variable geometry turbos
 

Since I started looking into these turbos I have been nothing but impressed the diesel industry has been using them for a while. They just started using a set courtesey of borg warner in the porsche 997 turbo model, supposidly lag is nearly non existent. To what i have heard it is comparable to the feel of supercharger without sounding like your alternator is on the way out. According to what i have read the reason they havent been using them in gasoline motors until lately is because they didnt seem to do well with the higher heat of the gasoline motors. I realize even though porsche is using it I wonder If our egt temps would be too high. If not this would solve the main issue wwe have of beuilding big power (no low end). has anyone tried these? As far as i know borg warner seems to be the main supplier.

Failure due to high egts is a theory that doesn't seem to be supported by the facts. There are a couple of us on the forum that hope to try them.

they are still pricey

How would you control it? There goes a lot more $$$ for the electronics......Maybe the diesel guys have some sort of aftermarket stand alone controler?
-Spence

You can get some of the holsets for less than $200 shipped. The electric controls are un-necessary, they can be replaced by wastegate actuators. If you want to maintain the electronic control, the pinouts should be relatively easy to find.

just get one of these

http://cgi.ebay.com/ebaymotors/ws/eB...m=200350746277

you are welcome

does that actually work? ^^^

works fine
boost kicks in WAY earlier and keep pulling
key is using divided turbo with undivided manifold
research

Sound performance thinks so.
http://www.youtube.com/watch?v=_KNLKVgg8po&NR=1
http://www.spracingonline.com/images/products/36594.jpg

^^ I am not sure how much truth are there to that dyno graph ....
the turbo should see the same max HP but earlier boost

to me its just the boost comes in earlier due to the fact that the flange changed the a/r say from 0.96 to 0.48 until the flange was fully open, 10psi in this case

I call bs on the higher peak numbers though

any added restriction would lower the peak numbers

It's not my data so I make no claim to it's accuracy. Is it possible that more boost earlier coincided with the engines torque peak? Is it possible that the faster spooling overwhelmed the wastegate momentarily leading to more peak boost than recorded?

it says quickspool on the dyno sheet with that 2jz but really 5000 rpms for that motor is still pretty high and the turbos for the point where they are coming online they really arent making as much power.

The reason I started this thread is I thought it may be a way to build some more low end power like the twins but the power of a larger single. there is a guy locally that is building a rb26 with a borgwarner turbo i dont know if its variable geometry but he is shooting for 1000whp we will see but if soo then 500 with a quickspool should be possible for us. I seems to me that the only power issue for the 13b wasnt lack of power for the fd but that the big power numbers made with a large single made the car so laggy it wasnt very streetable. maybe this will take care of that.

The a/r of the he351ve goes way way down and it opens up to well over 1.0. It's supposed to flow for about 65lbs/min.

I wonder if it could handle the EGT's of the rotary... ^^^

I intend to find out. It sounds like sex when the vanes actuate.

keep us updated man! ^ what size are you considering?

Hopefully the he351ve i mentioned above, but it's going to be a long term project.

http://c4.ac-images.myspacecdn.com/i...80990c78c3.jpg
http://c1.ac-images.myspacecdn.com/i...da545ffe00.jpg
http://c1.ac-images.myspacecdn.com/i...e561dbed1c.jpg

Could that thing work for a tubular stainless sequential TT manifold?

Don't see why not, they're kinda large though. If you hacked them to use wastegate actuators instead of the on-board actuator they'd be smaller, but you'd have to deal with subtle differences in the actuators causing problems.

Next to a DSM 14b:
http://i6.photobucket.com/albums/y21...2/P8021422.jpg

There used to be a few of them on ebay for <$100, a quick auction for a lot of 4 for $120. From what i understand the dodge guys are sooting them up and the core guys and resellers are letting them go cheap. One thing to note though, is the flange is kinda funny.

Video

did that thing get higher pitched... and then get lower pitched as it kept climbing in rpm? that sounded friggin weird!

On the forums the guy in the build thread (maybe the same guy) said that when the vane actuates you get a lot more turbo noise, but he was running an 8" screamer pipe so I dunno.

Ideally the vanes would actuate based on shaft speed rather than boost level, but you'd have to sort the pins out for that. I know they have a speed sensor and position sensor built in.

so to use the turbo would you need to use more electrical controllers other than a boost controller or is that about it? also where can i get one of these turbos?

You do know that Mazda had this type of setup STOCK on Rx-7's in 1986?

https://www.rx7club.com/attachment.p...1&d=1250895191

manifold was undivided and the larger of the two inlets on the turbine housing had a flapper and an actuator kind of like the FD's turbo control actuator. It was operated by vacuum and a solenoid valve. Mazda ditched it in 89 and went to a standard divided manifold/divided turbine housing setup.

boost threshold VS lag
 

You mean boost threshold? You mean the lowest RPM for which a desired boost pressure is attained, right? This seems to be what everybody who runs a big turbo, or a setup w/o good "low end", complains about.

Lag and boost threshold are two different things... lag is what you get when you mash the gas and have to wait for pressure to build and that is very dependent on RPM... for a non-seq turbo car, you have terrible lag below, say 4500 rpm. Above that point, lag is much less. For my car, as an example, 4500 rpm is the boost threshold for 13 psi. The two single turbo cars I've been in had pretty much zero lag (much less than my car for example) above their boost threshold point.

I think the new turbo technology tries to minimize both boost threshold AND lag.