Building a 900 for hillclimbs

[Jordan]

Looks like you're putting the TIG to good use. I'm going to try to make it to at least one event in the fall!

[KPAero]

With another hillclimb coming up next weekend I once again feel like there wasn't enough time to make a solid effort to diagnose and fix the boost issues. (Let alone do other items on the prep/to do list) At Okemo 1 the car still wasn't capable of making full boost. With the new BOV it did seem to make more pressure, around 10-12 instead of 5-7, and boost was coming on more consistently. So there was improvement even if that wasn't the root problem. It was also now sometimes making target boost pressure of 18 psi, but would then back down.

Normally I would suspect something T5 related. But with the wastegate hose removed from the solenoid, the car would only make around base boost. I started to suspect the actuator might be failing. While at okemo I went to the local ACE and picked up a spring to use as a helper. Unfortunately the spring selection wasnt great and I ended up with a spring that was not very strong, but it did make an improvement.

So after the event I ordered a new actuator from forge. After doing some reading it sounded like even if this didn't fix things, it would be somewhat worthwhile in its ability to help control boost more consistently than the cheaper actuators. Anyway, I installed that yesterday after some modifications, and also completed the pre intercooler intake pipe.

The actuator I ordered was for a Viggen, so obviously the bracket didn't fit, nor did the rod length. I sorted the rod by removing it from the actuator, cutting the middle out to make it an appropriate length, and welding back together.
Here is the new bracket after a rough cut on the band saw.

And with some cleaning and holes drilled.

Here it is installed, you can see I ended up cutting it shorter and welding back together. Original measurements were slightly off and the actuator rod was not level.


Here is the new intake pipe finshed up and welded. I definitely am starting to see some improvement welding aluminum as I start recognizing what Im doing right and wrong. Some adjustment in torch angle and arc length really helped this go more smoothly than the last time.

Here is where I welded one end to make a lip for the coupler to seal on. You can see the weld still isn't super consistent, but Im getting better!

And installed.


One thing I would like to get done before Okemo II is to get a T7 BPC valve conversion finished. I also drained the trans and filled with fresh MT-90. Everything looked good there, fluid was a little dirty, but nothing ominous come out.

[airsweden]

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[Jordan]

Are you planning on going to the new Ascutney event? I know it's the same weekend as SCD now.

[DrewP]

Looks way better than when I first learned to weld, looking good!





Engineering paper means it's an engineered solution! (At least we pretend it's that way at work....)

[SwedeSport]

There are 2 kinds of people that can fuse metal,...

1- People who weld.

2- People who use the welder.

I kinda like to fancy myself to be somewhere above middle.

If it was a street car, I would grind the welds and polish it for a seamless look. (and to hide my work)

Looks good!

[Geoff]

Engineering paper means it's an engineered solution! (At least we pretend it's that way at work....)

You can tell if someone knows what they're doing by which side of the paper they use

[KPAero]

Just realized I forgot the close up picture in the above post.

[KPAero]

Are you planning on going to the new Ascutney event? I know it's the same weekend as SCD now.

Undecided, I am definitely going to SCD as it will be the last one my Dad organizes and I just enjoy going anyway. But, I would love to run the full Ascutney course. And I feel like the MAX BMW crew is going to be able to put on a great event. They have certainly started off the right way with their website, online registration etc. So I may go run Saturday and leave early Sunday morning for SCD. I need to decide if thats worth the time/$.

Engineering paper means it's an engineered solution! (At least we pretend it's that way at work....)

Obviously it was an incredible piece of engineering! Proven by the need to re-size after intitial completion. Question is, did I use the right side of the paper? Seriously though, this was one of the few times I have sketched something out and written down measurements etc. I'm going to try and do this more often from now on.

[KPAero]

So I missed Okemo II after the new actuator didn't solve things. Ended up deciding it was the turbo after coming back from a test run, pulling the intake and spinning the turbo while things were still hot. It seemed like there was some extra resistance, so maybe some abnormal wear on the journals? Anyway, not a ton of shaft play, and when cold it was hard to feel anything wrong. While lightly used, that turbo had sat on the shelf for 10? years.

Somewhat reluctantly, I decided to order another turbo. To keep things simple I went with another T3/T4 Garrett that I got from ATP. Both my old swing gate housings had started to develop cracks around where the wastegate flapper seats. I also got a new wastegate housing with a 3in v-band outlet to go with a new down pipe.

Heres the new waste gate housing:



And the new turbo with waste gate actuator in place:


The mounting bracket I had previously made did not fit the larger diameter of this compressor housing. So that was re-done. This was one thing I rushed a bit trying to finish in time to get some sleep before SCD. The new bracket fits well, but is a bit flexible. I may go back and stiffen it up or make it again out of the same thicker material I used before.

And mocked up in the car:

You can see the intake also didn't really fit anymore, so that was slightly modified as well.

And this is the new downpipe first being mocked up.


And finally the finished downpipe:


It is a 3in V-band into 4" and then back to 3 after this section. Also added a second bung for wideband, EGT sensor etc. if its ever needed. Along with the downpipe I also re-worked the rest of the exhaust. Re-using a lot of old pieces I just tweaked things for a slightly better fit, made new hangers, got rid of the muffler and moved the cat to the end of the tailpipe. It's a little louder now but sounds pretty good.





Heres the new tail section with the cat at the end. The hanger is made of a heavy leather, the night before SCD I realized I hadn't picked up anything to make the hangers out of. Needed something more secure than traditional rubber hangers anyway, they were breaking or popping loose at ascutney, so I figured this heavy duty leather (~3/16" thick) would work well. Strong, resistant to heat, abrasion resistant. Hopefully they work out, I had originally thought of using heavy mudflap.

[KPAero]

Well, for the first time I've gone and broke a transmission. Second run on Saturday coming out of turn 10 or 11 (I forget which) as I shifted from 2nd to third there was a crunch, followed by some more broken noises as I limped up to the ambulance turn checkpoint.

Without having a way to trailer the car home I drained the fluid back down in the campsite, found one whole tooth and some filings. I did end up driving the car home, with the fresh fluid it in it and less debris it went alright. Everything worked somewhat except third and fourth gear.

So, I currently have the engine ready to come out, just need to hook the crane up. From there I am going to try and see exactly what has failed in the transmission and what else might have been ruined. I do have a couple other transmissions, both with issues, so hopefully I have enough to make one good one. I'll probably end up with some questions as I've never really worked inside a transmission before.

[Jordan]

Which transmission was in there?

My guess is you just overpowered the gearset. A later transmission will help a little, but you better start stocking up or saving up :)

[DeLorean]

yep, this will happen with 900's. A broken trans just means it was a strong runner! 89+ transmissions are slightly more resistant to stripping the gears, but the power delivery you get from the 900 motors (lots of torque) tends to be real hard on things. I actually think a really big turbo, like maybe an HX30 might be a bit better on a 900 because it would eliminate the low RPM torque hit due to the fact it won't even spool till 3500 RPM's

[99Super]

Sorry to hear it! I'm dreading the day this happens to me!

John

[KPAero]

One of the spare boxes is from a 92' turbo, and is what I would like to use next. It was originally in the white 900 that some of you have seen at some rallyx/hillclimbs. When I got that car the transmission had a blown reverse gear. Ideally I would like to fix that one and then also fix the current one in the car to have as a spare.