OldeSkool

Anyone thought about... or tried a rear mount turbo on a supercharged car? (forgive me if this has been brought up before) I know what some of u might be thinking... why spend so much money when you can get a single FI system to supply all the boost you ever need... I was just thinking if i ran a low boost STS and fed it into the intake of a low boost blower I'd have a sufficiently boosted and very streetable car with lots of potential... hope this generates some good discussion.

96SCTA

I was just about to ask this question. I already have a blower and selling it is not worth it cause i will only get a grand or 2. So why not just add a rear mount turbo. This way i do not have to get a real big expenisive one. In The back. I will only need to get a smaller one that will put out like 10 lbs to go with my charger thats putting out 9-12lbs.
I Will run the tube up from the turbo to murge with my supercharer in a custom y pipe to then run into my front mount intercooler. Im sure Im going to loss some good boost through all of this but. I think it will be worth it. And i really hope that no one shoots any big holes in this idea. Cause Im half way done. (in my head that is) lol.

NXRICKY

iTrader: (1)

I have seen turbo stacked or ran in series on deisel trucks. And have heard of multiple turbos and blowers on a monster truck pulls. But have yet seen it on a street car. The only thing that I could see being a problem is the heat from the first pressure device could become compounded by the second. Also the 2nd pressure device would or should move the air easier since it is not having to suck it in. pretty interest, give it a try its only money. lol
Ricky

OldeSkool

Im no expert on FI... but I dont think merging the two together is the best way to do it.. run the tube from the turbo right into the blower inlet... that way your blower is compressing air that has already been compressed by the turbo also... maybe the suction of the blower will help get the turbo up and running faster...

96SCTA

I may be way off. But i dont think it would be wise to run it into the inlet for the supercharger. LOL...

Richiec77

iTrader: (3)

You should run the turbo into the blower or vice versa. That is how you compound the 2 together. Compounding is used to generate ultra-high PSI #'s. Formula 1 used to due this with turbos and then run toulene to alchole mixtures around 90/10. They would generate around 80-110 PSI for their motors to generate hugh Power.

It would help more to run the blower into the turbo too make it spool really fast. Compounding is good if you want to run high PSI without overspinning the Compressor.

As far as heat goes.....I would assume it would generate alot. Compressing Air generates heat.

OldeSkool

Thanks Richiec... thats what I was thinking... I can see the advantages of running the blower into the turbo, but for say... an STS application, I think running into the blower would be the easiest solution... what im wondering is if someone knows some compounding equations. This is where the forementioned "merge" issue comes in... if u take a 5psi blower and a 5psi turbo and merge them together.. u get 10psi. But by feeding one into the other, i'm sure the compounding effect creates a bit more.. anyone have an estimate? "80-110 psi" certainly is impressive, do u know what kind of boost they would put out if they werent compounded Richiec?

hangslo

the extremely high boost here is due to the PR of the turbos ... if you have 2 turbos with matching PR's (but obviously not the same airflow), the PR's are multiplied ...

I have seen a turbo feeding a roots style blower on a small V6 and it kicked *** ... the blower produced instantaneous boost off idle, but ran out of air on the top end since the blower does not compress air in the case, only in the manifold when there is a restriction ... and the turbo (which compresses the air in the housing) supplied the extra air necessary on the top end that the blower could not move ... the turbo was actually turning the blower on the top end and negating the parasitic loss of the crank drive ...

instantaneous boost on the bottom with lots of boost on the top ... isnt that what everyone is trying to accomplish?

NXRICKY

iTrader: (1)

I did see on a diesel truck we sponsor that there is a small turbo feeding a large one. It was set up like this. The exhuast goes into the small turbo turbine inlet, then the down pipe or out let went into the larger turbos turbine inlet,and then out. The small compressor feed the larger compressors inlet then into the engine.
I ask why, and they told me the little one got things working and the larger one could feed more over all air. But what about the exhaust. I was told same energy so it had to choice but to spin booth units. now this is a diesel that runs in the 8's in the quater mile, I do not know if he was telling me the truth but it was interesting.

Ricky

Richiec77

iTrader: (3)

I can see why it would be easier to run into the blower. The only consideration is that when you are not in the Boost threshold of the turbo, that you have suffecient intake air for the blower to use.

As far as the P/R of the turbos, I don't know. I can't find my Maximum Boost book ( think it's at my buddies house), so I don't have any formulas to work with right now.
As far as just multiplying the 2 P/R's together; I don't think that makes sense because 0.5 X 0.5 = 0.25 or hence or lower observed PSI. I'll dig up some info If I can.

Here is a useful intro.
http://www.hotrod.com/techarticles/e...bo/index2.html

96SCTA

So let me get this straight. Cause now im really confused. It actualy may produce more power buy running the turbo into the blower. But wouldnt the blower just have to recompress the air again. .. Or is it more like the turbo outlet is now the supercharger inlet so the air would not decompress.

Richiec77

iTrader: (3)

Yes, yes and yes. The air path would be like you described. The fresh air would enter the turbo, then be piped through to the inlet of the blower and then go through an intercooler ( a Must have at this point) and then into the intake manifold.
I'm guessing you have a centerfugual blower. This is the same as a turbo, but is driven by a belt instead of exhaust gas. Depending on how the blower is geared and what pulley is used; you should experience a low RPM boost and then when the turbo kicks in, you would then have 2 effects in place for more potetial power.

1.) You will be making more observed boost (PSI) overall. More air + fuel= more power.
2.) The Positive pressure will then be pushing the blower causing less parasitic drag of the belt system. (hangslo mentioned this in his post).

The downside is that you MUST cool the incoming air because of the heat generated by compressing it. Some designs use an intercooled between the 2 systems to reduce the incoming heat to the second system and then would have to cool the charge going from the second system to the manifold.

I must confess that I'm not an Expert on Turbo's. I plan on putting a system on my car when Finances are available. I do study everything as much as possible to inform myself. (god I wish Rob was still posting to help with this)

96SCTA

Well I really like the sound of this. I am going to give it a Try. I am going to be getting a front mount air to air intercooler to cool this down. But i think it will need a little more than just that. I have a votech blower, with the water to air intercooler but it works like crap. It gets heated up very quickly.
What size turbo do you guys think should be used for this type of set up.

96SCTA

here is another question. would i want to find a turbo cam or a blower cam....

S_J_H

I actually thought about the same thing recently. My g-trim would not be worth much cash so may as well keep it. A rear mount turbo that flows more air than the g-trim would be needed. Plumb the turbo outlet into the blowers inlet. The belt driven blower would produce quick spool up of the turbo and the 2 combined could produce ridiculous pressures without overworking either .

I would never conisder this arrangement if I already did not have a blower.

But slapping a rear mount turbo on the existing combo would be easy.
I think the trickiest thing would be to keep it from overboosting and I'm sure a lot of experimentation would be needed.
But it's been done before and series forced induction is how super high boost levels are made in some forms of racing.
Steve

96SCTA

Does any one know how to predict how much power somthing like this will make.

lets say your blower puts out 10 psi and the turbo puts out a maximum of 10 psi. Do you now have 20 psi or a lesser more consistant number That pulls through more of an rpm range.

Richiec77

iTrader: (3)

Probably need at least a gt-67. The baseline turbo, gt-60-1, runs out of steam up top, which is where you are looking for the turbo to kick in. I would think the GT-67 would work or you could go with a GT-70 if you are looking for even more output!!

The only thing I wouldn't know is what kind of PSI you are going to produce. Also, you are definetly going to need more fuel and hope your motor is setup to take the boost you are about to start producing. Definetly going to need lower compression ratio, and MUST cool down the intake charge.

The centerfugal Supercharger compresses in the same way a turbo-charger compresses so you might be able to get an idea of the out #'s by looking at other set-ups like this ( compounded turbos). Don't the Supra guy's do this? Also I know that Porche forums discuss this from time to time. Man I'm really currious how this will turn out!

Richiec77

iTrader: (3)

Another thing I'm curious about is what your setup is right now. I know you're STOCK........lol, but I'm curious as to what the exhaust should be like for this.

96SCTA

Yeah,, Im pumped that i got somthing new to think about.

My motor is out of the car right now. I am doning the build up . I was thinking 383 LT1 all forged set up. But If i am going to run this much boost. I may just stay with a 355 LT1 so i can turn up the rpms even more. I will have to go with real low comp pistons. like 8.5:1. Right now im still on the stock compression ration. With 9-11lbs of boost. (never consistant)

The question that i really need to find out is how much can a v8 handle.

96SCTA

My exhaust is hooker lt's jet hot coated with a 4inch y-pipe to an edlebrock rpm series muff. (the muffler is blown open ...lol) I know i will replace the muffler with a ....turbo....