Rear Turbo Dyno Results - At Last
Turbo Mini Forums

http://img.photobucket.com/albums/v233/wke...l/turbovsna.jpg

Finally got the car on the rollers. 47 naturally aspirated horsepower at the wheels, vs. 78 with the turbo making 8psi measured in the manifold. Very pleased. This is (so far as I know) a totally stock 1275 other than LCB, high ratio rockers, and Weber 32/36. And a turbo of course! I'm sure the car would have put down more power naturally aspirated if I had worked with the fuel curve more, but still very happy with the outcome. 68% increase at the wheels without touching the motor internally or doing any firewall surgery. Not sure how long the power would have held on before dropping significantly, but I let off at 5700RPM due to the stock bottom end. This is running on US Super Unleaded gas, which is 91 Octane by (R+M)/2, about 95RON.
Depending on how large you believe the flywheel horsepower Easter Bunny is, I'm getting right about 95HP at the flywheel. This engine is not from a Metro, so it has a smaller cam as I understand it. Engine code is 12HC01AA, indicating a low-horsepower 1275CC engine from 1986.
My son and I went on a drive over a 10,000 foot mountain pass Saturday, and the car had very nice power all the way. Notice the horsepower weather correction factors. 1.19 on the NA pull, and 1.17 on the turbo pull. This is due to the 5,000 foot altitude.
The wideband O2 showed 10.7-10.9 through most of the pull, going up to 12.3 right near the end where the power jumped up. I'm getting a wideband installed on the car next week, after that I may tweak the fuel curve in more to get better power throughout the range. The hump at the end says to me there is more mid-range to be had, but I need to be very careful. The dyno operator said it sounded to him like the engine was making more boost right at the end of the pull. Not sure what to make of that.

Photos of the install:

http://img.photobucket.com/albums/v233/wke...oinstall055.jpg
http://img.photobucket.com/albums/v233/wke...oinstall004.jpg

1275 with Back Door Turbo

Let's try to get the images to show up directly.

1275 with Back Door Turbo

By the way, it does have a muffler now. My neighbors were very tolerant, but my wife found the car very embarassing without a muffler and I was always driving very gingerly past police cars. A glasspack after the turbo makes it much nicer.

1275 with Back Door Turbo

Think I mis-calcuated the mythical flywheel HP actually. 95HP at the flywheel only allows 18% for losses. Seems many are seeing 22-25% loss. Hallelujah, Easter Bunny brings 100+HP at the flywheel.
Now just gotta get the kink out of the curve so the top end power has a useable rev range. Good start though.

1275 with Back Door Turbo

How does the oil feed/return system work having to get it back to the engine??? where have you put it back too?

www.miniman.com.au

"""LazyGoodForNothingSmartArseKnowItAllBackYardMiniMechanic"""

well done ff pioneering in fort collins !

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

whats the lag like?

Alex

AlexF

There is a scavenging pump near the turbo which sends the oil back through a plate over the mechanical fuel pump mount.
I find lag not a problem. I develops 3psi @ 3000RPM, 8psi @ 4000RPM, so the power comes up quickly as you pass through that range, but I don't see significant time lag on building power at a given RPM.

1275 with Back Door Turbo

How does the boost curve compare on the road, vs the Dynojet ???

I know on bigger engined cars, a lot of dynos cant load up enough to build decent boost.
On the road, boost characteristics are very different than on the dyno.

Also....might be worth lagging as much of the exhaust as possible, to try and retain heat before it gets to the turbo. Are the normal clamps, sealing 100% ???

And finally...congratulations on a very different project !!!

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Boost curve was pretty much identical. This is a Dynojet, which uses the weight of the rollers as the load. In fact I did the pulls in 3rd gear because it accelerated so slowly in 4th. The rollers model a 3000lb. chassis, a bit much for the torque of 1275cc even huffed.
Clamps seem to be sealing OK, though I see a bit of seepage marks around them.
Been considering lagging the pipes, just haven't gotten to it yet.
One more thing: this setup cools fine with no airflow modifications. Most of the extra turbo heat is out back.
Thanks for the encouragement. On to on-board wideband!

1275 with Back Door Turbo

Well done - I love this install especially the fact it's on a stock motor. I think it's brilliant. What CR is this engine (assuming totally stock), anyone know?
If you can lean that fuelling out in the lower and midrange you'll see more power. Somewhere around 11.5 is still safe on boost and will net you more power.
Any idea what ign timing figures your getting across the rev range?
I agree on the lagging and also would suggest a Megasquirt or Jolt to give you mappable ignition which you can tweak to improve your off boost torque improving spool.

Edited by Daniel on 7th Oct, 2006.

I'd be interested to know the turbine spec myself - just to see how what you say about the boost / rpm compares. :)

Timing is either 28 or 30 degrees @ 4500RPM, can't remember which.
TurboDave, the turbine is the one you recommended:
"ok, I've done the numbers - and there is one clear winner: http://www.turbobygarrett.com/turbobygarre...48_466755_3.htm

I also took the liberty of spec'ing it out for running 12psi - for the point at which you'll invariably want to wind the boost up (admit it - you will want to!!!) Even at 12psi, it's running the same efficiency! Fantastic! So, I keep increasing the boost; pulling up to 14psi at 6700 rpm and it's now starting to fall off the efficiency map.

Basically - it is the PERFECT turbo for your application. It has a integrally wastegated turbine of a very small 0.35AR - I reckon this will make 4psi at around 2500 rpm, and full boost by less than 3000rpm; and it'll spool up like a supercharger... It also has the rectangular fitting - much easier to use than the triangular unit...

I hadn't looked at that message in awhile, and now see the boost is not building as quickly as predicted. However, some of that must be down to the rear mount location and the cooler exhaust gases. I'll get the pipes lagged next week and we'll see how she likes it.

1275 with Back Door Turbo

oh - That was you! LOL!

That turbine is to all intents exactly the same as the R5GT spec unit.

"3psi @ 3000RPM, 8psi @ 4000RPM"
That is definately worse (as we'd expect) than a R5GT turbocharger mounted in the traditional place. I'm sure I datalogged this ages ago - I'll have to see if i can find my logs.

Good Stuff :)

Lagged pipe improved low RPM boost a bit. Now seeing ~4psi @ 3000RPM, ~2psi @ 2500RPM.

Now that I've got a wideband O2 sensor on board with data logging, I need to install the MAP (manifold absolute pressure) sensor so I can create data logs of A/F, boost, and RPM vs. time. This is the system: http://www.prologger.com/

1275 with Back Door Turbo