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I just wanted to get the opinion of some of the experienced engine builders on this site. I have been searching through many of the old threads looking for information on how many HP stock pistons will stand up to. Looking thru most of the treads it appears that it is the rods that fail and not the pistons. Knowing that peak pressure does not change much on turbo engines I was wondering how much HP a set of stk pistons with aftermarket rods would hold up to? My thought was to try and get my D15B7 up around 300hp. I wanted to stay away from Vitra pistons because of the low compression even with custom length rods. The engine would be a dog out of boost. I am looking to build an efficient daily driver with the added excitement of boost. I would like to avoid the expense of forged pistons If I can. I was thinking that Vitra pistons are not forged and have a pretty thin top land. What makes them stand up to 450HP and why wouldn’t I be able to get about 300HP out of factory?
 

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I also would like to know but i can add what i have found my self. I would like a better tuner here to add what they have to say.

the stock hypereutectic pistons where good for 250hp.
Thats what i have read but i really didnt like the source. I rather go off of a proven engine then books.

the Vitara pistons are not forged but they are higher quality and they are also Teflon coated to resist head and build up.
stock pistons have silicon that makes them brittle.

I dont know the specs on ycp pistons and if they have a lower % or higher % of silicon
 

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the ring lands are much thicker on vitaras, no thin spots like stock, and CP shelf pistons. Vitara rings also are a lil further down than stock pistons. I never had a stock rod fail, only pistons. It burnt/melted a hole in ring land. Vitara are nto DOGS out of boost, they make MORE POWER than stock pistons/rods. its been proven. like 112whp vitaras, and 98whp stock. check out speedfactorys build. that is with intake mani and cam and such soo that does throw it off a bit. butt dude, vitaras are far from dogs out of boost.





 

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Even though peak pressure wont change, you have to worry about the combustion and how hot its going to get. Our stock pistons are only cast and with the stock compression and boost im sure they will get to hot and melt. Or fail before they can.

Edit: Damn it, I was to late haha.
 

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Looking thru most of the treads it appears that it is the rods that fail and not the pistons.
most of the time the rod fails before the piston however, the piston will fail shortly after. both happen due mostly to tuning issues. stock blocks have seen over 300 whp in serveral applications.

how much HP a set of stk pistons with aftermarket rods would hold up to?
before i try to answer this, you should take note that stock pistons are not designed for aftermarket rods. in the end, aftermarket pistons on aftermarket rods will be cheaper.. ok, as far as pistons go.. well they will not last long under that kind of pressure/heat. if you read the thread: http://d-series.org/forums/forced-induction/115117-when-550whp-vitaras-isnt-enough.html , drunkinmaster1 has a very good post as to piston material make up and how they hold up to pressure/heat. its also well known that honda pistons have shitty ringland design/thickness when it comes to high whp applications. personally, i would not take a stock piston (d-series) past ~300 whp.

I wanted to stay away from Vitra pistons because of the low compression even with custom length rods. The engine would be a dog out of boost.
if you search around, most of the vitara builds are quite good out of boost. iirc, some have actually had better slips with the vitaras then stock. just saying.

I was thinking that Vitra pistons are not forged and have a pretty thin top land.
they are not forged, but have very good design and material.

What makes them stand up to 450HP
design, compression, material for the most part.

why wouldn’t I be able to get about 300HP out of factory?
you can make +/-300 whp out of a stock block. its been done. just have to have a very well made engine. refer to: http://d-series.org/forums/forced-induction/95785-go-autoworks-sohc-build-part-ii.html
 

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im sure you could even boost a stock block pistons and rod to 400hp ... it would last, for a few seconds.

We buy new pistons and rods for the longevity on our engines and a peace of mind.
oh well and more power never hurt any one either!
 

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Discussion Starter #8
Even though peak pressure wont change, you have to worry about the combustion and how hot its going to get. Our stock pistons are only cast and with the stock compression and boost im sure they will get to hot and melt. Or fail before they can.

Edit: Damn it, I was to late haha.
The heat is an area I was concerned about, and I think is most likely where things will fail. But I do not know much about the make up of a stk piston. If any one can inform me it would be great.
 

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But I do not know much about the make up of a stk piston. If any one can inform me it would be great.
this is well covered on the net. if you check H-T, there is a thread with a full break down for the piston make up.

sorry, but spoon feeding is strickly prohibited on DSO. since this is d-series.org not spoon-feed-the-newb.org. and yes, i realize your not really a newb, but the point still stands ;).
 

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The heat is an area I was concerned about, and I think is most likely where things will fail. But I do not know much about the make up of a stk piston. If any one can inform me it would be great.
As i said about the heat issues, on the vitara pistons we run are teflon coated = less heat and the stock ones are not.
 

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Discussion Starter #11
the ring lands are much thicker on vitaras, no thin spots like stock, and CP shelf pistons. Vitara rings also are a lil further down than stock pistons. I never had a stock rod fail, only pistons. It burnt/melted a hole in ring land. Vitara are nto DOGS out of boost, they make MORE POWER than stock pistons/rods. its been proven. like 112whp vitaras, and 98whp stock. check out speedfactorys build. that is with intake mani and cam and such soo that does throw it off a bit. butt dude, vitaras are far from dogs out of boost.





I know what some of those dyno charts show, but look at some of the ones with higher compression. There is an expediential growth in power with higher compression. Have you ever ridden in a car that has had .020 shaved off the head with nothing else done? There is a notable difference. I just do not see how an 8 to 1 compression engine can compete with a 9.3 to 1 compression engine without boost. You may be correct that they are not dogs and I know at the track with the boost spooled up the vitra setup has a lot of advantages, but that is not what I am looking to build. I want a responsive daily driver on a little boost
 

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Discussion Starter #12
this is well covered on the net. if you check H-T, there is a thread with a full break down for the piston make up.

sorry, but spoon feeding is strickly prohibited on DSO. since this is d-series.org not spoon-feed-the-newb.org. and yes, i realize your not really a newb, but the point still stands ;).
it's cool sometimes it is hard to find info when you do not use the correct search word. thanks for the direction.
 

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like said, vitara setups on just motor, have been faster than stock cr d16's. if u are worried about not having much power down low, put a .48 ar exhuast housing on a t3 turbo. you will get 300whp, and still have tons of throttle response. its simple dude.
 

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Discussion Starter #17
I have a .48Ar hsg to put on my T3 and that was the direction I am going with that for good responce. the head is also ported and polished, and I installed Z6 intake and a A6 cam. I was wanting to make 300hp but knew the rods would not stand it. it just seams the efficiance of the set up would fall back with lower compression.
 

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can you explan this more?
a little hard for me.. cause english is not my first language...

with less compression you can use more timming without detonation, so what you lost in compression you'll gain on timming... so is perfectly possible to have all oem @98whp and less compression with vitaras @112whp with timming adjusted..
 

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Let me put it this way, would you rather build your engine once or twice after it blows up? Spend the money now and you wont have to spend it later. Forged pistons and rods are stronger because forged material compresses 50% more material into the same volume meaning they expand more, are heavier and are alot stronger along with being able to absorb and transfer heat much better. Just so you know, the reason honda engines are capable of such high rpm's and boosted well over 200hp reliably is because stock they have forged rods and crankshafts that are incredibly strong. The guy that made 600hp used a stock crank just goes to show how strong it really is.

We just saw a guy make 600hp on vitaras so i think its safe to say, if you know how to tune you can make stupid high HP on vitaras and with stock sleeves. Meh im babling on.

rapa said:
more timming capability is the answer...
Alot more timing is not allways good, this invites detonation and puts alot more stress on the rods as its seeing more than the usual combustion pressures since the gasses are expanding before it reaches TDC.
 
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