I've already played with an early VATN.
Not ready for prime-time, I'm afraid.
They are extremely sensitive to over-spin.

 

Isn't Porsche using them in their new 911 Twin Turbo? Some company in the US designed it for them if I remember right.

 

you are correct about the new porsche, also these turbo's are very popular with diesels.

 

The Porsche 997 uses a Garret Turbo with variable vanes around the periphery of the turbine. Smiths has a similar approach except it uses gates rather then vanes. More reliable and no overspeed.

Volvo's is more like like a 2-stage turbine system controlled by manifold pressure although it has only one turbine and a stator. They've used VGT systems on their diesel trucks for a while now, but they've had issues with sticking vanes.

 

This point was made by RG a few days ago . We also have some evidence of turboed motors failing due to heat issues at the exhaust ports as reported in this thread.
Wonder if this will become a major argument in favour the super charger vs the turbo on our engines ........

 

Probably not.
Corner seal failures are going to be a function of port design, anyway.

BTW - I don't agree with the correlation between higher exhaust "back pressure" and higher detonation. Higher latent heat is the issue with exhaust retention. High port pressure at the exhaust will lead to charge dilution which reduces the likelihood of detonation.

 

Yea what he said!

 

Where the heck did you get that idea???

 

What do you mean?


That is the essence of EGR. You can jack the static temps all you want - if there is an over abundance of non-combustibles in the chamber, detonation will be suppressed.
"Back pressure" is not the actual issue leading to detonation. It is elevated temps in the engine materials from reduced flow.
That is, to some degree, offset by reversion.

 

??

 

Ahh. OK. I'll check my PMs.

 

Sorry Ray it's been a busy week with the new job training and all. You actually caught me when I was at a restaurant the other day and by the time I got free it was nearly 10 PM here. I don't remember what time zone you are in but I thought it was too late.

 

^^ I'm warming up the grill and chilling down the pool! If you hurry up, you can help me rebuild this Renesis I have sitting in my garage!

 

You're producing low compression rotors?

 

I don't know where he gets these ideas.

 

Nah - I'm not a big fan of the "low-compression, high-boost" concept.
No, I want to do a straight rebuild - maybe a slight clean-up of the ports.

 

Yeah, swa that earlier.

 

Keep in mind that the "concept stage" as of now has no stage to follow it in the works so it will remain there for quite a while.

 

I'm all about not changing too many variables at one time.