3 turbos... just a thought.

[paulg25]

Posted this up on the UK forum but didn't get much response... what about leaving the standard turbos where they are and adding a 3rd large one where the downpipes meet? Has it been done before? Would need a controller to handle the wastegates but have a I missed something obvious? Comments please.

 

[DVR]

Did RX7s have sequential turbos for the same effect?

 

[bradc]

Yes, you would be looking at something similar to what Subaru used to use or what Mazda used on the RX7. The stock turbos on a VR-4 can provide over 1 bar boost from 3000rpm to about 5500rpm. You could have a larger turbo take over and provide power from 5500rpm up to 7500rpm or so. 1 bar at 7500rpm would be a ton of power!

Getting it all to work reliably would be a pain, fitting it into the engine bay would be nearly impossible and finally getting a smooth transition from the two stock turbos to a single larger turbo would be damned near impossible!

Do a search for valley of death or VOD on some subaru forums or google

 

[bradc]

http://www.clubvr4.com/forum/showthread.php?t=41054&highlight=legacy+turbo

On clubvr4 we had a good argument about it

Most of it is good natured sledging between Legacy and VR-4 owners. Post number 76 in particular makes me LOL everytime i read it. There is quite a bit of VOD debate too though.

A quick google search only bought up one graph for a Subaru twin turbo, here it is http://www.torqueperformance.co.nz/i/dynoplots/subaru/01-b4-std-vs-s1.png

This is also posted on the cvr4 thread, go to about post 127 and read from there. Check out the numbers in post 137. The Subaru primary turbo spools up early but doesn't provide much power at all really compared to the turbos in a VR-4. For example at 4000rpm the stock VR-4 makes 134kw, the Subaru is 80kw. Once the large second turbo starts spooling the graph rises nicely.

 

[king_panther]

The 13B & 20B used sequential turbos. Weren't they the first production engine to do so or something?
Haha reading all about the 'blip' in the B4s when they first came out.

Has anyone though about removing 1 TD03 & replacing it with a larger one to create a sequential scenario? Or does each turbo feed a bank ?

 

[frozen]

The 13B & 20B used sequential turbos. Weren't they the first production engine to do so or something?
Haha reading all about the 'blip' in the B4s when they first came out.

Has anyone though about removing 1 TD03 & replacing it with a larger one to create a sequential scenario? Or does each turbo feed a bank ?

if you have a look under the bonnet, youll notice that 3 banks go into one turbo, 3 into the other. It really wouldnt work.. think of the way the pipes join. If one had alot more coming through it than the other.. you get the idea

 

[SupremeMoFo]

Mercedes made a tri-turbo diesel V6 a few years ago.

 

[paulg25]

Is there such a thing as an air bypass valve that could be used to bypass the original turbos once a 3rd one had spooled up?

 

[bradc]

Paul, yes there is. Have a look online for schematics on how the Subaru turbos worked, or the RX7's

 

[paulg25]

Thanks for that Bradc. Anyone know how effective the wastegates are at controlling the standard turbos? If they are held fully open will the turbos generate any boost? I guess it depends on the amount of exhaust gas trying to get through the turbo. Will they cause a restriction if a 3rd turbo was fitted?

 

[bradc]

If you wanted to use the wastegates to redirect the exhaust flow to a big single I think you would want to weld the stock ones shut and put in some external wastegates and have those go into the big turbo.

 

[king_panther]

Where the hell do you plan on fitting the 3rd turbo???

 

[ygoslo]

Hole in the floor, mount turbo in passenger footwell, only drive in winter.

Sounds good to me.

 

[bradc]

If you have a full ecu, which of course you would need with this setup there is a TON of room above the gearbox

 

[king_panther]

If you have a full ecu, which of course you would need with this setup there is a TON of room above the gearbox

Bah, just poke a big arse supercharger out of the bonnet. Coupled with NOS lol.

 

[SLY-031]

If you have a full ecu, which of course you would need with this setup there is a TON of room above the gearbox

Which would suit a GT3037(3076R) or slightly larger without issue, and you wouldn't need two smaller ones to spool it up...

 

[bradc]

Yeah you would because a GT3076R wouldn't spool until 5000rpm