Homebrew Bay Window Turbo

[Zander]

So lately I've been playing around with my daily driver 68 Westy and decided it needed a Turbo too Got it all put together and it really is fun to drive. So much more pep and passing power. Maybe someday I'll put it on the dyno to see what its putting out. One problem I'm having is that I can't get it to boost past 8psi. Ive disconnected the waste gate and wired it shut in order to see if it will build anymore and it just builds a consistent 8psi. If any of you guys have any ideas why it will only build that much I'm all ears. You won't offend me, my header is low buck but I built it myself and I made my own pvc cold air intake up to the scoop on the side of the bus Still need to clean up the wiring etc. but I'm really having fun with this thing, just trying to troubleshoot the 8psi max thing. If i can build more boost a water/air intercooler is in the future. It's nice not having to build things show oriented, daily driver beater is where its at!

So here are the specs:

AS41 case
2007cc (90.5x 78 stroke)
Engle 110 cam
Stock heads cut for 90.5s
Single heavy duty valve springs
Stock rockers
Mexican fuel injection
MS2 V2.2 with edis
Td04L turbo off an 07 WRX with stock wastegate
Header and j tubes are 1 3/8 then 1 7/8 up to turbo
Exhaust is 2 1/2" through a 12" glasspack

Let me know if i forgot something y'all would like to know. I've checked and there are no exhaust leaks etc.

Thanks!
Ryan

Some pics:

[gaston]

Maybe flow restrictions of the head and the runners. The basic engine needs to support the right flow values to support the compressor map of the turbo charger.
Better performance/ efficiency should be possible with an intercooler It's easy to fit in your setup.

[Buggsy]

First of all, absolutely love your set-up. Very smart mounting the turbo off to the side which makes everything else so much more accessable.
Easiest thing to start with is lose the glass pack temorarily and see if that fixes it. Turbines hate backpressure on the exit side.
Check your volume fuel delivery. Should fill a pint jar in less than a minute. If that is ok............
Dual springs may be needed. I find it difficult to believe with stock size valves, but everything else should support 180 horsepower, and sounds like your only getting 120.

[Zander]

Thanks for the tips guys.

Gaston- Yea I've pondered the same thing with the heads and runners. I've really been thinking a nice set of big valve heads with dual springs may liven things up.

Buggsy- Thanks for the compliments. It works out good being mounted where the battery used to be. Like you say, easily accessible. The battery is now under the rear seat. I have run it without the glass pack quite a bit and still just the 8 psi. It just looses some of the great whistle with the glass pack I will have to check volume fuel delivery but suspect that it is all ok. Afr's stay right where I want them and injector Duty cycle is about 65% all out. I have heard numerous times that you really need some good spring pressure when running boost. Makes me wonder if duals should be a definite with turbo.

I've really just been curious whether it's something that just stands right out but I'm missing it. Like too many sharp bends in my header system. Too small of heads. Improperly sized turbo etc. I mean its a heavy bus! There shouldn't be any problem loading the turbo. Overall I'm really happy with the setup but as everyone knows with boost you always want more. Or at least the ability for more. I don't think id ever go over 12psi or so as this has to stay daily driver dependable.

[Clonebug]

That turbo should easily put out up to 17 lbs.

You must have a leak somewhere.

Check to make sure your blow off valve isn't coming off the seat and bypassing the air.

I have a Subaru turbo and the stock internal waste gate is set at 6 lbs. I have no problems with it putting out 12 lbs. right now with a manual boost controller I made from a 1/4 inch brass tee.

I have just as much extra exhaust tubing as you do and have not had a problem.

Something is letting air get out I would say.

[Zander]

Thanks CLonebug, Your build is actually the inspiration for the way I did my header. I thought..... that's so easy and just bolts right on. If it works for him I'll give it try!

This issue is just so weird. This is my 3rd different setup on a turbo VW and I've never had a problem building more boost. Neither have my buddies cars that I have helped with. I definitely don't have any BIG exhaust leaks or anything as there is no "ticking exhaust" leak sounds or black exhaust blown out at any joints. The charge pipe is pretty basic and all clamped down so I doubt its there, but I'll check again. I agree though, I can't see any reason why with my configuration I can build over 8psi. It has to be some leak somewhere! I'll spend some time this weekend and see if I can come up with anything.

Thanks for the input guys! Just wanted to make sure it wasn't something right in front of me I was missing

[kubelguy13]

Awesome work!

[Chip Birks]

Check your intake manifold nuts at the head. I had this exact same issue with my turbo mexi setup. Couldn't hear it, tuned right through the extra air accidentally, but eventually found that I literally had nuts missing. Put new ones on good and tight and was right up to 12psi.

[Clonebug]

What kind of blow off valve are you using???

It looks like the same one I use from a Saab 9-3 turbo.

Post a pic of it installed would you???

[supaninja]

Zander, you are a wild man!

[Zander]

Don't make fun of my clamps there will be nice t-clamps on there soon. I will verify these are or aren't holding pressure this weekend.Thanks for the heads up on the intake nuts chip. Hadn't thought of that but did verify they're tight. I think I'm going to build a setup to pressurize the intake and check for leaks. Then from there it has to be exhaust leaks. I think I did find a small exhaust leak this morning at the #2 exhaust to head Joint. I'll fix that this weekend and see what happens. That's the only small one I noticed right off.

[gaston]

What kind of blow off valve are you using???

It looks like the same one I use from a Saab 9-3 turbo.

Post a pic of it installed would you???

It's a Bosch blow off (0 280 142 110 older one with softer spring ends with 103). I've this in my 95 Saab-Performance.

[Clonebug]

Turn it around.
As far as I can tell the pressure is supposed to be on the side connector.

That is how I have mine hooked up and I have no problems to 13 lbs.



Do you have it hooked to vacuum and boost?? Mine is hooked to the manifold just below the carb so the blow off valve is open during vacuum and closes at about 4 lbs vacuum.
I run the filter on it since it is open during cruise conditions.

You could switch it and try it to see if it holds the other way.

[Vee Dub Nut]

We'll wouldn't you know... Clone, looks like your right! I've been running mine backwards all this time. Just haven't upped the boost to notice the problem yet...

http://www.sjmautotechnik.com/trouble_s ... tml#bypass

[Zander]

There seems to be a lot of debate about the correct plumbing of the bosch bov. I did try it both ways and didn't notice any difference to speak of. I've found sites on the internet showing both ways of connecting it. Even an old one here on STF http://www.shoptalkforums.com/viewtopic ... 3&t=117598 I had originally plumbed it the way as pictured just because this seemed to make the most sense to me. On my bug with a Turbosmart vee port pro (or any other aftermarket bov) the plunger faces towards the intake then the boost is shot out the sides of the valve. So in theory I just put the bosch one on the same way....plunger towards intake and boost out the side. Though again, I did try it both ways with no noticeable difference. Same boost, same sound.

On another note I'm pretty sure I found the leak! Its a doozie.....

Built this to pressure test the intake:

Took me 5 minutes to build the pvc contraption...took me 15 to find a squirt bottle and fill it with soap and water

Hook it up to where the air filter would be on the turbo:


Pump it up and spray the entire intake system. Find bubbles!! Glorious bubbles!! My daughter enjoyed them. She was helping me.


Just to clarify. It didn't take 30psi or anything crazy to cause the air to come out of the throttle shaft. I can litterally let the handle on the bike pump fall at its own speed and bubbles form. 1 psi or less and this things a bubblin. I did however pump quite a few times to get lots of bubbles for the picture I can pump as fast as i want and still cant build over 3 psi with so much leakage.

I guess its time to build an adapter for the ford TB I've got sitting on the shelf. I like building the adapter. I just really don't enjoy trying to figure out the whole funky accelerator cable deal. I can do it though, did it on the bug.