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We need to back up and reassess before trying to fix a problem that we don't know the cause of. I've been preaching to monitor knock forever and it still looks like most here do not. You need to know if failures are coming from knock or from something else. Once it's confirmed that knock is or is not the cause you can move on.
An EGT probe needs to be used even if you can only get an average temp of each bank. If it's pre-ignition which is way worse than detonation you might not hear a knock and EGTs will drop way off yet you will have piston meltdowns and you won't be able to figure out why.
Collect the necessary data and then move on instead of guessing. There are a bunch of theories as to why some engines survive and some don't but it will take a very long time to figure out with no hard data.
Excessive exhaust backpressure will cause detonation. I would be looking at exhaust back pressure if all else is the same with the two designs of heads. One might have a large single exhaust port but is there really that much more area for hot exhaust gasses to heat up the head over three separate ports? Probably not. Is it easier to get more water jacket area around the exhaust with one single port, yes. With the water jackets being near the exhaust anyway, this should not be the cause of detonation. A cooler thermostat should be used, within reason. Fully open at 180F is good for an aluminum head street turbo engine. It might be a good idea as suggested to run a very cold thermostat for testing. It's not something I would do for any length of time but going to one extreme might eliminate one variable or get you closer to the problem.
It's still hard to imagine this head design being too restrictive. The turbo will still be the biggest restriction, especially at spoolup. I've had quick spool designs that were too restrictive and there's a very easy way to fix it if that's the problem but looking at these heads I highly doubt this is the problem. If long tube headers are the real reason for less detonation I would suspect it's more to do with the fact that the turbo is farther from the heads than the actual headers. You will encounter less backpressure before the turbo the farther it gets from the heads but you will also kill spool. There is a simple fix for this, I'm sure you guys will figure it out.
In the engine that trashes one bank of pistons, is it a single or twin setup and if single, is it the bank nearest or farthest from the turbo?
I still have no idea why many try to run high compression on a street turbo engine. You lose at the most 3% power for every whole point decrease in compression. Compression is more important for mpg and mpg is the main reason manufacturers push for higher compression. It's a VERY minor loss for a huge gain in the amount of boost you can run and you will usually see better spool up hence better low end power with lower compression. More importantly, low compression is easier to tune and the consequences are not as high for errors. It's easier to tune it for quick spool with low compression.
Oil burning.... High or low compression, doesn't make a difference, neither makes an engine more or less likely to burn oil. Oil has a very low octane. Just a little oil getting past the rings or the compressor can cause significant detonation in a turbo engine.
Plug heat range... Only a problem if the plug itself is the source of pre-ignition.
Air balance.... How well does the intake tract distribute air. Does one bank run leaner than the other? Do the last two cylinders run leaner than the front ones? This is why I have my heads with the intake manifold flowed as a unit before they go on the engine. I match flow as best as I can. My injectors are always flowed. When I assemble the engine I make sure the highest flowing injectors go on the highest flowing cylinders. As air balance is important, so is fuel balance. Is there an inherent pressure drop on some cylinders?
Tune..... Rich is generally considered safer but there comes a point where too rich will cause detonation and worse, preignition which is hard to detect other than melted parts. I rarely run anything below 11.5 AFR. There also comes the point when too much timing retard causes not only detonation but way too much heat in the exhaust tract starting from the exhaust valves. You can end up with a hot spot such as the exhaust valves themselves causing detonation. You also increase exhaust back pressure with too much retard.
These engines are generally designed for the quickest possible warmup which means running water around the exhaust ports. More exhaust port area means more area to heat the water. They run EGR right through the water jacket. EGR should always be blocked off on a turbo engine. They run far less coolant in the block/heads than older engines for quicker warmup. Many of the things that are done in the name of emissions and even longevity for a stock engine go against you in turbo form.
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.
That seems to be the failure mode for stock engines. A tight gap is fine for stock hp and heat levels and has some advantages. The rings grow too much when excessive heat is applied for too long of a time. Just running the proper gap even on the stock parts should fix that problem.
Matt, what are your thoughts on the recent failure of Utah's motor - with all the broken skirts? The tops looked fine. The consensus appears to have been 'limitations of the parts' which I don't agree with completely. I think there is something other than excessive horsepower causing the skirts to break as they did, especially since it was all on one bank (if I recall correctly.)
Vit said that he has talked to Acura mechanics that have said they have seen numerous instances of that on NA engines, which I cannot corroborate. The J series spark plug blow out is well known, and well documented across the web, with MDXs, TLs, Odysseys, etc, and many by non-enthusiasts just looking for advice. Broken piston skirts? Can't find ANYTHING about that being common.
For cracked skirts in general, my understanding is over-revving or high-rpm/load before up to operating temp are some causes of cracked skirts, but all in one bank? Seems unlikely.
I wish maddog had posted pics of his recent built motor failure - it would be interesting to see what occurred since it was tuned, and running meth.
You're friend is right about the bank failure episodes with these engines. I've seen several of them fail like this. More so on stock motors than FI engines. I'm quite sure it's the load from the detonation breaking the fragile high silicone cfirstontent pistons. Think about it, when excess cylinder pressures occur instantaneously, the piston has to pivot as it sits on the pin. The skirts aren't meant to handle loads like this so they break.
Matt, what are your thoughts on the recent failure of Utah's motor - with all the broken skirts? The tops looked fine. The consensus appears to have been 'limitations of the parts' which I don't agree with completely. I think there is something other than excessive horsepower causing the skirts to break as they did, especially since it was all on one bank (if I recall correctly.)
Vit said that he has talked to Acura mechanics that have said they have seen numerous instances of that on NA engines, which I cannot corroborate. The J series spark plug blow out is well known, and well documented across the web, with MDXs, TLs, Odysseys, etc, and many by non-enthusiasts just looking for advice. Broken piston skirts? Can't find ANYTHING about that being common.
For cracked skirts in general, my understanding is over-revving or high-rpm/load before up to operating temp are some causes of cracked skirts, but all in one bank? Seems unlikely.
I wish maddog had posted pics of his recent built motor failure - it would be interesting to see what occurred since it was tuned, and running meth.
Wow, I had no idea that happened. I had something similar, are there pictures around here in any of the turbo threads. I have a good idea.
We are gathering parts to run this thing cooler the under hood heat and heat soak is off the charts, we have a Mishimoto thermostat and a 2 inch thick 3 core Mishimoto radiator the fan we haven't ordered yet we need to make sure it will fit it's a dual 13 inch with a full coverage shroud and 4000 CFM it has a ton of great reviews like it's a hurricane under the hood it moves so much air then there is the water meth injection kit my kid is putting together we will see what this does for us we can't give this thing any timing without the rattle can detonation noise
A little hard to tell but it looks like the piston broke above the top ring and the chunk of piston and a piece of the ring got smashed a few thousand times in the combustion chamber or a piece of the valve head broke off ?
A little hard to tell but it looks like the piston broke above the top ring and the chunk of piston and a piece of the ring got smashed a few thousand times in the combustion chamber or a piece of the valve head broke off ?
Hard to tell from the pics, but that's what I thought - the top part of the piston looks to have broken off. However, it still looks like it has a lot of pitting that could have been detonation induced.
From my experience with the monoport K24Z7 not wanting to take any timing, I'm going to say that the single port heads here are simply retaining too much heat, above the ability for octane to mitigate predetonation.
One potential avenue is to lower dynamic compression by changing to higher lift/duration cams--sure they'll bleed some boost but you'll flow more at the end of the day and keep things cooler that way.
Has anyone straight up called or contacted HPD in any way for insights? They've been running a modified J35 setup as the HR35TT below. I know it has DI which will help cooling but it also has a monoport exhaust setup.
The new NSX also has a monoport setup:
I hope the answer isn't "DI helps cooling" but it might be? It also might be worthwhile keeping the turbos farther from the heads, blocking EGR, and swap cams.
Even in standard non cast in head manifold engines the coolant goes around the exhaust ports, but probably not as much as the J- series.
I find it interesting that Auto TL's are taking a beating compared to the 6 speed guys. I know boosting in 5th (over drive gear) is a no-no among turbo b series so why would it be different for the TL's? The Auto trans 4th gear is terrible compared to the manual trans, even after the final drives. High load is going to cause EGT's to ski rocket.
You guys could just pool money and get a bracket designed and fabbed for a rotrex setup...that would solve the whole 20lb turbo-acting-as-a-heatsink-strapped-to-the-head issue and also get you some traction as well?
You guys could just pool money and get a bracket designed and fabbed for a rotrex setup...that would solve the whole 20lb turbo-acting-as-a-heatsink-strapped-to-the-head issue and also get you some traction as well?
Or swap out to a J32, we aren't having these problems. Most of us have run 400+ hp on stock internals for a long time. Maybe it is the auto, I boost in 6th gear once in a while and 5th all the time.
It really does seem like the J32 and J30 have less issues. I talked to a friend of the owner of that 700hp TL that Tony the Tiger built, and they initially had far less issues with the J32A3 internally stock + GT35 setup making 380 whp than the later J35 setup which he promptly blew up. They're actually on a J30 bottom end now and expect it to hold up better than the previous two.
Oh and I should add it didn't last very long at 700 hp.
Hard to tell from the pics, but that's what I thought - the top part of the piston looks to have broken off. However, it still looks like it has a lot of pitting that could have been detonation induced.
How did the combustion chamber and valves look?
Sorry for the poor pics, I'm dealing with some back issues so it's difficult to get around at the moment. There wasn't much more damage to any other piston. Several cylinders had cracks, and the valves were burnt up and there was damage to some of them.
I think much of the issue also stems from lightweight designed internal engine components which began to become a major focus starting with the j35a8 in the 05 RL. As said, the older j32a2's really didn't have these sort of issues and I even made a thread titled "How many bottles of nitrous does it take to blow a j32a2". It took 54 15lb bottles of spray to finally kill it. This was using 200hp+ shots and using roughly one bottle every 1-2 days and was using a single nozzle wet kit that injected before the TB. The engine even had 130k miles on it before being subjected to the abuse. Try doing this on a j35a8 and see what happens.
I think much of the issue also stems from lightweight designed internal engine components which began to become a major focus starting with the j35a8 in the 05 RL. As said, the older j32a2's really didn't have these sort of issues and I even made a thread titled "How many bottles of nitrous does it take to blow a j32a2". It took 54 15lb bottles of spray to finally kill it. This was using 200hp+ shots and using roughly one bottle every 1-2 days and was using a single nozzle wet kit that injected before the TB. The engine even had 130k miles on it before being subjected to the abuse. Try doing this on a j35a8 and see what happens.
You do realize that the pics maddog posted are of his built motor - pauter rods and forged pistons - I think. I don't recall what brand - Arias possibly?
You do realize that the pics maddog posted are of his built motor - pauter rods and forged pistons - I think. I don't recall what brand - Arias possibly?
Yes, I do. I was just mentioning some facts more or less.
You do realize that the pics maddog posted are of his built motor - pauter rods and forged pistons - I think. I don't recall what brand - Arias possibly?
Those pictures didn't show up the first time I viewed this thread. That's textbook detonation. Severe detonation doesn't just break the ring lands and crack the skirts, it also makes the tops of the pistons look like the moon with small craters for each severe event. Obviously some of that is chunks of piston that broke off and helped speed up the carnage but you can see that the engine was run for a while after some of those pits were formed and even after parts of the ringlands broke.
The little craters that are away from the perimeter are textbook detonation. To be fair, he could have had tuning issues early on and cracked the top of the piston. Once you get a hot spot like that it's all downhill from there because it usually leads to preignition.
I'm curious what the rod bearings looked like. The top of the bearings should be hammered out badly. Severe detonation tries to separate the top of the piston from the rest. Preignition is going to beat up on everything but with very high pressures for a longer period of time and can even damage rods.
At this sort of detonation you should begin seeing cracked cylinders. For the cylinder diameter I believe the frequency to be around 6.5khz which, along with the pressure spike, will crack cylinders and piston skirts. I'm surprised the cylinders were ok.
I have to assume that once again knock was not being monitored.
We may have to face that this is pre-ignition too, and pulling timing and running methanol is not going to help that much. If the preignition is occurring just before the spark, you've likely got detonation too. Detonation can cause a hotspot which can cause preignition. They're two totally different combustion events but very closely related. One can usually be heard and will usually take time to destroy and engine. One is usually silent and other than EGT and a power loss, there's no good way to tell unless you happen to check you plugs in time.
The tell tale sign if it's detonation or the much worse preignition is EGTs. Detonation doesn't affect EGTs too much. Preignition will cause an instant and drastic drop in EGTs. I'm guessing the engine in the pictures had both.
Don't forget that piston speed is faster at a given rpm for the longer stroke engines. That might be a factor in all of this.
Sorry for the poor pics, I'm dealing with some back issues so it's difficult to get around at the moment. There wasn't much more damage to any other piston. Several cylinders had cracks, and the valves were burnt up and there was damage to some of them.
I should have read this thing through. So there WERE cracked cylinders..... That makes more sense.
These burned valves, did they occur on other cylinders that did not have missing piston material but did have some form of damage?
This could all have been an improper valve adjustment causing the exhaust valves to become a hot spot.
IF there is more backpressure with the single port and it becomes too much backpressure with the turbo, it might be time for stiffer valve springs. I don't know if this engine had them or not. There's more backpressure with a turbo no doubt but I still doubt the single port is the problem.
I know a few people run the tapered manifold design and though it can increase spool time and response, this could creating restriction at higher revs. People forget that underneath it all, increasing horsepower (even by means of forced induction) still demands a minimum diameter exhaust size tube to efficiently evacuate exhaust gases. If the diameter is too small, the engine will see higher EGT's and combustion temps at higher engine speeds and/loads. Then the issue begins to snow ball because the hotter exhaust gases require demand even more area in the tubing. Sometimes most of this process can all happen quietly under the radar and at times transform into preignition.
This is why its so important to properly size turbo manifold tubing based on expected max power output, better to be oversized than not large enough obviously. This is also why it's equally important to fit the correct turbo to the engine in regards to power, response and efficiency....NOT by exhaust manifold tubing size.
Let's not forget the rest of the exhaust system as well. The downpipe, for instance, must be large enough to meet the demands of the engines power capabilities. This also means that the entire exhaust system must be without significant restriction so the waste gases can be easily expelled. The longer the exhaust system length, the higher the resistance is in the tubing and if this factor is unaccounted for when determining diameter, you can still end up with the same problem of increased EGT's. Granted hotter gases can move more easily through the tubing but there is a limit to this "fact". This is all heavily dependent on length from entry to exit. If the diameter is adequately sized for thermal expansion from beginning to end, maintaining exhaust temps through wraps/shields can benefit the setup even more.
Pretty much everything though can affect combustion temps and EGT's from excessive IAT temps to ECT temps. That's why it's important to ensure the systems on the vehicle are 100% both mechanically and electrically. The engine by itself is highly dynamic. Then adding in another system such as forced induction that has another plethora of influential factors and you have a the perfect recipe for disaster.
This being a rear mounted system, how does backpressure play into that equation? I don't believe there were any mufflers - just the fake tips off the downpipe and wastegate. Also, when you say that there is a minimum exhaust pipe diameter - I've been preaching that for years on the TL and think people disregard it, even on an NA motor. Having a stock J-pipe on this probably didn't help flow any, but would it help cause these issues? It's crazy that with lower compression and running meth, that there was that much detonation.
The crazy thing is I've been preaching knock monitoring before the turbo TLs existed.
As a point of reference look at all of the supercharged J32 failures on here with 350-390whp without the back pressure of a turbo. Knock has to be monitored and the owners need to learn to tune their own stuff. You can't find tune on a dyno. You can get it close on the dyno but fine tuning is done on the street. Most dynos can't/don't load the turbo cars down enough. Tuning needs to be done on the street over months.
I see all of these AFRs in the 10s around here. What is that about? That will cause detonation in and of itself. Upper 11s is the richest it should ever go. If it's still detonating you need to take a different approach than adding more fuel.
I think backpressure is going down the wrong road. It can contribute under some conditions and in some conditions it can have an EGR-like effect. It can and will cause detonation but it has to be extremely high.
One guy mentioned going with large cams to reduce detonation by lowering the dynamic compression. This does work even though big cams are not needed with the turbo. You lower cylinder pressure at lower rpms. The only thing is, you can get the same effect by electronically limiting boost at low to mid rpms if that's where it's detonating.
I've been down this road before and I'm amazed everyone refuses to collect data still. The first thing I would do is get facts. Monitor knock and EGT. The knock sensor will pick up detonation and a rapid drop in EGT is preignition. Backpressure is very easy to monitor as well. We need real information but for some reason no one will monitor knock which is much cheaper than a new engine.
It's clear that these turbo Js need to be tuned for zero knock. Not 1 degree. Zero. The detonation might be leading into preignition which the knock sensor won't pick up and will kill and engine quicker than detonation. Even the few that have monitored knock have allowed some knock. I learned pretty quick that nothing more than zero was acceptable when pushing over 700hp at the crank on a stock cast bottom end. I think the Js need the same. As I said earlier, methanol and more octane don't help a lot for preignition so these cars need to be over octaned so no knock occurs ever. If knock isn't going to be monitored, run it at low boost and 100 octane at all times.
Screamin- this was a rear mounted setup???? Stock J pipe??? Please tell me there were no converters. I came up with the cure for excessive backpressure for a rear mount turbo years ago to the point even with a relatively small uppipe into the turbine, backpressure was similar to a traditional setup. From your description it was not done right. You don't run 500hp worth of exhaust through that length of the up/inlet pipe, backpressure had to be horrible. On the other hand, if the diameter was sufficient, say 3" or so, the exhaust would have cooled by the time it hit the turbo and the biggest restriction which is the turbo would be less of a restriction than it would be in a normal setup.
No, maddog had RV6 PCDs. i don't recall what size/kind of piping was running to the turbo. I'd be surprised if it were 3in tho. My random guess would have been 2.5 at most.
Unless I'm mistaken, this was road tuned by Vit and was not experiencing any knock, and was using meth purely as a preacution. Maddog, please correct me if my facts are not right!
Granted, it may not have knocked on any of the data log sessions, but in my eyes, you should (should being the operative word) be able to tune a vehicle to have no knock, and be satisfied that it is tuned well. Perhaps even reduce the threshold a degree or two - I'd gladly give up 10 - 20 whp to gain longevity and reliability.
I've had other FI cars and I didn't monitor knock at every moment - only when dialing in the tune. After that, I've felt confident that I can beat on it and other than catastrophic issues, I'm ok.
Monitoring knock has been a little tricky on the J35 we could hear it plain as day but getting the knock sensor to count knock when it happened did not happen until Dom started messing with the knock sesitivity, we now have a very good tool to tune for no knock, the kid is working on getting this cooled down a bit and destroying my garage LOL
You know, I didn't think about that. If the knock sensor isn't picking it up, then there is no guarantee the tune is good.
I ran into similar behavior bone stock. I added timing and the knock sensor never saw anything, or pulled timing, but boy were there marbles rattling around...
Perhaps a J&S safeguard is cheap insurance for these after all.
No, maddog had RV6 PCDs. i don't recall what size/kind of piping was running to the turbo. I'd be surprised if it were 3in tho. My random guess would have been 2.5 at most.
Unless I'm mistaken, this was road tuned by Vit and was not experiencing any knock, and was using meth purely as a preacution. Maddog, please correct me if my facts are not right!
The exhaust size was 2.5. It was road tuned by Vit and not experiencing knock.
This being a rear mounted system, how does backpressure play into that equation? I don't believe there were any mufflers - just the fake tips off the downpipe and wastegate. Also, when you say that there is a minimum exhaust pipe diameter - I've been preaching that for years on the TL and think people disregard it, even on an NA motor. Having a stock J-pipe on this probably didn't help flow any, but would it help cause these issues? It's crazy that with lower compression and running meth, that there was that much detonation.
Again, I'm just stating basic facts in my response. I wasn't speaking specifically about Maddogs setup. I'm trying to keep matters on the topic rather than getting into just one persons issues so that the info is usable to everyone who reads.
As for the j-pipe, it all depends on the amount of power he's trying to push through it and its restriction. In my experience, an aftermarket j-pipe generally won't return much gain unless the engine is around 300bhp. If you've noticed many engines below 300 seem to make hardly any power with large diameter j-pipes which tell me they would probably become pretty damn restrictive above 350hp+. Most stock j35 j-pipes have a 2.5" ID at merge. How much power does a 2.5" ID pipe generally support? Most charts specify no more than 225-250hp.
The j-series is designed differently from 'most' other Honda engines because they are built for high torque. This is because they are used in such a wide range of vehicles that Honda/Acura manufacturers and 95% are heavy 5+ passenger tanks. I point this out because the intake and exhaust ports are all designed with torque in mind therefore their volume, port size and shape are made to have quick air velocities so they are tiny. When you try and push large amounts of airflow through them, things get clogged up quick. This would also be another reason why the single port heads worked so well for the j-series. It runs all exhaust together in one solid stream that's evacuated quickly due to its small size. You can bet your pants that Honda designs the rest of the exhaust system with a large amount of back pressure at its usable powerband for complimenting the production of torque too. The engine doesn't even hit VTEC until roughly 5k revs because its so efficient at making power on the low lift/duration cams that only the remaining 1500-2000 rpms till redline were worthy of using a greater lift and duration cam profile. TB Motorworx and Evans Tuning makes mind blowing amounts of power using 3.7 displacements that are what....revved to 8k+ rpms. This is only made possible firstly because they use the older multiport heads that can outflow single port exhaust heads when making an appreciable amount of power. Secondly, they run huge intake and exhaust port/tubing diameters because again, enlarging them is the only way to reach those numbers NA.
Bottom line is just that, to get reliable power from the j-series, you gotta get the heat out of the chambers. The greatest thing (IMO) for improving this problem is opening up both intake and exhaust in accordance to the expected power range to overcome their design flaw of being a torque motor. Also, don't forget about the cam profiles. With the "green leafiness" direction Honda has been going here lately, it can be expected that whatever profile they've been sticking in these motors is surely one that doesn't support safely making decent amounts of power. I bet (due to emissions and efficiency) their overlap is murdered and probably just enough to cleanse the chamber of spent exhaust gases and shut down right before the ingestion of cool air takes place on the high cam. Though they say in official news releases that "overlap is increases by XX percent compared to previous models", I bet it's not in a manner that helps any performance oriented enthusiast such as us. Also, on the subject of increased lift. Hondas improvements on lift can be a joke. Its hard to stay on what exactly they do with the newer engines because they literally run different base circle diameters on almost EVERY lobe on each cam but I have been seeing barely detectable measurements on their supposed profile aggressiveness. Honda knows that a torque based engine makes almost nothing in regards to emissions so they develop the largest engine they produce around this concept.
Four key factors in building an insane j-series engine:
* thermal coatings to keep out the heat
* increase port/tubing sizes in both intake & exhaust tracts
* use a camshaft profile to compliment the application
* run a thorough tune that keeps the engine out of detonation
The first one works around the issue of limiting the amount of heat absorbed by the poorly designed cylinder heads. The last two remove the design flaw of the j-series being a torque based motor and actually helps the first key factor. The last one is self explanatory but is still often overlooked or done incorrectly. And 99% of the time most are unaware that it was done improperly even after engine fails because nothing was monitored correctly as they should have been.
The exhaust size was 2.5. It was road tuned by Vit and not experiencing knock.
It was 1000% experiencing extreme knock. The proof is undeniable. Did you have some sort of monitoring at all times such as an audible or visual detector? It's kind of worrisome that the knock sensor is not picking up knock in some of these engines. That would be the #1 thing to figure out in the interest of making it live. Forget all of this head flow stuff, it is not the cause of your failure.
2.5" was a good call by the designer. It's going to be restrictive at that length but 3" would have significantly hurt spool. It's still not optimal but it's probably the best compromise. There is another design that would have allowed a 2.5" pipe to have very low backpressure but it seems no one is doing it. I did it on an LS1 car with very good results and I've never seen it used since.
How much boost were you running, what was the compression, where can I find your build?
Even if the knock sensor does detect knock on the j-series, the stock ECM will not make any immediate adjustments to the timing as most typically do. The knock system is more or less trims the timing table long term based on knock frequency and intensity. The only thing the factory knock system is good at doing is simply detecting knock and it won't even do this correctly until sensitivity is set properly. There is an obvious variance in either the sensor itself or the sensitivity tables as some of the cars I've seen can be too sensitive or not sensitive enough. Because all tables pretty much mirror one to the next in numerical data, I, convinced its design variation in the sensor itself or maybe even the block itself. I suppose it could also come down to the components of the ECM's circuit board itself I'm regards to their quality control measures but I'd put my money on the sensor. Regardless, they all require adjustments to provide trustworthy knock detection. Again, the stock ECM does nothing to combat the knock once it's seen immediately. But if you have an audible alert setup on FP datalog while the info is being graphed, it can help only if its being viewed live. As I've always said, running a knock controller is the safest and most reliable way to fight detonation. And like the stock ECM, the controller should enable the user to tune the knock sensor to itself so that it can provide accurate alerts/changes when detonation is seen. I've seen some knock systems being sold as "tuned kits" where the module and sensor have been supposedly pre-matched to one another but I call BS as the only this can happen is AFTER being installed on its intended block as bore size, block material, block design, etc can make definite changes to frequency the sensor listens for on that specific block during detonation.
IHC , you are right for sure about the knock... that's why I asked to look at the map and log and see what was wrong...
As a tuner, do you normally suggest running a standalone or piggy back knock detection system since your reputation will essentially be up for question if something were to happen and jeopardize the tune being done correctly? I've always wondered this about all tuners. Just seems like if this was my daily job, I would become fearful of things like this. The engine is totally reliant on the tune but there will be moments where the tune can only protect so far and ensuring the vehicle left with a failsafe (or at least having suggested one) would give me a sense of, I dunno.....job security? Lol.
IHC , you are right for sure about the knock... that's why I asked to look at the map and log and see what was wrong...
I literally think it's that simple. Have someone with experience look at it and the problem will be evident. It's tuning.
Are these guys really running 5-6 degrees of timing and AFRs in the 10:1 range? That's asking for extremely high EGTs. I wonder if the exhaust valves are causing some of the problems.
Are the engine builders out there leaving additional exhaust valve lash on these turbo engines? It's extremely important and I never hear it mentioned.
I read over the rear mount thread and it's not good. One full point of compression loss is 2-3% power loss before boost. Going down to 8:1 is a 15-20hp loss before boost and lower compression does not harm spool at all. In my experience spool is quicker with lower compression. With everything optimized the turbo is going to start contributing by 1,500rpm in the form of less vacuum for a given throttle opening. So even before it goes into positive pressure, you're making more power just off idle. The people who usually talk of these slow, laggy, can hardly move without boost usually have not tried lower compression. This is not about anyone in particular but I hope those building these engines take all advice into consideration.
The engine was rebuilt with forged parts without figuring out the detonation cause so naturally it happened again. I saw the scavenge pump went out and the car was driven for a while like that. They don't just dump oil out of the exhaust, it gets into the intake plumbing and that alone could have started off the detonation that was the end of that engine. Isn't that the one that lasted less than a day? So much was missed and overlooked in that thread. I know it's all in the past but too many myths are still going around without being questioned. Even that kit is bad, just bad. The wastegate setup was incorrect.
Can you elaborate what was incorrect with the wastegate setup? I'm going from memory, but I recall the wastegate was at the rear near the turbo and then plumbed to the other side of the car as a tailpipe. Should the wastegate be closer to the engine than the turbo? Typically everything is near the engine anyways, so I didn't know if the heat made a difference.
As for maddog's setup- what did your CR end up being with the forged pistons. I don't recall seeing it in the thread, only that you were considering 10:1 pistons. I know you said Speed Factory was able to add more timing and boost, so it makes sense it was lower than stock.
07-07-2015, 04:30 PM
