RB27 Tuning Update! Need Help.... Issues stilll...

[Carl H]

yeah man, typical on these engine...normally only on the 26 but with the greddy plenum same can happen.basicaly more air gets pushed into cyl 6 than the rest, with 1 getting the least...

[Shocker]

yeah man, typical on these engine...normally only on the 26 but with the greddy plenum same can happen.basicaly more air gets pushed into cyl 6 than the rest, with 1 getting the least...

Gotcha yeah could be the case #1 #2 and #3 were the best looking cylinders, #6 was the worst... so quite possible could be a combo of EGT and lean. Its funny once I started tuning the car myself I made SURE to keep the a/f's very rich during boost because of that effect... ehh.

So its quite possible I needed even more timing, or a lot of the damage had been done during the 500 miles of driving prior to that with the exhaust cam fully retarded.

So most likely get an EGT on the #6 runner eh? hah.

[Carl H]

wouldnt be a bad idea, ive got my egt gauge on the number 6 runner.worst of the system so gotta keep an eye on it.its possible most of that damage was done during the cam retardation, may have sent egts thru the roof.

[DriftingisLame]

I'd like to dissagree.

I blew a motor before in the same way as you did, I believe I just wasnt watching my AFR gauge as attentively as I should have. I didnt think I leaned out so I assumed it was from detonation. I removed all my pistons and found at least some melting damage on the intake side of each piston, so bad on cylinder 6 that it got down to the ring.

I showed a couple of techs at my work and one of them just happened to be a partial owner of a 6.30 second funny car. I made the mistake of telling him it was due to detonation, he quickly set me straight and assured me it was due to a lean condition. He said he'd blown more motors in his racing career than you can shake a stick at, and melting pistons on the intake side, is no doubt too lean. Your piston looks exactly like mine did, that motor was run lean.

Think about excessively high EGT's and the affect they have on combustion chamber components. Just because you have a high EGT does not mean for sure that your timing is too retarded, just like it does not for sure mean you're too lean. Running lean will affect combustion temperatures because of too much oxygen in the mixture, making the burn more violent and much hotter. Retarded timing, assuming you have a stoichiometric AF mixture, will have a normal initial burn temperature. The reason your EGT's will read high is because combustion is not done by EVO(exhaust valve opening), this is not making combustion any hotter. Therefore wouldn't the components after the combustion chamber (back of valves, etc.) be the only thing in danger of melting? I may be wrong but I do not see that affecting only one side of the piston, and if it would affect one side, why would it affect the intake side? Has anyone blown a motor before due to excessively retarded timing? Theoretically it should melt exhaust valves, maybe the head, make your turbo or manifold glow, or maybe burn the exhaust half of a piston.

Detonation, the same tech, and all of my schooling says that detonation causes more of a violent destruction of pistons. If you had major cracks, holes, etc in your piston, I would blame detonation, this is definately not caused by detonation.

Please correct me if I'm wrong, but I've been in your position before and I'm confident with what I wrote.

-Max

[Shocker]

Thanks for the advice Max.

I wonder if the accuracy of my AEM wideband dropped off... I'll be sure to do all of my tuning on my local dyno next time to compare a/f's with his.

Things to change before being ready to fire.

-New Pistons-Different fuel setup in engine bay-Move Rad/Clutch fan-Egt on #6 runner.

Also anyone make a dual feed side feed rail with central hole for the FPR for the 25? I'd rather not have to get new injectors...
Modified by Shocker at 1:37 PM 8/15/2008

[Darius]

I'm no expert, but my question is why would it only melt on the intake side of the piston? Does that mean there's not enough mixing taking place in the combustion chamber prior to ignition? Could that be caused by lack of valve timing overlap?? Anyone have an educated opinion?

[Carl H]

i'd honesly ditch the aem wideband, they're cheap for a reason...they loose accuracy with frightening precision.

[Shocker]

I'm no expert, but my question is why would it only melt on the intake side of the piston? Does that mean there's not enough mixing taking place in the combustion chamber prior to ignition? Could that be caused by lack of valve timing overlap?? Anyone have an educated opinion?

Wondering the same thing myself. Which was why I was curious if it was due to my retarded timing... I figured it would be equally distributed since its one chamber of hot air.

Carl what do you use for a wideband?
Modified by Shocker at 2:44 PM 8/15/2008

[Darius]

Innovate LC-1 or LM-1

[gawdzilla]

I'm no expert, but my question is why would it only melt on the intake side of the piston? Does that mean there's not enough mixing taking place in the combustion chamber prior to ignition? Could that be caused by lack of valve timing overlap?? Anyone have an educated opinion?

my uneducated guess is because the intake side is where the hot flame sits the longest. exhaust valve side is cooler because the exhaust valves open right there so that area is the first to get relieved of the combustion flame. *shrug*

Shocker - your results really scare me. there was about a 2 week period of time where i ran the car very retarded on ignition timing (dont have adjustable valve cam gears like you do). saw a lot of glowing a heat issues, but eventually resolved them. i've been using a zeitronix wideband and it has been accurate for me (within .1 AFR in comparison to two shop dyno wb's)

good luck with the rebuild though, doesn't look like too much damage

[Shocker]

my uneducated guess is because the intake side is where the hot flame sits the longest. exhaust valve side is cooler because the exhaust valves open right there so that area is the first to get relieved of the combustion flame. *shrug*

Shocker - your results really scare me. there was about a 2 week period of time where i ran the car very retarded on ignition timing (dont have adjustable valve cam gears like you do). saw a lot of glowing a heat issues, but eventually resolved them. i've been using a zeitronix wideband and it has been accurate for me (within .1 AFR in comparison to two shop dyno wb's)

good luck with the rebuild though, doesn't look like too much damage

Seems like a very good "uneducated" guess to me Gawd. Actually seems like a good possibility.

My AEM was on par 100% with my tuners innovate last year. But who knows that was last year...

Only way to know for sure about your condition is leak down and compression test... I hate doing those. I had a 2 week period of super retarded timing as well....500 miles ish.

Thanks for the luck. It could have been worse. I'm learning to just STOP everything if I feel I have an issue and to figure it out before proceeding.

[240z4u]

Don't buy a zeitronix, I have no way to calibrate that sensor and it scares me!

I would drop the bucks on the innovate products. I have a couple buddies who have street tuned with those products and made mad HP.

Evan

[gawdzilla]

Don't buy a zeitronix, I have no way to calibrate that sensor and it scares me!

I would drop the bucks on the innovate products. I have a couple buddies who have street tuned with those products and made mad HP.

Evan

haha, i kind of see it the other way. the fact that you CAN calibrate the innovates adds some additional variables that you could potentially mess up or go out of calibration eventually. a friend of mine melted his rb25 tuned on an innovate. double checked his AFRs on a dyno and they were reading high 13s full boost. so really its a matter of opinion i think.

most widebands use the same sensors anyway. i think there are only 2 popularly used wideband sensors out there.

[Carl H]

i am very happy with my tech edge 2a0 kit, they dont produce a finished version anymore but it worked well for my app since i use my e-01 profec as the display.200$ including sensor, just had to solder it together.

[Shocker]

most widebands use the same sensors anyway. i think there are only 2 popularly used wideband sensors out there.

Yup ntk and bosch.

Bosch ones it seems that you cant calibrate them and ntk's seem that you can. Bosch is what PLX and AEM use.

I might add a wideband so that I have two to compare with lol..... this sh*t scares the hell out of me. That fact that a faulty sensor can kill my whole motor worries me, since it is very possible thats what happened here.

I'm really liking the gauge and features of the DPX DM-100 unit, the fact I can run 4 different gauge readings in my face on the same gauge all at once I really like.

[ItzGenX]

I run an Innovate LM-1 (since it first came out serial #0002). I have always religiously replaced my used sensor with a brand new one before a major tune or remap. Although you can recalibrate the LM-1, I have compared results to a sensor that has been used for a couple race months (then recalibrated) compared to a brand new recalibrated sensor and found they could read .25-.5 off. In motors like ours that continually see high amounts of boost and very rich mixtures often, the carbon and heat eventually over powers the sensor causing it to read inaccurately. If you daily drive and cruise the vehicle, then the lean cruise mixtures should clean up the build-up if it isn't too much. My daily drive sensor was just as accurate as a brand new sensor, where as, my race sensor which only used for a couple months (twice a week, weekend track events) was inaccurate up to half a point. So here is what I ultimately ended up doing with my stash of sensors. One for DD, and one for dyno/street tunes. When the tuning sensor stops reading as accurate as the DD one, I chunk it and get another one. For race events, I put a plug into my front O2 bung (3 inches away from back of turbo) and installed it way down at the end of the down pipe. For the higher accuracy for tuning and street, I use the front bung since it can respond and sample exhaust gases right as they exit the turbine. Keep in mind, even if it is a daily'd sensor doesnt mean it is great. A poor tune in that department can make it kill sensors just as fast.

As for your pistons, I would read that as a lean condition, particularly during spool up (boost threshold). During torque peak is when an engine is vulnerable the most. Torque peak on boosted engines is usually during max spool or just after it. This is when heat is built up the fastest and can really wreck internals if not taken care of. The intake side of a piston is usually the first to go. It is the first and last of it all. When intake valves open, the air mixture will tend to do a horizontal roll into the cylinder towards the center and into the cylinder wall of the exhaust side. Picture a water slide when the intake valves are opened. Now as the piston reaches the bottom and begins to come back up, this rolling motion becomes a wave bouncing back to the intake side. So as it is ignited, the flame will travel will go normally right down the center til the end of the flame, a violent burst right at the end (lean trail left behind resides under the intake valves). This intense heat overwhelms the entire combustion chamber until the exhaust valve opens. The exhaust side of the piston is evacuated first so the intake side is last to go. Now the intake valve is opening again with some valve overlap to cool and bring in a fresh new charge (if your injectors are advance timed enough). The thing with valve overlap is, it only cools the center and exhaust side (oh bummer, that corner under the intake is still hot). In comes melting pistons, slowly but surely. Now go back and look at the plugs you posted pics of. I see goose bumps on them. If you clean the plugs entirely without scrubbing them, these goose bumps might be silver/gray. These are a sign of eroding aluminum from the piston having to travel across the plug to get out the combustion chamber and eventually some of them stick to it.

Now go back to this valve overlap issue. Valve overlap is just peachy for high performance motors since it has a cooling effect AND if tuned right, it carries in fuel/air mixture EARLY! This way your combustion chamber is filled with less used exhaust gases, since it was vacuumed out by overlap. Overlap is your friend in most cases, but if not tuned for, is your enemy in fuel injected vehicles. OEM ecu types have injector advance built in already and are good enough. When you go to a blank ecu and tune from scratch, often then not, you have to get injector advance in (usually has a degree map just like ignition). It times the injector to begin spraying at a certain degree of crank rotation. These values vary from cam to cam. If these values are late, then during that precious valve overlap, you are getting nice clean air (with no fuel!). These causes the edges of your pistons to have fresh air sitting there. Now during a normal burn, everything is all perfect til that flame reaches the edge of the pistons. Then suddenly a huge rise in flash heat right at the end cause the lean edges of air and no fuel. The wideband can't pick this up, because you can mask it by adding more fuel with a perfect AFR, but fuel still isn't added at the right time. So your mixture can read rich and you can still kiss your pistons goodbye because the lean edges after burned blend into the rich exhaust mixture making the gauge read normal still.

Now roll back yet again to your cam problem. When it was out of wack, this wasn't tuned for. Your setup, the problem can't be pinpointed because of the many changes it has seen since it has awakened, but we can narrow it down to a few choices. The category of the problem is definitely a lean condition. Sorry for the long post .

[240z4u]

haha, i kind of see it the other way. the fact that you CAN calibrate the innovates adds some additional variables that you could potentially mess up or go out of calibration eventually. a friend of mine melted his rb25 tuned on an innovate. double checked his AFRs on a dyno and they were reading high 13s full boost. so really its a matter of opinion i think.

most widebands use the same sensors anyway. i think there are only 2 popularly used wideband sensors out there.

Yeah, I can understand your point here. I just have no way to confirm that the zietronix self calibration setup actually works!

It is a scary proposition tuning like that. When I was on the dyno we logged with the dyno's WB and mine to check for consistency. Mine was reading on the rich end.

Evan

[l0nestar]

Good info man!

[Shocker]

Its Gen-X thanks for the very good explanation of all that. However I'm unsure how you would even tune for anytype of valve overlap. Obviously through cam timing, but on the injector side of it?

I've never heard it put so descriptively and honestly that post makes tuning a built motor seem a lot more difficult than I was finding it. I'm not even sure my Microtech unit can even set injector timing... I'd have to check my manual when I get home.

[Darius]

Does microtech have injector latency (lag) adjustment? You could manually change them to modify the injector timing. The more lag time you add, the earlier the injector will fire relative to cam position and vice versa. Refer to 240z4u's comment on the previous page. Milliseconds make a huge difference in how the engine runs even at idle.

ItzGenX-That is a vivid description of some serious combustion theory. I've never read anything on the topic, but what you wrote makes complete sense. And if it is backed by gawdzilla, it must be right

[TSL]

This is going to sound real harsh but that motor was doomed to fail from the start. If you don't get someone who knows what they are doing to set it up for you then the next motor will probably go the same way.

Don't get me wrong, it's cool to try and work on things yourself and learn as you go but you also have to know your own limitations.

Problems with the engine from the fuel setup, cam setup, tune and god knows what else would have been quickly diagnosed and rectified by a competent mechanic.

You don't have time to guess what might be wrong with a fresh setup. If something is not right and it is not fixed quickly then the motor will never bed in and run properly. As for the tuning by guesswork... at the power level you are trying to reach you need a tuner that is experienced and knows what they are doing.

Consider dropping the next setup off to someone experienced with these types of engines and have them set it up for you.

From reading this thread it seems like the only qualified person involved with this project was the engine builder. But despite you knowing all of the problems you had with the setup were not his fault, he was the first person you blamed when the thing blew up.

[ItzGenX]

My Haltech has an injector advancing map (called injector phase in the program). I believe all setups should have some form of injector advance, just all called something different. It would be totally retarded if fuel sprayed in right at 0 degrees. By the time the fuel travels past the valve, the piston is halfway down already. Tuning any standalone engine management from scratch is a big task. If you jump in with your feet barely wet or not wet at all, it can become overwhelming. When I build base maps for different engines for tunes, I always put the ignition timing to 15-20 btdc from idle all the way across the board to the top end. After that I play with fuel settings to get everything where I want it including dialing in the injectors themselves. When fuel is all good, that's when I can go back to ignition and add the cherry to the cake and make some power.

[Shocker]

This is going to sound real harsh but that motor was doomed to fail from the start. If you don't get someone who knows what they are doing to set it up for you then the next motor will probably go the same way.

Don't get me wrong, it's cool to try and work on things yourself and learn as you go but you also have to know your own limitations.

Problems with the engine from the fuel setup, cam setup, tune and god knows what else would have been quickly diagnosed and rectified by a competent mechanic.

You don't have time to guess what might be wrong with a fresh setup. If something is not right and it is not fixed quickly then the motor will never bed in and run properly. As for the tuning by guesswork... at the power level you are trying to reach you need a tuner that is experienced and knows what they are doing.

Consider dropping the next setup off to someone experienced with these types of engines and have them set it up for you.

From reading this thread it seems like the only qualified person involved with this project was the engine builder. But despite you knowing all of the problems you had with the setup were not his fault, he was the first person you blamed when the thing blew up.

Thanks for your opinion.

Person who I got to tune the car ran the lt12s on his 3 rotor, perhaps you are right in the sense for the type of engine. They deal mainly with rotaries not so much piston engines. Even if they do tune them. Which they do a GREAT job tuning rotatories and most every car that rolls into their shop.

I took advice and listened to a few people I shouldn't have and well obviously I'm paying for it. In the end the consequences are mine to deal with. There is no blame to anyone other than myself, this car has been a huge learning situation for me. I understand what you are saying and reading back through this whole thread my problems are almost an embarrassment for me.

I don't see where you say I blamed the builder? I never blamed him, other people suggested the ring gaps weren't aligned I was taking all possibilities into account. I called and talked to him that was that.

Right now we are working out getting new pistons and getting the block back together.

As for a new tuner, I might give accelerated performance a call. They deal with Supras and are about 1.5 hrs from me. I'd like to get this car running great on pump gas one day reliably. I am getting sick of it being my jack stand queen.

[rb25drag]

Hey I feel you man, Its all a learning process to us all, Seems like we have to break it to understand it better. Sucks you have spent thousands of dollars and still back on square 1, Which really makes you just wanna throw the project away, At least thats how I feel most of the time. BUT im sure when you get the right combination together its gonna Scream.

[Shocker]

I suppose I can update this thread now for anyone who cares. Over the past 8 months I've been slowly getting my 240 back together. The engine was finished from my builder back in the fall, and over my Christmas break I reassembled the engine, and stuck it back in the 240. Over my spring break I took the time to hook everything up and tidy things up a little.

Here are some pics.

Dedication.







First Start(I know the breather filter isn't on)



After tidying up.. not perfect but better.

I have a new tuner now a local guy to me. Kyle Deiwert he really knows his s***, and might be posted up here soon with some information a few of you might like.

We road tuned my car yesterday at around 13-14 psi. I'm still having boost creep issues, my wastegate isn't hitting and sticking, its only a 5.5 lb spring and its not holding it. I have a few ideas on how to try and fix that hopefully they work.

Cars running really well right now for the most part, I have around 150miles on it I have a few issues to work out, it needs an alignment bad. My power steering rack seal started to melt again. (its the seal/bushing right where the steering column enters the rack. Its very close to my manifold I need to try and make a shield between it and the manifold.

Dyno tuning maybe this weekend or the following we shall see what it makes on pump gas. All seems well so far, hopefully it stays that way. I'll update as it happens.

[fast_s14]

looking good, im glad to see it back together. How much power are you planning to make?

[Shocker]

looking good, im glad to see it back together. How much power are you planning to make?

Thanks.

I'm looking in the ballpark of 500whp. If I make it great, if not that is fine. Id rather have my car driving than blown up. I shall see.

Here are some pics of the car itself I just had my girlfriend take. Nice misaligned body panels.. yum.



A new mod for this year is a straight pipe as of yesterday... A weld broke on an exhaust hanger while driving down the highway. I used my belt to keep it up and went over my buddies where we replaced the rear fart can with a 3" stainless straight tip off his camaro. Cars a little louder, but I feel the straight out back pipe looks way better than the farter... if only my bumper wasn't toasted.

[Darius]

Are those MT drag radials?

[matafied]

Are those MT drag radials?

man i have been waiting to see this car rolling again. looking good

[Carl H]

depending on manifold design you MAY need to recirc the wg in order for it to control boost properly, i was having issues with my setup and the 14psi spring was creeping to over 21psi.once i recirce'd the wg boost holds rock steady now with absoloutely no creep...guess some manifolds need the venturi effect to help pull gasses out of the manifold.granted the hks cast manifold has the worst placement for a waste gate evar but yeah its a thought.glad to hear its back on the road man...dedication indeed.