Blew my motor again @ 16psi 13* timing on 93.

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sdaigle240
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Blew my motor again @ 16psi 13* timing on 93.

Post by sdaigle240 »

Guess I'm just venting frustration.
All of 50mi After spending over 12hours doing the lower chain, It seems some ringlands have cracked. (heavy smoking on decell etc) I just had to walk away. I'll leak down test it soon. But it's doing the same thing as last time I cracked ring lands.

Stock bottom with maybe 5-6k on rings, rod bearings and HG, Running 15-17psi with 13* of timing on 93 octane A/Fs in the 11s.

I don't claim to be an Angel or Ramon, but wtf!?!? I didnt think my tune or boost is that nuts compared to some of the crazy stuff they do to stick block down in FL.

If some bosses wanna skool me I'll post my maps tonight.

I'm just pissed cuz I'm going forged and just wasted all this time trying to squeak 2 more events out of the stock bottom.
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Post by redpotatoes »

Sorry to hear that...post your map, I will take a look and compare it to mine if you want.
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Post by sik_z33 »

Damn that really sucks man. Owning a ka-t really is a pain sometimes, I've had mine for a year now and every month is always something but hang in there bro. You seem pretty sure it's the ringlands but i'm hoping the best for your engine!
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Post by p00t »

It is possible it is something other than timing causing this. If you are running track events you are stressing your motor a lot more than most people on this forum ever do.

Valve temperature and spark plug temperature can cause preignition/knock. You are going to need an 8 heat range plug or hotter I would think, the coldest plug you can get that doesnt foul, might have to use something separate from street/track.

I would take a peak at the valves too, if there is a lot of pitting on the sealing surface they are probably overheating. The worse the sealing surface the hotter they will wind up running because that is one of two surfaces valves can cool through.

Problem with dialing back timing is it throws more heat into the exhaust stream which makes that type of problem worse.

Or you could just have typical knock due to timing.

If it keeps happening in one cylinder I would suspect the injector.

Either way it's a **** thing to hear, let us know what you find man.
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Post by ppctx »

Sorry to hear this. Hope you get it sorted out. p00t makes good since.
Original owner of a 93' champagne colored, corn eating fastback. Growl and bite is a bit meaner, but she's still my little girl.


I'm not out, just doing a couple of other things for a bit.. brb
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Post by p00t »

Also while I'm out in bench racing land have you ever thought of modifying the head a little?

I have heard the large quench pads on Nissan heads are detonation "risers" on boosted cars. Many reputable shops cut them out on SR and RB motors. The Nissan GTiR motors did not have them from the factory. The pads probably help low end and MPG but at higher RPM they are probably more of a hindrance. I can cite plenty of references if you need to see.

Just a thought. (see if the ringlands are cracked right under those areas)
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Post by NateDogg »

You have to reduce cylinder pressure to run higher boost on pump gas, especially on a high compression 9+ motor.

This can be accomplished by many ways, including tuning, cams, head work and shorter intake runners, etc.

The easiest way is to ramp the timing up with RPM so that it doesn't create a danger zone around the torque peak. At 18psi I run 10* at 4000RPM. At 6000RPM it is 14*.
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Food for thought. Sorry to hear about your motor. We've all been there.
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Post by s-14 »

p00t wrote:Also while I'm out in bench racing land have you ever thought of modifying the head a little?

I have heard the large quench pads on Nissan heads are detonation "risers" on boosted cars. Many reputable shops cut them out on SR and RB motors. The Nissan GTiR motors did not have them from the factory. The pads probably help low end and MPG but at higher RPM they are probably more of a hindrance. I can cite plenty of references if you need to see.

Just a thought. (see if the ringlands are cracked right under those areas)


what are quench pads? Never heard of that one.
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Post by emo_tactical9 »

Damn dude. Sorry about the bad luck.
I would be looking at what the others said, timing at peak torque and other issues that could have caused it.
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Post by p00t »

s-14 wrote:
what are quench pads? Never heard of that one.
Basically if you look at stock SR/RB/KA cylinder heads you will notice that it is round for only the part of the cylinder in-between the valves, with the area under the valves having a straight portion that sticks out into the cylinder. Giving it a "box shaped combustion area." If you had a normal full hemispherical or pent-roof chamber the cylinder outline would be round to match the cylinder bore.

Quench is important for every motor but for Nissan and Toyota (2jz) it seems to be some sort of air deflector. Or whatever you want to call it. It doesn't just serve to quench the fuel/air mixture. If you look at the piston it has a dish in it and it doesn't match the shape of the head surface.

If you are unfamiliar with quench basically it is any area between the piston and head at TDC that is at a close tolerance (say .040-.060", typically the size of the head gasket). The fuel/air there is cooled by the piston and head and will not combust even at high temps/pressure. It will have to wait till the piston moves further down the bore and it is no longer is cooled by the piston/head before it burns. It is important to control detonation/knock that originates at the edge of the cylinder.

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Post by sdaigle240 »

Wow lots to respond to, thanks for the condolences guys. Great discussion points and I appreciate the helpful comments and certwily wouldn't mind others participating. Kfred klatt Miami you guys know who you are.

sorry for the upcoming wall of text, but poot and nate always have thought provoking posts….

Poot
you are correct, I participate in track events (mostly drift) and when I do street drive its guaranteed to see 3rd through 5th pulls, and has even seen 6k in 5th more than a few times.  However, when I track, I run 13psi and when it gets over 90*F a tend to run 13 as well (not always).  Im currently running heat range 7 plugs and never considered going colder.  The 7’s do look nice and light brown though. Great suggestion, easy enough to try, but I don't think I've ever heard anyone running 8s before.  I didn’t notice any pitting on the valves which I did lap about 6k ago last time I blew the motor (almost same conditions)  also the pistons didn’t show signs of detonation, which led me to believe excessive intake temps were the cause as Id like to trust my tomei injectors.  I could not agree more that my “safe timing curve”  leads to excessive heat, and I had planned to get on the dyno THIS week.  Ive yet to inspect which cylinder went this time.  I’ll also add the the pistons that went in this past build were used with at least 100k on them, but never previously saw boost.  I simply got the pistons out of the parts bin, honed, re ringed and threw in std rod bearings.  I know exactly what you are talking about with the quench pads.  My friend removed them on his build (which I now have all his old forged parts) and I think if I was staying stock internals I would too, but im moving to aries 8.8s.  We imagined that this dropped the compression considerably,  who knows maybe as low as 8.0?  moving forward on the built motor im looking to run 20-21 psi and am hoping 8.8 will be a good compression.

NateDogg
   I totally agree that 9.5 comp, 93 octane and anything over a bar is pushing it.  I probably shouldn’t compare myself to tuners like angel, ramon, Jason etc making 500whp on peoples stock blocks.  I really had no “cyl press mods” ran s13 cams stock intake mani etc.  as for tuning, because I could only guess where my peak torque was  I based my tune around that and just never raised timing in the higher rpms.  So I was running 13* more or less from 3500 to redline (I WILL POST THE SCREEN SHOTS, Hopefully tonight) my timing on the gun matches timing on calumsult so I would say its true and not skewed by variation in how the base timing was set.
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Post by Kfred »

I don't agree with the removal of the quench pads. Large hemispherical combustion chambers in a street car make me cringe. The only benefit of such a chamber is de-shrouding of the valves, reduction of compression ratio, and reduction of emissions. I would only recommend removing the quench pads if it is a race engine that always uses very high octane fuel. Try to find the discussion of combustion chamber design between mazworx and some guy that has immense knowledge of the physics of combustion, it is a very good read.

You should definitely get your injectors flow tested this time around. The only thing worst than busting a stock block, is busting a built one.
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Post by sdaigle240 »

i will most definitely dig and see if i can find that. i will absolutely test the injectors over the winter.



here she is. few notes. this is a massaged calum tune. so i left the cruise regions which some may call high, 47* and also the very low timing numbers in the "unused parts of the map" ex 80tp @ 1200rpm. it actually runs 11s, i guess its 12* and as you can see my timing below 3500 is low i think i was messing with spool. ill acknowledge that some timing areas dont look text book smooth, but the car does what i want it to, timing per boost wise. the second to last colum is pretty much EDIT 8psi (not 13psi) and the last is pretty much 16psi. my boost gauge has an alarm shut off so i know i have never majorly over boosted. dig in, im here to learn.

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Last edited by sdaigle240 on Thu Oct 06, 2011 11:47 am, edited 1 time in total.
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Post by NateDogg »

Here's my latest map. As you can see, it ramps up timing with RPM. This does a couple things. It reduces max torque and increases top end HP, resulting in a more linear powerband.

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Post by sdaigle240 »

Nice, good to see more maps. I would do the same if I had got to a dyno too. So ur in column 65 at 18psi? I take it nothing jumped out at u on mine?
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Post by sicks13 »

It looks like you have too much timing, especially around peak torque. This screen shot is from a 15 PSI stock block tune

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Post by sdaigle240 »

What's ur tp at X boost? Can't interpret much with out that.

How is 12* at 16psi too much. I would lean toward it's too little and making me run hot.


This is sweet that everyone's posting maps.
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Post by sicks13 »

I have found that pulling one degrees per psi keeps my stock blocks happy, You have 18 degrees at 56TP and 12 at 80TP, it will not run 12 degrees of timing because it interpolates between 4 points..

On the map i posted, 15 psi is closed to 108TP
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Post by orion »

IMO, the 45/50/56 columns of your timing map is WAY too aggressive for a stock block.

18*, between 2400-5200...is a lot. Like somebody already mentioned, too much for peak TQ (which is peak cylinder pressure).

My JWT tune runs ~14-15* at throttle tip-in (3000rpm or so), and dials in a degree after peak TQ...then one more before redline. 17* total.

Of course, my JWT cams lower the dynamic CR...but my stock-block motor has probably seen more WOT track miles then most any on this forum. And it's doing great.

Fix your motor, load a safe tune...and you'll be good-to-go.

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Post by sdaigle240 »

Woah woah woah..... I goofed

56 column is 8psi not 13.
65 is 13
And 83 is 16 (colum labeled 80)


confirmed real time the car runs 12* from before full boost (3k-3.5k) to red line at 16psi. I am 100% positive. It pegs the last column and runs it.

Likewise on 8psi It runs 18* from before full boost to redline.

On 13 psi it linearly interpolates and yields 15*


So with that clarified....I assume u all feel differently?

Blam!

I put "0 ish" partly cuz I don't remember and partly cuz it was harder to find with this turbo then the last.
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Post by joshpntbl07 »

tuned on the dyno.

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Post by killa_snake3 »

Are you tuning on a dyno or the streets?
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Post by killa_snake3 »

Are you tuning on a dyno or the streets?
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Post by redpotatoes »

Your timing map looks aggressive compared to mine. I would rather do something like this on 93:

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to

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I am in the progress of testing few maps lately for my water injection setup and the max timing I have put is 16-18*. Dyno time is the best way to make sure it's safe. I have run my tune (without WI) for few year on my stock block at 14.5psi on 91 and never had problems.
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Post by sdaigle240 »

Thanks for the dyno map., it shows I'm in a good place with mine. And I'm street tuning.


I'm not trying to reject advice or be difficult but u guys are misinterpreting my map.

Mr potater
Y would I pull 10-12* to run 8 psi And only have 16* at4-5psi(45tp)?

My 18* for 8 psi is already pulling 7-8*.
Rough calc says 45tp=4-5psi so Your 16* would be pulling 2*/psi. I'm not trying to be cocky, I'm just saying that's how it breaks down.

I'm swapping in a short block and will get on the dyno.
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Post by ppctx »

If you're not already doing it this way, next time you look for 0psi, you can use the pedal to keep the boost gauge at 0psi. For me, TP scales linerly between 0psi and max psi. I use the last colum of the stock map for 0psi. I've always wanted to log an NA car to see what timing colum they are in while on a WOT pull to redline.

That 1deg per psi seems to be common advice.
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Post by sdaigle240 »

Yup Aaron that's how I do it.
FYI Wot na is 108tp. It runs the last column which is 104iirc

Brian and sicks13 if u see this go back and re peep the updated map for me. Thanks
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Post by sicks13 »

I don't like the way your tuning, but that's just me preference.. I like finding 0 boost TP and i make that the second column in the map, Then i find max boost and make that the second to last column. That leaves me with really good map resolution for boost and one over boost column.. I'm not picking on your tune, I'm just saying its not my style..

I can tell you this for experience, If your on a stock block and you have even the smallest amount of knock (if the knock light reads any knock at all) the ring lands are done.

I have tuned and studied many different tunes, after all was said and done i took a lot from the enthaply tunes. they are so smooth with the timing and fuel curves, and it shows in how the car runs.. Now I'm not saying that i just copy his tunes, I just use his method of tuning the timing and fuel maps.
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Post by sdaigle240 »

Cool ya thanks for checking back in. I know what you are saying. I'm not claiming Calum is a tuner but that's the method he taught me. He simply said find 0, then make low boost 2nd to last and force high boost into the last column (I have overboost in my electronic boost controller) Obviously jwt or enthalpy is something to emulate so I'll def give it a shot and make up a tune with less cruise resolution and more boost resolution. Last time I cracked tge lands. I couldnt find detonation marks anywhere which lead myself and others to excessive heat or lean condition theories. I'll post up results from this teardown.
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Post by sicks13 »

I couldn't find signs of detonation on my motors either... but in my case that's because it only detonated for a fraction of a second and that's all it took..


I'm not saying its your tune for sure, but there are several people tracking their car regularly with no issues..
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