Rear mounted turbo...

[Army of Six]

My pontiac actually seems to run cooler with a turbo in the engine compartment vs. when i had a Vortech. im thinking mostly because the motor works less at cruise and idle vs. constantly having to turn the supercharger. but underhood temp havent been a problem for me either.

isnt a turbo more efficient closer to the motor? seems like ive learned that its the hot expanding exhaust gasses are what helps them spool and that you want heat in the turbo (hot side, not cold side). i know i get better spooling and more boost after driving it around for a while or the second time around when getting on it. with a rear mounted system seems like you would need a slightly smaller exhaust AR to compensate for the now colder more condensed exhaust gasses that have lost 100's of degrees in temperature.

im not trying to pee on your parade...i would just hate to see someone spends countless hours and dollars installing a rear mounted turbo, running all the tubing, engineering a robust oil pump return sytem only to barely see boost if any at all on the maiden test drive.

good luck and keep us posted with build pics!

 

[Falcon Ranch]

Nice look 'n Pontiac!

I'm not arguing that it's a bad thing guys to have the turbo under the hood...I'm doing it just for kicks and to be different and to see how well it will work...one reason is if a whoop the pants off a Chevy and he wants to see my motor I want to see the look on has face when he see's an inline six starring him in the face, besides the carb hat it will look bone stock because the pop-offs, waste gates will all be hidden under the bed with the turbo...it's part of the whole sleeper package...besides the air cleaner and oil breather there is no other big shiny chrome stuff...my motor looks stock outside but it's what's inside that makes the difference...besides, chrome is an option that takes a lot of attention to stay looking nice...I just wanted a stock appearance and low maintenance.

 

[JGTurbo]

Pull off the housings and measure the major and minor diameters of both
the wheels. If you post this information I'll do some cross-referencing and
let you know what your turbo is capable of.

STS runs slightly smaller exhaust housings on their turbos because of the
rear mount. This is done because the exhaust is cooler and therefore more
dense at the back of the car. This means that more exhaust can fit through
a smaller space, hence the reason for the smaller housing. So there is less
volume, but higher density. The end result is the same.

I have always found the argument between heat driving the turbine and
pressure driving the turbine fairly amusing. People can go back and forth
for days and not get anywhere. I personally believe it is the pressure
differential that causes the turbine to spin. There is a heat differential as
well, but this is caused by the pressure differential (just like how air from
an air compressor is cold when it is released). The turbine does not have
the means to convert heat directly into energy, what it does is use the
pressure differential and resulting mass flow.

Then there are the racers who swear that they got better spool up times
when they wrapped their turbo manifolds. Well, they should get better
spool up times because the exhaust gasses are kept hotter, resulting in
more volume, so the turbine acts like it has a smaller A/R. They could get
the same results from a non-wrapped manifold and a slightly smaller A/R.

In my opinion, the rise of Squires Turbo Systems should have marked the
death of the heat drives the turbo theory, but it lives on in forums across
the web.

Just my 2 cents.

 

[JGTurbo]

Also, if there is any controversy on the spool up times due to the long intake
plumbing, STS ran some calculations and found that it takes about 0.05
seconds for the turbo to compress the air in the long intake tube. I expect
that it takes about the same amount of time for the engine to build the
required exhaust pressure in the long exhaust tubing. So as long as the A/R
is right, a rear mount turbo's response should be within 0.1 seconds of one
mounted under the hood.

Just some more thoughts spilling out of my head...

 

[Falcon Ranch]

Pull off the housings and measure the major and minor diameters of both
the wheels. If you post this information I'll do some cross-referencing and
let you know what your turbo is capable of.

That would awesome JGTurbo...I've always been curious of the power this will produce.

So you want me to measure the diameter of both the widest part and the narrow part of the turbine wheel?

Considering that it came off of a diesel, they need to really spool up to produce any kind of usable boost...so hopefully it will work out for my application.

Dave 8)

 

[tjnavyblue]

You know how some import guys put their air intakes on the roof? Why not put a turbo on the roof. You could run the intake ram air style, and then run the pressure side down of the the windshield pillars. Oil drainage would be superb, the bov would be nice an loud if you plumbed it outside, and cooling would not be an issue. You could then do a sweet 5" exhaust pointed straight back.

 

[JGTurbo]

Why didn't I think of that before? Sounds great to me as long as the exhaust is kept nice and short, you know, to help out the pressure differential. Just weld a chrome tip right to the turbine housing for killer looks and a nice deep sound. It gets better: press the washer switch for a clean windshield and... water injection!!!

It just seems so ideal. I'm not sure why you haven't done it to your Accord yet. I'll loan you a turbo.

 

[JGTurbo]

Yeah, both diameters would be helpful. Also, does the turbine housing have
a divided inlet?

 

[Falcon Ranch]

Yeah, both diameters would be helpful. Also, does the turbine housing have
a divided inlet?

When you say divided inlet, do you mean like this one?...I did not plan on using this part.

I will take it apart tomorrow and have some measurements...also, will I ruin any of the seals by ding this...because I am not sure of what it is...I'm not sure if I could get any parts for it...I will also try and get a decent shot of the maker...all I know is that it says "KAMA" and next to that is a Russian symbol that looks like a number 3...I had a co worker look at it as he is Russian, and all he can tell me is that it was made from his country...this is where the Unimogg is built and they were sold to the Iraq military...when my brother first got to Iraq, they were raiding warehouse's looking for weapons of mass destruction, my brother stumbled upon 8 crates of spare diesel engines and removed them for spares for the US military but found out they wouldn't fit, so he brought this one back for me as I have had it for about 3-4 yrs...now I would like to use it on my Falcon Ranchero...I will also take some shots of the turbines as it might help with your research.

Dave

 

[tjnavyblue]

That part is kind of like adding a divided inlet to your exhaust housing - not the same, but I bet it would help a little. Exhaust housings with divided inlets run the divider up a ways, helps with spool. Ask JG how.

That turboed Pontiac is very clean. It should make V8 owners around the world wonder why they haven't turboed their cars yet. If they weren't already.

Yeah the turbo on the roof: The chrome exhaust tip welded on would have to have a giant red TYPE R painted on both sides before it even came near my Accord. Other than that... not a bad idea.

Also, I have to admit, I did do a google image search for roof mounted turbos. Alas, there is none to behold.

 

[JGTurbo]

I was able to find one. I bet you could sell a bunch of these to import guys.
Tell them to plumb their air filter inside it for maximum boost. Just look, it
can even be color matched to the roof.

 

[tjnavyblue]

Woo Hoo! I saw that one too and totally overlooked its incredible performance potential. Can you imagine the swirl effect... I think the idea is to use some sheet metal screws to attach that over the top of the roof mounted turbo, with only the Type R exhaust tip sticking out. It would be a complete, streamlined package, totally disguised from the average citizen.

 

[JGTurbo]

Falcon Ranch, I don't think you will ruin any seals by taking the housings off.
They usually don't run seals under the housings, just sort of a a taper fit.
Just be careful not to bend the blades on the wheels. That's an interesting
looking part you've got there. If that's a T4 flange, it could come in useful
someday.

A divided inlet turbine housing is divided all the way through to the wheel.
The A/R can be varied by partially or totally blocking one of the inlets. I was
just curious.

 

[JGTurbo]

I like where you are going with this, tj, but let me take it a step further. Now I know that it is made to be mounted on the roof, but I propose that we put it UNDER THE HOOD of your mustang. The straight six cylinder heads were always known to have poor swirl, so just think what that could do for it. Use it as a breather on top of a matching aluminum valve cover and you're looking at 20RWHP.

 

[Falcon Ranch]

JGTurbo, here is the exhaust side pictures...the wide part measures 3" and the narrow part at the top measures 2.5"

The intake side measures 2.75" at the widest part and 1 7/8" at the top.

There was this metal plate I had the remove.

I hope these pictures can help you determine what this compares to and what kind of pressure I can reach...if it works out to be a low pressure system, say 5-7 PSI, then I will be able to do the install without needing a WG or a BOV...the shaft also feels as if it is riding on bearings...does not feel like a bushing style shaft it spins way to easily.

 

[TCIC 300ci superbeast]

will i have never seen a roof mounted turbo i have seen a hood mounted turbo

 

[JGTurbo]

It looks like the compressor should be good to around 300hp. The turbine is
quite large. It's right up there with a T4 "P" Trim. I hope the turbine housing
A/R is small. With such a small compressor and large turbine, you might not
need a wastegate. You never really know until you drive it. I'd recommend
putting a wastegate flange on the exhaust and just block it off. Then you
could test it and see if you need to spend the money or not.

 

[JGTurbo]

I would also recommend using dial calipers to measure the diameters.
Perhaps you did, but by the fractions it sounds like a measuring tape. The
difference between 300hp and 380hp is about 0.074"

 

[CobraSix]

I know I"m chimming in late, but wouldn't it be tough to keep the exhaust temp and velocity up at the rear of the car?

Also, are you plumbing it before or after the muffler? If after, you've lost A LOT of pressure. If before, that's a really tight fit.

I'm not saying it's not possible or that it won't provide boost. I'm just thinking it's a lot of work when the simple solution seems better. As far as popping the hood, they'll be sick losing to a 6 either way, charged or not. There's being different and then there's being DIFFERENT. Tom Cruise is different, but Michael Jackson is DIFFERENT.

Slade

 

[JGTurbo]

exhaust temp huh?