A long time waiting, but I got to fire up my SC400 today for the first time in 2+ years. I was very excited.
This is the first time the motor has run since it has been mated to the 6-speed Getrag, and the new TT setup. Now the car didn't move, but it was pretty cool to see her run again. i was pretty excited. Hopefully everything will be back together and running just in time for the chicago winter. LOL

 

Wait, WHAT???

no wastegates???

you realize you can't do that without causing some serious issues, especially on a street car...

You are going to severely shorten the lifespan of the turbos by great numbers... how exactly do you plan on controlling just boost and not manipulating the exhaust???

 

There is no need to eliminate the wastegate... that is just silliness...

the wastegate is there to prevent premature turbo failure, and anytime you lift off of the throttle, your proposed plan falls through the floor as the turbo will lose its spool right there, wastegate or not... the only way your proposed theory will work is if you don't lift to shift, and even then, there are better ways - stutterbox, anti-lag, etc...

Check it out, here's a 4 cylinder crate motor from Magnus running 198 mph traps, making 1400 hp out of 2 liters, and guess what... he runs a wastegate... http://www.magnusmotorsports.com/raceteam/index.htm

here's a 9 second Evo... again, wastegate http://www.buschurracing.com/racing-evors2.htm

And yet another: http://www.buschurracing.com/racing-evors.htm it doesn't say anything, but that small pipe coming out of the bumper with the large exhaust pipe is the wastegate exhaust...

 

Congrats on it running again, That has to be a great feeling.

 

Rdm, any dyno #'s yet?

 

any dyno #'s yet? LOL the car hasn't even moved. :-)
Only started the motor for now :-)

Thanks Scott. It was a really good feeling, and it ran really well too.
Anything new with your car? are you still coming up to Chicago anytime soon.

 

Thanks Mitsuguy, you are right. wastegates do increase the turbos life. I'm not really concerned with that.
And I believe you about big HP motors running wastegates, but I'm not really looking to do that either.
It made my setup much cleaner, and I’m controlling boost to the motor by venting the pressure off, instead of venting the exhaust off.
The shop doing the work has this setup on previous cars, and it works really nice.

 

I am knee deep in fabrication of parts for the new motor, Slow steady progress.
Last time I went to Chicago I ended up getting rushed and couldnt hook up. I am sure I will be there again soon. I get there about 4 times a year at minimum.

 

I thought this was a pretty cool photo.
Thought I'd share it.

 

Wow this is just too awesome, lmfao at this thread. I'm definately not running wastegates on my next project. I want better spool too, I never knew that could be achieved by eliminting the wastegate all together. That's brilliant. Good luck man!

 

Thats just the thing - you won't get better spool by eliminating the wastegates...

a wastegate only opens once boost pressure is reached, therefore it is completely closed until preset boost pressure is reached, therefore no difference in spooll... all that running no wastegate is going to do is overspin the turbos...

lets look at a turbochargers operation during a typical drag race with a car that has a planned boost pressure of 20 psi, but a turbo that is capable of 30 psi on this application...

with no throttle, the turbos are idling, spinning quite slowly, the accelerator is pressed and the turbos spin up... here comes full throttle - the turbos are accelerating quite fast up until 20 psi, at which point the wastegate partially opens to vent some exhaust gas... lets say the turbos are spinning at 60,000 rpm to make 20 psi at the high end of the rev range on this particular car... the wastegates open, and 20 psi is seen at the intake manifold - you lift off the throttle to shift, and the turbos slow down, back into gear, back on the throttle, and the turbos spin up again, wastegate is completely closed until 20 psi is met...

now, without a wastegate and varying boost pressure only, this all starts out similar, but instead of a wastegate regulating turbo speed to control boost pressure, the turbos are allowed to spin at pretty close to their maximum speed once they have spun up... there will be no difference in spool time... even though target pressure is 20 psi and requires about 60k rpm at the turbine shaft, without a wastegate, that turbo may spin up to 80 or 100k rpm (close to it's maximum speed), for no change in boost pressure... the same applies here though, as soon as the throttle is closed or even let off partially, the turbos are going to slow back down, wastegate or not... even if the throttle is left open during the shift, the lack of load on the car will mean not as much exhaust gases will flow, and the turbos will slow down anyways... the ONLY benefit to this is that while you are between gears, the mass of the spinning turbo will take just a split second longer to slow down...

like I said originally, there is zero need to not run a wastegate, and if you are looking to keep the turbos loaded during shifts, you are better off running an anti-lag setup...

The only time I could see not running a wastegate would be when you are going to max out a turbos flow/pressure on a certain engine, but even then, you don't want to max out a turbos flow/pressure because it will lead to a very early death for the turbos... Every turbo has a "sweet spot" on a compressor flow map where engine flow and pressure cross and work on a particular engine with a particular volumetric efficiency... This is why you can't just throw any huge turbo on any car...

For the record, I have owned 4 turbo cars, with one Talon making 500 AWHP... I know a little about turbo theory... I have also worked with the guys at Cartech, where a little known guy named Corky Bell got his start...

 

Basically mitsuguy is correct, except that no wastegates causes a surge of a few pounds as you shift gears. If you are running a desired PSI of 20, the shift into the next gear gives you a small psi surge (23-24 psi), instead of a lower psi, and then waiting for the turbo to spool back up. the initial spool should be the same.
Basically it causes a mild surge in the car each time you shift.
It won't help the turbo life any, but again that’s not what I’m concerned about.
Now an anti lag, although that’s for a launch and not during shifts, delays the ignition until the exhaust valve is open, sending the combusting gases into the header to spool the turbo. This is basically the worst thing if your worried about the turbos life, and over spool. but it's great at building boost off the line. I'm thinking about installing an anti lag system also, but thats a later step. I’m not aware of an anti lag system that works during shifting.

 

What is the chrome cylinder looking deal down on the left in the picture by the harmonic balancer?

 

Never mind, I think I figured it out, Must be a belt tensioner to replace the stocker. Where did you get it?

 

That’s my secret go faster chrome cylinder. LOL

You are right, it's a belt tensioner. I think it came off a supercharger kit that Chris installed on a different car. the kit wasn't right for the car, and the tensioner couldn't be used.
He had it around the shop, and pit it on.
I think he had to modify it a bunch. it was designed to pull the belt, and now it pushes it, and the wheel was for the inside of the belt, and was grooved. He machined it down so that it's flat for the outside of the belt.
Nice eye Scott. I can’t get anything past ya. ;-)