Turbo VTEC

I started some thread drift over in my "Hood Ornaments" thread in Viewfinder.
So I'm opening the discussion here :)

I thought the principle of the dump valve was to dump pressure on the inlet side?
So that when you lift off the throttle the exhaust gases keep the turbo spinning, it doesn't stall against the build up of pressure.

I can't see a reason for a dump valve on the exhaust manifold. This looks more like a separate atmospheric wastegate, where my car has it internal in the turbo housing bypassing into the exhaust outlet under computer control.

Though I know race cars aren't at all like my road car :)

SW
Perhaps I am misunderstanding what pipe you are referring to..Can you put an arrow on the photo to the different pipes to make sure we are both on the same page?
Thanks Javier

Quote:

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Originally Posted by SmartWombat

I can't see a reason for a dump valve on the exhaust manifold. This looks more like a separate atmospheric wastegate, where my car has it internal in the turbo housing bypassing into the exhaust outlet under computer control.

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What you're saying makes sense to me. As I (very basically) understand it, that's how my VW TDI works.

Here are the images, I didn't want to edit and repost them without your permission.
I've marked the exhaust flow with little arrows, and outlined the junction plate on the turbo and ringed the valve.

Basically, the waste gate is used to control the amount of exhaust flow to the turbine..This is what is used to control the boost...

http://img221.imageshack.us/img221/2...eengineyq3.jpg

http://img407.imageshack.us/img407/1...engine2jz7.jpg

Thanks, looks like it's mechanical with a set boost pressure ?
Or is that little brass pipe in the last photo a union for a pressure feed, to give the driver a boost control?

In this picture it is mechanically set to 9 psi.

Wow, that's just over 0.5 bar - my road car is running 1.0 and with the remap 1.5 bar
And that's such a huge turbo too, I was expecting around 1 to 1.25 at least.

SW
Oh, that was min boost..This engine was run at 45lbs of boost and made over 900Hp.

That's more like what I expect form a turbo that size !
How long do you expect the engine to last when delivering that power?

It will last about a season of drag racing.

If the boost on my engine is turned up to 1.5bar, and the engine remapped for 120bhp (only 50% gain from 80bhp) then the life is estimated at 6000km.
So that is pretty poor compared to the impressive lifetime you're getting !

Man, what I'd give to have my old CRX-Si back with THAT stuffed under the hood :eek:

Hm, it might not fit in a CRX but maybe it would fit on an Atom.
They tend to use supercharger though, not turbocharger, around 100bhp less.

It'll fit with a little front end work ;) Do a search on a guy named Ed Bergenholtz and take a look at the CRX he used to race :eek:

Looking at the photos it looks like it's hooked up to a DTS Dyno?
JB

Quote:

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Originally Posted by Jimmy B

Looking at the photos it looks like it's hooked up to a DTS Dyno?
JB

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Good eye..It is indeed..