mark kibort

Yes, racing can be costly... I've been pretty fortunate to have run the 928 as long as i have at full tilt. have 110hours on the stroker motor since 208, and 120 hours on the holbert motor before that when i was jumping in any race i could , sometimes 2 per month during the year. (pca, poc, nasa TCRA, SCCA, SCCA pro, etc) and before that about 4 years tracking the 84 with and without the 5 liter. never any issues with the motor. Ive put a few more gs on the car than you might have on the "lemons" racer ("estate") running 2:04 with the old 5 liter, (no oil cooler) 2:01, with the holbert and 1:57s in the stroker at T-hill.

i have to add up the hours, (and by the way, most of my weekends are near 3hours unless i do only one race), but 120hr with the Holbert car, 110hrs with the stroker and call it 50 hours with the 84 chassis and its motors, and that being over 20 years, is in the 280hours of racing. thats half of your hours and if you add the extra stress and speeds, which generally go up with the square of the speeds, I could say we have equaled out to prove the 928 is quite reliable. (not to mention , most say heat cycles are more of a wear factor than just pure hours) Almost all blown motors ive heard about, have had some element of suspect issues. between you , petty, scot and myself, the engine can be reliable if some precautions are taken.

Yes, i lost the holbert car to a guy driving a Civic who shouldnt have been out there. (some bad luck) and kissed a wall with the 84 , which set the stage for getting the holbert car.

Now, you mention being meticulous with maintenance and care of the motor, and i personally think that is a huge part. my engines have never raced without 3 weekend old (max) amsoil or being warmed up before racing . i think, there could be other factors that have kept me safe, but short shifting hasn't been one of them in many years now... so, it could be the design of the components of the engine builder, or Porsche.

I cant believe how long this one has lasted and i just hope it can last through the process of qualifying for the SCCA national championships this October. (one more national majors tour weekend, and two regional races and im in! )

scot should be back next season with the "gold racer" Ljet 5 liter ,, petty is also threatening to come out, (CIS 5 liter) which should be fun to go out and race the 928s together again.

maybe you can get another one and join us!

Mk

mark kibort

http://www.automobilemag.com/news/se...estival-speed/

Rob Edwards

mark kibort

Thanks Rob!! so cool.. too bad it was such a short time together on the track.

mark kibort

the first few mins are cool to see the 928, but life gets real interesting at 18:30 (at 140mph) ) check it out... wow!!
https://www.youtube.com/watch?v=mp8KefZbF4I&feature=youtu.be

mark kibort

one more pic video up soon

justaguy

That's sad to see. Its worth noting the last engine I blew was on the 3-4 up shift. How many engines is that now Mark? 4 for me but the sum total of all is much less than the cost of your latest. you have my condolences. I'm glad you got out and were able to save the chassis.

Sean
for reference we attributed this particular failure to a dropped valve.

GregBBRD

I'm going to have to quit melting down Mary's old cooking pans and quit making connecting rods in the garage, at night....

In all seriousness, it would be great if more of this pieces of this rod were present than the rod Mark broke in his own engine, so Carrillo can tell more about the failure. All that remained of Mark's rod was the very bottom of the beam and the round crank end. Carrillo's engineering department analysed the metal to see if it was correct, or if it had missed one of the steps of production, but it was perfect. They re-ran the design parameters through their computers and found no problems, what-so-ever.

It's always bothered me that we are running these connecting rods/pistons very close to the maximum piston speed for a road race engine....however rod failures have not been common, in the past.

Regardless, it really bothered me that the other 7 rods were absolutely perfect and they approved them for re-use.....how can one rod fail and not even remotely damage the other 7 rods?



In the end, without any recorded rpm data, they could not explain the failure and recommended that no changes be made to the design (they had my complete blessing to make any changes they deemed necessary or though would make a better connecting rod.) Absolutely no changes.

In all truthfulness, I'm much rather have an engine fail from some mistake I made, than fail from a product made from a very high quality producer of engine pieces, which I have no control over....much easier for me to fix.

mark kibort

Do we suspect that Joes motor's rods failed in the same way that Mark's motor failed? i know we dont have more pieces yet, but if we did , there might be some evidence for the failure analysis.
what is the max piston speed , based on RPM for this engine design?

I would think it would be quite a bit higher than the stock S4 motor that had much heavier piston and rod combos. were the forces, for example with a lighter set of rod, but a 1/2" longer stroke, greater or less at 6600rpm? could it be the oil ? if a ring failed or there was poor piston lubrication, and the piston jammed in the bore, could that break a rod like this? is that very common as far as engine failures go?

What were the changes made to the engine design that had lasted for 8 years, that grenaded due to the intake failure, as compared to the new design?
I always had thought that component failure with the 928 engine was the least of our concerns.

Yes, things fail, that's the nature of the this sport, but for the same change to the same design low hours engine, failing at the same track, at the same spot on the track, is eerie coincidence.

in any event, what a MAJOR bummer!

justaguy

3-4 up shift at red line after high G corners after a long straight. Call me a conspiracy theorist if you like but we have 2 race 928's with well built engines broken under similar circumstances.
Not trying to be a pain in any ones *** here but I would just like to come up with a plausible reason for the failures and a possible solution to avoid similar failures in future. Other wise how could any reasonable person continue to race a 928?

Could it be possible That the sudden full throttle-off throttle-up shift -full throttle could be more rigorous than the engine design was meant to take? Just wondering The 3-4 up shift take place at 6,000 RPM and around 100 MPH.

mark kibort

and ive done 1000s of those shifts for 20 years with multiple (known engines) with no issues. you can see the video with this engine, the S4 motor , or the old 5 liter euro , or even the 84 4.7. never had an issue.
Nor the others ive built for friends. However i will say, ive seen upshifts and especially downshifts, by some, that could cause undo stress on the engine if not performed well. the upshift 3-4 vs 2-3 makes no difference to the engine as long as it is done smoothly. ive been to willow springs a bunch of times with no issues and had quite a few laps at cal speedway where i thought, if there was a weak link, it would happen there. goiing full tillt boogie, 6500rpm, going into a very hard left turn at 150mph , at over 1g is pretty nerve racking...... but more than the g loading, i was worried about the gathering of oil in the heads by being over 6000rpm for near 30 seconds straight. didnt seem to bother the motor.. took the oil to Blackstone and they came back with the engine passing with flying colors..
im suspicious of anything that might restrict flow and even keep oil splashing in the piston , rod areas (scrapers) as well as baffles and windage. there might be something in my heads, though when we worked on them, everything was stock dimensions, with no mods visible. im also suspicious of most peoples warm up routine. I'm a HUGE believer in all metals in the engine at operating temp, putting them at full expansion, which is not just when the oil reaches 180F , or the water being at normal temp... generally, ive always done a 10 min warm up to heat soak everything, before he car ever hits the track . .

GregBBRD

There's no doubt that the components in these engines are lighter than previously used....all in an effort to reduce the stresses on the engine block. We had been seeing damage to both the main bearings and the housing bores.....as well as cracked blocks from the pounding of the mass of the rotating assembly.

RPM's are the real enemy in race engines, however there is some safety margin built into all the pieces.

Chevy's engineers were involved in building a road racing Chevy engine with a 3.750 stroke, several years ago. Even with ultra light pistons and titanium rods, they determined that the engine would not last past 7600 rpms.. They finally limited the engine to 7200 rpms, and had no problems. Remember....crazy light pistons with the best titanium rods available. 7200rpms maximum.

With a good steel rod and a heavy piston, that rpm limit is probably safe...but certainly not much higher.

Which brings up an entire set of additional questions that have to be considered. Here's a few:

1. How accurate is the stock tachometer in these two race cars? Sharktuning has shown that the stock tachs are terribly inaccurate. (It's very, very common to see stock tachs off by more than 10%...or more.)
​​​​​​When was the last time the tach was calibrated? Ever?

Is the engine being subjected, constantly, to 10% more RPM's than the tach reads? 5%? Does anyone know?

2. For that matter, what is the internal rev limiter set to? Mark's engine was set to 7600, I believe...certainly well into the "death zone".

2. Without a RPM record, who knows what the maximum rpm that the engine has been subjected to? Could there be a chronic track/driver issue on one of the downshifts? How about when the tire blew at high rpm on the banking? Certainly when a front tire blows, the opposite rear tire is unweighted and the RPMs can instantly go crazy.

3. What fuel was being used? Mark Anderson has always "mixed" race fuel with street fuel, to save a few dollars. A very tiny amount of detonation/pre-ingnition at 7,000 rpms will add a whole bunch of load to the connecting rods. This was a high compression race engine, designed to be run on race fuel....not the "false economy" of race fuel mixed with street fuel.

For that matter, this car has been sitting for quite a long time. What fuel was left in the tank? What was that fuel's octane after sitting?​ What fuel was "loaded" on top of this fuel? What percentage?


It's really easy to blame the engine builder for failures. Tougher to look in the mirror. Mark Anderson has ALWAYS blamed me for his engine failure...we barely talk or do business any longer, because of this failure. Additionally, neither Joseph or Mark has even informed me, called me, texted me, or E-mailed me (no contact in any form) about this latest failure! Wouldn't everyone here call their engine builder, first, if their engine failed?

There's no doubt that I've been tossed under the bus, again, for something I did not do!

​​Absolutely nothing in my workmanship failed in Mark Anderson's engine. I used very high quality pieces...certainly some of the best components available.

And Carrillo's final analysis of Mark's connecting rod failure?

Rod failure most likely caused by exceeding the RPM limit or mild detonation at high rpm. Without RPM data or more pieces of the rod, impossible to determine. No changes in the design of the rod recommended.

Perhaps more can be learned, from this failure.

Impossible to know, without the broken pieces, much less a phone call!

Mark Anderson

You can check every dyno pull I've ever made. The rev limiter comes in at 6800

GregBBRD

1000's of shifts at 7000+rpms with a high compression race engine making over 500 rwhp?

How does your experience have anything to do with this failure?

GregBBRD

The local dyno guys all shut down before 7,000 rpms....even when I'm standing there telling them to go higher, they stop.

If Rob has your computer, we could download it and see what the rev limiter was set to.

But even if we do that, it tells us absolutely nothing about your downshifts.

Like I said....nothing in my workmanship failed in your engine....or most likely in Joseph's engine.

Although you clearly blame me (and have all along).....you show me anything wrong in my workmanship and I'll buy the damn engines.