This tread is to try and figure out why we have had so many piston failures due to detonation on boosted single port J series engines lately, two of us broke skirts on our stock pistons exactly the same on the rear bank, new forged pistons destroyed on one new engine along with cracked block and we almost melted down our new JE pistons while tuning

 

This is from another thread discussing the head design as part of the problem
I agree, but I have a k24Z3 with 8.5:1 pistons running 16-17 LBS of boost and a small precision 5858 with tiny .58 AR turbine housing with the turbo bolted up 3 inches from the head (picture of manifold) making about 450 WHP and not having any detonation issues on pump 91 so it's kind of frustrating why we have such a hard time with the J35A8 I think it's the high compression ratio kicking our butts we will find out soon, we are messing around with our tune with Domsgsr right now to see what we can get out of it with the 10.4:1 pistons then we are going to free up the exhaust and see what that does to the detonation problem and the final fix will be going to 8.5:1 pistons and a lot more boost to see what it will do, we are looking for the most safe power on pump 91 with no meth or water injection

 

I would install an EGT sensor on each cylinder bank and monitor your exhaust gas temps prior to the turbo.

Are you running returnless or return fuel system?

 

We need to bring up another build that really is going against all of our theories, and that is the build Tony the Tiger did. Sadly he was ran off by IHC, but lets take a look:

1. We think the single port heads are a problem. Tony the Tiger was using a single port head on pump gas.
2. We think the high compression is the problem. To my knowledge Tony the Tiger was a higher compression than anyone here......he was 12.5:1.

The parts that REALLY get me about Tony the Tigers build is he said that he was running 12.5:1 compression and running 14 pounds of boost on PUMP GAS!!!! He then said he used water meth injection to take it up from there. So I ask my self......what is it about Tony the Tigers build that allows him to do what other people are saying is impossible. Answer: His exhaust. He had a HUGE and SUPER LONG exhaust on that car along with a very large turbo. Yes the set-up was laggy before the boost came on but it didn't matter as the car has such a good VE that he was making over 250 ft lbs of torque from like 2500 on up if I remember.

I brought this up before but Mazda on their sky active motors was running 15:1 compression on pump gas, but said that they could only do it with their super long tube headers. When the headers couldn't be fit onto the car and pass US safety crash standards, the motors compression was dropped to 14:1 to avoid detonation on the short header design. This tell me the exhaust flow is SUPER IMPORTANT if running higher compression or boost.

I'm a ways out on my turbo build, but I do plan to do a "laggy" set-up with a large turbo and larger primary exhaust piping.

 

One thing to consider is the slight difference in stroke. Tony was using J32 not a J35 - I doubt that is the root of the issue, but definitely something to be noted.

 

we have a returnless fuel system, I have a EGT on my K24Z it helped with the tuning somewhat as soon as detonation started the temps dropped like a rock 300-400 Deg.

 

Tony the Tiger is the only guy that has done it. So either he has god parts, running methanol 24/7, or something off. Everyone else with 11+ CR on boost are capped at 8-9psi. Lower compression brings it up to 11-12psi from what I see so far on daily driven cars.

Good point on the long headers. This brings me to the idea that the exhaust ports on the heads need to be gasket matched. Last time I check there was 2-3mm on each side that could be taking off. Someone on here told me not to remove too much material on the exhaust side because you lose low end torque due to a decrease in low speed velocity. But for turbo guys it might be looking into. I also measured Richie HFPC and the opening matches the gasket perfectly. So maybe instead of having the pipe on the inside for 2.5in maybe you could use the outer diameter to get it close to 3in and a 3in+ exhaust.

I also think that the offset pins might be a good idea because it increase cylinder pressure way to fast on a boosted motor and will cause early detonation.

Looked up some good info from this website.

https://www.savvyanalysis.com/articl...d-pre-ignition

Just wonder has anyone been measuring their EGT? Gasoline Autoignition temperature is around 280 °C (536 °F). on an N/A car the highest I have seen via flashpro datalog is 230. This is with an outside temp of 90* so far.

here some reading on EGT:
http://www.bankspower.com/techarticl...t-is-important

Too rich condition also cause high EGT.

 

Maybe you just need to be patient and see how this tuner guy will do on your tune he as just started... But I'm sure that the real fix is the watermeth route for sure...

 

Isn't Honda also using a single exhaust port head design on the new turbo NSX?

 

Well looks like I am buying a C32 NSX then

 

I picked up a set of 07 type-s heads with 70K miles on them and have torn them down to check everything and then install the new spring seats, seals, etc.

Now that I have a larger combustion chamber, the C/R should be where I planned in the 8 to 8.5 range. I'll check that when I get everything back together.

Unfortunately, house stuff has clogged up my garage again so until I can get the lawn mower, snow blower and lumber to expand the shed out, I am stalled.

I have a meth injection system installed but my goal would be to not depend on it but have it there and use it only for scramble boost.

With regard to someone mentioning Libert69 running in the 10's at full boost, every tune I ever got from Rodney for both the FI/C and MS3 would all go into the 10's. There were also posts from him running +20lbs of boost. He was driving seemingly trouble free up until the accident.

 

Why? Honda somehow got it to work just fine on the new engine, otherwise they wouldn't be releasing the car for sale. How much more boost over stock can it take before it runs into these same issues - that is the question. But who cares, the first question here for us is how did they do it to begin with?

 

My k24z3 is running right at 11 AFR on 8+LBS boost and a flash of 10 AFR on 14+LBS boost

the cloud of black smoke is kind of embaresing sometimes when I'm beating on the throttle LOL

 

I mod my car. Regardless of how fast they are. I got itchy butt syndrome.

lovefab NSX!

 

I was diagnosed with the same syndrome years ago

 

Does anybody think that part of it is something to do with the trans type? Seems to me like manual TL's handle boost better than the autos.

Less load in 3rd and 4th gear for MT vs Auto's.

 

i thought he had a j35 bottom end?

 

the guy seems pretty clever. we'll just have to see how things go.
water meth is definitely a plan for the future.

 

Seems so according to Tony's post:

"For the build, it has a 3.5L bottom-end with high compression setup using Wiseco pistons with HD pins, 5cc dome and with the J32 head. The static compression ratio is 12.5:1 CR."

 

Are you using a lot of oil when in boost with your low comp engine? I'm going thru a lot of oil on this engine while in boost and getting a fair amount of smoke and soot build up on the exhaust. I'm running almost twice the boost I was on my stock engine, but the oil use worries me. With the tinted windows its had to see exhaust smoke, but looking at the tips I seem to be burning off a lot of oil and the dip stick confirms it.
Just wondering if this is normal for low comp high boost setups with possibly looser tolerances or if I need to rebuild the engine.

 

My car sounds a lot like that NSX with the exhaust cutout open ( sorry, I forgot to show you that ), but it draws a lot of attention so I rarely open it. I love the sound of the turbo spooling, with my stock low boost setup it was mostly for intimidation or starting a race. Haven't opened it yet with the new engine.

 

Kind of normal for loose pistons and big piston ring gaps, I was using a quart of oil every 1500 miles or so, my precision turbo started smoking at idle I rebuilt it and it seems to use about half of that now

 

Check your oil pump. The seals leak. Seems to be somewhat common for us. Look for oil residue on the bottom of the oil pan by the oil pump.

 

Honda uses single-port heads on their LMP2 motor for years now. Winning the FIA-WEC World Championship as well as the ALMS Championship for it's class.





And they stuffed that in the back of their CRZ GT as well:

 

^ race engine just has to last the session, or even just the race.

but that is just sexy as hell

 

Oh and....

 

Look at those manifolds

 

OH! And it's also somewhere down in here... http://jalopnik.com/the-ferrari-beat...-ac-1710118418

 

I think the problem might be exhaust back pressure, and not necessarily the single exhaust port design.

 

I am leaning to agree with you. While the single port design isn't ideal, I don't think it is such a deterrent in flow and a detonation problem that the design should be ditched. I think the single port head instead means one must be MUCH more concerned with exhaust flow and pressure. I plan to stay with the single port design on my turbo set-up so we will see how it goes.

 

Here's my theory on the matter:

The integrated exhaust manifold (IEM) style heads absorb significantly more heat from the exhaust gas than multiport heads due to a few reasons:

* the gases stay into contact with the cylinder head itself longer
* the head material is aluminum which has a high heat transfer rate so it pulls heat from the exhaust at a quicker rate than traditional cast iron or steel
* there are added water jackets around the exhaust port outlet that also pull heat out of the gases via heat transfer from the head material
* exhaust gas restriction from pre-cats can decrease heat loss depending on cell count as well as the location of the converter(s) itself and its high heat radiance back into the block and heads
* some IEM engines eliminate or decrease fuel enrichment under WOT (full load) for the protection of the catalytic converter of which can also assist in removing heat by evaporation

The head design is great for reduction of emissions due to converter placement and also fuel efficiency as less heat is being wasted into the exhaust. However, for those of us running increased power levels on these motors, even more heat is being seen in the head and I believe this is what's leading to being more susceptible to knock. The head relies heavily on the coolant flow around the exhaust ports to function below an acceptable temperature and I'm sure if that temperature is not controlled or regulated properly, knock thresholds can be approached pretty quick.

To some, it may seem like the best way to combat this problem would be decreasing thermostat regulating temps, or enlarging head gasket coolant passages so the heads receive more flow, but lowering engine temps will take the engines fuel management system out of its ideal element and create additional problems. I would say the best way to fight the issue is by reducing the amount of heat being absorbed from the exhaust gases or in other words, killing the originally intention of the head design itself. Seems to me this can done by applying thermal barriers to any part of the cylinder head that will see high levels of heat such as the combustion chambers, valve faces, exhaust valve stems (down to guide), and pretty much the entire area of the exhaust ports themselves. Doing this should effectively shield the heads material from collecting heat and returning it BACK into the exhaust flow. And when I say thermal barriers, I mean the thick white ceramic coatings such as those seen in products like White Lightning. Not the DIY products from eBay or other BS companies. These coatings require complete professional application in order for them to last and to be as effective as possible.

Also, once passed the exhaust port where the pre-cats bolt to, one would also benefit from running unwrapped or unshielded exhaust tubing beyond this point to maximize the amount of heat being "pulled" from the cylinder head from the cooler piping.

 

I agree with Robert completely. It's all about getting heat out of the combustion chamber. The H22 is Honda engine that has traditionally not been known for its acceptance of boost. However, that has been mitigated by running a full tubular turbo manifold rather than a log manifold. I've seen numerous examples of 400+ WHP stock motors on H22s, as long as a tubular manifold is used. It simply gets heat out of the head much more efficiently than a log manifold.

While I love how simplistic a turbo setup is with the single port, I really wish the A2 heads were easier to retrofit.

 

[QUOTE=screaminz28;15480412]I agree with Robert completely. It's all about getting heat out of the combustion chamber. The H22 is Honda engine that has traditionally not been known for its acceptance of boost. However, that has been mitigated by running a full tubular turbo manifold rather than a log manifold. I've seen numerous examples of 400+ WHP stock motors on H22s, as long as a tubular manifold is used. It simply gets heat out of the head much more efficiently than a log manifold.

I think heat is a huge part of the problem also, we are going to try a very cold thermostat from mishimoto and see what this does for us, we (Dom) can set the closed loop target lambda limit at whatever temperature we need to with the FlashPro so we shouldn't have problems getting it into closed loop and running correctly

Acura NSX Racing Thermostat, 1993-2005, by Mishimoto

 

Stainless and Inconel tubular headers actually insulate better. They trap the heat inside the exhaust giving it more power/velocity to spin the turbo. I'm not so sure they do anything to cool the combustion chamber.

What plugs are you guys running? Stock are NGK in the 6 heat-range. Has anyone tried the colder plug options like 7 or even 8? Do they even make ones that fit? Usually this is preferred method of cooling the combustion chamber.

 

I'm running 8's.

 

I've been running NGK BKR8EIX (8 heat range on the NGK scale, which is different from many other spark plug manufacturers) for years with much success on nitrous and boosted J35 setups. I've run NGK coppers too, but with no added benefit and obviously shorter life (by design).

 

^Are you guys running the NGK 8's having detonation problems with the single-port heads?

I do agree a long-tube equal-length tuned manifold will be more efficient all around (offering the opportunity to make greater power on a given setup), which helps explain why a builder would want to go that route. I just can't see the single-port design as being the cause of the problem. Then again who knows.

 

I'm assuming you meant "multi port exhaust"?

I run Autolite coppers in 6's because they are the ONLY company that makes the extended reach tips the j37a4 heads require at a lower heat range. I'd prefer NGK myself if I had had a choice.

Btw, I have an R70 series head I plan on dissecting here soon in hopes of learning more about the water cooled exhaust port so stay tuned for some photos of this. I've read many places Honda uses the single exhaust port for thermal recovery but I'm a bit confused TBH on how transferring the heat to the cooling system rather than out the pipes increases the engines efficiency. I assume it's the ignition retard at startup that gives the precats quick light off due to the scavenged exhaust flames that Honda was REALLY after...and the removal of the heads heat after the initial start up was just an annoying byproduct from decreasing emissions that needed to be dealt with.

 

I did mean single-port head. I'm pretty sure I re-read the thread and couldn't confirm if of the ones having the detonation with single-port heads were running cooler-than-stock plugs.

For NGK, a higher # is a colder plug (removes more heat from the combustion chamber).

 

I logged the occasional knock but never saw any metal on my plugs while stock. My failure appeared to be due to ring ends butting together and cracking the ring lands but only on #5. All the other pistons were fine. I was running a high flow (100cel) cat behind the aftermarket O2 sensor so I may have the problem encountered with less than optimal exhaust flow.

I've dropped my C/R by a good 2 points so I am hoping that this won't be an issue for me.