LocostUSA.com

I'm sure the process was aggravating for you, Kurt. At the same time, seeing what actually happened is rather humorous (now that you have it solved) too. Who'd thunk?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

So was there a reason to go with front steer uprights as opposed to rear steer FWD ones?

Yes, to simplify things by using one common (Miata) source for suspension and steering.

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Update:

Back on 20 February 2016, Midlana had another track day which went great - until it didn't. First picture shows me hot on the heels of a Porsche GT3 which couldn't get away. In fact, about the time I was thinking when to pass, the situation "changed."

Second picture, I found this in my oil pan... First time I've ever blown up an engine and was surprised how sudden and uneventful it was. While expensive, being able to pester that GT3 almost made it worthwhile. Video at bottom.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Wow! Bummer. Say Kurt, are you still on the turbo 4 bandwagon? Or in retrospect would you have rather built around a larger, less stressed motor?

Sticking with the turbo-4. I've had seven experts look at the parts and virtually no one agrees on what happened. Some say it ran lean, others say it was rich. Some say there were signs of high EGT while others say there was none. Some say I was running ignition timing too retarded, while others say it was fine. And finally, a few said that it looked as though the piston pin failed on its own and chalk it up to bad luck.

Starting over, maybe I'd go with something else but I don't know what. Other than the VW VR6, Midlana isn't configured for anything larger. Eventually I'll reach an age where I don't "need" so much power and a dead-stock drivetrain would no doubt live forever.

That said, my brother's been pushing me to design something specifically intended for the LSX engine. Yeah maybe - I can't argue with 430 hp for $6000 with a factory warrantee, but on the other hand it really belongs mid-ship, and proper transaxles are crazy expensive.

Regarding what I might do next, I always think of the Robert Frost poem:

" ...Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference."

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

I'm a fan of the current generation of V6s. 300ish HP with potential for more. But two sets of dual-cam heads certainly do take up space. Well I have no doubt that you'll bounce right back and pester more Porsches.

Too bad. Midlana is a fine package, you don't need a bigger motor.

A couple of driving pointers. It's a priority with a blown engine to get off the line quickly, you're probably oiling the track and driving into the next turn can really add to the cleanup. Also raising a hand will help warn people behind. Actually, I guess you have brake lights!

You're being way too nice in asking for the point by. It's business, you pay to be there, you getting track time for a car you built. If they are busy holding you up, there not learning from following a faster car - it's a waste of everyone's time including the car in front. Your brakes should be good enough to keep yourself off their bumper with just a car length gap. Right behind his mirrors.

Interested in doing any thinking out load about ECU abilities or features that would help with this? Does your engine have a knock sensor? I wonder what it was hearing before this happened ( they listen for knock but I bet they hear bearings going )? I think some oxygen sensors are fast enough to read down to milliseconds and could detect individual cylinder mixtures. Lots of possibilities...

Consider posting about your project and motor on Speedtalk. It has a great engine forum, http://speedtalk.com/forum/viewforum.php?f=1&sid=4516e9e3005fd71feb7a74a5cea2fd37. THey will want lots of pictures. These folks are at the top of the business and people that design cams and cylinder heads in real life post there.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Regarding the ECU, it has everything and was set up to protect the engine from low oil pressure, high coolant temp, high intake air temperature, knocking, and high MAP. It also has onboard logging which works great... except when it decides not to log for some reason. Wouldn't you know, it decided not to log the event in which the engine broke. I was able to estimate that the car was at 220 kpa (18 lb boost) and ~6000 rpm when it let loose. There was no inkling that trouble was brewing. The engine was built for 800 hp and 9300 rpm, so it was being run very conservatively and on E85 for added insurance.

Regarding the racing line, I agree. I was so surprised that it happened I wasn't thinking what I should be doing right then. It was good that a dry sump system was in-place so not much oil was lost, but still, I should have immediately killed the engine and moved off the racing line. The session went on without issue - with me getting to see the GT3 lap me over and over...

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

For an admitted curmudgeon, you're taking this well. If it were me, I'd be vacationing in the land of depression, self-pity and alcohol consumption.

Sorry, I didn't mean to sound critical. I was picturing you with a shocked expression and laughing at myself for thinking you needed to raise your hand. You'll be all over it next time and here's hoping you don't get too much practice!

I know you had good stuff in that motor , so I was trying to think past some of the obvious stuff and think about the ECU from a more general angle. The one I am designing is having some proto boards assembled about now, so I can't help but think about this a bit.

At one end of this, how would you know or would it be possible for the ECU to kill your engine that way? It looks like the little end broke in tension during an exhaust stroke? Is that it? Is that broken piston pin in the oil pan? Did the piston pin mark the top outside of the little end?

If the ECU should have saved data and it didn't, that's a real problem. This is an issue they had in the Toyota cases. No saved data didn't mean no problem. It meant the data saving code was mixed with the throttle code and guess why there was no data at the smoldering wreck?

Maybe the ECU didn't have code to save the data just because the motor stopped turning...

Anyway I'm sorry this all happened. Maybe I'm not the best for advice on the driving style vs. politeness. We didn't have point bys in my day. Students like me were well and truly scared crapless out on the track. You were taught to stay on the line and faster cars should be allowed to go around you. Passing in turns was discouraged though. Still if you think you can go faster be up close about it, no reason for the guy in front to have any doubt about it after a little while. It's just more practice for you, maybe someday you'll go wheel to wheel and going bumper to bumper is how to start.

I think your camera makes it looks like you have more space than you do though also.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Yeah I'm leaving volumes out regarding the broken parts but there are a lot of pictures of the parts on my site. The piston pin looks like someone hit it with a hammer and it was made of glass, it's pretty much shattered. What came first - the initiating factor - may never be known; it could also be a defective part from new. I agree that the rod looks as though the pin got pulled out of it and before I disassembled the engine I fully expected to find that the piston had seized in the bore, but no such luck. Probably the biggest "problem" is the lack of a smoking gun; the cylinder walls look perfect, the three remaining rods look great, the bearings show zero sign of heat/oil problems. The piston bottoms show no sign on high heat. What most (but not all) experts say is that I was running excessively retarded ignition timing, but that could be a misunderstanding of what I said. That is, I said it was running 11 degrees advance when it popped, which is true. They may have misunderstood that to mean that I started out at 11 degrees and retarded it from there. There's a general rule of thumb I was using, that timing is retarded 1 degree per psi of boost.

The actual engine failure happened so fast I didn't hear a thing, in fact I thought I'd just lost a spark plug, because the car continued to idle fine on three cylinders. For that reason I don't think the ECU caused this. It wasn't until I saw smoke did I realize how serious it was and even then I was (and still am to some extent) mystified about how something could have broken on such an over-built engine being used so conservatively.

Regarding the point-bys, that was a rule imposed by the organizers. While I "could have" gone into the pits to give the slow car more space, I didn't want to waste the downtime. I was fairly close and you're right, that the GoPro's wide-angle lens makes the car look a lot farther away.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Who's to say that that isn't going on in parallel? By diving into the rebuilt it keeps me from being too down.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

The piston pin looks like someone hit it with a hammer and it was made of glass, it's pretty much shattered.
Kurt: That my be the the smoking gun, I mean smoking wirst pin. Usually you neck down or deform the pin Vs shattered. I would take a pc of that shatter pin and a good pin and get a comparsion hardest test done. My guess is that may be the heat treat process was screwed?
A lot of pins are actually made fron tool steel and it needs a much longer heat cycle, then medium carbon steel. Dave W

First, sorry to hear of your misfortune. That's really too bad.

Second, do you know how much horsepower you were getting with the tune and ECU you had at failure? I ask just out of curiosity and wondering what general horsepower range you're in.

Third, and knowing this is really an unlikely change for you to make, but you might want to take a look at the current generation Chrysler/Dodge 60°, 3.8L Pentastar V6. It is small and light, but powerful, and it likes turbocharging. Our pedestrian, sedan-tuned version has 283 HP naturally aspirated and redlines at 6,500 in that form. Fiat is using in Lancias now and there was talk of an Abarth version for Alfa Romeo and a twin-turbo version for Maserati.

We have one in our Dodge and love it. If I could start my build over (it wasn't available when I started) I would switch to it in a heartbeat. I like it that much. It comes in FWD and RWD configurations, so maybe a match in terms of transaxle adaptation? It's just a thought, anyway.

Regards,

Lonnie

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886