OK, I've come to the conclusions that there's a potential area of my drivetrain stealing my HP and causing my MPG to be lower than it should. I've got about 57k miles on the car. I wish I could get my engine on an engine dyno then onto a wheel dyno and compare the numbers to get an accurate assesment of the % loss, but pulling the engine and finding an engine dyno is cost prohibitive. What parts of my drivetrain should I look at having replaced? Is there a way to test/check each of these parts?

 

Has this always been the case, or have you seen a significant change recently? What are your baseline numbers, and why do you think they're below par?

You can check to see if the engine is running efficiently with OBD2 diagnostics. If it's running pig rich (richer - all MCSs run rich) that would lower MPG and power. The diagnostics or a sniffer should tell you something.

Another possibility is drag/friction. Easy enough to lift up the front of the car and make sure everything turns smoothly. But I highly doubt the tranny could drag THAT much on the car without breaking.

 

It's not something that just happened. It's been an ongoing concern of mine. My A/F accoring to the dyno are great...maybe a little lean on the lower RPMs.

 

So what are your HP and MPG numbers? And what does the torque curve look like - is it 'normal'? It could be you have a 'loose' engine from the factory. Could be you just have a heavy foot.

 

I was reading a little low on HP for the mods and for the boost levels I was running. Maybe about 30whp too low for that high of boost. Just got thru refreshing the entire engine and it has new pistons, rings, all seals, all gaskets, all bearings, new freer flowing head, bigger valves, better cam. However, something still is quite low on the HP at the wheels. I did gain some hp and some torque. The engine sounds wonderful at full song. I'm very pleased with the sound. A local buddy of mine has fewer mods but puts down well over 25hp on the dyno more than I do. I've got a new/used supercharger on the way...maybe my old one is robbing too much of the hp. After that, there's not much I can do to the engine to try to find the part that's limiting the HP my car should be making. I have to find ways to free up the rest of the drivetrain. I've looked thru the parts book and the only parts between the wheels and the tranny is the hub carriers. Maybe I've got some bad hub carriers? Maybe the tranny too tight? Can the hub carriers be lubed, or are they throw-away parts.

In regards to the MPG, I've always got lower than what I would think I could get outta the car. See some of my posts from back in 2003 talking about fuel economy.

 

Wow! Well, if you've already gone through the engine, at least you can rule that out. Boost levels rule out a leaky bypass valve, and I would say the SC as well.

I don't think hub carriers are serviceable, but it's easy enough to spin the wheels and see if they're significantly stiff. Doesn't seem plausible.

I can't imagine the tranny could be that tight to suck up THAT much HP, but you've pretty much ruled out any other options.

Do you have bigger, heavier wheels/tires than your buddy?

 

This whole thread is a joke right

You turbo your car and are worried about mpg loss... Now you want to see where your driveline is taking the power from you?

 

Sorry if this goes without saying, but back to basics: are you comparing your car's output to your friend's car's output all on the same dyno? Comparing between dynos can give you unpredictable consequences, as you know...

 

Don't get narrowed into one of the two items I'm using to determine that I may have some loss issues. The MPG issue, as state before has been on my mind since 2003 well before the Sept 05 T/C kit install. My car's always been slower, regardsless of the mods installed. I've done virtually everything to the engine to ensure there's no lossy points (one last thing as mentioned before...the supercharger). Now I'm onto the items after the motor. Can the hubs be re-lubed/refreshed, or do I need to buy new ones? How about the tranny? Anything there might cause it to be tighter than other ones?

 

We've been side by side at WOT in the same gears and he wheels on my car like he has an extra 50+ hp. Plus the dyno my buddy ran on is a mustang and I ran on a dynojet....we all know what that means....

 

No leaky bypass...I had that thing welded shut. Cut a disc to fit inside and welded it down. The SC still posses a threat. Maybe it's old and is starting to drag too much on the belt.

Bummer... I can't turn the tire easily by hand when the car's in the air and no tires are touching the ground. Maybe this is due to the quaiffe.

I believe he's running 18" and I'm running lightweight 17".

 

try a run down test: coasting from 70mph to 40 and comparing times with your bud. Seems like Andy mentioned something like this to estimate drivetrain loss.

 

what pulley do you have on your car? And have you ever had a boost gauge on the car previous to the twin charge?

 

are you running the same boost? WHat about fuel? 91 octane dials back timing between 14-18....101 is 25-30...Also, I would think when you refreshed your motor you turned the boost down...every lb of turbo boost is 10 hp..while SC is only 5hp per lb....Finally, have you had the car back on the dyno since the rebuild?

 

Going to try that...Sounds like an excellent idea. :-)

I had a 15% Alta pulley on the car for about 30k miles. I currently have a stock pulley. No boost guage on the car prior to t/c'ing it...there was no need. ;-)

Boost is 1.84 bar on the APEXi readout and reads about 27psi on a Defi boost guage. Dyno'd the car yesterday. Got 10 more ft-lbs of torque and it's much fatter across all RPM bands, especially from 4k and up. A/Fs look really good. Maybe could lean it out slightly just after 6500...but not too much to match the before rebuild dyno pull. Sure the boost controller can be tightened so the turbo boost comes in much stronger earlier, which should give me more torque down low...but I want to wait until that supercharger replaced and then re-tune the beast. It should scream really well after I get that replaced. But hey, the car is a tonne of fun to drive as it is. Very, very quick! But if there's more to be found..then I want to find it...expecially if it is something that may be bogging the motor down, which will only decrease its life.

I think the best way to determine would be a coast down test with a few other local MINI owners. I've got two-way radios...

 

I'm guessing here, but I would think for the coastdown, leave it in gear (third?), clutch depressed and no throttle; maybe do it on the same road, both directions.

 

1.84 is in the 26 range...26.6 if you wanna be nippicky...also...my apexi was reading 1.87 (27.1lbs) when I was only making 22 lbs...

so what was the car at? you say you dynoed it...

what fuel were you running...

what kind of Dyno....and where you logging boost during the run?

 

So with clutch pushed in, that would test out both the hubs and the tranny. Very cool. I'll have to get together with one of the locals soon.

 

As some have said, the voltage coming from the sensor (which the apexi uses) doesn't read reliably at the higher boost readings. So you have to calibrate each car independantly. Mine on the gauge and the sensor voltage do appear to be running side-by-side.

253whp. However, on pump gas, I should be making 290-320 whp with the parts I have on the car. Prior to the rebuild, I should have been making 250whp @19psi, but I fell well short of that getting 210whp at 21psi. The tuner pre-loaded the mechanical boost controller even more to around 25psi max on the dyno in 3rd gear and that got my car to run 233whp. Well short of what the other 30 kits he's sold get at a much lower psi that I had to run. So with the new parts I gained 20hp. Good gains, but not great considering just one of those parts added supposedly gains a pulley'd car over 40whp. But overall, all along, my car's been slower.
pump gas for each and every run.

All my dyno pulls were done on a dynojet. The numbers I give are with a smoothing factor of 5 to get rid of abnomolies and also SAE correction to keep the temp/humidity/atmos press differences accounted for. I used the APEXi's max function to determine max boost in bar.

 

This would test out the hubs and driveshafts, but not the tranny, right? If the clutch was engaged [I mean not depressed], then you'd be testing the tranny, too. That's my thinking...

edit: Another consideration in doing a roll-down comparison should be the weight of the flywheels in the different cars, if the clutch is engaged, since less rotating mass means less resistance/energy loss.

 

also why are you dynoing the car in 3rd gear?

 

With the clutch depressed, the wheels are still turning the tranny. The clutch goes between the tranny and the engine.

Visualize this: Engine - Flywheel - Clutch - tranny - differential - driveshafts - wheels

 

Keeping it consistent with the previous pulls. Plus since I'm at a dyno facility that cannot simulate the massive airflow over the engine, it allows the full RPM pull to be quicker so you're straining the engine less without getting wierdness due to heat issues.

 

Oops. Yeah. Thanks for correcting that...

 

Interesting. Perhaps I should do this, too.