***ASYMMETRICAL TURBOCHARGING G50 VH***

[i-Zer0]

Does anyone know what the diameters of the exhuast pipes are at the point they all come together on either side of the engineI have figured out a way to add a turbocharger and I have quitea variety to choose from for the setup but need an idea of pipe dimensions to narrow things down - thx - - -

[elwesso]

I have a set of manifolds but Id guess its a little over an inch.

[elwesso]

might post this in the VH forum too! I may move it there if thats what youd like.

[qsiguy]

Care to share any details yet i-ZerO?

[Jeff Williams]

There is quite a restriction at the inlet of the PUP cats. I would say it was closer to 1.5".

Wes and I have the HICAS pump on the driver's side (1994 Q45t), so clearance would be an issue for us.

[Jeff Williams]

Passenger side:

[elwesso]

I dont really see the HICAS thing being in the way.... Its mounted on the frame rail and doesnt really get in the way... You wouldnt want your turbo up there anyway.

[i-Zer0]

Care to share any details yet i-ZerO?

Not just yet - I'm still sizing everything up - standby, I know you are very anxious - the idea is as follows - Saab used the concept of asymetrical turbocharging on their 9-5 product in the late nineties - asymetrical, as in utilizing a single turbocharger on half of the vee six engine and letting the other half breathe free - the concept was to minimize lag (being the time lapse from the instant the driver pushed on the accel pdl to the time the turbo actuall kicks in, full force [for those who don't know what this phenomenon is]) - since they create a significant deal of backpressure, the engine has to overcome all of that inertia - if, however one side does not have such back pressure, then there is less lag - that said, it's been a controversial issue in the forum for quite some time now anyway - considering the space restrictions associated w/ attempting to symmetrically (or twin) turbocharge, as opposed to asymmetrical - my theory is that the desired result of 1 horse per 10 lbs of vehicle weight will be obtained - - - - - -

[qsiguy]

Interesting, you'd think that having more backpressure on one half of the motor would do strange things. Never heard of a setup like this. You've peaked my interest.

[one ton garage]

Those saab guys come up with pretty zany ideas sometimes... and although conceptually cool, not all of them are too well-implemented, or well thought out for the long run, which is why you eventually see those ideas phased out of their production cars within a couple years. As for making room for turbocharging the G50... while still maintaing its creature comforts, the "secret" is to relocate the accessories from the sides of the block, to more along the front.... like so: Of course this will also require a new radiator and electric fans in lieu of the stock clutch fan.. but believe it or not, it is quite doable (my Q's engine bay has been apart for a little while now so every once in a while I move accessories around to check for clearances)...

[i-Zer0]

There is quite a restriction at the inlet of the PUP cats. I would say it was closer to 1.5".

Wes and I have the HICAS pump on the driver's side (1994 Q45t), so clearance would be an issue for us.

I jUSt wanted to clarify - you said an inchand a half - that sure looks small for a high-perf V8 - does anyone have a set of inside calipers to get more of an EXACT measure - it seems that SAE measurements are a little too much on the vague side of things for this application - can anyone get metric values on this please - I want to be as close as I can possibly get, considering that the turbocharger I want to retrofit is very likely going to be off some other make of vehicle - possibly an Audi - - - -

[i-Zer0]

Those saab guys come up with pretty zany ideas sometimes... and although conceptually cool, not all of them are too well-implemented, or well thought out for the long run, which is why you eventually see those ideas phased out of their production cars within a couple years. As for making room for turbocharging the G50... while still maintaing its creature comforts, the "secret" is to relocate the accessories from the sides of the block, to more along the front.... like so: Of course this will also require a new radiator and electric fans in lieu of the stock clutch fan.. but believe it or not, it is quite doable (my Q's engine bay has been apart for a little while now so every once in a while I move accessories around to check for clearances)...

Having owned four Saab vehicles in my past - I can fully relate to their 'creativeness' - yet those cars are about as individual as any exotic out there IMO - they have been turbocharging for many yearsand although eccentric this idea, it definitely sounds workable, and would be quite a stir for such a modest-looking/performing high-perf lux sedan - I am not just creating small talk here - I am about to undertake this little proj - just needed some actual references off the car so that I can then integrate everything to the 'foreign' parts I am about to purchase and addto it - any other suggestions or actual dimensional references supporting THIS project/thread are greatly appreciated - will have a full report, excluding stats once it's done - thx everybody for the input thus far - - - - -

[i-Zer0]

might post this in the VH forum too! I may move it there if thats what youd like.

pls do so - thx

[pdqwrx]

Not to be a downer on your idea as it has it's merrits, but wouldn't it be a whole lots easier and cheaper to build one of these?

http://www.ststurbo.com

I looked into this for my 240sx but it didn't really have the room, the Q45 on the other hand might. Robert could map us an ECU and were done. And any decent muffler shop could peice together the tubing, no need for expensive machine shops.

Just an idea...

Scott

[elwesso]

good luck runningany sort of piping up there.. Also, good luck on getting the damn thing to spool any sort of boost before 4000 RPM

[mtcookson]

Actually... I've considered the rear mount setup for a while now on another project and if done right you can actually get some very decent results. If you use a slightly smaller turbo on the rear than you would on the manifolds, it'll spool just as quick yet still not run out of breath.

STS claims all of their turbo setups spool before 3,000 rpm, which after doing a lot of studying on the setup, is quite feasible.

For the VH45DE, I think a pair of T3/T04E 50 trim turbos with a .48 a/r or maybe at the largest a .63 a/r turbine would spook quick and give awesome power. I'm still trying to confirm that setup but from what I've found so far... that would work out very well.

The more I think about it... the more I come to the conclusion that although maybe not quite as efficient as an ordinary turbo setup... it is still very capable of making a lot of power while spooling quickly. You don't have to do a crazy manifold design, tight engine bay spaces mean nothing, underhood temps stay lower, oil coking in the turbo wouldn't be an issue, better weight distribution (ableit small, but there), etc. etc.

If you're going for all out drag race sort of power, I think the traditional setup would show the best results... however for a street driven car the setup would do wonders. They're still capable of making a lot of power so taking a car racing with the setup would still be possible as well.

[elwesso]

still for a STREET driven car, the supercharger setup would be far easier IMO... PLus we know you can get it for under 4 grand.

[mtcookson]

If you do the rear mount turbo setup yourself, I bet you could do it for under 4,000 easily. Granted it would take a bit more custom work, the end result would definitely be worth it.

[pdqwrx]

I have a good friend who owns a high performance muffler shop (Two actually) and they do some kick but work. In the next week or two I will get the Q by his shop and put it on a lift and get his opinion. He loves stuff like this and would probably enjoy the project. When I get to this point I will repost with what he thinks as well as some pictures of the underside of our cars.

CheersScott

[sijoko]

Regarding a remote turbo system for the G50 Q45: There is plenty of space underneath the car for two T3/T4 turbos. The best spot is where the mufflers are located, just after the main cats.

If you are going to do a setup like this, I would suggest you devise a separate lube system just for the turbos using 2 pumps and a reservoir. Some copper tubing or an inline oil cooler should be used to dissipate heat before the oil reaches the pumps after leaving the turbos.

The turbos will not need that much oil pressure to operate. A 40 psi pump should be enough. Another plus is since the lube system is not shared with the engine, the oil won't be too hot such that the life of the pumps will be shortened.

Another idea: You could also use a fuel pump controller, such as the Billet Pump Speed Controller p/n #16302 from Aeromotive, to vary the speed of the pumps with engine speed and/or load. This will help in making the pumps last longer and also in cutting down on pump noise.

With this setup, there is no way for a failed pump to take out your engine. The worst case scenario is that you would have to rebuild the turbos. Better than rebuilding an engine because it ran out of oil.

[pdqwrx]

I was thinking of a single turbo system with maybe 5-7 lbs of boost and great response. Something like the http://www.ststurbo.com kit for the chevy truck.

SB

[elwesso]

but STILL, if your running lower boost (below 10lbs) the SC is probably the way to go... No custom fab, just bolt it on! And you dont even consider turbo lag, its going to be instant tire roasting action!

[pdqwrx]

Wes- All your SC points are valid and if it was affordable and readily available I would already have one. Problem is, it's not available and somebody has to put up some serious money to see if it works. I think the turbo system could be done for around $2500 or less and it would be easier to make it pass smog in Cali because it could be removed easily and retrofitted with a stock muffler.Parts needed-Turbo 1000.00Piping 250.00oilpump and lines 500.00ECU Reprogram 250.00Custom muffler system 250.00misc bits 250.00

I actually think I am being generous on all the amounts except maybe the Turbo if I go a new unit.

Just seems more cost effective and I'm not out to make the Q a 1/4 mile terror, rather I want to give the car the power it actually deserves to make it a true Grand Tourer.

SB

[elwesso]

scott... The SC is TESTED and AVAILABLE the first person just has to man up and put it on... Theres nothing to develop the kit is ready to rock and roll, trust me! Id have it on my Q, but last summer i spent all my money on suspension (which I am eternally grateful i did)..

It is an eaton Rootes type SC. The kit includes all the pulleys and stuff.. All you would need to buy is the annoying parts (like belts, oil and crap like that-----easy stuff).

OIts not terribly efficient above 10lbs but running 5-8lbs itd be fine... You could run an alchy injection to make it work really good, which woudl not require intercooling...

PLUS you dont have to worry about all the oil line crap (which IMO youll find will be a bigger PTIA than you think)... The SC is the ultimate thing for the daily driver if you dont plan on going with huge power... The SC is basically maintenance free, you just replace the SC oil every so often and its cheap and easy to find.

You can even run this on your stock exhaust if you wanted, but i wouldnt recommend it...

If anyone is interested, ill get this project going... Now you guys have me thinking...

[Mettler]

I want to supercharge my engine, but I'm gonna wait until I've got my car running and driving around etc before I start looking into boost... I'd prefer a centrifugal blower because they can be hidden under the bonnet & easily intercooled, but this seems like it might be an affordable option too !

[mtcookson]

If you are going to do a setup like this, I would suggest you devise a separate lube system just for the turbos using 2 pumps and a reservoir. Some copper tubing or an inline oil cooler should be used to dissipate heat before the oil reaches the pumps after leaving the turbos.

Why do that? If you just an oil line from the engine to the back of the car, the oil will cool down substantially just as if you were running an oil cooler. From there it goes through the turbo to a scavenge pump that pumps the oil back to the engine while cooling down on the way back as well. (this scavenge pump seems pretty decent http://www.turbowerx.com/page1/page2/page2.html)

On turbo lag... it would likely not be noticeable at all. If you used a couple T3/T04E 50 trim turbos they should spool very quickly and combined should be enough for nearly 900 hp. At low boost I bet you would see similar spool times that the STS kits do... which is full spool before 3,000 rpm. So, you would have quick spool and a very efficient compressor.

I want to supercharge my engine, but I'm gonna wait until I've got my car running and driving around etc before I start looking into boost... I'd prefer a centrifugal blower because they can be hidden under the bonnet & easily intercooled, but this seems like it might be an affordable option too !

A centrifugal supercharger would be the last form of forced induction I would go for, personally. I would choose a roots s/c over one of those. They may be efficient... but boost is linear so that you don't reach peak boost till redline. Power delivery would be more like a larger normally aspirated engine with a very peaky power band. The roots supercharger would give much better mid-range response. It would allow for a much more fun daily driver than a centrifugal would.

Like I've said on a few other forums... the only time I could see the centrifugal being any good would be if it had a sort of CVT belt setup that kept it at constant peak rpm so that you had full boost throughout the rev range. This would likely make the centrifugal s/c as good as a screws supercharger.

Soooo... basically what I'm trying to get at is if you want to go the supercharger route, I would highly recommend going with the Eaton supercharger setup that Wes is speaking of.

Oh yeah... I about forgot. ITS NOT TURBO LAG!!

Its foreplay

http://www.slowboyracing.com//...ea830

Modified by mtcookson at 6:53 AM 6/12/2006
Modified by mtcookson at 6:53 AM 6/12/2006

[Mettler]

A centrifugal supercharger would be the last form of forced induction I would go for, personally. I would choose a roots s/c over one of those. They may be efficient... but boost is linear so that you don't reach peak boost till redline. Power delivery would be more like a larger normally aspirated engine with a very peaky power band. The roots supercharger would give much better mid-range response. It would allow for a much more fun daily driver than a centrifugal would.

Like I've said on a few other forums... the only time I could see the centrifugal being any good would be if it had a sort of CVT belt setup that kept it at constant peak rpm so that you had full boost throughout the rev range. This would likely make the centrifugal s/c as good as a screws supercharger.

Soooo... basically what I'm trying to get at is if you want to go the supercharger route, I would highly recommend going with the Eaton supercharger setup that Wes is speaking of.

This doesn't make sense to me... all typical superchargers are belt driven off the crank, why would a centrifugal be any different ? The higher the RPM, the faster the supercharger is being driven. I can just run a bigger pulley and the supercharger will spin faster.

Understandably with the centrifugal being further away and pushing boost through an intercooler, there will be a bit less instant power... but at least I can keep the intake charge cool, and keep the supercharger setup discreet and under the bonnet. I don't really want my HR31 to have a big blower out the bonnet, it'd be too blatant Also, since the motor's already 10.5:1 compression ratio, it's only going to need 6-7 PSI to get the desired effect, and a centrifugal can hit that way before redline !

The other thing is that I'm not building a burnout machine with too much power, I actually like the sound of a linear power delivery, it'll allow for hard but smooth acceleration all the way to redline, and respectable power at any RPM and in any gear... controllable, the way a track car should handle.

[Rex]

I have a good friend who owns a high performance muffler shop (Two actually) and they do some kick but work. In the next week or two I will get the Q by his shop and put it on a lift and get his opinion. He loves stuff like this and would probably enjoy the project. When I get to this point I will repost with what he thinks as well as some pictures of the underside of our cars.

CheersScott

Here's a pic ...

[mtcookson]

This doesn't make sense to me... all typical superchargers are belt driven off the crank, why would a centrifugal be any different ?

A centrifugal supercharger requires RPM to compress air, like a turbocharger. The higher the RPM, the higher the pressure. A centrifugal supercharger spins upwards of 40,000-50,000 RPM. A turbo's compressor wheel is designed a bit differently and can spin well over 100,000 RPM.

Roots and screws superchargers are positive displacement superchargers. Basically, for every roation they move a measured amount of air. The Eaton M90 for instance is a 1.4 liter supercharger if memory serves. For every rotation of the pulley, it should move 1.4 liters of air. That's how a roots and screws supercharger can deliver nearly instant boost.

Now... to separate those two you have the roots supercharger, which is a blower/pump. A screws supercharger is an air compressor, like the centrifugal supercharger and turbo.

This is why the roots supercharger is the most inefficient of the common forced induction methods. It basically forces air into the intake so fast that the air compresses in the intake itself. This causes a lot of heat. Roots superchargers have an adiabatic (heat) efficiency nearly half or less of the other methods.

The screws supercharger is a true air compressor as it actually compresses the air between the screws. The Lysholm design had a peak adiabatic efficiency of around 60% on the smaller models. The new Whipple screws superchargers are some of the most efficient superchargers out there. The smaller model (1.2 liter) has a peak adiabatic efficiency of 81%. The only downfall to the superchargers is the parasitic losses, which, when compared to a turbo, will make it a bit less efficient overall.

Centrifgual superchargers have adiabatic efficiencies in the upper 70's and some probably hitting 80%. Turbochargers have the same, which is interesting to note as well because a lot of people think the exhaust housing causes a lot of heat transfer into the compressor. As you can tell by the adiabatic efficiency, heat transfer is very minimal.

The benefit of the centrifugal compressors is you can easily add an aftercooler to cool down the air charge even more. Roots and screws setups, when bolted to the manifold, require an air to water aftercooler. Roots superchargers with the aftercooler can see huge gains in performance because of their low efficiency.

Quote »The higher the RPM, the faster the supercharger is being driven. I can just run a bigger pulley and the supercharger will spin faster.[/quote]Correct... but with a centrifugal supercharger you can run only so much boost. Take the Vortech V2 for instance. Maximum boost pressure is 20 psi at 53,000 RPM. Boost will build gradually up till the maximum pressure and RPM. Granted you will have higher boost through the rev range, boost will still be linear. If you use a screws or turbo at 20 psi, you would have that throughout nearly the entire rev range, giving much better low end and mid response. Basically, they will be more powerful at any given RPM at the same boost pressures.

Quote »Also, since the motor's already 10.5:1 compression ratio, it's only going to need 6-7 PSI to get the desired effect, and a centrifugal can hit that way before redline ![/quote]But, if the motor can't handle any more than 6-7 psi you would be required to set the supercharger up so that you only hit 6-7 psi at redline. Otherwise, you would only be able to rev half way before blowing your motor.

Quote »The other thing is that I'm not building a burnout machine with too much power, I actually like the sound of a linear power delivery, it'll allow for hard but smooth acceleration all the way to redline, and respectable power at any RPM and in any gear... controllable, the way a track car should handle.[/quote]The only forced induction setups that I've seen that aren't controllable are setups producing way too much power for their available setup, and turbocahrgers that are grossly oversized. If you use a roots or screws supercharger you will have instant boost till redline making the power delivery essentially linear, just more powerful. The same can be said for a properly sized turbo system. You can have quick boost that stays till redline giving linear power.

Problems occur when you have a turbo that is too big. It takes a while to spool and when it finally does, it feels like you just activated a solid fuel rocket. That's why proper sizing in a turbo system is everything. If they weren't good for linear power delivery, track cars wouldn't have them. Audi makes some very successful track cars that are turbocharged. Some of the older F1 cars were even turbocharged.

I think the big key word we want is usable power. Sure you can control something that has a high power band, but everything below is useless. If you're on a tight course, you're going to want some lower end grunt to get you out of the corners and I don't see a centrifugal s/c providing that kind of response like a positive displacement supercharger or a good turbo system would be able to.

[Mettler]

Points taken mtcookson, just a couple of points in your essay that I'd like to query...

You comment that you need to set up a centrifugal to be boosting peak desired psi at redline, and if set up to do so earlier in the rev range you'll blow the motor. Wouldn't that be easily fixed by installing an adjustable pressure valve in the intake (in fact, the perfect place would be the frost plug in the side of the plenum chamber) to bypass through to the exhaust ? That way maximum boost pressure is always set at the valve, and you can overdrive the supercharger to boost harder, earlier.

Further to the overboosting problem... if a roots blower pumps 'x' volume of air per revolution, then as it speeds up, isn't it pumping an exponentially higher quantity of air as the RPMs increase ? How is this any different if you are only wanting to get 6-7 psi into your engine, and you're getting that straight off idle ? How do you prevent overboosting with one of these ?

As for fuel efficiency... wouldn't a roots type blower provide the worst fuel efficiency out of three engines, each of which is equipped with a different type of forced induction ? And also the worst reliability, since the air entering the cylinders is significantly hotter ?

Where does the aftercooler go on the roots blower that's been set up for the VH engines ? (The one that Wes can supply.)

Lastly, surely an engine that already produces a significant HP & torque output with a good set of extractors (340+ HP at the flywheel) in a lightweight car with good gearing and a 4.375:1 final drive ratio, is going to have mean as acceleration out of corners in almost any gear, even BEFORE supercharging it ?

I ask all these questions because I'll quote up the price difference in parts & fabrication for a centrifugal & the roots supercharger from here, and weigh up the pros & cons, and make a decision from there !