Aerodyne Aerocharger...

[OutKlast]

Anyone know any companies that have prices for just the turbo? Been thinking about investigating a dual aerocharger setup. I've got mixed feelings about it as I don't know of anyone with a Camaro much less a twin/higher displacement. I've read through Corky Bell's "Maximum Boost: Turbocharging" nice book though his review of the aerocharger seemed odd when compared with the format he had been using for the other pages. Normally he would mention what something is supposed to do point out its negatives, say when and where it should be used if it all then onto the next thing. His aerocharger review however was all praise and talk of the technology. Upon further "investigation" it came to my attention that Aerodyne and the Aerocharger are made by Bell Engineering who's owner/founder just so happens to be Corky Bell author of Maximum Boost.

That being said it makes me weary of buying them because they may have negative points which I have uncovered a slight bit. One of them being a wastegate should be used with it. This being due to the fact that while under heavy load (say hard launch on strip tires) even at maximum setting the VATN angle is still to much and more boost then desired is created. I've also heard some stories with repeated failures of the turbo though they did comment that it was replaced all 6 times until they sold it.

I've also looked at the Garrett T25 but information is a little sparse on it and it seems to be an even lower flow turbo. I also didn't think it had a self contained oil system one of the perks imo with the aerocharger. I'm emailing Bell Engineering for laughs to see there thoughts on a twin setup on a 3.8L V6 and cost for 2 turbos if they'd even sell them directly to me.

[Wicked 3800 V6]

Don't bother with twins.
T25 is way too small.
Having a self-contained oil system would be nice, but doing the oiling is actually not that bad once you get it done.
Piping is more expensive than anything else. Don't forget that.

[OutKlast]

Well that's just super. Got an email back from Bell Engineering.

"Thanks for contacting us. Aerodyne, the manufacturers of the Aerocharger
turbos, is no longer in business. So finding the model you are looking for
may prove to be a bit of a treasure hunt. We do have a source for
replacement parts and rebuilds that may be able to help you with your
questions."

That pretty much rules that out.

[T-Punk]

hey bro, if you are dead set on twins ill try to help you out. im doing a twin setup on mine now so i can let you know what all you need to get to make it work. i cant really tell you what turbo to get because that depends on what you want your car to do (standard street car, drag car, road couse, or whatever) and even then there are some other things to picking the "perfect" turbo for you. i still havent quite decided on mine yet but im pretty sure im going with a twin T3 setup. the only other one i was looking at is the t25. after you choose what family turbo you want though there is also the trim and the different ar's to work with. the only other thing that makes twins a pain is with our cars there is no way to do it without a scavage pump (since the aerocharger is a thing of the past). If you want more info feel free to email me and i can give you the specs im working with on mine right now and give you some info on scavage systems and all the fun stuff that goes along with a custom turbo setup. i chose to go twins because they offer optimal placement of the turbo for slight gains in performance, and because i like to be a little different than everyone else.

[OutKlast]

Originally posted by T-Punk:
hey bro, if you are dead set on twins ill try to help you out. im doing a twin setup on mine now so i can let you know what all you need to get to make it work. i cant really tell you what turbo to get because that depends on what you want your car to do (standard street car, drag car, road couse, or whatever) and even then there are some other things to picking the "perfect" turbo for you. i still havent quite decided on mine yet but im pretty sure im going with a twin T3 setup. the only other one i was looking at is the t25. after you choose what family turbo you want though there is also the trim and the different ar's to work with. the only other thing that makes twins a pain is with our cars there is no way to do it without a scavage pump (since the aerocharger is a thing of the past). If you want more info feel free to email me and i can give you the specs im working with on mine right now and give you some info on scavage systems and all the fun stuff that goes along with a custom turbo setup. i chose to go twins because they offer optimal placement of the turbo for slight gains in performance, and because i like to be a little different than everyone else.

I'm not really dead set on twins and infact I'd kind of like to avoid it if possible. I was just looking at twins with the aerocharger because they woulden't be able to provide sufficent air flow as a single. There are some VNT T25's but at set specifications and even twins of VNT T25's I don't know if that would be enough for future upgrade. Information on the VNT T25 is sketchy at best hard to say how far they could go. The seller listed them as about 225hp for one but thats no doubt bhp and 450bhp is nice but not that high for 3.8. It would probably be sufficent for my inital needs as just slight boost about 300rwhp or so but once I start upgrading to go faster I'd quickly hit there limit supposing its 225bhp each.

[OutKlast]

Upon further research VGT/VATN technology seems to be a fairly old idea found some articles from the late 80's about them. I also found info on a Holset HY55 VGT turbo which is much larger but most likely to large, made for turbo diseals. A single modified one helped set the land speed record for a truck, a dodge putting down 1300ft-lbs and 700rwhp that did 217mph. Also it seems the new line of Cummins turbo diseals for semi's use a VGT, though there VGT is a damn fine idea as opposed to the Aerocharger in terms of realiablity. Instead of multiple small vanes moving the outer vanes are locked at that angle and the whole thing moves in or out exposing more or less surface area of the vanes which in turn controls boost. Interesting stuff but still no real leads can't really find anyone selling the HY55 and can't seem to find specs on it either.

[OutKlast]

Mmmm I'm still talking to myself but no reason to stop here. It appears Holset is still in business and can apply there VGT technology to many of there existing turbos including something a little smaller then the HY55 which is made for something like a 12L Diseal. But I get the sinking feeling that although it can be done it would have to built to order and shipped from them in Europe to the US, that can't be cheap but I'll probably get ahold of them anyway and see if they'll just take a thumb and toe instead of an arm and leg.

For those who haven't caught on yet I have a serious boner on for VGT/VATN turbos.

[Lord_Verminaard]

Actually, I have thought long and hard about VNT turbos. Twin VNT25's would be one of the most ideal setups for street and strip. The way a VNT works, is that it doesnt use a wastegate to control boost, it uses an internal penumatic device that actuates moveable vanes in the turbine housing to allow more or less exhaust flow around the turbine wheel. Click here: http://jacky.wallet.free.fr/Jacky/Au...ion/le_tgv.htm
for a picture.

I've worked with a lot of VW Diesels, especially the latest TDI 1.9 engine, which uses a VNT Turbo, although it is a VNT15, and it's TINY- like the size of a coffee mug. Stock boost is around 14 lbs, and it hits maximum boost at about 1500 rpm. The VNT25's are a bit bigger, and two of them could supply more than enough air for the 3800. VNT's have a reputation for being unreliable, but the majority of failures are due to driver error. The Vanes in the turbo can get caked with carbon build-up, which causes the vanes to sieze and not function, either producing no boost or overboosting until they eventually fail due to heat stress. This is usually caused by the driver "bogging" the engine, i.e. not running it to the upper rpm ranges enough, therefore not actuating the vanes enough to keep them clear of build-up. On a 3800, two VNT25's could probably run in the 7-10 psi range EACH and only be used to about 50% of their capacity. Boost responce would be nearly instant.
Some issues with VNT's- they are more restrictive in exhaust flow than traditional turbos, so there is more backpressure. Also, the mechanism to operate the VNT system needs more than just manifold pressure, it also requires vacuum and therefore some type of vacuum/pressure controller would need to be devised.
Some positives- instant boost responce. No extra exhaust provisions for wastegates, making piping a little more simple. (or as simple as it can get with twins)

Either way, if I had nothing but money and time, that's what I would do. ;) I doubt anyone on here wants to get that involved in a turbo, but it shure would be neat.

Brendan
2000 Camaro L36 M49
1984 VW Scirocco 8v

[T-Punk]

well they are going for 400 a peice on ebay right now and that seems like a good price. i know very little about the vnt's but i havent heard anything about vacuum being needed to run them, could you elaborate? im kinda interested in these since i'm still not dead set on a specific turbo yet for my twins.

[OutKlast]

Originally posted by Lord_Verminaard:
I've worked with a lot of VW Diesels, especially the latest TDI 1.9 engine, which uses a VNT Turbo, although it is a VNT15, and it's TINY- like the size of a coffee mug. Stock boost is around 14 lbs, and it hits maximum boost at about 1500 rpm.

Yea I've read about the carbon buildup didn't like the idea of the added worry of "cycling" the turbo vanes. I thought I read somewhere they setup some kind of control which allowed them to cycle the vanes at any rpm. It'd be nice to automate it on startup/shutdown or something like a module that keeps a turbo car running to continue oil flow. Do you have specs on the VNT T25's? I didn't think they were optimal, thought they were near max operating speed at 400-450 bhp (with twins).

[Lord_Verminaard]

Cant find the specs right now, I'll post them if I can find it. Here is a quote on how a simple boost controll is set up with a VNT turbo:

The boost setting can be mechanically adjusted within a limited range by shortening the rod length. Make sure the diaphragm does not bottom out before reaching the full stroke. It can also be adjusted with an electronic adjustable boost control system that is designed to control a conventional wastegate.

A pressure regulator can also be used as a "boost over boost" control to raise the actuator pressure control point just as it is used on a wastegate. In a nutshell you run a controlled amount of boost to the "wrong" side of theactuator to cancel out part of the pressure on the boost side. Each psi put on the back of the diaphragm raises the boost setting by 1 psi and so on. This is plumbed by hooking up the actuator pressure port to a boost signal (i.e. the fitting on the compressor housing) directly as usual. Then hook up a second from the same boost signal to a pressure regulator and then to the vacuum side of the actuator. Setting the pressure regulator to 1 psi raises the boost `1 psi etc...

In an off road or race only application this simple system will suffice. As a minimum a " part throttle open" controlcan be easily achieved by connecting manifold vacuum through a check valve to the vacuum side ( big tube) of the actuator. The check valve is to block boost. To prevent any pressure from being trapped between the check valve and the actuator, a .030" bleed orifice to atmosphere should be used. This will open the nozzles when vacuum is present at idle and part throttle.

This has some important benefits:

1. It cycles the vanes every time the throttle is depressed which helps them stay free of carbon.
2. It prevents excessive EGR due to higher then normalbackpressure which affects idle quality.
3. It improves fuel economy by eliminating backpressure caused by the turbo.
4. It prevents part throttle boost which heats the intake air unnecessarily.
5. It provides a more linear feel to the throttle pedal position."

So they require slightly different pluming needs, but I'd rather deal with soft vacuum lines than mess with welding extra metal for a wastegate. [img]smile.gif[/img] If I find the specs on them, I'll post.

Brendan
2000 Camaro L36 M49
84 VW Scirocco 8v

[T-Punk]

i found a very informative website for the vnt 25, i suggest you read it if you plan on designing anything with these turbo's.

http://www.thedodgegarage.com/turbo_vnt.html

it includes info on why a wastegate is still recommended and the author says that a twin vnt 25 setup would work well with the buick 3.8 so it would be a good decision for our engines as well.

[OutKlast]

I've read both of those sites. [img]tongue.gif[/img]

I believe the first one about boost control is the article I was referring to about cycling the vanes.