformation on the board these days

high comp + boost for the win!

BiGANG
20-08-2005, 03:15 PM
where would be a good place to enquire about getting hi comp pistons for a FI setup? Also because of the high static compression ratio, would i have to run special fuel so i dont get detonation?

BLKCRX
20-08-2005, 03:21 PM
where would be a good place to enquire about getting hi comp pistons for a FI setup? Also because of the high static compression ratio, would i have to run special fuel so i dont get detonation?

No just special tuning by a special expert using a special ECU ;)



Only reason to run special fuel would be to run 30 or 40psi of boost on 12.5:1 and up compression engines ;) but I don't think anyone is in that boat here... apart from me ;)



Regards James

alta'd n13
20-08-2005, 06:11 PM
this is ozhonda not pulsar.org alatd ;) we run highcomp everything, cause our engines are engineered well.. lol..

your best bet when looking at a high-comp setup is either going custom, or getting pistons suited for a different engine and running them. all b18's and b16's have different squench area'sclearences, and differnt combinations will come to different static cr's


i realise that but then again you blew out your bottom end by adding boost did u not?
im speaking as to safe level of boost with high comp pistons to make a reliable every day compromise.
i realise that high comp is a way of life on this forum but as a general guide as ive said so many times before, the general guide is for every 4 pound of boost you add one point of compression so an engine running 12.5:1 compression before boost add 8psi and you are looking at somewhere around the figure of 14.5:1 compression the more boost you run the higher the compression goes obviously.
yes your levels of tourque will be large on high comp high boost but risk factor is also high to drive it like that on a daily basis.

poweredbyhonda
22-08-2005, 08:08 AM
You have to realise that some manufacturers use more of a high silicone content which makes the piston heat up quicker to reduce the "warm up noise", but in turn it actually makes the piston a bit more brittle especially under extreme load "big boost". Best thing is to choose a lower silicone content so that it may take time to heat up but at least it is stronger and can withstand extreme amounts of load. For N/A you would most likely go with a medium to low silicone content. The Type-r ones are high in silicone content which is why the motor is very quiet when on cold idle. There should be a limit of how high of a CR you should go especially with boost. Unless you are using race gas, try to stick to what many boosted Hondas use, don't go looking to becoming a black sheep, you might end up learning the hard way.

BiGANG
22-08-2005, 09:14 AM
Unless you are using race gas, try to stick to what many boosted Hondas use, don't go looking to becoming a black sheep, you might end up learning the hard way.

Whats a pretty common CR ratio is running a hi-comp turbo setup? Is 11:1 too high and are off the shelf pistons available? Also, is the low silicon content of forged pistons the reason why most heavy duty setups sound like a truck on cold idle?

Weq
22-08-2005, 05:48 PM
i realise that but then again you blew out your bottom end by adding boost did u not?
im speaking as to safe level of boost with high comp pistons to make a reliable every day compromise.
i realise that high comp is a way of life on this forum but as a general guide as ive said so many times before, the general guide is for every 4 pound of boost you add one point of compression so an engine running 12.5:1 compression before boost add 8psi and you are looking at somewhere around the figure of 14.5:1 compression the more boost you run the higher the compression goes obviously.
yes your levels of tourque will be large on high comp high boost but risk factor is also high to drive it like that on a daily basis.

i cracked some ringlands cause i wasnt tuned.. :( timing is everything, keep things cool and ur stuff will last.

alta'd n13
22-08-2005, 06:22 PM
thats gotta suck man.

like i said though i realise that high comp high boost is an option it isnt always going to be reliable, maybe our definitions or high boost are different too, im talkin in excess or 12 - 15 psi

crx_boy7
22-08-2005, 07:06 PM
12-15 dosent sound that high
the onley thing to worry about is DETONATION a very big and scary problem with good compesion and good boost wat it dose is shake the cilinder walls in directions the werent designed to move solution - a good I/C or water injection system(cheaper and less cooling)

alta'd n13
22-08-2005, 07:08 PM
in excess of 12-15psi is pretty big boost for a high comp forced induction setup though

crx_boy7
22-08-2005, 07:12 PM
when usay reliable i guess ud be talking about stock cranck and rods but unlike ur pulsar our honda internals are verey well balanced out of the factory which is part of wat makes honda so dam good and with its fairly high compession (stock) they can hold as much as 15pounds in almost all honda motors

crx_boy7
22-08-2005, 07:15 PM
if u get good coolinr and balanced internals(stock requirement for honda =) )i once herd a story about a ZC cranck sent to get balanced onley to come back with no bill and a sticke saing (PERFECT!!) Yea thats honda!

locote
22-08-2005, 08:42 PM
so a honda motor with a 9:1 compresion would be perfect to run 12+ boost with the correct tunning.

poweredbyhonda
23-08-2005, 08:33 AM
To give you an idea, I am running around 9.8 with the inverted dome Arias pistons pushing 14 psi. I need stronger rods which is why I limit the motor to only 14 psi. I know a couple of people pushing 7 psi on stock B18C & B16A motors. It all depends on the piston & rod choice and then more importantly the ecu & tuner choice.
Yeah that's right, low silicone content sounds like a truck big time. Sounds like a time bomb or something, but when it gets warm it sounds like a normal car again...
IMO 11:00 is too high for street, you'll give your tuner a hard time but I am no mechanic so don't qoute me on it. I'd stick to around the 10.0 mark.
Swapping heads can also drop the CR ratio...

crx_boy7
26-08-2005, 09:54 PM
thats true 9.0compression is wat i was given [with rods and balanced crank] and told a similar setup is holding 40pounds in a shop in california
9.0 comp is the lowest comp ratio u can get -excuding custom jobs
if ur running 15pound or less get like 10.5 . with a good intercooler and precice tuning it will give great output
thats wat they normally run on superchargers {12pounds}

alta'd n13
29-08-2005, 07:52 PM
when usay reliable i guess ud be talking about stock cranck and rods but unlike ur pulsar our honda internals are verey well balanced out of the factory which is part of wat makes honda so dam good and with its fairly high compession (stock) they can hold as much as 15pounds in almost all honda motors

im currently running 8psi of boost on factory internals on an engine thats done upwards of 100,000kms with absolutely no dramas.
i will be running 12psi as soon as i get my braided oil feed line made up for my turbo feed, the only other thing restricting me at 8psi was the factory single coil ignition system which has recently been upgraded to a dual setup. another n13 i know of has run 17psi on stock internals with an extremely good reliability factor also.

im just not 100% sure on what your classifying as high comp. my compression stock is 8:1 and i consider that very low, high comp to me is around the 11:1 or 12:1 type compression and running boost with that in excess of 12psi is insane to say the least coz that would equate to around the 14:1 or 15:1 compression running that much boost