Rear Mounted Turbo!?

[Skatony]

My buddys going to be getting an SC at some point this year and he has this wild idea that hes going to mount a big single turbo out back by the dif or between the trans. and the dif.!
isnt he going to loose significant amounts of boost because of the loss of heat and are these systems worth the amount of plumbing they involve??

 

[Zuffen]

Do a Websearch.

It's quite common on Corvettes and seems to work OK.

 

[XR8tt]

http://www.ststurbo.com/
Don't ask these guys though!! If your not buying there product they get a little
legal with patents copyright etc..
But anyone can do it.. I prefer mid mount if you can around gearbox/ bellhousing area.. You require an electric trans cooler pump to return oil back to engine..Similar to http://www.summitracing.com/search/...r-Differential-Oil-Cooler-Pumps/?autoview=SKU
The good part is it can be delivered back to cam covers. No need to drill and weld sump for oil return... Usually two T25's / VF30 / TD04 sized turbo's with internal wastegates..Yes small turbo's but very punchy for street use..
Btw the latter two are used on Subaru STI engines... 430 CFM @ 14 Lb...

 

[Skatony]

But anyone can do it.. I prefer mid mount if you can around gearbox/ bellhousing area..

i was really considering that myself for my build, seems like there would be more heat to help spool the turbo up faster.

 

[stevechumo]

i was really considering that myself for my build, seems like there would be more heat to help spool the turbo up faster.

I'd like to build a rear mounted turbo myself, too. Just to experiment it. Anyway, to keep the pressure and the heat high, and to eliminate turbo lag (twin turbo preferrably for this setup), use small pipes before the turbine and after the compressor. I'd think between the ID of 1.5" - 1.75" for each turbo is ideal. Then you can run 3" from the intercooler to the TB.

 

[Skatony]

that sounds dead on to me, but ive never built a turbo system before. i've been trying to memorize the page on the garrett turbo website about building a turbo systems. heres the link and i'm sure a few of you guys already know a lot of this but everytime i look at the page i learn something new, so i figured a few of us could use some of the info!
basics http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech101.html
advanced- http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html
expert-
http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html
like i said, i'm sure a lot of you guys know a lot of this but its good info so i figured someone could probably use it!

 

[XR8tt]

Here's a forum dedicated mainly to Detriot engines..
What would work on a 5.0 pushrod ? Be close to healthy 4.0 or so..
Gives you bassic ideas etc.. Prev Mustangs.com
http://www.theturboforums.com/smf/index.php?action=search2

 

[tuning haus]

yeah the STS guys seemed to be working it okay. i knew a camaro SS that had a rear mounted turbo set up and his car was running good.

i heard that it can cause possibly a 300-500 rpm lag vs. turbo kits/systems that run closer to the engine bay.

but with these 1uz-fe's there really aren't too much space, so if it has to be done, i think it wouldn't be too bad.

i don't like the placment of the turbo/s on a lot of the turbo 1uz's... it's right behind the radaitor etc.

if anything, maybe in place of the battery... but the weight distribution of the car may be imbalanced..

 

[Zuffen]

I was reading about this today in ZOOM Magazine.

They claim the exhaust gas is denser as it has cooled a little before it gets to the turbine.

This also makes the turbo run cooler and thus not heating the charge air from contact with a red hot turbo.

Lastly they claim interccoolers aren't required as the air has time to cool on the way back up front.

 

[JustenGT8]

Yup that whole Zoom article is BS...a bit disappointing really that they have even printed such utter crap....i can only hope they are guilty og being lazy and printing the marketing guff. Turbos are driven by delta T period...if there was even the vaguest benefit from cooler exhaust gasses for turbos you'd see this in race cars without doubt. There would be exhaust based water injection and all sorts of attempts to get these amazing cooled gases

Yes these setup work on large capacity engines because they only need mild levels of boost and have cubes on their side for off boost performance. Try this with a 4 cyl or smaller cube 6 or 8 and you'll soon find the flaws i suspect.

 

[tuning haus]

obviously turbo/s are better efficient closer to the engine...

but the big problem with v8's and 1uz's in the soarer is that there aren't too much space to mount/place the turbo/s!!

as much as people place the turbos in front of the motor (between the radiator) i don't really like that set up and placement...

so it may not work as efficiently, but if you want to get some boost (turbo) set up with the car, rear mount might definitely be one way to go.

 

[tuning haus]

also if we were to do a rear mounted turbo set up...

will having headers help (if so long or short tube)? or it wouldn't make too much of a difference..?

 

[stevechumo]

also if we were to do a rear mounted turbo set up...

will having headers help (if so long or short tube)? or it wouldn't make too much of a difference..?

You want to hide the turbo, don't you? Most of us want to show it off and I'm included. The exhaust gas velocity is very critical in a turbo system. So when you talk about the aftermarket headers, they're built for NA and their size is big. Big pipe will slow down the velocity if the gas has to travel a long distance before reaching the turbo. You should build your own headers with reduced pipe size specifically for the rear mount turbo for the best flow.

 

[XR8tt]

Yep I have 1" 1/4 [steam pipe] on a 330w V8 Ford with over 650 r.w.h.p at the wheels..



Std shorty headers are 1" 1/2, with 1 5/8 used on hi performance N/A applications..
At 18 Lb and at 6400 rpm it has 24Lb back pressure and climbs from there, on a pushrod engine rpm much higher isn't required.. .. Maybe due to twin .63 A.R turbine housings..
Turbo's also use pressure to make power as well .. BUT you have to keep track of back pressure !! On a street engine 2 to 1 back pressure is acceptable..
In most cases 8 to 10Lb is sufficient...

 

[stevechumo]

I love to see that number on my SC400 anytime.

 

[tuning haus]

Yep I have 1" 1/4 [steam pipe] on a 330w V8 Ford with over 650 r.w.h.p at the wheels..



Std shorty headers are 1" 1/2, with 1 5/8 used on hi performance N/A applications..
At 18 Lb and at 6400 rpm it has 24Lb back pressure and climbs from there, on a pushrod engine rpm much higher isn't required.. .. Maybe due to twin .63 A.R turbine housings..
Turbo's also use pressure to make power as well .. BUT you have to keep track of back pressure !! On a street engine 2 to 1 back pressure is acceptable..
In most cases 8 to 10Lb is sufficient...

Thanx for the details... So on a standard 4.0 liter 1uz motor, what's size piping at the header pipes and also on the exhaust piping would u recommend going to the back?

Also what size intercooler piping coming back up front?

On a 600-700whp set up

 

[XR8tt]

I would keep the intercooler piping just a little bigger than turbo's outlet for approx 350 mm then up to the size of the intercooler inlet / outlet..
In most cases it's better to have smaller from the turbo to simply get pipe through engine bay... It also keeps air velocity higher..

On a street engine personally I would use 31mm with flange area the same size as port.. On a forged rotating assembly, ported heads etc.. 42mm with turbo's I guess over 70mm to keep a balanced assembly..
Keep in mind there are 6 cyl 4.0 making good power [over 350 rwkw] with 31mm primaries and they only have 6 for the same capacity..
A GOOD designed log style were primeries are 150 mm before entering log at 45* angle is quite a good manifold..Try to avoid sharper bends more than 45*...
Must think different from N/A when it comes to turbo exhaust headers..
On a rear mount ?? Size is debatable ?? I would run cold pipes longer at the turbo's outlet size due to longer straighter pipes...