Beans Above the Frank Build

[Mizzle]

So basically you're catching them on the technicality that while the heat rises in the oil itself, it's more of a thermodynamic thing that the head spreads into the other portions of the engine - not because heat rises, but because it wants to even things out by traveling?

[Mizzle]

Well, would the heated oil not, in turn, heat the surrounding air... causing some heated air to rise and, in effect, partially warming the engine if only slightly... ergo heat rising?

[Dano]

Originally Posted by Mizzle So basically you're catching them on the technicality that while the heat rises in the oil itself, it's more of a thermodynamic thing that the head spreads into the other portions of the engine - not because heat rises, but because it wants to even things out by traveling?

mizzle!!! you're missing my shiznizzle....

[Mizzle]

Yep.

[Dano]

great! as long as we are on the same page....well...or different page as the case may be.

[ms3blackmica]

do i needa pull out the thermo books lol

[silvapain]

Originally Posted by SPEED6 KILLAH Any Update

No updates yet. I've been too busy with work to do testing on the car this past week; case in point: I'm posting this reply at work right now.

I have leaned out my WOT AFRs to 12.29:1 (0.836 lambda) and will try to get some logs and EGT data today after I get out of work.




The rest of you are just jealous of my Thermodynamics skillz.


Tapadatass

[Enki]

Originally Posted by Mizzle I totally missed this. So they intentionally use lower-temp parts in a diesel turbo...?

No, not intentionally. Turbo technology didn't really start making leaps and bounds until it became popular for manufacturers to put smaller, boosted engines into their production cars, as well as racing teams looking for that extra edge.

The turbos used in "modern" diesels aren't usually the same as gasoline engine ones; a VGT (for example) turbo won't last terribly long in a gasoline engine unless you monitor/tune for EGT specifically to prevent the shit from burning up. Since diesels are so much more efficient than your standard gas engine, they lose less energy to heat (and thus EGT); this isn't the case for gas engines.

[silvapain]

More WOT runs, with WOT AFRs leaned out to 12.29:1. EGTs peaked at 1650-1700°F, and still no significant KR with timing advanced to 18-18.5° at Redline. All WOT runs are done in 4th gear BTW.

There isn't enough data yet, but it does appear initially that I am suffering from heat soak on pump gas with the stock TMIC. You can see if you VD the attached logs that power reduces as I take more logs.

[btstarcher]

Why you no haz BAT logged?

[BlueStreak]

I'm scratching my head here as to why your motor isn't freaking out with 10.5:1 compression, K04 bats, 12.2 AFR and 18.5* timing on pump.

[speedms6]

Originally Posted by BlueStreak I'm scratching my head here as to why your motor isn't freaking out with 10.5:1 compression, K04 bats, 12.2 AFR and 18.5* timing on pump.

been thinking the same thing since i saw this earlier this morning

[Dano]

super duper atomization and combustion due to angry piston design??

no hotspots generated like on a dished genwan piston??

Also, brand new pistons with zero carbon buildup is likely better for reducing/eliminating hotspots??

just seeing what sticks...lol

[BlueStreak]

Looking at the datalog, I was expecting the car to be ripping the tires off. Then I dropped it into VD and the power output wasn't congruent with expectations given no KR on what appears to be a very aggressive tune on pump.

Silvapain. Out of curiosity, has the timing method you used been successfully implemented in other motor buillds?

[btstarcher]

They look like my logs plotted on VD whenever I fucked with Jason's tune, trying to get more power by increasing target boost levels. I ended up with plenty of torque down low, but at the expense of power past around 5k rpm's. It happened every time.

[djuosnteisn]

The ideal spark advance for a given motor has a direct relationship with combustion speed inside the chamber. Faster flame fronts require lower ignition advance in order to hit that sweet spot of peak pressure ~14 degrees ATDC for maximum torque. Shoot, in a perfect world... combustion would be instantaneous, and the plug wouldn't even fire til ATDC... but real life isn't that easy.

Combustion speed in the chamber has a direct relationship with the air / fuel mix, and actual combustion path within the chamber (these two are related as well). For instance, one of the reasons racers back in the day disliked the "hemi" design, was that the pistons necessary for higher compression builds resulted in an inverted dome shape... which in turn resulted in a longer flame front path and the need for more spark advance. More spark advance generally increases the amount of negative work the motor has to do (compressing combustion), and it also increases the potential for detonation to occur.

Poor air / fuel mix can have a similar effect. Think of combustion as throwing a match into the middle of a dry grass field. The fire will expand in a uniform ring away from the ignition point. Same thing happens in an ideal mix inside a combustion chamber.

Now imagine the field has a few dry spots without grass... and a few real clumpy spots where the grass is kinda wet. You can imagine that the fire won't expand anywhere near as fast as the ideal dry field example above. Again.... same thing happens in a combustion chamber.

This is why manufacturers include things like tumble valves and focus so much on swirl and mix in the chamber. It's a very important part of the combustion process.


I have a feeling the dish in these new pistons is resulting in a very rich spot centered around the plug. And the dish on the far side of the piston would then be resulting in a lean spot. It's hard to say for sure, but that would explain the blow out issues Dan was having on e85, as well as how much spark advance he's able to run on pump gas alone (especially with the higher compression pistons).


His EGT temps don't look terribly high though, which is a good thing. Generally poor combustion results in higher EGTs, since more of the combustion process occurs out the exhaust valve.

[speedms6]

talk about an explanation... thanks @djuosnteisn;

[djuosnteisn]

Originally Posted by Speed3eak So I'm curious - if you have this non-homogenous mixture in the combustion chamber, but combustion still looks good, is it a problem? I know we have our injectors spraying in from the side, rather than from the top down, but I don't know about the speed of the flame front at different lambda values relative to the geometry of the combustion chamber to know what it all means...

I don't think any of us can do more than speculate at this point. Dan's pioneering this approach, and he's the one with the real world results. High compression and custom pistons is a whole new ball game, and we're fortunate to have someone as smart as him up to bat first.

Pioneering ain't easy, but if nobody did it, we'd still be romping around like the flinstones, haha.

[BlueStreak]

I definitely don't debate that the dished pistons make a difference. The question is "how much?". The GenPu's have dished pistons and all else equal (boost, timing and AFRs, make about the *same* power as Gen1s. In other words, they don't have 20-30hp on us automatically.

I plugged silvapain's first datalog into VD and with a Dynojet correction factor, came out to ~280hp and ~344tq (no adjustments made for temp and baro); this is with airflow at 280g/s, AFRs at 12.2 and 18* timing by redline. In my mind, given these inputs, the engine should A) reject the tune because its too aggressive on pump or B) be incredibly quick. Neither A or B have resulted.

I think we have enough info on MSF to have certain expectations that x tune with y modifications will make z power. Heck, silvapain himself knows what power he was making given his previous setup; the only material difference being the higher comp dished pistons. Power should at least be on par.

Seems like something else is up.

EDIT: The power output seems more consistent with a tune running roughly 10-12* timing up top (with a proper ramp up). To say an additional 6* is necessary to make the same power seems like a bit of a stretch.

EDIT x2: That being said, I am eager to see this build become a success. I have a bag of popcorn to my left and some crow to my right should I need to eat my words.

[J-Liss]

so as of now....HCP are not the way to go with the current design?

[Speed3eak]

Haha damn I thought I got away with deleting that post before anyone saw it - after re-reading your explanation it was a little more clear in my mind.

Thanks though for clarifying - I'm wearing out my mouse buttons hitting refresh on this page, love the concept of a high compression build. Partly because I haven't seen any before and partly because when I dream about high compression motors and medium frame turbos I wake up with white sticky stuff all over me.

edit:

Higher compression definitely makes more power given two otherwise identical engines - especially in N/A applications. I imagine the same would hold true for turbos. Just because he isn't making more power yet on this setup doesn't mean that he won't. This is still a preliminary tune as far as I know - we still have to figure out other things.

For example, the injection timing is the same as it was on his stock 9.5:1 CR pistons. His piston is however taller than it was before - does this mean fuel is hitting the top of the piston? Does it mean that the air flow in the combustion chamber is all funky monkey? He could be making the same power on a wacked out fuel mixture. We don't know yet. I don't want to presume that this is as much power as he can make at WOT at this early of a stage.

[btstarcher]

Hell I'm just surprised he can run that much timing and still not experience significant KR on pump gas.

[Dano]

Originally Posted by btstarcher Hell I'm just surprised he can run that much timing and still not experience significant KR on pump gas.

haha

Dustin just splained all of that.

those mountains and valleys on the piston are greatly reducing flame front travel thus requiring more advance to make all things equal. More specifically, the mountains and valleys are causing rich and lean spots in the fuel mix.

at least that is one theory and personally the one I subscribe to ATM.

This is all a very new piston design so time will prove out its merit.

[Ziggo]

Eh, my theory is much less complex. The motor is timed funky causing the dynamic compression ratio to be lower than it otherwise would be and/or causing a discrepancy between what the ECU reads TDC as and actual TDC. This isn't an assault against you or your engine building skills, I just like to start with the easiest explanation.

All things being equal theory says a 10.5 CR motor is only about 2% more thermally efficient than a 9.5 CR motor.

Ideal Thermal efficiency (gasoline engines). = 1 - (1/CR^.4)
Zigatapatalka

[atvfreek]

Originally Posted by Ziggo Eh, my theory is much less complex. The motor is timed funky causing the dynamic compression ratio to be lower than it otherwise would be and/or causing a discrepancy between what the ECU reads TDC as and actual TDC. This isn't an assault against you or your engine building skills, I just like to start with the easiest explanation. All things being equal theory says a 10.5 CR motor is only about 2% more thermally efficient than a 9.5 CR motor. Ideal Thermal efficiency (gasoline engines). = 1 - (1/CR^.4) Zigatapatalka

I am going with a similar theory (base timing issue). I think bluestreak is thinking the same. I wonder if the engine timing is now 7* retarded. All speculation of course.



Freekn tappin

[Dano]

hahaha

that is LESS complex?

BTW he did readjust TDC by what 7* according to the CCAG?

so he may be 7* retarded when the ECU records 0*.

I can't remember for sure but I think he wanted to put a dial indicator on and measure piston height...not sure he has done that yet.

Edit: Justin beat me to it!

oh and this is now my new theory since I just recalled his timing shift.

[silvapain]

Originally Posted by Ziggo Eh, my theory is much less complex. The motor is timed funky causing the dynamic compression ratio to be lower than it otherwise would be and/or causing a discrepancy between what the ECU reads TDC as and actual TDC. This isn't an assault against you or your engine building skills, I just like to start with the easiest explanation. All things being equal theory says a 10.5 CR motor is only about 2% more thermally efficient than a 9.5 CR motor. Ideal Thermal efficiency (gasoline engines). = 1 - (1/CR^.4) Zigatapatalka

That's been a concern of mine for a while; that knowing our issues timing this engine, we didn't get #1 at TDC when we set mechanical timing. I bought a dial gauge and have been meaning to verify timing with it for a while, but just haven't gotten around to it yet.

Don't worry about making me butthurt. This process is all about expanding on the already large amount of great technical information on MSF.

[J-Liss]

things are starting to come together.

[Dano]

Originally Posted by Ziggo This isn't an assault against you or your engine building skills, I just like to start with the easiest explanation.

Dan's asshole is made of BeCu so...

Originally Posted by Tokay444 It should expand 10 fold what the brass will.

Originally Posted by Ziggo You are correct, we use pure beryllium in the structures, not BeCu.

so you see.... it can expand 10 fold so no pain is felt when attempting to hurt the butt.

[phate]

Dano verified timing peg = actual tdc on a good crank. Unless timing slipped on silva's engine, degreeing will give the same tdc result as a dial indicator. Would be good to verify, I suppose. Check things off the list

[Dano]

Originally Posted by phate Dano verified timing peg = actual tdc on a good crank. Unless timing slipped on silva's engine, degreeing will give the same tdc result as a dial indicator. Would be good to verify, I suppose. Check things off the list

b but I thought you guys verified TDC was not established with the peg on his crank and adjusted accordingly?

I must be missing something.

[Ziggo]

Originally Posted by Dano oh and this is now my new theory since I just recalled his timing shift.

Just BeCuase you figured out how to cross quote threads and confuse the shit out of me doesn't give you the right to be stealing my theories!



Zigatapatalka

[Dano]

went looking for those did you?

hahaha

you can't steal something the other person still has possession of.

jussayin

you still have the theory and I subscribe to the same theory...thus we are sharing said theory.

oh and I see what you did there...nice

[phate]

Originally Posted by Dano b but I thought you guys verified TDC was not established with the peg on his crank and adjusted accordingly? I must be missing something.

That's my point, lol. Pin aside; degreeing will give the same result as a dial indicator. You verified a good crank flat and a good pin = TDC, as verified by a dial indicator...so there isn't some offset machined into these things, TDC means TDC. It's two tools (dial ind/deg wheel) that are doing damn near the same thing.

So, unless we really fuckered something up or his timing slipped, I'd bet that it's good.


EDIT: But, yes, it is odd that his engine is taking so much timing and still picking up power. It could definitely be a mechanical timing issue (I'm just arguing the two methods are near identical), or it could be related to flame speed. Time will tell.

Silvapain - if you want a hand this weekend, I'm available.

[Tokay444]

But the piston is attached to the crank with the rod. So even if timing slipped, before or after the build, the peg should still hit the crank when the piston is at it's highest.

[silvapain]

Originally Posted by Tokay444 But the piston is attached to the crank with the rod. So even if timing slipped, before or after the build, the peg should still hit the crank when the piston is at it's highest.

The issue was that with the peg in the block and the crank touching the pin, my #1 cylinder wasn't at TDC. That's why we had to use a different method to determine #1 TDC when timing the engine.

If timing slipped and the reluctor wheel on the crank pulley isn't lined up properly with #1 TDC, my 18.5° of spark advance won't actually be 18.5°.

What I need to do is put the car up in the air, pull the #1 spark plug and find TDC using a dial indicator, and then verify that the CKP is lined up with the center of the 20th tooth after the gap on the crank pulley reluctor wheel.

[Tokay444]

Yes.

[Dano]

Originally Posted by Tokay444 But the piston is attached to the crank with the rod. So even if timing slipped, before or after the build, the peg should still hit the crank when the piston is at it's highest.

^^^^^

this...I thought that when the peg was installed in Dan's block and you rolled the crank around until it stopped [on that flat spot that is machined into the crank for this exact purpose] that the piston was not at TDC and that it was either 7* BTDC or 7* ATDC, can't remember which.

what say you?

edit: asked and answered.

[J-Liss]

let me guess you guys used the old extension in cylinder one at its highest point method lol

[Tokay444]

Dano used a dial test indicator.