Has anyone tried asking some Honda techs this question? I've wondered what they do about replacing the stock pistons.. the stock pistons are available in a OEM overbore IIRC, so that would mean (to me) there's some procedure for replacing them that is endorsed by Honda. Forged pistons are another matter altogether.. I can see some good arguements for why they might not be a good idea.
Resleeving is a ***** if you only have one motor, though.
I believe from reading a thread on the honda-tech board is that the problem is that the forged pistons don't work well with the coating on the cyl. walls. Thats the real non technical description, but to get you on the right track to understanding the problem.
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I've read through that thread.. it seemed to end on an inconclusive note. For sure, there's some good arguements for the forged pistons not working. The block wasn't designed to run forged pistons in the first place. I'm wondering if that carries over to the OEM replacements or not.
Asked what Honda-Techs? If you're talking about the monkeys at the dealerships, I'll pass on asking them anything. I'm not certain why you brought up stock pistons at all. They are cast pistons. Nobodies saying you can't put in stock pistons or even stock overbore pistons into the engine.
I want to get this out of the way. The cylinders are NOT nikasil coated. Nowhere is there even a hint of Honda using nikasil coated sleeves on any motor other than there motorcycle motors. If we did have nikasil coated cylinder walls we wouldn't have a problem. There are companies in the US that do nikasil coating and if you got your sleeves overbored you could just get them recoated. Like you said, there are OEM overbore pistons which many people have run successfuly with just a machine shop reboring and rehoning. If our cylinders were nikasil coated this would not be a possibility.
As for long term effects I don't know of anyone personaly, only the few people who put up some experiences on the net, like Big James.
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Mark Higgins
Toronto Prelude Club www.hondaprelude.to
Egad, people are touchy about this. By honda techs, no, I don't mean the monkeys that change oil at the dealer. They usually have someone who knows something in the area though, I'm not sure how their classifications go. I'm certainly not going to say all honda techs don't know anything, because I know that's not the case. I'm just not sure what they're privy to that I'm not.
I brought up the stock pistons because I've seen conflicting information. The service manuals for the prelude indicate there isn't a problem with honing, so maybe I'm not helping things here.
It'll be really interested to see what happens long term with forged pistons.. I imagine I'll find out myself eventually. Good to see you around Dirtylude BTW, how's your project going?
Originally posted by DirtyLude There are companies in the US that do nikasil coating and if you got your sleeves overbored you could just get them recoated. Like you said, there are OEM overbore pistons which many people have run successfuly with just a machine shop reboring and rehoning. If our cylinders were nikasil coated this would not be a possibility.
So your saying we can use forged pistons If we get our stock sleeves overbored and nikasil coated? or were you talking about stock Honda cast pistons?
even If we could use forged pistons with stock or nikasil coated sleeves we would still have to do someting about the excessive cylinder pressure from 10-15+ PSI right? cause eventually th e cylinder wall will crack from the pressure. now NA is a different story.
some people on H-T asked that on the FI forum I think. They asked If they could just use forged pistons and rods and boost 15 PSI without re-sleeving. But I figure the sleeves become the next weakest link so why not just change them too?
__________________ Blue
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I definitely can't say that I have been to the Honda factory and they are not doing nikasil coating, but the evidence that they are not is overwhelming. Before I got married and sold my motorcycle I talked to the mechanics working on the nikasil coated engines and they would talk about rare occurances of nikasil flaking and problems they had with the nikasil coating. The fact we have not had any of these problems is a clear indicator besides the other reasons I stated.
I think there is enough evidence to support that if we have anything it's frm cylinder liners. I don't know if anyone has a picture of the top of a stock block with a closeup of the sleeve tops, but I was looking at a couple blocks the other week and you can actually see about 1/3 of the way through the sleeve that the metal changes colour from the greying of the liner to the more silvery of alluminum. I'll have to take a picture this weekend.
Going back to the forged piston debate, I don't think anyone has any real solid answers or empirical test results. If you're going to try it, try it at your own risk.
__________________ DirtyLude
Mark Higgins
Toronto Prelude Club www.hondaprelude.to
People are posting faster than I can reply. I haven't been around lately since the TPC webboard blew up and I've been trying to get it back up and do general site development. I should be getting my car running again this weekend. We'll see how it goes.
Forged pistons with nikasil coating. There are issues with running pistons with nikasil coating. You'd have to ask the nikasil coating place as to whether you'll have to change the ring pack for the nikasil coating. It's a good point though. If you're having problems with the FRM, you can get the cylinder bored than nikasil coated. At least then you know for sure what you're working with.
__________________ DirtyLude
Mark Higgins
Toronto Prelude Club www.hondaprelude.to
Hmmmm!! Ahhh!!
back to the original question, or infact, since it seems nobody knows i'll ask a different question which I think I will get some better results. Is it common to burn stock pistons on a H22a at below 9psi boost?
Quote:
Originally posted by bradboy Is there anyone at all on this forum who ACTUALLY has used forged pistons in stock H22a block? Come on guys, I need some expirenced input here.
ok im really into honda motocross bikes... used to work at a dealership. i know for a fact that you can use forged pistons in a cast cylinder. and i know you can run a forged piston in a Nikasil coated cylinder. im running a forged piston in my bike. the thing they always warn you about is to make sure your bike is semi-warmed up, because the forged metal and the cast metal expand at different rates when being warmed up.
also, when people get forged pistons to run high boost, they are also usually lower c/r pistons... somewhere in the vicinvity of 9.0:1
ive seen as low as 8.5:1...
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Well, thanks for the info, but we already knew you could run forged pistons in nikasil sleeves. I've seen it done as well and it's even advertised by a few places on the web. The discussion here is that our sleeves are not nikasil or straight cast sleeves. They are Fiber Reinforced Metalic like on the NSX and the S2000. The FRM is a liner which is placed in the sleeve while casting.
Expansion of a forged piston is dependent on it's silicon content. High silicon forged pistons like SRP's do not require the warm up time that low silicon pistons like JE's do.
Anyone else see that S2000 runs forged pistons with FRM sleeves? I wonder if they do anything to them or if it's just the ring package you have to change to run the pistons on FRM sleeves like some people say. I guess when they start running standard forged pistons we'll have our answers. http://www.honda.ca/models/s2000_ben...escription.asp
I have 2 responses here.... People are talking a bout boring their cylinders but they dont want to have it resleeved??? That doesnt make any sense to me. What are you gonna do, run the stock sleeves even thinner on an open deck motor? Bad news, it'll be weaker than stock.
And 9psi isnt much worse than 7psi bradboy. Its when you get into the range of 11-12 psi that there are problems. Just like Smilez said, dont allow any detonation. The thing with running higher boost is your chance of detonation increases, and if you experience detonation at higher pressures, its easier to burn up a piston ring than at lower boost pressures. This wont be a problem at all though if you can keep detonation to a minimum. If you're running a 12:1 FMU i wouldnt recommend running more than 8psi because the engine can run from lean to rich both because of vtec. vtec dumps tons more fuel, and the FMU cant be tuned for that new VTEC fuel map that's there. Thats why people complain about turbo'ing VTEC motors, because of that switch between settings, it would essentially take 2 FMU's to get set correctly until you encompass something programmable for the fuel and ignition maps. (I dont think 2 FMUs is possible like that, but i hope you get what i'm saying).
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I talked to the mechanics working on the nikasil coated engines and they would talk about rare occurances of nikasil flaking and problems they had with the nikasil coating. The fact we have not had any of these problems is a clear indicator besides the other reasons I stated.
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