Mythbuster: continuing project thread of my 1303 '75 - Page 41

70Turbobug · #1 March 12th 2011, 06:40

Quote:

Dude! What do you think is going on in a bug at 1.9 bar boost and 5K rpm on a public highway (german Autobahn)?
I was lucky to check the boost gauge and notice that too high setting at all , let alone watch other gauges

LOL...I meant the log files

Or is that not recorded? You must overcome your fears young Padawan and drive on the autobahn every day..

Wally · #2 March 12th 2011, 09:52

Ah! No, those temps are both measured with a thermocouple and the ecu doesn't have the ability to register those. Unless you have an expensive adapter box...

Today was a dyno day, but on the way there, I had almost no boost anymore. Engine runs very well, but no boost

I checked and even removed parts of the intake and downpipe (turbo spins fine, no play), but couldn't find a leak or anything, so I returned home. Still no clue as what the cause is.

**volkdent** · #3 March 12th 2011, 15:13

I wondered about the machining on the turbine space, the gap around the wheel. Is it possible that one of the faces needs to be machined more to tighten up the seal around the wheel?

I am not a turbo guy per se, but it looked like you just added a larger housing to your existing piece, and I wondered if maybe they needed to be matched somehow?

Lame question, but I think you might understand what I'm thinking. It's not like you to do something wrong, and the engine still runs so it's not like you left a rag in there or something, but low boost could be that the air is not being channeled well around the turbine wheel to create boost? Just a thought.

Jason

Wally · #4 March 12th 2011, 16:01

I understand your question and its a very valid one. This extra turbine house is however meant for a small series of same-size frames.
Most turbo's can be ordered with a variety of turbine A/R's so they all have the same 'form' so to speak.

After some wrenching today it turned out I had an exhaust leak from the complex part where I made the twin exits into one for the wastegate.
I have welded most of it shut now (saw some black traces) and had full boost again

Not the same respons I had on my trip with this housing to germany last week, but close enough. Maybe I missed a spot, will have to look lateron some more into it.
Pfft..

judgie · #5 March 18th 2011, 04:26

that was a lucky escape, not worth thinking about the damage it could of cuased.

70Turbobug · #6 March 19th 2011, 06:31

...that was a close call!

Humble · #7 March 19th 2011, 13:14

That could have ended very badly! Hopefully you can get that turned around and get it running again soon.

Wally · #8 March 19th 2011, 16:25

Yeah, did my best today to get it running next weekend. Used a ticker plate and had the divider wall protrude through the tube so I could weld it all the way through. Its 5 times stronger now 4sure and had now room to port the transitions inside the wastegate tubes a little as well

**volkdent** · #9 March 19th 2011, 17:24

Is there any reason to go with an external wastegate vs. an internal(turbo housing)? I'm trying to keep it simple, and I can't for the life of me figure out out if the external is necessary for my project.

Jason

**NO_H2O** · #10 March 28th 2011, 16:16

Can't keep a good man down for long. Good to see it back in action.

Sandeep · #11 March 28th 2011, 23:08

Now that's a great picture ! Great to hear it roar again.

Sandeep

70Turbobug · #12 March 29th 2011, 09:52

Sounds great Wally! You can really hear the spool up - very cool!

Wally · #13 March 29th 2011, 10:55

Thx guys! It was great to be out on a track again.
Mark, where you hear it climb in the revs suddenly very soon, is where it spins the rear wheels...

Steve C · #14 March 29th 2011, 18:14

Hi Wally

There was a post on here about bolt porn, the sound of your car is aural porn, love it.

Steve

Wally · #15 April 9th 2011, 13:10

tnx Steve! Here's another run I found from that day:
http://www.youtube.com/watch?v=8MF7GaaDzVA

Did a new dynorun today with same sort of problem as before: running lean up top...
Its not too small injectors, but since I can log fuel pressure as of yesterday, it showed that FP gradually deminished from 3,5 bar to 2,5 bar at 1,3 bar of boost. Even though I have a boost referenced fuel pressure regulator!
Lambda was approaching 1.0 again...and misfires occured.
I even changed the fuel filter on the dyno and gave a bit more max fuel correction (30 instead of max 20% before). Even though the run didn't misfire this time, it still ran lean (lambda 0.95+ but just rich enough not to misfire and the run ended in 418 hp up top (max rpm 7200). Atm, I think its too small a wire I used for both fuel pumps.

This was at 1,3 bar. I never got to my intended 1,6 bar...

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