rear mount turbo ML Triton V6

[turner]

I have undertaken a project to give the 6G74 in my 2007 ML triton glx-r a bit more go using a rear mounted turbo set up, to my knowledge because it hasn't been done before on a triton.

currently the triton has a 2'' lift using dobinson suspension, 265/75 16 scorpion rubber, black sunrasia wheels, gme 2 way,60l sub tank that feeds into main tank using a solid state fuel pump, 18LED light bar, 2 power vision 75w HiD pencil beam spotties, 2.5'' exhaust deleted the 3rd cat and have two high flow cats, aux battery, redarc charger, modified towbar. secondary trans cooler. k&n filter. egr pipe and all lines from engine to intake deleted or blocked off. (needed for boost reasons). snorkel (which will be useless soon also)

so over the last 12 months I have collected/purchased/fabricated all the parts needed to set this turbo up. im going to share it with anyone who is interested on this site over the coming months and maybe even share your thoughts wether good or bad with me, im not a professional but have built a few cars in the past so im not completely up the creek without a paddle.

so far I have the xcede processor which is a piggy back ecu that will control all the injectors including the 7th injector whilst under boost, the 2 bar map sensor, the internally wastegated turbo (I have two different sizes to try) the 60lb 7th injector and injector holder, scavenge pump to return oil back to engine, extra in line oil filter for turbo feed line, pressure sender switch to let me know if scavenge pump fails, pilot light to warn me of scavenge pump failure, Blow off valve (which im going to try and quieten down), exhaust tube 3'', 2.75'' and 2.5'' plus bends donuts etc, aluminium intake tube to feed into intake manifold, 3'' aluminium tube for suction into turbo, inline pod filter which will be mounted in tray almost directly above where turbo is being positioned. 2 extra exhaust sensors and weld in bungs, fuel pressure regulator (fuel pump from what im told will be good enough for 6psi), boost controller, all the braided oil pressure lines for supply and return for the turbo, plus a box full of fittings, clamps, hose and bits. as im building this I think I will still be short of parts

plan is to initially run 6psi, then see how 8psi runs, im not doing the ecu or tuning myself im trusting that to a bloke who sets up turbo cars for a living and "jail breaks" into any ecu on any car. 8psi may ask for a bigger fuel pump and different spark plugs from what im running now (which is not standard). tranny may need some loving too but if that goes well I feel confident I can sort that out.
want to thank salt36 for the ecu breakdown that has help myself and the tuner out a great deal.

I will post some pics now of the ute and some parts and will update when I have made some changes (before and after)

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[turner]

unreal thanks mate appreciate it

[NowForThe5th]

Wow!

'Bout time there were some more serious V6 mods happening here. I'll be watching this with interest.
'
I'm sure you've researched this but putting the turbo so far back - is that feasible/practical in terms of gains? Certainly these engines respond to turbocharging, as has been proven by the Magna guys getting crazy outputs from a single turbo mounted on one side, even twin turbos.

[turner]

yes that is a great question and the overall answer is yes there is big gains to achieve but its also a little unknown to a lot of people on if it will work effectively, because the turbo will be mounted further down the line then say on a regular turbo set up the exhaust gasses will be a lot cooler, that is a plus and a negative for a few reasons one is that the expansion of hot gasses will be less further down cause the turbo to spool up a little slower causing "lag" but a correctly sized turbo will reduce the lag considerably, the plus is that the turbo can run cooler, you can in most cases eliminate the need for a intercooler so you have less "intake piping" to pressurize with charged air. I do have a intercooler that I can fit if I need but if I can get away without using it I will. mainly cause it will give away that the car has had some mods to it if its fitted. the turbo will be mounted in the void that is on the drivers side opposite the fuel tank, from the 'Y' pipe there will be approx. 2m of straight exhaust pipe with no mufflers so hopefully the exhaust temp wont be too cool for a decent enough spool. one single turbo muffler will be mounted after the turbo to reduce drone but im doing this all myself so im going to see what works and what sounds like a heap of sh*t down the rd.

im aiming for at least 150hp improvement but I will let the dyno figues do the talking I may end up with more or less either way a improvement is much needed.

another great thing with the xcede is that I can run dual maps so I don't have to run 98 fuel all the time and switch back to 95. as this ute was the first new car I saved up and bought with cash and prob the last time I will ever be able to do that due to being now married with kids I don't want to cut corners and the research ive done is crazy. hopefully it goes well and maybe someone else with a v6 ml will want to do the same thing.

like I said would love any questions and ideas on this and will update as soon as I progress, im fabricating the bracket to hold the turbo at the moment so will post that when its completed also.

[NowForThe5th]

you have less "intake piping" to pressurize with charged air

This was one of the things I was thinking of. That's a fair distance of intake plumbing, from rear of cab to manifold. Guess it depends on things like pipe size and whether you can effectively pressurise it from down low in the rpm range. I find it a fascinating concept and it does sound like you've done a bit of research into it. Does it have more potential benefits than, say, a pair of small turbos at the manifold, which would spool up quickly? I'm thinking of my experiences with the various 6G7 motors I've had, all of which had only barely sufficient torque down low, were not bad in the mid-range and then turned a bit asthmatic at the top end. Reasons why I was looking at similar to what Salt did.

[Tony]

There are a few remote mount turbo set ups around and all worked well aside of the inevitable pressure drop so perhaps not as efficient. Main reason being the thermal air has cooled and somewhat contracted by the time it reaches the drive side of the turbo.

The positives of a set up like this far outweigh what I have said above and would be much better set up for making horse power than the Eaton blower on my Rangie.

Like the piggy back chip and seventh injector for fuelling. I run a rising rate regulator on the rangie with two high pressure EFI pumps and the injectors sometimes jam closes with extra fuel pressure. not a good set up so ditching for Delco-Haultec management and larger cc injectors. Again, your idea with the additional injector will be much easier to live with.

Watching with interest.

[salt36]

Good to see it happening Mate

The rear mount turbo will work a lot better with the auto than it would with a manual box.

The Galant and Eclipse guys in the US are getting good HP out of the rear mount turbo's

I think you will need to upgrade radiator....

[chrisdoherty87]

I have done a similar setup on an infinity 4.5L V8 but the mounted 2 turbos roughly under the the rear floor pan. Worked well with no where near as much lag as anticipated. Used a bilge pump with separate oil reservoir to supply oil to the turbos and a separate pump as a return as we didn't want to take oil pressure away from the motor. I think your on to a good thing here it will be interesting to see the finished product.

[chickencake]

any reason its not going in the engine bay?

[turner]

with the piping I think its a good idea to keep the piping that comes out of the turbo the same the whole way through, I have two turbos im going to try both with different outlets for example one has 2.25'' and the other is 2.5'' so I will make up the 2.5 intake tubing first using the larger of the two turbos and see how that goes, as I have the 'T' piece for both the MAP sensor and the BOV in 2.5''. if the 2.5'' spools up too slow I will try the slightly smaller turbo that has the 2.25'' outlet the only problem is that it will 'step up' to match up with the two ''T" pieces.

two smaller turbos on the v6 will work but I think costs will skyrocket as im keeping the current exhaust manifolds in place and id rather solve several rubicks cube's then try and get them out again and then fab up new ones

ive spoken to rpw in perth and bullet in goldy about some supercharged set ups and the factory radiator was retained and I think one triton ran 10psi but they wouldn't go into detail as it was obvious I was fishing for a lot of information but rpw are in perth so I wasn't going to see them in person as I live the complete opposite side of austraila

the 7th injector is purely to stop leaning out as I want to keep the standard 305cc injectors and use the 650cc injector to ramp up with boost pressure. 8psi is my goal but I may have to go larger injectors to 390cc even though with the xede I may be able to tweak the stock injectors a little bit. I will still be happy with 6psi if that's my limit (budget will be my limit).

would be nice if 6g74 SOHC were as cheap and available as 3.8 ecotec's

[chrisdoherty87]

Where are you mounting the 7th injector? Keep in mind it nay not spray evenly across all 6 cylinders.

[turner]

yes that's right, im still working that out most likely it will be housed in its own plate between the butterfly and intake manifold or a weld on bung will be used and it plumbed directly into the intake, or even before the butterfly to try and achieve a more even spread of fuel. its a bit of trial and error (hopefully not too much error)

[chrisdoherty87]

What style injector does your motor run? I ask because on Nissan RB25 I have hi flowed the standard injectors by re drilling the pintles on the injector caps to achieve almost an extra 200cc per injector. This may apply to yours if your lucky and that would eliminate the need for 7th injector. Also another to think about is turbo oil seal. With the long extended feed line you will be left with quite a bit of oil in the line and will drain into the turbo. This is normally fine as it gravity feeds back to return to motor. In your case it will not feed back to motor and will pool in the turbo. I had this problem at first and was causing quite a bit of smoke at next start up. Not trying to put a downer on the situation I'm just trying to help out from the lessons I've learnt in the past.

[chickencake]

Where are you mounting the 7th injector? Keep in mind it nay not spray evenly across all 6 cylinders.

extra injectors are a very old school method, think early 90's, thomastown and vlturbos - triggered with a hobbs switch
they work allright but far from optimal, your going to want to run it pretty fat because not every cylinder is likely to receive the same air/fuel ratio

if i were you id be getting a haltech ecu or something and running a set of 400-600cc injectors.
i cant imagine its a massive deal to upgrade the fuel pump, even if you do a basic surge tank 1.5L -2L with a return and a single bosch fuel pump.
last thing you want to sell your self sort on is fueling and tuning its the only thing holding it together.

also hows the piggy back going to react to the two bar map sensor ?

[chickencake]

What style injector does your motor run? I ask because on Nissan RB25 I have hi flowed the standard injectors by re drilling the pintles on the injector caps to achieve almost an extra 200cc per injector. This may apply to yours if your lucky and that would eliminate the need for 7th injector. Also another to think about is turbo oil seal. With the long extended feed line you will be left with quite a bit of oil in the line and will drain into the turbo. This is normally fine as it gravity feeds back to return to motor. In your case it will not feed back to motor and will pool in the turbo. I had this problem at first and was causing quite a bit of smoke at next start up. Not trying to put a downer on the situation I'm just trying to help out from the lessons I've learnt in the past.

once again thats not the best method having injectors re drilled, poor spray pattern, for what its worth fork out and buy a decent set brand new set

[turner]

good point about the extended oil feed and draining into the turbo whilst shutdown I hadn't thought of that, if I was to look at the ute from side on and draw a imaginary line from the oil pressure switch (from where im taking the oil pressure from) and where the turbo was mounted the turbo would sit slightly higher but if I park on a hill it will definitely hinder so maybe a 5psi check valve mounted before the inlet of the oil feed may be the go..., it would close on no pressure and hopefully keep the oil from entering.

the xede ecu needs to 2 bar map sensor to operate (they are sold by chiptorque together in the kit) the car already has a map sensor to control the standard ecu but that will read incorrect under boost. the xede can control timing, fuel injectors and has a ability to control water/meth injection, from what my tuner informs me (and its a bit over my head) he gave me the "this is what you need and don't worry it will work fine" haha and with just that I was confident

the injector holder, injector and wiring was not too pricey few hundred $$ so if it doesn't work we will step it up to larger injectors for sure but from our calculations we will only be using maybe 30% to 40% of the extra injector potential at full 6psi. good thing its really easy to get the injectors out of the 6G74 too
at the moment im using the standard 305cc injectors but may need 390cc or even bigger who knows..

[chrisdoherty87]

Check valve sounds like it would work. Have you put much thought into the oil feed how much pressure it will supply the turbo and how much pressure it will take away from the motor? If it does become an issue then consider running a separate oil reservoir as I did. Just needs an extra pump for a feed with a pressure regulator.

And chickencake, you are correct in saying that high flowing the injectors by redrilling is not as good as a full aftermarket injector as the spray pattern isn't the same but we have used this setup s few times on skylines making in excess of 550rwhp on e85 so it does work and is a cheaper option if the injector is capable.

[turner]

I have had thought of using a separate oil system for the turbo oil and I have a 4l tank that will do the job but im using journal bearing type turbo's (cheaper) which need a varying oil pressure which off the engine will be perfect, BB turbo's can have just one set oil pressure (from what im led to believe) but journal bearings don't love it as much. if the engine drops too much oil pressure I will have to look at it more maybe try different oils or see what orifice's in the turbo make a difference but hopefully it has enough oil pressure in it to make it a non issue. once I get this bracket finished to support the turbo I can mount it, fab up the exhaust and run the oil lines and see what happens. fingers crossed

[chrisdoherty87]

If you do decide to run the other oil tank then the way to vary the oil pressure to the turbo is with the use of a rising rate pressure regulator. Just run a vacuum line from motor to the reg and when its in vacuum it will be low pressure and as boost rises it will raise the oil pressure. You can get the regs in a 1:1 ratio right up to about a 6:1 ratio. So for every 1 psi of boost it will supply an extra 6psi of oil and so on.

[turner]

ok that sounds perfect then, that's a great option and I think I will investigate that a bit more, what oil pump do you suggest for the feed?,
I have a scavenge pump that uses brass gears and im not sure what psi it pumps out but from what I researched they are bulletproof but im not sure if its right for that application. id say if the oil tank is fitted in the tray I will still need the scavenge pump but I think it may be overkill to buy another of the same for an oil feed pump....

[chrisdoherty87]

We used a pump off eBay its specifically designed for pumping oil but for some reason it gets quite hot and should really be water cooled or something. I've heard of a few people running holden astra power steering pumps as they are electric and that's what we will try if we can't sort this pump out.

[MilkmanDan]

Beat me to it, was going to suggest a Haltech and be able to run larger injectors to do away with the need for a switched injector. Fuel and spark tables will be a hell of a lot easier to setup this way.

Where are you mounting the 7th injector? Keep in mind it nay not spray evenly across all 6 cylinders.

extra injectors are a very old school method, think early 90's, thomastown and vlturbos - triggered with a hobbs switch
they work allright but far from optimal, your going to want to run it pretty fat because not every cylinder is likely to receive the same air/fuel ratio

if i were you id be getting a haltech ecu or something and running a set of 400-600cc injectors.
i cant imagine its a massive deal to upgrade the fuel pump, even if you do a basic surge tank 1.5L -2L with a return and a single bosch fuel pump.
last thing you want to sell your self sort on is fueling and tuning its the only thing holding it together.

also hows the piggy back going to react to the two bar map sensor ?

[chickencake]

simple is usually best with turbo setups, all this talk of oil pumps and massive return hoses and additional oil tanks and pumps sounds like a bloody disaster.
different kettle of fish but i hung a 700hp garrett bb turbo on a v6 commodore years ago and it was a bloody nightmare with unforseen issue poping up, id hate to think what will happen if you try and run massive long oil lines the length of a car and use electric pumps to try and return the oil to the sump or additional oil tank.

my advice would be keep it as simple as bloody possible, use nothing but braided lines or hardlines to and from the turbo, get a good ecu - haltech or as such, get a good fuel system - new injectors to suit, fuel pump to suit and maybe a basic surge tank setup.

also id be bracing the turbo somehow aswell which im not sure how you would do considering the body moves independent of the exhaust which the turbo will be mounted too

not trying too shoot you down or discourage you too any degree 100% behind you just do things right and do them once - hopefully it works reasonably well

also 6psi... whats the point youll get over it fast, realllly fast, boost is addictive

[chrisdoherty87]

I agree in all sense the ideal way would be mount turbo under bonnet as normal setup with full stand alone ecu and bigger injectors. However due to the parts he has he seems he is set on going rear mount setup and I do love seeing people do something different. Yes a normal feed and return and conventional mounting is easier and arguably better but the infinity we did is still to this day going and makes 599rwhp on a dyno dynamics dyno through a standard auto box.

[hvac guy]

www.ststurbo.com they do this setup a lot