ZColeon

Are the stock pistons of a forged material, will they stand against 10-20 lbs. of boost, anyone ever try..... looking for a cheap way out to complete my zc project.... thanks

b18bturbo

nope they will start to give around 15-20 psi the reason behind that is the material they are made with. They are nice stock pistons but not really reccommend for use on the bosot you are talking about.

X2BOARD

hahahahahahahaha! **breath*** HAHAHAHAHAHAHAHAHAHAHA.....HA... '

Stock pistons are pretty much good up to 6.5psi, reliably, then... it's really questionable.. FI is really harsh on pistons, you can run more than 6.5psi, but you never know what will happen after that... you might be OK for a long time, or you might melt within 500 miles.... stock pistons are picky that way, just depends on how good of production run you car was...

ZColeon

thank you much , much to my dismay I will have to get JE and spend the money, thanks for the input...

boosted hybrid

Hmmm...that is funny maybe i should turn the boost down on my stock block ls...running 15lbs these days. It all comes down to reducing cylinder pressures to keep the forces off of the ring lands and bearings. While the stock pistons are weak compared to forged counterparts you can safely run upwards of 15lbs of boost on them. Stoopid ran a stock block ls on 18lbs making 390whp for over two years, it comes down to a solid fuel system and good tuning. The sky is the limit. Remember boost is only relative to fuel and timing, if you decided to over aggresively tune you engine, say running air/fuel in the low 13:1's and run stock timing, then yes you are going to blow your engine. But if you keep your air/fuel in the 11:1 range and reduce timing dramatically you can run silly boost pressures. Power is more relative to timing and fuel then it is to boost.

X2BOARD

dropping timing on an LS motor will allow higher boost pressure, but it will kill most of your low end and you will see some nasty turbo lag....

[QUOTE]Hmmm...that is funny maybe i should turn the boost down on my stock block ls...running 15lbs these days. It all comes down to reducing cylinder pressures to keep the forces off of the ring lands and bearings. While the stock pistons are weak compared to forged counterparts you can safely run upwards of 15lbs of boost on them. QUOTE]

That is crazy.... 15psi, even with the greddy kit is waaaay to high to be recommended. Not to mention going up to a medium sized turbo..... as you approach 10 psi, that's getting dangerous...
A good tuner and fuel system can get you up to 10 on anything at or below a T3 trim, but beyond that.... hmmm .... I don't think so... any other view on this ?

VTC_CiViC

Well I can only relate my experience.

10psi on a stock D16Y8. As of last weekend when I checked, 100% compression, 0 smoke, no oil loss whatsoever. Obviously I can't get a good look at the piston tops w/o removing the head, but from what I do know, everything is A-ok thus far. Take it for what it's worth

boosted hybrid

Well considering that 12psi lasted me for a few months, and 15psi has been fine for the last few weeks i dont think that reliablity is an issue. I am using a t3/t4 turbo, so i dont think that larger turbos have anything to do with boost pressures. Psi is only relative, but the airflow of the turbo is what dictates the power characteristics...and the t3/t4 out flow the greddy 18g's. The timing is not really an issue, i have full timing on low throttle settings and partial throttle to allow for low end to still be there, on high partial and WOT the timing has been taken out when the boost kicks in. I did have higher temps on my egt before i added the water injection kit, this was due to having have the timing set low, but after running water/alcohol injection my egt temps are actually below normal. I would way rather run 15lbs with minimal timing then 8 psi with full timing, there is still less stress placed on the bearing and ring lands, and this is the real determining factor when having a boosted motor that is reliable.

X2BOARD

?Actually elevated boost pressures in the combustion chamber have a hell of a lot to do with engine reliablility, your stock knock sensor can take care of advanced timing, where do you get your logic from ?

BTW, a larger turbo pushes more CFM, thereby, more air... *doh* increasing your A/F ratio, heightening the chance of detonation w/o proper fuel management.
Also, Psi is NOT relative, it is linear.
Running 12psi on a stock bottom end can be done, hell I have pushed 14psi on stock LS's before without many issues, but I wouldn't do it on my car, and all motors and parts are slightly different, I've seen stock GSR's blow from 8psi of boost, now that's relative !

boosted hybrid

Well here let me clear this up. I simply meant that higher cylinder pressure in conjunction with high boost pressures creates detonation as we know it. High cylinder pressures are determined by either running to lean or running excessive timing when compared to boost levels. Of couse air/fuel has a lot to do with the cylinder pressures, and running the car rich is of course the trick to "cool" down the combustion chambers b/c of this heat generated by the higher than normal cylinder pressures.

By the turbo statement i simply had a brain fart. I just meant to say that running a larger turbo is not always bad, and that the boost pressures that you run on say a t3/t4 compared to a t25 are only relative to the state of tuning that you provide to the engine. Of course you are going to have to be way more accurate in your tuning when running a larger turbo b/c of the massive amount of air when compared to the little turbo. I am not saying that the little turbo doesnt need accurate tuning, but you can be more lax with timing and fuel running at the same boost pressures of the larger turbo.

Overall, the stock pistons are good ones and can regularly see boost pressures of 15psi and i have proven that. For the money forged counterparts are much better. Is it worth the money to buy them, yes, does everyone have the money to buy them, no. It all comes down to your hp and reliablity goal. But for stock pistons, Honda did a very commendable job.

Now as far as gsr block blowing on 8psi, you are totally right. I only use quality components in my fuel system and a standalone is part of that. I am only speaking of running these kinds of boost levels with very conservative tuning. You would have to be a fool to believe that you can achieve a reliable daily driver running around on 15psi with a fpr and inline pump. If his question was stated, how strong is a stock piston running fpr and inline pump i would say as strong as your fuel system. I only assumed that we were talking about quality tuning with quality products (i.e larger injectors, intank fuel pumps, standalone, wideband, etc).

DIRep972

iTrader: (1)

hummmm, im enjoying this little debate.. keep it goin im learning things from the both of u..

LsTurbo91

I also KNOW of a built GSR that blew 4 times!! 1 stock and 3 rebuilds! running 8-10psi on a silly FMU!, thats not really relevant, like he said it all comes down to tuning.

X2BOARD

I think you're kinda mixed up on the principle of advanced ignition timing, detonation and cylinder pressure.
Advanced ingintion timing will increase the chance of detontation, that is why you need to use higher octane gas to avoid detonation when running advanced timing.... when boost is brought on, cylinder pressure increases, and your knock sensor retard timing to avoid detonation.

Check the definition of detonation, and how it occurs.... you might be in for a surprise...

But I gotta go back to my hotel now, and don't have access to the net there... but I'll be back with more time tomorrow morning !!!

P.S. WA is COLD !!

boosted hybrid

Also i just want to add one more thing:

"Actually elevated boost pressures in the combustion chamber have a hell of a lot to do with engine reliablility, your stock knock sensor can take care of advanced timing, where do you get your logic from ?"

The knock sensor does take care of advanced timing on the stock engine, or a lightly modded n/a engine. But the knock sensor will not rescue your *** when your timing is stock running high boost pressures...your engine goes boom. Also, i get my logic from reducing cylinder pressures keeps the stress off the vital components such as the bearings and ring lands. The ring lands are most likely to go, followed by the bearings. I have had friends actually spin a rod bearing b/c they were running stock timing and boost...so it goes to show that it isnt always the pistons that go first. Keeping the cylinder pressures off the pistons creates less stress, (this is obvious), as well as keeping the cylinder temperatures down. The key to keeping cylinder pressures down is take timing out and increase the fuel to cool the combustion chamber down. That is the basic rule of thumb when it comes to tuning a fi car. Maybe my logic is all wrong, but using my logic i have successfully been running my car with high boost pressures and have had no problems what so ever. I am doing a comp and leak down test the end of next week to make sure everything is ok.

Also, there is a thread on clubsi.com in the boost section where Stoopid speaks about tuning a stock block LS to run 18lbs and make 390whp. He uses the same philosophy as i do, i dont think that two ppl could be wrong, especially when Stoopid is considered a premier tuner.

boosted hybrid

Yeah but i am running a b18b, there is no knock sensor on these blocks. So what do i do when the engine detonates...nothing i dont and the engine is screwed. Also the knock sensor is not going to save you when your block detonates, just like the J&S is a bandaid for poorly tuned vechicles. Why do you think that ppl even bother to shell out 500+ for the units, so there is that safety net of taking the timing out when detonation occurs to try and rescue your engine. If the stock knock sensor was able to do that then there would be no need to even have a J&S unit. You are missing my point of backing out the timing so you can run a more reliable fi engine. Yes you can run higher octane fuel to compensate for pinging, but who can afford to get 110 all the time, and next to no gas stations carry it. I know what creates detonation, to lean of a fuel mixture, or to much timing, or a combo of both. I will stick to my philosophy of running a fi car rich and backing timing out to be able to run higher boost pressures. I will state it again, i would rather run 15lbs on rich mixture with minimal timing (conservative tuning), then 8psi with leaner mixture and full timing (aggressive tuning). What engine is going to be more reliable...the one with the conservative tuning. What will make more power, well that depends. With the aggressive tune you are compensating lower boost pressures with leaner mixture and full timing to create the power. With the conservative tune you are letting the turbo make all the power, essentially. There still will be less stress placed upon the weak internals of the conservatively tuned engine then the aggressively tuned engine. When the original question was stated the strength of a stock piston, i was simply giving my opinion of the stock piston in terms of my conservative tuning. I should have stated that with my opinion.

jinxproof99

i'm not writing a book, but i will say that i ran 20+ lbs on a small t3/4 and ran over 360 to the wheels on stock gsr pistons, rods, block. that was with a stock ecu, afc, fmu, headgasket, larger fuel pump, 440's and race fuel. that lasted for 1 year and was still running perfectly when i pulled it out. i have personally seen this set up last for 2-3 years in multiple cars if tuned correctly.

i'm sorry if this ruins any of your theories.

boosted hybrid

I totally believe it...so ppl get lucky others dont. You also said the key word, racing fuel. This allows for aggressive timing. Remember what i was saying is that you need to take out timing to run the car on pump gas, 93 octane. When you run higher octane fuel you need to increase the timing, or boost pressure or the benefits of the higher octance fuel is losted. For those who dont know the benefits of racing fuel, it burns slower, so you need to increase your timing to try and burn it faster, or increase the boost pressure to keep the timing and boost pressure consistent. Either way you get a significant increase in hp. I would rather just increase the boost though, still more relability there over the timing option.

X2BOARD

Ok, first off, race fuel does burn slower and thus, more consistently and evenly.
Second, advancing distributor timing does NOT "burn it faster". Advancing timing will allow your spark to occur earlier in the combustion process, thus allowing higher octane (slower burning fuel) to have a longer period of time to burn on the combustion portion of the stroke, resulting in a longer power stroke, giving more power distributed to the crank as according to the crank angle, (but this will put more stress on the rod bearings in a boosted motor). (Do some more research)
I don't understand how you can tune a car, yet not understand the concept of distributor timing on a Honda ??
The reason you need to run higher octane when advancing timing is than higher octane fuel has less of a chance of "self combusting" which is what most engine tuners refer to as ???? DETONATION, look it up one of these days.

PS, rings typically go before the lands do, and more than likely, on a boosted honda, that is because of an inadequate crankcase pressure breathing system than high boost with advanced ignition timing.

Increasing boost pressure causes increased cylinder temperatures, thereby increasing the chance of hotspots in the combustion chamber, promoting the chance of detonation, which is why you would retard timing, which would create less exposure of high temps to the piston top and cylinder walls. Unfortunately, this will result in less of a complete burn in the chamber, leaving unburned fuel in the chamber.... when running your "conservative" tuning to keep the motor "cool" will result in wasted fuel, and an inefficient engine.... the whole point of turboing is to increase the motor's efficiency.

True, lean conditions will result in increased chance of detonation, but, but the point of this post was piston strength as pointed out earlier, so, yes, some people do run 15+ psi on stock honda pistons, but I would not recommend it, as it is entirely possible to melt one at 7 psi, and if you can't afford to buy a good forged or heat treated piston, why are you willing to push a tried and true envelope and melt a piston or all pistons, you're gonna need to buy new ones when that happens ! If you couldn't afford them in the first place, why risk it ? Because we all know that if you get new pistons, might as well spring for forged rods, then you need new rings, throw in some new rod bearings.... alignment hone, balance the pistons while yer at it, new head gasket... got at least a $Grand laying around for just parts ? Hope you know how to do this yerself, because I'll charge you about $600 for the job (cheep). The point is, under boost, your pistons don't "hold up" they SURVIVE, even the all mighty Honda parts !

The fact is Honda parts are ***** strong, that's why we boost stock bottom ends, but if you can't afford it, don't push it... somewhere around 7 psi is the safety limit in my, and many other honda tuner's opinions... don't rely on the results of 1 or 2 people that run 15, 16, 18+ psi on stock pistons... that is crazy talk.... but more power to you if you do.... as long as I don't haveta rebuild yer motor... that's a Pain IN the *** !

Honda pistons are strong... not as strong as some assume, but strong nonetheless...

If you want to talk about the prior argument, maybe we should start a post entitled " Distributor timing and detonation" in the FI forum...

Cliff's Notes:
Read it, you might learn something.
Boost + Honda= Fast Mo Fo
Know what detonation is
Buy 87 octane to blow yer sh*t up
This is a long F@*king post
Don't get turbo, so I will always be faster.

X2's tip of the day: Don't melt a piston, it sucks.....




[Modified by X2BOARD, 11:58 AM 2/28/2002]

boosted hybrid

Alright you bring up some good points that i would like to address, but first i must address what i meant buy trying to burn the fuel "faster". I simply meant that you try to ignite the mixture of the higher octane fuel so that it has a longer burn time, thus achieved by advancing timing. But you can also increase boost pressure and keep timing constant and once again create the situation where you now are able to keep the increase cylinder pressures off the vital weak components such as pistons, bearing, etc.

Now to move onto the statement about trying to have the most effiecient engine. I would have to agree with you partially, but in some extent i dont. We are all trying to make the most hp possible with reliablity in mind. After all you wouldnt want to make a 1000hp for a minute, when you could make 300hp all the time with no problems. Now take the cases of the conservative and aggressive tuning. Which would you rather have on your personal daily driver that you depend upon? I will take the conservatively tuned engine that produces the same power, but is unefficient. Yes fuel consumption will be greater, but at the expensive of engine longevity. It kind of comes down to efficiency vs. reliability in terms of engine tuning IMO.

I will admit the only tried and true way of knowing the true strength of a stock piston is to see what kind of heat ranges and temps it can withstand, and what kind of forces it can withstand before failing.

PROFILES2000

my ring lances went at 12 psi but the rest of the piston was ok

X2BOARD

That sucks... It happens tho... FORGED PISTONS BABY !!!


As far as efficiency Vs. reliability, yes, somewhat retarded timing will increase longevity of the motor, but kill some low end and peak Hp (low end being the most notable) Especially with LS pistons at that low compression, losing low end will be quite noticable, but the boost will eventually make up for it... This is why I am running a BTM, advanced ignition timing can be retarded with the onset of boost, reliably.

Typically, a T3/T04 hybrid can run lower boost and make up for the lack of boost with higher flow (CFM), this is a better way to run than a smaller, let's say, Mitsu Turbo like a 25, kick out higher boost with less CFM per Psi, but this would put a lot more stress on any bottom end. But running 8+ psi on stock pistons is not a very good idea.... this may be my opinion, but I am surprised that few people have stepped up to agree with this statement .
Elevated levels of boost on a stock bottom end is, let's be scientific here, asking for it.... Honda pistons were not designed to withstand elevated cylinder pressures, especially that created by FI, with heated intake charges.... yes you can push more fuel in there to 'lower' the A/F ratio, but the point of tuning is to maximize your efficiency, not flood your motor to claim reliability, we should at least pretend we are trying to save the fossil fuel, while burning up the road... (HA! my azz)...

dustin

Well, I hope we all understand the relationship between pressure and flow.

Turbos flow air, they do not create pressure. Pressure is created by the inability of a motor to flow a given amount of air.

So a larger turbo can flow a lot of air at lower shaft speeds. A smaller turbo (read mitsu turbo from greddy kit) needs to spin up much higher to FLOW enough to create enough positive manifold pressure. The wastegate regulates this. If air consumption is held constant (aka, we are using the same motor), it takes the EXACT SAME AMOUNT of air to create a given amount of pressure in the intake manifold... regardless of the type of turbo. So CFM per psi is a worthless number.

What is lost through higher shaft speed is efficency, in that the air is heated up. This is what you may be referring to... as the air is hotter and makes the motor more susceptible to preignition (and thus detonation).

Dustin

lucas569

these are the threads i like to read!

Xerxes

X2BOARD you bring up some good points but i believe you are confused (or misinformed) on a couple of points:

If you are experiencing "self combusting" or pre-ignition, then you are running too lean of an air/fuel mixture. no amount of ignition timing retard will help you in this case. self combusting means that the air/fuel mixture combusts on it's own, due to pressure & temperature, i.e. without the help of a spark. The only way to combat pre-ignition is to run higher octane or richer air/fuel mixtures.

Here's a key reason for retarding timing that I feel has been left out of this discussion so far (unless i didn't see it!) ->
When you run a lot of boost and have a denser air/fuel mixture in the combustion chamber, that mixture burns faster. If you have an extremely fast-burning mixture with non-retarded timing, then it's possible for the mixture to try to force the piston down while it's still travelling upwards in it's compression stroke, which leads to a LOT of stress on the engine. This is why high octane fuels allow you to run both more boost and more timing.


[quote]PS, rings typically go before the lands do, and more than likely, on a boosted honda, that is because of an inadequate crankcase pressure breathing system than high boost with advanced ignition timing.[/b]

Can you please elaborate on this? I've heard some instances of crankcase pressures causing problems but I haven't heard a good explanation yet.
All of the blown engines i've seen have had cracked ring landings and good rings, with stock honda pistons. I would believe that rings would fail more than landings when you're using forged piston though.

BTW my planned setup is 10-11psi on a stock b16a, with 11:1-11.5:1 air/fuel ratio and conservative timing . All tuned via standalone so that i can run advanced timing for great driveability when not under boost . Just need to get my hondata romeditor software (coming next week!) and i'll be set.

-Xerxes

X2BOARD

Ooook.... let's review, decreasing the A/F ratio will prevent detonation (ie, add more fuel), but you may not be fully clear on this concept. The reason you run higher octane fuel is because of it's characteristic of a slower, more controlled burn... lower octane fuels (faster, more un-controlled burn) are more prone to pre ignition, because areas of the combustion chamber, under a lean condition will tend to have an uneven range of heat, and in some cases, some parts of the chamber will be hot enough to cause 'self ignition' of the mixture, which is what we know as detonation, think of it as having multiple explosions in the chamber, when you should have only one. NOW, when you advance ignition timing, you allow the ignition side of the combustion process to ignite prior to stock position which will then result in a longer period of time for the burn to occur (Read: A more complete, clean burn).


An extremely retarded timing set WILL result in detonation, regardless of octane, advancing timing allows you to have the spark occur sooner in the combustion process than normal, which gives more power, allowing the 'explosion' to apply more of it's energy to pushing the piston down, however, overly enthusiastic advance will eventually result in ignition prior to completion of the compression stroke, which will put undue stress on the piston, rod, bearing and crank... AND

A boosted engine will be putting a larger volume of air and, for arguement's sake, fuel into the chamber, this air is compressed, which, by nature, will be hotter than an N/A intake, this heightened temperature makes the chamber more prone to detonation, which is why, under boost, you need retarded timing to prevent the chamber from seeing the 'hot' side of the combustion process for extended periods of time. This will disallow pre- or self-ignition under boost (retarded timing).
One CANNOT cause fuel to burn faster as you put it, just more completely, which extracts more power from the A/F that you are igniting.

Do you understand now ?

Yes, rings will fail more often on a forged piston, because the strength of the lands are above that of the rings.
whew.... it is necessary for an engine to have thourough crankcase ventalation because a motor is a very picky customer, and having excess pressure on the 'backside' of the piston will result, eventually, in the elevated cylinder pressure to 'give' and bleed past the ring/wall clearance, due to the boost pressure having no where to go but down, resulting in damaged rings and/or lands... which is why you would run a catch can system on a boosted motor and not a breather valve by itself.

<----*Wipes drop of sweat from brow....*

Cliff's Notes:

Damn... you want me to type more ????


[Modified by X2BOARD, 5:13 PM 2/28/2002]