twin turbo Idea...

I was just reading through Lincs excellent thread, great reading. And it got me thinking. In regards to spool up and the 3 into 2 type
of turbo inlet housing, would it be feasible to run 2 x small VNT turbos out of say, a 1.6 or 2.0 VW golf or something?
My reasoning is that a 1.6 or 2.0 revs up to 6500 and my 2V engine is looking at peak hp at 4800. So, even if the turbos were technically a bit small,
they wouldn't run out of puff because I'm not winding the engine out. Also, because of the VNT nature of the design, I would have spool very low down in the rev range and that, to my way of thinking, would be ideal with my leggy 250 and should produce a pretty mental low end torque. Am I right? Any thoughts on this?
Cheers,
Steve.

Interesting. How are you going to control the variable part?

I kinda figure that the actuator would be boost referenced. The one I saw *appeared * to be pulled manually by a can?? Like a wastegate?
There would have to be a way to do it. Even an electronic boost reference could be made to operate something surely? Not sure.
This is why I posted this. Need info and/or solutions to my problems.
I live in the hills and there's lots of them (hills) and the roads are windy, so grunt on tap would be a great situation for me.
I just say no to V8's.

Sure it'll work!
The beauty of twins is that the turbo's can be smaller which reduces the lag. But since there are two of them, they also can provide plenty of airflow required at the top of the RPM scale.

The downside...just about two of everything and it'll eat up engine compartment room real fast!

Will

I have been toying with the idea of running twin turbos on my 3.3L Fox Mustang.

I wanted to run two Garrett T25's, they were original equipment apparently on some Saab's.

I want to run the two in parallel with a highly modded log with direct port fuel injection.

Ha Ha yeah Will, it will eat up space, My steering is also on that side, and the starter motor. I can move the starter to the other side I reckon.
I could also get an RRS rack system and get rid of the steering box, something I wanted to do anyway. Or I could move to the US and get rid of the steering on that side.
I'm really very keen on this idea, especially in regards to the VNT aspect. In addition, My coupe runs on straight LPG (propane)with an Impco 425 carbie, so I can set up the converter
at the carby for a freezing cold fuel supply.
have a look at this if you are interested in LPG.
http://autospeed.com/cms/A_107764/printArticle.html
This one pulls a stonking 375hp at the wheels. It looks like an E Model converter bolted straight onto the Impco 425 carbie.
No blow off valve either, but a cool butterfly operating with the throttle. AND the license plate drops away for more airflow under boost!!Sick!
Still need to work out how to actuate the variable aspect on the turbo though.
OK
Steve.

HA HA check out this animation of a vnt. This is getting very serious!

http://www.youtube.com/watch?v=Gc2awh0O0Bc

2 little vnt's could be the way to go for street I reckon.
Steve.

I don't know much about turbos at all, but could you use the voltage signal that is sent from the DUI or MSD box for the tach as the signal to 'open' or 'close' the vanes as the revs go up and down?

I'm sure someone could work it out mate! I'd be happy to see how it works with the can under boost.
It looks nice and simple, and you could hard link the 2 cans together to keep them in tandem. Does any
one know where I can a map of the t15 t17 and t18 turbo's? I have looked, but just can't locate any.

Are the gains to be had from the variable pitch worth the hassles of implementing them? How much would you gain over a pair of large trimmed conventional T025 or small trimmed T03 units? Personally, I have no idea but it seems like a lot of aggravation for what might turn out to be marginal gains.

Yeah the turbo map calculator at squirrel shows a pair of gt2056 to be a good pair for my application, if I am reading it right, and there's no guarantee of that. But I would like to have boost right down low. This car is my daily driver. It's a manual. And I think it's what I want. Who knows why!

I guess a good question would be how low you want it?

I know the fairly stock 200 has no problem moving the car down low on my falcon, its when i get beyond 3 grand it has nothing left unless the timing is advanced to hell then i can get almost to 4 before it runs out of steam.

You have to keep in mind your working with a reasonable amount of displacement here so you should have enough torque to get the car rolling as unless your hoppin up a van most of the cars these were installed in were fairly light.

Yep, my coupe is about 1200kg or so. I'm running an oz 2502V head, mild cam at the moment and LPG. I have no real dramas getting off the line
or anything like that. I have juice well beyond 3k so what I was thinking was a very broad torque curve that starts at 1200 or less and peaks at say,
3600 where the hp is starting to kick in and a peak at 4800. I have been looking at Torque curves from VNT dyno's and the T curve is long and high.
I reckon it would be ideal for a grunty daily driver, and great in the hills.( I have a 20% hill on my home stretch) I am starting to narrow in on some cheaper ones, no use spending heaps of cash on it, that would defeat my purpose. I can get crow to make me an lpg/turbo cam to spec, but will chat to them about it when the time arrives. I just need some local dudes to get on board so I can iron out the bugs. All I hear is "get a big turbo/v8/just leave it/go nostalgia" Noone has said, "right on man, try it out, can't hurt" Which is what I intend to do. But, I would like to try it on my mild motor first to see what happens. I'm really not interested in doing something that is tried and true. Where's the fun in that?
Cheers.
Steve.

If you're set on a VGT turbo, you might consider simplifying things and using a larger single. One of somewhat proper size should still spool by 2000rpm. The tricky part then is still finding one with a mechanical actuator instead of an electronic(Holset) or hydraulic(Ford). Another more conventional option is to build a pulse-paired header and regular turbo with a twin scroll turbine.

I will also add that tuning becomes even more critical as cylinder pressures increase at low rpm.