For part 1 - Commercial origins, see here:

https://www.northamericanmotoring.co...ec-engine.html

As mentioned in part 1, the basic design concept and technical specifications of the 1.6L naturally aspirated Tritec engine had been completed prior to Chrysler Engineering management meeting with different OE's in search of a commercial partner. The main focus of the early design concept work was on the cylinder head design, based on the bore and stroke that would be required to make the power and overall engine length targets, amongst others. These "pre-JV" early concept efforts on the cylinder head were spearheaded by one engineer and one main designer. This early concept design work was conducted in 3D solids in Pro-Engineer CAD by a very seasoned engine designer named Bill Maciejka who was at the tail end of his career. The engineer who was guiding Bill in the basic layout, valve sizing, port and combustion chamber design was Pat Baer.

Pat is very well known as one of the leading technical experts in the areas of engine performance airflow. He regularly gave engine performance/airflow development seminars through Superflow (a company that manufactures flow benches that have become a sort of defacto industry standard) and had been considered the "airflow guy" at Chrysler since the late 1980's. You can buy a DVD of his seminar (conducted with Ken Sperry of GM) here for $300:

http://www.technical-insights.com/En...VDs-EADVD1.htm

The predecessor of the 1.6L SOHC was the 2.0L SOHC from the Dodge Neon, which Pat also had a major hand in developing. Pat was also the unofficial supervisor of the Chrysler flow room. The flow room was staffed by 3 (sometimes 4) very experienced engine mechanics/flow tech's who had been porting heads, manifolds, air cleaners and throttle bodies and testing them on Superflow benches for many years. The flow room was in a very private area at the Chrysler Technical Center in Auburn Hills. It had locked access and very few people had authorization to enter.

Because air flow results vary with atmospheric conditions, the flow benches (there were 3 Superflow benches in the lab) are in another attached climate controlled room. There is also an attached fabrication lab where the flow technicians could fabricate almost anything. The fabrication lab had at lot of specialized equipment, like mandrel benders and a Serdi valve seat machine. They were constantly busy working on cylinder heads, fabricating manifolds, etc. They serviced every engine design group within Chrysler and then some. Every engine performance engineer in the company was competing for their services. All of the flow tech's were great guys and wonderful to work with in spite of the heavy workload and demands on their time. All guys with real passion for their work.

One of the flow tech's, Tim Connolly, was a real gem and he would play a big role in the development of almost every Chrysler cylinder head port from the early 1980's through about 2008, including the 1.6L Tritec. He left Chrysler in 2007 or 2008 and went to McLaren, which was a very sad day at Chrysler Engine Engineering. Tim had developed a reputation throughout the industry as one of the best engine porters in the world and was well known to McLaren. The Lamborghini 3.5L V-12 formula 1 engine of 1991 was a beautiful Mauro Forghieri design, but was struggling to meet the power numbers expected and was not competitive. Lamborghini sent a couple of cylinder heads to Auburn Hills for Tim to work on. Chrysler owned Lamborghini at the time. My recollection, is that the head Tim developed pulled about 70-100HP more than the previous design, bringing the Lambo F1 engine of the 1993 season up to around 730HP. They used to keep one of those heads on the rack in the flow room (along with many different competitive engine heads). It was quite a sight to behold! Chrysler and McLaren had a handshake agreement to supply McLaren with Lambo engines for the 1994 season but that fell through, Chrysler sold Lamborghini and it never happened. Word is that Senna wasn't too happy about that! Read about it here:
http://jalopnik.com/when-bob-lutz-pu...-to-1493199017

The early design efforts of the 1.6L proved to be very challenging. The small 77mm bore needed to meet the engine length target was proving a challenge for Pat, who had been doing a lot of WAVE modeling to come up with the needed intake valve and port size to meet the power target. WAVE is a commercial "1D" simulation program developed by Ricardo Engineering that is used throughout the industry. The "poor man's" version of WAVE that can be purchased very inexpensively is called "Desktop Dyno. Desktop Dyno was developed and coded by a guy named Curt Leaverton (whom we brought in to Chrysler to conduct an engine tuning seminar). So the unconventional decision (at the time) was made to go with a 1.3:1 Intake/Exhaust valve diameter size ratio (1.2:1 was more conventional) and incorporate a very tall exhaust port to maximize the exhaust ports discharge coefficient to make up for the smaller valve size. It's important to understand that all of the "pre-JV" design efforts (and for several months after the JV was penned) were geared toward a naturally aspirated engine only, with no consideration for supercharging, since the Rover desire for a supercharged version had not yet been revealed.

Although the 1.6L Tritec engine was based on the 2.0L Neon engine, it had almost no parts in common. I think maybe the hydraulic lash adjusters are but I can't remember for certain. Here are some pictures of the 2.0L Neon cylinder head. Other than the 2.0L using a belt drive, instead of a chain, the similarities are obvious (see attachments).



Prior to the 2.0L SOHC engine, the first engine at Chrysler to use this basic cylinder head layout was the 3.5L V-6 that premiered in the Dodge Intrepid in 1993. That cylinder head design effort was done in the Advanced Engine Engineering department. My Dad, Jose F. Regueiro, was the Supervisor of Advanced Engine development in charge of combustion from around 1983 until 1991 that developed the 3.5L head. Pat Baer worked for him. My Dad gave Pat his start in airflow and combustion development. Here are some pictures of the 3.5L V-6. Again, the similarities are striking:



Of note is the signature "cloverleaf shaped" combustion chamber, which was changed in 1995 to the characteristic "apple shape" (which was carried into the 2.0L and 1.6L Tritec engine) and of course the SOHC 4V construction. Just prior to the start of design of the 1.6L Tritec engine, Chrysler's Small Car Platform Engine Engineering group (of which Pat and I were a part of in developing the 2.0L) had been working on the 2.0L North American Touring Car (NATC) engine that would power the oversized (for this race class) Dodge Stratus to victory in the 1996 season. This 2.0L engine produced over 300 HP naturally aspirated! A lot of Pat's prior experience went into the development of the intake and exhaust ports for the 2.0 NATC and the lessons of those ports were directly applied to the Tritec engine. It's why the intake port window is rectangular with a 2:1 aspect ration (width:height) and the exhaust port window is D-shaped. Careful attention was paid to the aspect ratios amongst many other fine details. While the intake port design remained unchanged from early flow box development, the exhaust underwent 2 major upgrades. The initial design had a true pure D shaped window, instead of the elongated D that made it to production. But the port proved to be too restricted at the window and was costing the naturally aspirated engine about 8 BHP. So the port window was widened into the elongated D. Then, with pressure from Rover Group during the development of the Supercharged engine (or HPD as it was called internally), I was given more free reign to do more than just expand the window and Tim Connolly and I worked to raise the port roof and drop the floor, and widen the waist and window areas to increase the section area even more to handle the requirements of the HPD. We also looked at different exhaust manifold primary runner inside diameters to determine the smallest diameter that would produce the most power. Ideally, I had wanted to take the port window out to the size that the JCW ended up at, but manufacturing constraints would not permit this. I will address this in a future post. So the 1.6L Mini engine can rightly claim a pedigree of the 2.0L NATC racing engine, the 2.0L Neon, 3.5L V-6 Intrepid and even a sprinkle of F-1 Lamborghini V-12!

Building the Tritec team:

Once the JV contract agreement was signed and the engine program fully staffed at Chrysler, work began in earnest on all of the mechanical elements, from block, crankshaft, pistons, rods, valvetrain, etc. Rover Group was in charge of the vehicle design with very little input from BMW out of Munich. All of the Rover guys that we interfaced that were working on the vehicle or powertrain (such as the engine calibrator) were in the old Longbridge facility in Birmingham England. The Chrysler engine design and engineering team consisted of about 25 Engineers, supervisors and managers, and probably 10-15 designers working in CATIA. In addition, Chrysler had a group of Advanced Manufacturing Engineers working on construction of the factory and production tooling to be installed in the all new Tritec plant in Brazil. Rover group sent over a couple of Engineers to be co-located with us in Auburn Hills and BMW sent one. They would be acting mostly as Project Management liasons, attending our meetings and helping with coordinaton with the vehicle team back in Birmingham. Also arranging things like getting us exhaust systems, Mini airboxes, wiring harnessess and smoothing the way when things like difficult vehicle packaging issues might arise (which they did in spades when the HPD was introduced!).

Chrysler and Rover assigned Program Managers to oversee the entire project and regular technical reviews were held, typically every 6-8 weeks where either Chrysler engineering would travel to Birmingham, or Rover guys (much more frequently) would travel to the US for these meetings. There were a lot of team building activities taking place in the evenings and the team camaraderie was very strong. One one trip to the UK, the American visitors participated in indoor cricket. On another, we went to a football game between Manchester City and Birmingham. There were many close personal friendships developed between the US and British team. I hooked up one of the Ex-pats with a rental home on a lake that was being vacated by a friend of mine who was moving to Europe for work. This was quite a luxurious lifestyle for a British engineer! Two of the British Ex-Pats found great jobs in the US after the project was finished and still live in the Detroit area.

On one trip to the UK, the US team went with the Rover guys to an old military airfield where Rover used to conduct vehicle testing. We had our first chance to drive prototype Minis. In another interesting turn, the Rover guys sent over a classic Mini and we test drove it on the track in Auburn Hills. I think that some of the Rover management folks were concerned that with a Chrysler designed engine, the new Mini would lack "Mini character" and they wanted to be sure that the US team understood what that meant. They needn't have worried really, as two of the Senior Engineers on the engine program (myseff and Tony Barr) were rabid British sports car enthusiasts. We both owned Austin Healey 3000's. Tony and I were two of the hardest chargers and "customer advocates" on the program, often butting heads with our own management. We would both pay a price for that.

There were many extremely talented and passionate people that worked on the Tritec engine. Too many to list. Pat Baer, whom I wrote about earlier left the Tritec program after about a year to work on the Dodge's re-entry into NASCAR. He would work on the cylinder head and manifolds mostly. He would be joined on the NASCAR engine program by the Tritec camshaft and valvetrain engineer as well. One of the young engineers working for me on the performance development of the Tritec engine was hired away from Chrysler by Toyota Racing Development in California to develop their Indy car engine, These are just a few of examples. The design engineering team at Chrysler was organized by functional areas of the engine. There would be a cylinder head and valvetrain group, a block group; crank, pistons & pumps group and a performance and reliability development group (which I headed). Chrysler was thankfully unique in the industry in that the performance development group was under the management of the engine design department and not under a separate reporting structure hiding in some dyno lab dungeon! This allowed for a lot of performance influence into the engine design. Things like the very tall exhaust port caused some consternation with the cylinder head design supervisor, as the exhaust valve would have quite of bit of unsupported (by the guide) length, as just one of many examples of refinements to the engine that the performance development group was able to influence or push through.

 

Can I just say that this may be one of the most interesting development stories I have read in a long time, you do a great job at taking us through the tale of history and explaining things in a way that are engaging and entertaining. I would highly recommend that once you're finished with your series that you turn it into an article and submit it to Jalopnik or a number of other automotive websites, I hope that somebody will sticky it here so that it will stay on this board as long as the forum exists. Truly, thank you for taking the time and sharing and cohesively crafting your posts. I would much rather read and listen to and watch people talk about information like this than most news articles that are posted online today. It also holds a warm spot for me considering this generation of car is out of production, aging, and people are fiercely holding onto them with the incredible support and community that exists for the almost cult ish following of this car. I truly think it was a major undertaking when the redesigned mini came out and there simply has not been enough story and heritage put together to explain and showcase the development process and timeline that birthed into America the now extremely iconic brand. If you ever come by the southern Ohio Cincinnati area, I will absolutely buy you a beer and a burger. I do believe if mini of America were to check out the posts that they should send you some sort of memorabilia to commemorate you for your work done. If I had any, I would.
Looking forward to any more you have to share!

 

I will echo patsum's thoughts. Thank you for taking the time to write these articles!

I have a couple questions. What does "JV" stand for? You've mentioned "pre-JV" and "JV" a few times, couldn't find a place where you spelled it out.

A bit more involved: when you described your 2.0L NATC engine, you said it managed 300hp without forced induction. How is that achieved? Big ports and cams? I know that's not specific to the Tritec, I've just always wondered how naturally aspirated engines with similar displacements can be so varied in power output.

 

Joint venture

 

Thank you for the very kind words, Patsum and Sevin.

I wasn't involved with the 2.0L NATC program, but it was being developed by Engineers in my department that I worked with regularly so I know a bit about it. The power was made by boring out the 2.0L to almost 89mm (so it was also destroked to 2.0L). Bigger valves and ports designed to make peak power at 8500 rpm (the ports weren't as big as you might imagine). Cranking up the compression ratio (I think up to 13:1), using huge cams, and individual trumpet runners for each intake port, with the proper length to tune at 8500 rpm. Both intake and exhaust cam durations were a bit over 300 deg. with about 13mm lift. I think they didn't even start power runs on the dyno below 3600 rpm!

Here's a nice article by a long time Chrysler engine guy. The first team picture in the article has two guys that worked full time on the Tritec engine before moving to the NASCAR engine program. A third of the way down the page is a picture of the NATC engine:

http://www.allpar.com/corporate/bios...ocurement.html

In part 3, I will write a lot more about the technical details of the Tritec engine.

 

Do you have any pictures/diagrams you can show us in your next article? I like tying words in with pictures if possible.

 

Hi Sevin,

I have some studio photographs of the engine somewhere and I think one photo of the very first prototype engine to make it into the Dyno test cell, but I'll have to dig them out of storage. We used to make sure that the corporate photographer would come take pictures with all of the team members when the first prototype engine made it into a test cell. I hope that I'll be able to find that picture!

Concerning technical data and graphs, I'm limited in both what I have available and what I can share, due to corporate record retention policies and the fact that I'm no longer with Chrysler so have no access to old records either. I do have the original SAE paper that I authored and the associated graphs and pictures. I think the pictures are OK to share since they are in the public domain, however I cannot provide the SAE paper itself, as publication rights belong to SAE.

In part 3, the design details and unique features of the engine will be revealed, so more graphs and pictures will be included.

 

Thanks! Looking forward to part 3.

 

" Once the JV contract agreement was signed and the engine program fully staffed at Chrysler, work began in earnest on all of the mechanical elements, from block, crankshaft, pistons, rods, valvetrain, etc. Rover Group was in charge of the vehicle design with very little input from BMW out of Munich. All of the Rover guys that we interfaced that were working on the vehicle or powertrain (such as the engine calibrator) were in the old Longbridge facility in Birmingham England. The Chrysler engine design and engineering team consisted of about 25 Engineers, supervisors and managers, and probably 10-15 designers working in CATIA. In addition, Chrysler had a group of Advanced Manufacturing Engineers working on construction of the factory and production tooling to be installed in the all new Tritec plant in Brazil. Rover group sent over a couple of Engineers to be co-located with us in Auburn Hills and BMW sent one. They would be acting mostly as Project Management liasons, attending our meetings and helping with coordinaton with the vehicle team back in Birmingham. Also arranging things like getting us exhaust systems, Mini airboxes, wiring harnessess and smoothing the way when things like difficult vehicle packaging issues might arise (which they did in spades when the HPD was introduced! "

Awesome info. Made my day, like back in time.

Prototype











http://www.pistonheads.com/gassing/topic.asp?t=1353121

 

Great stuff ECST! Loved reading the article in the links.

 

Welcome.


Yea, those old school 1999 days are very cool.

Thats rover prototype was cool to see , I like how they modded an R50 hood to fit the new eaton SC and Behr intercooler.

 

Oh man, that's nothing! I once took home a Dodge Neon mule car and put 300 miles on it over a weekend. The car had the Neon underbody, engine box and Powertrain, but the whole rest of the car was a Dodge Omni! Fun times!

 

Your design perspective is fascinating. Thanks for coming aboard. MINI recommends extended life oil (BMW LL-01) and an extended oil change schedule (15k here in the U.S., as counted down by the thing in the odometer or 1 year).

I'd like to hear your thoughts on this. My wife and I both have high mileage R50's and have stuck to this schedule or the 1 year interval. I do my own changes and use LL-01 oil. We've had no engine problems except for a burnt exhaust valve on my wife's car, probably caused by low-octane gas. When we tore the engine down it was not sludgy inside.

Thanks-

Val

 

Hi Val,

Sorry to hear about your burned exhaust valve. Unfortunately, it's probably one of the more common failures even though premium valve materials are used (23-8N exhaust in the R50, Inconel in the R53). I'm curious to know how many miles the car had when this failure occurred. BTW, this has nothing to do with the oil changes. Rover (who did the engine calibration for the Mini), was pretty aggressive on WOT fueling, spark and exhaust gas temperatures (much more than Chrysler would be). They calibrated for "trace knock" on 95 RON fuel (about 91 Pump octane) for the R50 and rely heavily on the knock sensor to retard spark if it's detected. Good for performance and fuel economy but harder on valves.

My recollection (it was a looong time ago!) is that Rover group approached Chrysler with a requirement for a 10,000 mile oil change interval at the beginning of the development program (or it might have been 20,000 km, I really can't remember), at a time when Chrysler was publishing 7500 mile intervals. This was a point of contention for a while but eventually an agreement was reached. Chrysler later changed back to 6000 mile typical intervals on the rest of their engines (non-synthetic). Rover/BMW obviously bumped it to 15,000 when they decided on a synthetic oil.

Personally, if I want my engine to last 250,000 miles +, I'll be doing synthetic oil changes about every 8000-10,000 miles and non-synthetic about every 5000-6000, or at least once a year, whichever comes first. Depends on how hard I'm driving, whether I'm spending time on dirt roads, etc. Chrysler vehicles (my '09 Challenger has it) now have an algorithm that sets a "change oil" message in the cluster. It takes into account number of starts, mileage, # of engine cycles, etc., to determine that. Sometimes it lights up around 5000 and sometimes 6000.

As the engine gets older, it might require more frequent oil changes, not less, as an increase in blow-by gasses into the crankcase can dilute the oil with both fuel and water vapor and also cause the oil to sludge. Fortunately, the Tritec engine PCV oil separator (inside the valve cover) and PCV circuit works really well and I don't ever recall seeing any issues with oil sludging. Sludging has been a huge issue in some modern engines.

 

Great info. On oil changes that what I do and I am at 255k+

Yes, the LL-01 development and the economy of free service played into the 15K oil change. Nice to hear the inside of that story.

 

I'm quite sure in hindsight, that the "free regular maintenance" that was sold with the Mini played a big part in it. Of course, we weren't informed of that when the development agreement was signed.

 

Here's a closer picture of the head as it came off. Only one valve was burnt but it sure made the engine a dog. We ended up having this head done- we only had to replace one valve and we also had the guides and seals done as well as the standard resurfacing. I know the head was otherwise in good shape and it was cost effective.

Mileage at this junction was about 112,000 or so. We bought the car in California at about 56,000 or so. We don't know about the first owner but we did use 87 and 89 octane fuel quite a bit until this happened. We now only use 91 octane. We've learned our lesson.

Val

 

I never burn any fuel less than 93 octane. Also I use mobile 1 synthetic and change @ 3k miles. I'm sure it's over kill but it's worth it to me 😉

 

Hi Alex, thank you for all this information!
can´t wait for part 3!

Thanks!

Juan - From Argentina!

 

So cool to have some inside info on how things came to be with the "new" Mini! Any chance of a part 3?