In some situations, Japanese companies are very slow, or find it impossible to correct, mistakes that would have been obvious to a first year engineering student. If the last name of the idiot that has suggested the change is a socially prominent one, they will go to great lengths to avoid shame from falling on such a person no matter how deserving he may be. One of my drivers is the test driver instructors at the Transportation Research Center in West Liberty Ohio. Each Japanese engineer who will serve an internship in one of the Ohio Honda car plants will pass a very advanced test engineering drivers course, including vehicle dynamics and actual driving skills and data recovery in a collection of vehicles that most of the engineers have never seen up close. My favorite is a real L88 powered circle track car. Big slicks, enough power to light the rear tires anywhere, and the ability to spin like a top. It is fully adjustable and each day they all get to change something on it and spend the day testing the change. Each engineer writes up whatever he thinks the change caused and why. Then they are graded by American engineers, and their driving is graded by Roger Schroer the driving instructor. My current driver Terry Whitlock and I went out there to evaluate the new car and give them some ideas as to how it could be made more effective for this use.

 

The Honda home team had laid out the rules, and one of them is that, if a student spun any of the test cars, he sat out for a year and took the course over the next year. Myself and all of the Americans and some of the home team protested saying the opposite. Every driver should stress the car to the limit and beyond.

 

I know you can drive. I want to see you drive at the limit while thinking about vehicle dynamics and staying on the road course. So the rules got changed. Nobody has committed suicide (yet). The race car has never been damaged, but has spun many times. Often a little person will climb out of that car with a big smile.

who has never smiled at work before.

There are 200 channels of data stream going for each student, and the American engineers and Roger know in real time about anything that may have happened. Honda turns out car engineers who know their vehicles. They test drive prototypes of new cars or new ideas built into older chassis every day. Here and back in Japan. The list to go to America and take this course is a long one.  Even Honda had this problem of not telling anyone that we looked at your idea and the engineers all had a great laugh over it, before rejecting it.

They just see themselves in the same position bringing shame to their parents and relatives. But not all companies have come along as far as Honda. Roger is the fastest by a full second, I am second and the current driver is third by a hair. The car has improved much since then and will now turn right without slowing to a crawl. If you want a great car buy a Honda.................Made in the USA by Americans.

 

Mazda got the idea that machining the "O" ring grooves in the irons rather than the aluminum rotor housings

would improve something or reduce a cost some how. What the thinking was I don't know. But the failure rate of iron casting cracking out was noticeable right from the gitgo. So how could this have happened? What would be a perfectly good way to fix this production problem and move on? And certainly not keep making the same failing pieces year in and year out. pissing off the tiny collection of motor heads who would stoop to buying your product to begin with.

 

But there it was many years of the very same product, with the very same problem. The irons are sand castings. So there are several sets of permanent sand mold patterns mounted in molding machines somewhere pressing these pieces into the face of a mold box like a machine gun.

 

In the US, this problem probably would not have happened. It looks to me like the grooves in the iron idea was not washed through any system to detect the possible outcomes available. So a staff of engineers would have had a sample of the irons cut through the ring groove to look at and measure. Bingo, the groove does not meet the minimum  dimensions for a high pressure ring in iron. Too thin along the back of the curve here. Engineering magic?

Hardly. Common sense. Reading a book. Reviewing the possible outcome. Avoiding loosing your job.

Give this to the two trainees for two days and ask them for a report showing at least 4 fixes and watch them run the  engineering library. Over in the foundry the chief engineer confers with the foundry master and makes a pen and ink change in the red line production drawing. The line is shut down the several steel patterns are removed and taken to the die maker who studies the drawing for a few seconds and calls in the welder, who lays a bead along the outside of the problem area on each pattern. The die maker smoothes each weld bead with his die grinder and right after lunch all 4 patterns are again pounding out perfect and much improved molds for a product you would love to have.

 

Apparently not the case in Japan.

 

I have never built an engine with the grooves in the iron. But I have read about the problem for years, and notice that the Renesis has the grooves in the rotor housings where God intended them to be in the first place. Their excuse to change the location without bringing shame to somebodys grandson?

 

With this known weakness, I would not use anything but the stock compression "O" rings. It is easy to pop off a piece of the iron outer wall when the groove fills up and hydrauics when the stack is torqued up. There are some folks who swear by some after market rings that may fit in the grooves. Before I do that I will saw an iron in two and lay a piece of flat steel across the groove with a piece of the proposed "O" ring material, to determine if there is room for it in the groove. There should be room left over after the groove is clamped shut.

More typically, the ring must be allowed to move a bit to pile up against the far wall under the pressure being retained to work at all. Most of the rules for "O" ring grooves are in any "O" ring catalog.

 

I would be tempted to reduce the flat surface of the iron along the outboard wall of the groove to eliminate clamping pressure completely. Add a strip of sealant then to protect this area from coolant.  Many of these things must fail when the stack is torqued up the first time.

I would also be using a hint of sealant in the ring groove. The ring is not sealing against the several hundred pounds of flaming fuel in the engine. The flat surfaces with tons of pressure on them must do that. Any pressure that would escape into the seal groove just forces the ring against the outboard wall, and there it stays. Sealing out the water for the most part. In fact I used several hundred feet of 18 Gage Teflon coated silver tinned airplane wire for that "O" ring, and never had a leak. My friend Bill Koch has used Chinese 18 gage hook up wire (crap) and it worked fine. Just ad a very small amount of sealant, along with the wire.

Not for aircraft use of course.

 

Lynn E. Hanover

 

 

Chris,

Lynn is the expert in these things, but I was under the impression that the end housing grooves had to show signs of cracking before the seal would allow leaks. The seals, seal at the top and bottom of the seal, the sides of the grooves merely restrict the seal from moving from it's predetermined place. For instance a seal groove slot would need to loose a piece from the thin side ( water jacket side) to allow the seal to move and allow water in. That has been my take on it anyway.

The  reason Mazda went back to water jacket seals in the rotor housings like in the 12A, is because the steel liner is sturdier than the thin wall in the cast iron end housings and there is less chance of this happening.