Allpar Forums banner

1 - 1 of 1 Posts

Premium Member
2,291 Posts
Discussion Starter · #1 · (Edited by Moderator)
Marc Rozman on exploding engines, the turbo 3.3, and using data properly

We ran a production 3.3 with a turbo on it, with six or seven pounds of boost, as I recall. The 3.3s were a cast crank and not a forged crank, so we were sort of playing around to see what we could do here.

Running that kind of boost on it, we had good power, and then the cast crank gave out from the stress. There's a lot of load on there, a lot more load with turbo boost on there. But it ran well, it got good numbers, until it blew up.

The guys in the lab next door to me, in this bench lab across the hall, came running over, they had heard it over there on a Saturday. Luckily, I got my data before that thing blew up. You know, whenever you did a test, you have a power run, you would a certain RPM, collect data.

Computers were brand new back then. We had a computer in my cell, and the computer had taken most of the data. Once you took your last data point, you would kill the ignition; the dyno would keep the engine spinning, and you would adjust your RPM back to the last RPM point, take your friction numbers, you have to get friction numbers, too, to get corrected power numbers.

I took my last point at 5600 RPM, and I had my finger on the button to kill ignition, before I hit the keyboard and to save, it blew, and it kind of wakes you up …

I blew the engine up on a Saturday, got it cleaned up that week, that following weekend we had an open house. Every so often we have an open house. We had the place all **** and span, all cleaned up. And had a little show and tell, so I brought the family in, and here's my dyno and no engine. It was clean, but it had no engine.


When the engine blew up, I called up my friend at Photographic, and asked if he had any film in the camera, and he brought his camera down on Monday, took shots of all the broken pieces on the floor, so at least I have a record of that, as far as the pictures go.

This was the only major engine failure I had in 30 years of testing. I got all the data before it blew, too!


That was probably one of the last runs we did, towards the end of the program; we ran quite a few before that. We had gotten good numbers out of the 3.3.
We thought it was a great idea. We had some people that thought it might have been a good idea, and Pete Hagenbuch was instrumental.

We had turbos on the four cylinders, and they worked just fine there, so we thought, why not put a turbo on a V6? You'd need the make the parts more durable, of course, but it wouldn't be that hard to calibrate. More flow with the injectors, but we did fine there. It took very little to modify it to the 3.3 manifold. It had a 90° neck but it ran the wrong way, so we cut that neck off, flipped it 180, and welded it back on again.

I built the manifold by hand, a turbo manifold for the V6, and got it mounted up, and it ran great. You dialed what spark you need, dialed what fuel you need, and got the numbers we wanted, and I think we got 202 or 210 or 215, power wise, which was the bogey or goal for the new four valve piece [3.5 liter] coming out, shortly [it was rated, at launch, at 214 hp, and from 1998 until the end of its life in 2010 was rated at 232-251 hp].


I moved from Wing A to Wing B when that was completed. This is Cell 1.
Cells 1, 3, 5, and 7 were called "thermo cells" due to their ability to heating or cooling the oil, water, and combustion air.

We had the 3.5 on the drawing board, so we knew what kind of numbers they wanted to see with the four-valve. If we can get the same kind of power out of a turbo, we thought it might cost less, or be used as an intermediate motor until the four-valve [3.5] came out. But the powers that be said, "No way, no how, will we have a turbo on the V6."

So, that got quickly dropped. We had built up a second V6, I had made up a second manifold and put on the turbo, got it all built together, nice and pretty. We had a G-body convertible with no engine in it, that we could put this motor in for another show and tell. But I believe it came down from somebody that "you will not be doing this. Move on, people."


So much for creative engineering. We were playing by the rules then. That following week, we got the first four valve 3.5. It was already at that point where we were coming in that soon, but we hadn't ran it yet, so you got to figure a year, year and a half for that development process take place. We thought we could do the turbo first, it would be a good intermediate motor, but that wasn't in the cards.

I assume the operators are not in the same room as the engines any more.

Oh, no, no, no. Once, before I hired in there, most of the cells had no walls at all between the engine and the operator console. The earlier engines had power, but not the same degree as the 1960s engines had.

The turbo 3.3 was not Marc's first 3.3 engine project. "I worked a engineer from the coolant lab, who he had ideas regarding the amount of coolant needed, not only in the engine, but in the entire system. It was a lot of work, but we found that on the 3.3, we did not need the amount of coolant designed in. Systems are normally overly cooled due to lack of testing to see what actual needs are. Less coolant equals weight and cost savings."

There was a less chance of a problem in the old days, but once they got more powerful, there was more chance of breakage, parts flying around. There'd be fires and such when you got an engine exposed. You've have that hot exhaust, you'd have an instant oil fire. Usually the operator is closest to the door, so it depends on how fast you are and how healthy you are, you can get out pretty quick, and pull the plug on the fire extinguisher.

At some point, they made it mandatory to have a wall between the console and the test cell. It made for a tight space. Those weren't big spaces, at all, but they were all built prior to me coming in there.

There were a few cells, like the one I was in, that for some reason still had the console in the room. I'm not sure why. That were only a few like that. Water brake had the same thing. Water brake, we had the engine in the test cell, but you went in, did some tweaking, got some numbers and got out. You weren't there for a long time, so that was good.

But the cells that were built later on were better, they contained the engine properly, and the walls were built with bullet-proof glass, because when an engine fails, the parts come flying out pretty fast.

We had cells with a rod in the wall, and the guys used to buy a frame, an 8 x 10 frame, and put it over the rod in the wall and keep it there, and put a date on it. That interesting to see sometimes, but I was fortunate, I only had one major breakage in my testing time.


Some of them fail every week. Some guys get a new engine and put it in, and it depends on the situation, you may get a failure once a week, or once a year. It depends on what happened with the engine he had going on, and if you did the installation properly, it could have been a motor issue versus a mechanic issue. I only had one failure in my time, in the old dyno, so I was pretty fortunate there.

But it would happen… even in newer test cells, it would happen once a month, at least, you would hear the fire alarm go off and you had to leave the building. And the CO2 alarm would go off, and you'd look in the test cell and it would be all white. It never seemed to record those at all, you need a video on those, but hasn't happened very often.

They could be pretty catastrophic. They could be pretty brutal. What I had blow up, the crank shaft came out in three pieces. It had pistons on the floor, it was a pretty severe explosion on the bottom, broke the motor mounts and bent the vacuum plate. It was a pretty powerful explosion.

Troubleshooting: Numbers and charts

There are a lot of things you don't see all the time. Even for us, when we were doing the testing with the valvetrain, we had all kinds of proximity probes in there and measuring loads, strain gauges for loads. Proximity probes are a major movement. You try to record that stuff at high rate. We'd do a little blip RPM, we'd take it up to six grand and back, and you have the high speed recorder in there. You blip off a one minute recording, at so many feet per second.

Then you take it out in the hallway, and lay out 60 feet of paper, for a minute of blipping, and try and figure out what was going on. We know the valve opens and closes; we got springs doing whatever, and some of our load rates on the followers were ungodly. They were just out the roof. Why are we having such a high load? You know, it should be a cam going around the lobes, and hit the follower, and some of those that we saw were just out the roof. And we were breaking rocker arms in half. It takes a lot of load to do that.

We couldn't figure out why, but that's when we discovered that we had the oil pumped up, under cold conditions. If you have the valves open during combustion, while the combustion forces the valve back into the seat, and then you've got your pumped up adjuster inside, the next thing you know, you got all this pressure pushing the rocker arm in the cam, well that's going to snap.

But once I figured out the adjusters were pumping up too much, then we had to either go with the higher bleed down rate on the adjusters, or figure out how to control that better, and minimize breakage and keep things happy.

We had a guy come in one time, from a company, who brought a high speed video camera in. He was going to sell the company on this new product here, his new camera. And he went around different labs and different people to talk to, and show and tell, and for the heck of it, he put the camera on our test fixture, looking at the valve train operation, and we would play it back in slow motion, and it's amazing when you have the visual… once you see it, your brain sees a visual picture of what's happening, then all the numbers made sense.

You know, you see the valve and the spring and what's happening, motion wise, then you realize, well, we've seen this number here, because this is happening. You know, that works for your brain. Your brain can see numbers, but unless you paint a picture with that number, it's a whole different game.

We saw that one video, we knew we had a lot of answers for our number problems, and that was a really cool camera… the guy thought we were crazy, we were pretty ecstatic, "Wow, what the…"

"Okay guys, calm down, now. You want the camera or not?"

But they had surging going on where the valve was opening and closing, but the next you know, the spring would open, and the spring would surge, you see the inside spring just surging in there, out of control, and that creates some oddball numbers, and we had no idea why. But that video showed that spring just going nuts.


Later on we started adding anti-surge spring dampers in there, little spring inside a spring to keep that surge from happening. That's why it came about. I learned too, when you see certain numbers, in testing, try to visually paint a picture of what's happening, and that makes it much easier to understand and diagnose.

That's why later on, in doing testing, I always put the numbers differently. If they give me hard numbers, I prefer to have a strip chart. If they have a line graph, if you have certain parameters on a line graph, that gives you more of a visual or a little history too, where you can look at things, because numbers can be fast on you. It depends on how you collect the numbers.

From that day forward, whenever I could, I used the strip chart. We've got a lot more electronics, a lot more testing, computers and stuff like that, where you can create a line graph and maybe six or seven parameters on a line graph. Because lines don't lie. You can have numbers go up and down. You may not see them on the screen, because they happen so fast, but you get a line graph… you get a little blip in there, and the blip is either real or not real. And if it's real, then it's a problem.


There's a lot of things I caught because of that, and so I always try to get the other guys to use the line graphs, because it was just a good visual on what's happening. And it's just a lot more important to get it right, then record numbers.

Numbers is numbers, and you can make it what you want. We used to get some engineers that take this number as they make a graph so big. Well, you can scale it the way you want to and if you have a little blip there, well yeah, you can make it look real small, by scaling it a certain way. But you blow it up, that looks pretty scary, now. So a lot of guys would kind of play with the scaling of graphs, and make it look better than it was, and it depends on who's looking at it. A lot was learned back then. It was interesting and it's all a matter of what you want to learn and who you do it with, engineer-wise. If they have a good engineer, they can explain things to you.

I was always open, pretty much to new stuff. When computers came on board, I was kind of eager to grab the computer. I was the younger guy. The younger guys like the computers, and I got one of the very first ones in the test cell.


Mary Chapell was doing a SAE paper on combustion pressures. Monitoring cylinder pressure was fairly new, but became standard practice in our testing. I was working in building 135 at the time but would come over and run this 3.5 cell if the operator was out.

The old guys didn't want them. The old guys thought it was going to take their job. "I don't want a computer. It's going to take my job, they won't need me any more."

But the computers actually brought more work in in the long run, and they do a good job and they're still used today, quite a bit, but you still need an operator to get things set up correctly. Today's testing is much different now, it's all done by computer, and you can program it to do whatever you want. Any RPM, any load, any control you can do nowadays, it's pretty high tech, now. But the operator is still pretty much there, most of the time. So it's good to see, it keeps the occupation going.

The Marc Rozman interview by section

  1. Joining Chrysler, EPA testing, and running the dyno
  2. At the road test garage; working the water brake
  3. The famous Cell 13 and Hemi testing; working with legends
  4. Last 440, Pro Stock 355, and 3.5 V6
  5. Roller cams, cold oil, and snapping rocker arms
  6. Turbo 3.3, exploding engines, and troubleshooting
  7. The shaker table
  8. Working with engineers: learning and troubleshooting
  9. Marc's 1969 Dodge Charger

Chrysler HeritageHistory by YearChrysler People and BiosCorporate Facts and History

Chrysler 1904-2018

Spread the word via <!--Tweet or--> Facebook!

We make no guarantees regarding validity or accuracy of information, predictions, or advice - .
Copyright © VerticalScope Inc. All rights reserved. Dodge, Jeep, Chrysler, Ram, and Mopar are trademarks of Fiat Chrysler Automobiles.

1 - 1 of 1 Posts