Twincharged AWD EG Reinforced wagovan tranny + GT28/40+ M45

Post by **Gaskleppie** » Sun Jul 19, 2009 5:22 am

I am helping this guy with his very special project. Its a twincharger setup with a electronic butterfly valve for the switch over point from charger to turbo. This is his honda-tech topic about the project. http://www.honda-tech.com/showthread.php?t=2482958

My question is: What do you guys think will be the best way when to switch the electric butterfly valve. MAP? Delta-P? Revs? Vtec? We tested the engine yesterday for the first time with the valve closed. The charger made 15psi but strange enough the turbo did not boosted it up to higher levels. Because of oil pressure problems we had to stop testing. Maybe the turbo can not spool up because the charger is not providing more air. What do you guys think?

Post by **Bugermass** » Sun Jul 19, 2009 5:20 pm

the turbo is being restricted by the SC.. thats the first thing I though when I saw that pic.. you need to bypass the SC completely if possible after a certain RPM and let the turbo pull air on its own.. I can't tell where the butterfly valve is but I think it should be before the turbo, after the SC and it needs to be big enough to supply the turbo enough air.. that way the SC pushes boost through the turbo, then when the turbo spools you bypass the SC and the turbo pulls its own air ..

Post by **Gaskleppie** » Mon Jul 20, 2009 12:56 am

Here is the valve. Its an electronic Audi throttle body.

So we sure can give the turbo the air it needs. But how should we determine when to switch it open?

Orthello · Post by **Orthello** » Mon Jul 20, 2009 2:46 am

I'd say you should swich based on a MAP value. There is a point where the SC gets exhausted and the turbo picks up. Search for that point. Probably with a 2nd map sensor somewhere between the turbo and the SC?! On the other hand.... without a second MAP... wouldn't it be RPM based in that case? It's a cross car. So it will be at WOT most of the time. RPM based swiching would suffice in that case right?! errrrrr.... I just don't know yet. Need to think it over a bit more. (Don't want to delete the post as this might be a start of an interesting discussion)

combz · Post by **combz** » Mon Jul 20, 2009 9:23 am

thats crazy a saw that a few weeks ago!

Post by **Gaskleppie** » Mon Jul 20, 2009 11:00 am

There is a point where the SC gets exhausted and the turbo picks up. Search for that point. Probably with a 2nd map sensor somewhere between the turbo and the SC?!

Thats not happening strange enough.... I thing we have to do a test run with the valve open and then with the valve closed. See what the difference is and study the map levels in each run trying to see a possible way to measure the best switching point. Anyway, the guy found the oil pressure problem, (pressure valve stayed open) so after my vacation we will go on with it.

ge0ne · Post by **ge0ne** » Mon Jul 20, 2009 3:25 pm

What i think is.... The butterfly after the supercharger should open at precise angles that let the turbo breathe what it needs at certain rpms. Supercharger must come out of the game (work like an ac clutch) when it can't provide more air and it is suffocating, and of course not getting burned. The general thought is perfect, but more developing needs to be done, i need to thing about it more more close up photos can help.

ge0ne · Post by **ge0ne** » Mon Jul 20, 2009 3:36 pm

And when supercherger is off the turbo must breathe on its own no S/C in the way...

dbsharp · Post by **dbsharp** » Mon Jul 20, 2009 3:59 pm

I would think that until the charge piping between the feed to the turbo and the outlet of the supercharger reaches atmospheric pressure, the supercharger is not a restriction and is only helping. Once the turbo is trying to pull more air than the SC is suppling, you should see a vacuum in that section of the charge pipe. Until this event happens, I don't see how opening this chamber to atmospheric pressure would be beneficial.

Post by **Gaskleppie** » Mon Jul 20, 2009 4:08 pm

We were thinking about that also. With a delta-P sensor we can determine if the turbo is doing more than the charger. We have to see if that works. But first things first. The guy just called me that the oil pressure problem made more damage than we thought. 1 blue big-end and all bearings damaged. Even the crank is damaged.....

fah · Post by **fah** » Mon Jul 20, 2009 4:34 pm

thats a BIG turbo ... what size turbo back house are you using with what stage wheel?? It could be too laggy ... is that a SOHC? I am only seeing one B.O.V. between the super charger and the turbo. I think you are going to need another after the turbo. Setup and fabrication looks great.

elevation · Post by **elevation** » Mon Jul 20, 2009 9:28 pm

I wonder if the charger and turbo max intake air flow? It would be cool to attach some how an A/C clutch or one way clutch to the charger and stop it from turning when not needed to stop the pericidic draw.

Post by **Bugermass** » Mon Jul 20, 2009 9:47 pm

I'd say dissconnect the turbo from the SC and with it in free air, do a pull with a slow ramp like 4th or 5th gear and see when the turbo really starts to build momentum, Note the RPM, use that as a starting witchover point and move around from there till you find the sweet spot. On another note, the size of the pipe where the butterfly valve is doesn't look like it'd be big enough to flow a whole lot of air, especially with there being 2 90deg angles in the path of flow.. Try running it just turbo without the pipe on it and see if you make more boost, then try running it turbo only but with the butterfly open and see how it perfoems that way, then you can tell if the piping is flowing enough to support the turbo.

Post by **Gaskleppie** » Tue Jul 21, 2009 12:53 am

Try running it just turbo without the pipe on it and see if you make more boost, then try running it turbo only but with the butterfly open and see how it perfoems that way, then you can tell if the piping is flowing enough to support the turbo.

Thats a good tip! I had my doubts about the throttle size also but your advice is a good way to test if it is really too small.