Clean MINI with owner built engine combo. undisclosed cam, RMW head, pulley, CIA and header. Came in making 226whp and left making 249whp after Chris tuned it. We can tune any engine combo, not just our parts and combos.

 

Nice, but...

I just find it funny when people keep their mods or some of them secret like it's a race car or something.

 

Cat-cams?

 

I think he was working with someone on a custom cam for his car and didnt want to say.

 

Can you post both dynos?

 

I would love to but my dyno computer crashed and took out most of our dyno run data. Thank you Windows 8.

 

When you do tunes, do you measure AFR with a wideband O2 and/or measure exhaust gas temperatures? If you measure EGT's, where do you put the thermocouple?

 

We use a wideband for gas engines. With alcohol and diesel the EGT works better. If you're using an EGT you need one in each exhaust runner the same length from the exhaust port. You can do EGT globally but the probe will be farther from the exhaust port and total temps will be lower. Once you have a best line temp, then its a matter of tuning all the cylinder temps the same and finding the best temp for HP while not killing the engine. EGTs are very hard to tune by because lean and rich can make the same temps. Most of the time you read the plugs too when using EGT. EGT tuning is much harder and if you're running a gas engine widebands are cheap and easy to get. Also global tuning with a wideband works well in most cases. If you really wanted to get to the edge of a tune EGTs on each cylinder and global wideband would be the best setup.

Simple answer on probe location about 1 inch from the exhaust port if EGT on each cylinder and directly after the turbo or in the collector if using a global EGT.

 

Thanks for the reply Chris. When we developed the engine, we ran to an individual runner EGT of 930C max. and collector max of 900C. If I remember right, 900C collector max was a short term limit, and then more fueling would be added after something like 30 seconds (otherwise you risk melting the pre-cat). With an unported head and that God awful Rover collector, you have to start adding extra fuel (above LBT fueling, which we considered to be 12.5:1 AFR ) at around 4400 rpm with 98 RON fuel @ STP conditions. With a good porting job an a better header, that gets bumped up another 400 rpm. And you have to enrichen to around 10.8:1 at 6800 rpm, even with a good header and porting to stay under those EGT's. Here's a pic of a header we built for testing:




And a view of the dyno cell when we were experimenting with different primary runner diameters:




BTW, cylinder to cylinder distribution on this engine is really good so EGT's don't vary much between them. When you do a re-tune, are you only touching the base WOT map, and relying on the adaptives for changing conditions, such as altitude and ambient temp?

BTW, don't mean to thread jack. I think it's really cool that modders and tuners are pulling 250HP out of these engines without too many extreme measures!

Cheers!

 

NP on thread. I'm interested in your header and engine dynoing with cats. Why are you using cats anyway? Also what are you using to tune with? 930c is hot, how did you determine that, that is 12.5afr? I would say you're leaner than that at 930. Are you do emissions tuning? 10.8 is rich on the top end. We use a different intake manifold we make which fixes the 1 and 4 fuel and air differences and I can safely tune them into the 11.5-75 range. http://www.sneed4speed.com/mini-coop...take-manifold/

For retunes its mostly WOT and global adjustments in fuel and timing. You can then set the LTFTs and the ECU will adjust for AFR to target for cursing speeds. The learning and programming is pretty good from the factory for altitude and ambient temp so if you have the injectors scaled correctly it will mostly take care of itself within reasonable temps and altitudes.

 

Hi Chris, Maybe you didn't realize that I'm the original Engineering Supervisor at Chrysler that developed the engine and those pictures are from development tests run in 2000. The data I quoted is from our engine dyno's where the engine was developed. The exhaust manifold picture is just one of an experimental one Chrysler built to demonstrate to Rover group (who had design responsibility for the exhaust system including header), that they could improve the design to increase power and reduce EGT's and backpressure. Their original design had 1.25" ID primary runners which were a choke. We recommended 1.375" ID but I don't remember if they implemented it (have to go measure my Mini tonight, lol). Our design reduced backpressure around 10 kpa and dropped EGT's a bit. Made about 5kW more power too.


We often (but not always in every development test dyno) run inert cats (just the brick, no precious metal washcoat) in order to have the proper pressure wave dynamics, backpressure and EGT's. Yes, 930C is very hot, which is why the S/C engine has premium valve materials (Inconel exhaust, I think 23-8N intakes). So EGT's and pressures are instrumented with K-thermocouples (see picture of manifold and dyno set-up) and pressure taps. EGT's are very high for a number of reasons:


Very high mass flow
Small volume exhaust port
low expansion ratio - from low compression ratio
short primary exhaust header runners


Development engines could run 12.5:1 AFR up to about 4500 rpm before they would hit the 930C EGT and need more enrichment. 10.8:1 @ 6800 rpm was needed to keep to the 930C limit. Of course, those enrichments are based on steady state conditions at each speed. IOW, holding the engine at each measurement point (e.g. 6800 WOT) for at least a minute. Short term transients aren't nearly as hot of course or require as much enrichment.


One thing to realize is that we had durability tests where we ran 6500 rpm WOT for 200 straight hours (along with several other types of very abusive durability tests)! So the steady state fuel map has to be very rich to keep temps down. Exhaust headers would be glowing orange for 200 hours! Early development engines broke a lot of parts on these extreme tests (exhaust valves & rocker arms mostly) and all of those issues were fixed before production started. Production engines then had no problem surviving these tests.


OE's always calibrate WOT fueling to EGT limits since it is vital to long term engine durability. Emissions components are also long term warranty items due to OBDII requirements.


Cheers,


Alex

 

6500 for 200 hours?

That's crazy!

I haven't been beating on my car enough, I don't think I've even gone over 6000 in the couple years I've had my car.

 

Our "standard" endurance test (which I created) on this program was 500 hours, with about 25% of the time running at peak torque and 25% at peak power. Then several harsh transients (rapid accel's and decel's), some stair stepping of speeds and one point at the primary resonant frequency (good at breaking things like manifolds). And running to fuel shut-off rpm once an hour. We also did "double life" or 1000 hour tests on this cycle. Hence "The Unbreakable Lump!"

Too bad BMW didn't make Peugeot run those tests on the "Prince."

Don't feel bad though, my daily driver since Jan. 2009 is a Dodge Challenger with a 5.7L hemi, and I don't think I've driven that car over 95 mph and I rarely take it to the redline.

 

Hi Chris,

Forgot to mention about the intake manifold. Kind of a long story so I'll give the Cliff notes version as I intend to write about this in more detail in the future. Rover wanted more involvement in the "HPD" (S/C engine), since the base engine was 100% Chrysler designed and developed. So it was agreed that Chrysler would do the long block and Rover the intake manifold and S/C adaptation. About 4-5 months in, the Development Engineer at Rover cried "uncle" and said that they couldn't get the HPD to work because cylinder maldistribution was so severe they would never meet emission. So we offered to help.

I went to Longbridge. Walked into their dyno cell and stacked on the floor were about 25 different intake manifolds! Each a little different with diverters, baffles and every Rube Goldberg device imaginable. The Rover Engineer (who was quite experienced), says "I can't make any of these work at every load/speed." I just had to chuckle to myself a little as the problem was obvious to me. The runners that they designed going into the log plenum were incredibly short (like 40mm) and had no taper (and therefore very little volume). So the cylinders were "cross-talking" through the intake and screwing up cylinder fuel distribution. I said "give us a few weeks and we'll have a design for you that works. So I got to work with one of my favorite designers. Did some calculations and had her lengthen the runners (I think to 75mm), put as much taper into them as possible, and curve the runners slightly toward the inlet for a better transition. We built a couple of rapid prototypes on the 3D printer (we'd wrap them in fiberglass for extra strength) and shipped one to Rover and tested the other on our dyno. Worked perfectly. Rover was delighted but said that the vehicle package wouldn't allow it. So they had to get the vehicle team to push the radiator 20mm more forward, which they eventually did. But it also looks like they squashed the forward side of the plenum down as well, after taking over the design, as the original design we gave them looked pretty much like your modified version!

 

Isn't the solution obvious? Get rid of the cat.


You gotta love Rube Goldbergs. Some people can get really "creative".

 

The British for some reason have a reputation for taking the simplest problem, and devising the most complicated solution possible. I witnessed it first hand! (just that one time though). They were actually quite good to work with.

AFA the cat. Had to have the pre-cat to meet emissions. Notice however, that the Tritec engine has no EGR. Engine out emissions were very low which allowed EGR to be deleted (on at least MTX vehicles, don't remember of the ATX needed them).

 

So cool. I love the OEM testing. We dont have to test anything that hard. Our road race cars only see full throttle for a max of 30 to 45 seconds at a time. So we can get away with leaner fuel burn and more timing, plus we know what kind of fuel is going into the engine all the time. Also, our packaging constraints are nothing like OEM.

Very cool that you all came up with an engine combo that will make good power, survive all those test and fit in the car.

What did you do about NOx emissions with exhaust temps that high and no EGR?

 

It's really fun to hear about the original development of these motors. We have done a lot of speculating over the years as to how and why parameters like AFRs were set as they were. Regarding the relatively rich mixture above 5K RPM, we weren't too far off. The M45 produces so much heat, and, well, hot in, hotter out. When you saw the ballooning EGTs with the choked primaries that Rover suggested, did you ever consider ditching the M45 and going to a turbo?

 

The problem isnt with the supercharger pushing in hot air the problem is the header design doesnt effectively scavenge the header pipes and causes exhaust to back up in the head causing the temps to raise. I would guess a correct length header wouldn't fit in the design of the car and with a cat hooked to it, the collector is not going to work great anyway. The design he has pictured basically is just 4 pipes dumping into a cat. So you're not going to get any advantage of header pipe scavenging and you're dumping directly into a restriction. Its not going to flow well and that will cause a lot of heat. OEMs have to deal with so much emission and durability issues on their builds, its insane the power they make.

 

It's a combination of many factors. The hotter IAT from supercharging is one. The header is another. The very short 4 into 1 exhaust header is really "untuned," as the runners are too short to prevent interference tuning between cylinders. Plus they dump right into the pre-cat, which is a significant restriction and a source for reflecting pressure waves. If you really wanted a well tuned 4-1 header, the primaries need to be about twice as long as the production header. I think Rover stayed with the 1.25" ID runners (forgot to measure mine last night), which is a choke, as just changing to a 1.375" ID (with a good collector) will pull about 5kW more power on the HPD engine without even porting the head further. Bigger isn't always better though, as a 1.5" ID runner manifold performs slightly worse than 1.375" (that's probably not the case though once output levels get up around 230-250 HP).


So the runners are a bit of a compromise between having high velocity for good scavenging on the base engine (which they do), and having a low restriction on the HPD, as the headers are common between the two. For example, even with all of the emissions, durability and driveability compromises to the design, the base engine (the Neon version, which has a better intake manifold) is running at 100-101% volumetric efficiency between 4400-5600 rpm and peaks at 177 psi BMEP. Quite good for a production engine with no bells and whistles like double VANOS or variable intake manifold.


The original Rover designed header was a 4-2-1 with 2 pre-cats. Ridiculously expensive but worked better from a tuning perspective. I really like 4-2-1 for this engine when runner lengths are compromised (as they always are in production environments), as they tune better in the mid-speed range (they eliminate the anti-tuning dip at around 3600-4000 rpm).


As far as NOx emissions, when these vehicles were certified, the EPA used 2 test cycles, the FTP-75 City and Hwy cycles. There's very little (if any, depends on the vehicle) WOT operation on these cycles, so WOT NOx isn't an issue. At part load, were the concern is, the engine out emission levels are very low and are cleaned up by the 3 way catalytic converters. The lower compression ratio of the HPD helps slightly with lower NOx at part load.


Today, the EPA uses 5 cycles, one of them is an aggressive drive cycle where there is more WOT operation.

 

The 4-2-1 header is the best design. The 4-1 works good too with long runners. We dont use cats on anything if we can help it. I didnt know that about the EPA drive cycles. I had noticed that the OEM software tuning was changing and becoming more involved at the higher throttle positions and WOT, I assume its because of the testing but I didnt know the exact details of the new test.

 

Hi Helix,

AFA S/C vs. Turbo. That was strictly Rover's decision as they wanted exclusive rights to use the HPD engine. Their position from the very beginning is that they wouldn't be able to meet emissions with a turbo. Chrysler was quite surprised by this position, as Chrysler was the "turbo 4 cylinder company" for about 15 years prior, and had a lot of turbo expertise in production engines. AFAIK, Rover never questioned their decision and looked at a turbo, although Chrysler suggested it when their desire for an HPD was first revealed in mid 1997

 

So cool that we have someone from the inital OE design team on the forums. I just spent ~15 minutes reading through all of this and I understand most of it.

 

Can this engine survive @249whp a 25 minute road race?
and if it did what are the approx overhaul intervals?
I am deciding whether or not to build a R53 for track use.

 

Yes, our engines at this power level will last 2-3 full seasons before needing a refresh but most people run them much farther than that without problems.

http://www.sneed4speed.com/mini-r53-engine-1/