Holy Balls!
Turbo Mini Forums

BTW: We couldn't be more boost out of the turbo, even with running holes in the line that feeds the actuator. And this is with the stock Metro stuff and it needed a BDK needle (pig rich below 2k but almost spot on from 2500 on).

the next incarnation will be the GT15 turbo (super dinky) and a more traditional small bore head (12G295-- found a few for cheap).

There are loads of "issues" still, like we can't make any more boost and the boost-retard feature of the 1980s motorcycle aftermarket ignition system doesn't seem to be working, but for making due with what we've got I'm pretty happy with the outcome.

There were lots of aborted runs and "Wonder what happens when we do THIS" pulls (hence 30 pulls) but a good learning experience for 3 people who've never played on a dyno before.







We pulled 1 degree or so of timing back out between pull 29 and run 30, which were done on mostly pump gas (which were higher hp numbers than runs with pump gas with a splash of race fuel). Hoping that's a little safety buffer.

The car ran more boost and hp with higher engine temps (190). When it was 160-170, numbers were lower.

We were 45-52hp with a modified cam and 10-11.1 compression on a NA motor last year. This year a stock cam and about 8.5-9:1 compression and 8 lbs we get 64ish. Nice.

Don't know what our timing is. Don't trust the timing gun's absolute readings with the wasted spark (getting a shadow). Fueling is a bdk needle with the jet all the way down.

Is that at the wheels of flywheel.

I ran 18psi and 140bhp on a 998 with a metro T3, so I doubt the turbo is holding you back. Most likely the head is the restriction.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

pull the pipe off the wastegate and see what happens to boost .just for a second ..no longer !

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

We did. Sorta.

We put a T fitting in the line from the T on the turbo that goes to the actuator and in that extra capped off stub of a line we drilled 6 holes as our "bleed valve". That's how we got from 3-4lbs to 8 lbs.

Then we just completely pulled off that short piece of line with the holes drilled in it, leaving the T open, and we lost 1 lb of boost-- so the opposite effect of what you'd think!

We stuck the piece of tube with the holes drilled in it back on and the boost went right back up to 8. Weird.

We suspect there's a blockage in that T coming off the turbo, but we did the setup with it that way, are just hoping to make it through the next 24 hour race without the need for an engine swap mid-race, and have no more time to try to perfect it. We're just going to run it with instructions to all the drivers to keep an eye on the boost gauge and if it gets above 8.5 to back off and bring it in asap so we can replicate the blockage back to 8psi!

Our head is a 12G1316 with 1.31 intakes and 1.21 exhaust valves-- so the 1275 head on a +.020 998 and it's just a stock 1275 non economy, non metro cam. I opened up the valve lash to .014 cold for no real reason (to be honest-- thinking stock valves may get hotter under constant turbo use so didn't want the gap to close up too.
much)

Next incarnation is the gt15 turbo, 12G295 head and also an intercooler. We need an intercooler.

The fitting in the turbo compressor housing has a very small hole- maybe 1.5mm. Drill this out so it can flow some more and you will most likely fing you can bleed a bit more off.

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

Finally pulled apart the smoky turbo and found lots of coke and a trashed bushing. Housing is also scored and the cold side fan was hitting the housing. Oh, and the exhaust housing has a crack in it, too.


Josh, who pulled apart the turbo, says the exhaust turbine and shaft looks just like a volvo "stage zero" or standard T3 setup. he's wondering if we can just use the .25AR housing on some other T3 turbo like from a volvo.

Does anyone know if this would work?

In the mean time, we're going to build another 998 "endurance race motor" from scraps and use the gt15 turbo from a turbo diesel jetta. he's made a adapter so he can use a cam angle sensor from mitsubishi eclipse in place of the distributer at the distributer location (sing the dog drive of the stock dizzy). I think he is then going to work on a throttle body injection setup. Goal is 100hp-ish

not planning on anything fancy in the bottom end during the build, at least not this effort. Will use a 12G295 head instead of a big bore head. Not sure what sort of cam spec I should shoot for. With the metro stuff and a stock cam, we get boost from 3500-and tails off about 6k. I would prefer to have something closer to 3 and maybe just a smidge below-- say 2800 or so. We're not running a close ratio box and "power" out of the turns is our weakest point. I don't care so much about end-of-the straightaway speeds but would ideally like a bit more grunt out of the turns in traffic.

but it's a 998 so I guess that's asking a bit much.

Any advice on spec for cam is welcomed or any other bits of advice (or links to posts/threads I should read through repeatedly) would be great.

Thanks all.

Edited by Spank on 27th Aug, 2011.