Thanks everyone for your inputs. As we are a group of people investigating whats going on with our tunes, we discovered that this is happening only to N18 JCW and GP engines. At different altitudes and tunes, but all of them in Mexico. Wondering if there is something special in the ECU.

 

Nice dyno run, kind of looks like my stock turbo pull but no swing at the end like that. My stock turbo just ran out of air/breathe around 4500 just like what looks like what is going on with yours. Either boost leak or turbo would be what I would look at but I'm sure your tired of hearing that. Lol
Would be nice to see what the MAF was doing during that run .
That's your stage 3 turbo JMTC?

 

Ah no,
Sorry If I wasnt clear. As I was saying, a group of Miniacs here are experiencing somehow the same issue. The last graph was a stage 2, not mine. But it does the same as mine, "dies" at 5000rpm. N18 JCW

 

Different cars, different tunes, different engine models, in a different country --- not an easy problem to diagnose --- over the internet too.

Much as I'd like to offer advice / suggestions, I'm gonna pass.

 

Yeah those can be fun to chase ...
Keep your chin up and keep trying, how hard is it for you to drop down elevation and test ?
One thing that whipped my butt was a new K&N air filter that coated my MAF with oil, washed the filter and sprayed the MAF off with sensor cleaner and all lined out. I know your saying others are experiencing issues but it might be something to check

 

No no, dont pass!!!! Is a challenge for you!!

Only common to everyone is engine (N18 JCW) and drop in boost at 5000rpm.

 

So, there are no N14's in the group, or the N14 people aren't having this problem?

 

I have a couple customers from NM and CO, that drove their Manic Tuned to the California ocean and noticed a huge power difference. I know live 1000' above sea level and notice the car doesn't pull as hard.

mQubed Motorsport, Manic Tuning Dealer

 

I was thinking about this yesterday while loading a moving truck and something struck me (no it wasn't a box). We've all been forgetting pressure ratio and our compressor maps. We all know you can make 280 bhp (245 to the wheel) with a JCW turbo at sea level. Lot's of folks have done it. But what happens when we figure altitude into our compressor maps.

280 bhp needs 28 lbs/min or .17 M3/s of air flow. We also know that 1.5 bar or 21.75 psi of boost will get us there. So lets plot it on a JCW compressor map at sea level.

Pressure ratio = (atmospheric pressure + boost pressure)/inlet pressure. Inlet pressure at the turbo is typically calculated as 1 psi less than atmospheric due to the pressure drop caused by the air filter and inlet.

(14.7 + 21.75)/13.75 = 2.65 pressure ratio.

Now lets try the same calculation at 8000 feet where atmospheric pressure is 10.9 psi.

(10.9 + 21.75)/9.9 = 3.29 pressure ratio.

Here are those figures plotted on a JCW compressor. The blue dot is where we land at sea level and the red dot is at 8000 feet.

Hitting those pressure ratio and flow numbers at 8000 feet is just beyond the JCW turbos capabilities.

Just for kicks lets do the same thing with the JMTC 47mm GT Dominator.


Same story here. This one not only puts us beyond the rpm limit of the turbo but also on the wrong side of the surge line.

There's an old joke that goes like this. A man was driving across the US and got lost so he stops and asks this farmer for directions. The farmer scratches his beard in thought for a second and says "Well you keep going down this road till you get to the stop light in town... No, no wait a minute that ain't gonna work." He thinks a bit more and says "Ok young feller. Turn around and go back the way you came. When you get to the fork in the road... Nah that ain't gonna work neither." After thinking for several minutes the farmer finally looks at the man and says "I'm sorry son but I don't think you can get there from here."

In short, without a larger compressor exducer I don't think we can get there from here.

 

We have in our "team" a couble of N14´s, Manic tunned, and they do not experience this sudden drop in boost.

 

This is the kind of conversation I like to have. And for sure a excellent explanation of whats going on at high altitudes. Somehow as I was saying, the oxigen is there, the thing is that the turbo cant do the work. So either we set lower target HP´s (hence less air flow required) or get a different turbo, or trying to reduce intlet drop, or move to the right the dot

By the way MAP B is set to 1.4bar, that will put us in PR 3.15, right?

 

So Tigger, based in your input, I will have to fit one of these turbos for my application, right?

 

Thank you for this info.
In your opinion having this fault (if I do not have an option to update the entire car) is still ok for the tune and car?

 

I know you guys are talking about N18's but I did see a little performance lost the higher I went up but isn't that to be expected with the air ?
I got out and tried to do some walking/hiking and my performance was down as well. So i just decided to hit the ski lodge and have a few beers...lol

 

Lol no I'd pass on that one but I might well consider an Owens. It would hurt the pocket book but with the 60 mm exducer you'd have an even better trim of 54. Generally the smaller the trim the more efficient the compressor will be at higher pressure ratios.

 

I sent them an email last week and no luck so far. Do you have a compresor map/what turbo model they sell for the N18?

 

They only sell one. 44.5 mm inducer with 60 mm exducer. Should flow enough for 350-360 bhp. Call it 310 to the wheels give or take. I haven't been able to get a map out of them. Check some of our other outstanding vendors. Might have one in stock and might convince them to produce a map so we can get a better idea.

 

Perfect, thanks Tigger. So there is no way I can have this Dominator turbo? even dropping boost?

 

Although I didn't tune our friends in Mexico City I have been in contact with them and we are working towards a solution. Based on their boost log in stock mode it appears that lowering the boost alleviates the surging issue which makes sense as the pressure ratio being requested is lower.

 

Thank you tigger! I switch the map to A (R58 JCW with loba turbo) feels good, today run in the dyno

PD: sorry for bad english LOL

 

For some reason the ECM trigers the blow off at that RPM, we performed tests on another mini and got this results, we wired a 5v analog signal input to the connector of the BOV (OEM), see when torques start to goes down is the same time blow off discharges.

 

Interesting that now your are proving the theory I talked to Poncho and you said it was not what was causing the boost to drop No worries, just kidding.

But I think this can be solved via software, cant it?

 

We tried several times, focusing on map boost lock and baro boost lock and still the same problem. We even tried with european tuners that tune stage 3 minis and they also don´t understand why this happens. Another thing we tried is that requested torque to be higher than calculated (that might trigger this) but no luck also.

 

Based on the first set of DashCommand log files for a different vehicle in MC the AFR appear a little lean in stock mode. I have requested additional .lgf files in Map A and Map B. A lean condition could trigger the ECU to dump pressure in order to protect the engine. Tunerlab have you recorded AFR's during these runs or made log files using DashCommand that you could send me at lou@prototype-r.com? Also please provide any details you may have of the tune installed and supporting mod's.

To whomever installed these tunes please feel free to contact me at the email above. Any input you have would be greatly appreciated in helping resolve the clients difficulties.

 

Tigger

here is dyno runs for PONCHO Mini JCW with and without BOV (forge) and AFR measured with lambda on exhaust.