Variable geometry turbos

[Lefty]

In principle, could one of these (an aftermarket vnt) be retrofitted to any turbocharged car? What are the differences, if any, in inlet/oulet, boost control etc?

Cheers,
Lefty

[Megaflow]

In principle anything is possible. However, you will need some kind of ECU reflash/upgrade/change (depending on what you have today) to drive the VGT, the control gear of the VGT are typically water cooled, so this will need to be factored in, with all of it's complexities regarding increased heat rejection, water pump capacity, etc.

[Lefty]

Hmmm, I'm already using Syvecs which might be able to control it. Wasn't aware of the cooling issue though, thanks.

As you can tell, I really don't know much about them. I have an Impreza p1 with a 2.5 block and running a much larger turbo (RCM450). It makes great power torque in the midrange but still in a reasonably narrow band something like 3000-6000 while the engine could rev to 8000 happily.

I was watching the inside koenigsegg videos about the one:1 and it has 2x vnt turbos on a 5.0 v8 that make full boost ("only" 1.8bar) by 2800rpm and yet puts out 1340bhp (1360ps) at 7500rpm and revs to 8250.

I'd love to have a single vnt 2.5 4cyl which could reach 1.8bar by 2800rpm and make 680bhp at 7500 and rev to 8250...

There are plenty of turbos off the shelf that could take the subaru engine to over 600 but the boost threshold will be very high, probably 3500-4000 rpm.

Cheers,
Lefty

[Lefty]

I seem to recall that the 997 uses a pair of VNT's too?

[stevieturbo]

Lefty said:

Hmmm, I'm already using Syvecs which might be able to control it. Wasn't aware of the cooling issue though, thanks.

As you can tell, I really don't know much about them. I have an Impreza p1 with a 2.5 block and running a much larger turbo (RCM450). It makes great power torque in the midrange but still in a reasonably narrow band something like 3000-6000 while the engine could rev to 8000 happily.

I was watching the inside koenigsegg videos about the one:1 and it has 2x vnt turbos on a 5.0 v8 that make full boost ("only" 1.8bar) by 2800rpm and yet puts out 1340bhp (1360ps) at 7500rpm and revs to 8250.

I'd love to have a single vnt 2.5 4cyl which could reach 1.8bar by 2800rpm and make 680bhp at 7500 and rev to 8250...

There are plenty of turbos off the shelf that could take the subaru engine to over 600 but the boost threshold will be very high, probably 3500-4000 rpm.

Cheers,
Lefty

You'd also need a 2.5 block strong enough to handle that torque at low rpm, and heads/cams/valvetrain to be happy at 8k+

There may be some twin scroll setups that can get you close, without the complexity, whether it's a good idea or not is another matter.

[Lefty]

Yep there are a few options there, the best is probably the block inserts that effectively close the deck I think.

[stevieturbo]

Lefty said:

Yep there are a few options there, the best is probably the block inserts that effectively close the deck I think.

There are a few out there, but IMO not fully tried and tested, and certainly not attempting silly torque at such low rpm.

And whilst the insert does help stabilise the top of the block and liners, it still doesnt address the fact 2.5 liners are thin and prone to bursting. Low rpm torque will be more likely to burst things than torque higher up the rpms.

[chuntington101]

Lefty said:

Hmmm, I'm already using Syvecs which might be able to control it. Wasn't aware of the cooling issue though, thanks.

As you can tell, I really don't know much about them. I have an Impreza p1 with a 2.5 block and running a much larger turbo (RCM450). It makes great power torque in the midrange but still in a reasonably narrow band something like 3000-6000 while the engine could rev to 8000 happily.

I was watching the inside koenigsegg videos about the one:1 and it has 2x vnt turbos on a 5.0 v8 that make full boost ("only" 1.8bar) by 2800rpm and yet puts out 1340bhp (1360ps) at 7500rpm and revs to 8250.

I'd love to have a single vnt 2.5 4cyl which could reach 1.8bar by 2800rpm and make 680bhp at 7500 and rev to 8250...

There are plenty of turbos off the shelf that could take the subaru engine to over 600 but the boost threshold will be very high, probably 3500-4000 rpm.

Cheers,
Lefty

Lefty got the link to that vid? Sounds VERY interesting.

I know koenigsegg are suing a hyper boost engine. no idea what this or how it works though

[chuntington101]

Just seen the video of the new kornigsegg turbo. It's basically a twin scroll turbo with a quick spool valve. All you need is a new housing (devided) and a quick spool valve.