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andybp

diy rear mount

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Hi guys having a bit of time on my hands I've been looking into the process of selecting a turbo for rear mount set-up's most people seem to regard it as voodoo experience or just dumb luck

looking into it the big problem seems to be a lack of compatible turbo's the turbine and compressors are matched to suit a standard turbo type installation where the turbo is mounted on the exhaust manifold

under normal operating conditions the exhaust gas volume is approximately 4 times the intake volume due to it's expansion due to temperature intake temp 80 F exhaust manifold temp potentially 1800 F

but what surprised me was the huge drop in temp to the tailpipe to approx 300 F lagging the exhaust may improve this but not enough, the temperature drop is not all bad as the denser exhaust gas offsets this somewhat

 

 

if we apply Charles Law :wacko:

 

clgraph_zpsceb71613.jpg

 

which describes how gases tend to expand when heated we can see that the volume of exhaust gas in a rear mount installation may only be 1.5 to 2 times the volume of the intake so people saying

drop the Turbine A/R down from for example .63 to .58 as i believe they used in the STS set up does not seem enough for this type of set up but this is where we hit the problem i was talking about of no compatible turbo's because if you drop the Turbine A/R lower the compressor side also reduces because as i said at the start the turbine and compressors are matched by the manufacturers to suit a standard type installation so I'll try my set up as is when the sun comes back out next year but i think I'll be building a hybrid turbo before i'm happy with it :)

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...but i think I'll be building a hybrid turbo before i'm happy with it :)

 

ShitJustGotRealLlama.gif

 

:lol::teeth:

is that a llama cause the things freaking me out gotta stop staring at it :wacko:

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...but i think I'll be building a hybrid turbo before i'm happy with it :)

 

ShitJustGotRealLlama.gif

 

:lol::teeth:

is that a llama cause the things freaking me out gotta stop staring at it :wacko:

:lol: Yes it is. :)

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So the good news is the doc says i can go back to work Monday and if i'm well enough to work i'm well enough to play with the Z

When i took the turbo off the Z i noticed some oil in the compressor so i'm guessing the oil is not draining properly i'm going to put in a second pump to scavenge the oil from the turbo

Good job i have a few spare pumps knocking about i've already bought a second speed controller for the other pump and mounted both in a box just have to fit a cooling fan and then get started on the plumbing

really need to get under the car to sort out the plumbing and fitting the second pump but i wont be allowed to do that for a while yet :nono:

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Good news then Andy. Glad you're making a recovery so you can get back to doing what you love. :thumbs:

What i love ? you mean walking around the house naked. Edited by andybp

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Good news then Andy. Glad you're making a recovery so you can get back to doing what you love. :thumbs:

What i love ? you mean eying up women and walking around the house naked.

Whatever floats your boat. :lol:;)

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just a little update i'm convinced after my post of the 16th that the turbine on my GT35 is way too big i've ordered a new much smaller T3 turbine .48 A/R should arrive early January it's only money and you cant take it with you right ? :)

hopefully will be able to get on as long as it doesn't snow

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just a little update i'm convinced after my post of the 16th that the turbine on my GT35 is way too big i've ordered a new much smaller T3 turbine .48 A/R should arrive early January it's only money and you cant take it with you right ? :)

hopefully will be able to get on as long as it doesn't snow

Can't wait to see this build start progressing again, ...my mate had a similar thing with his Impreza re; the turbo.

 

Bought a turbo that was just way to big for what he needed so ended up selling it and getting a smaller one which generated power much lower down & is still good for silly horse power. B)

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just a little update i'm convinced after my post of the 16th that the turbine on my GT35 is way too big i've ordered a new much smaller T3 turbine .48 A/R should arrive early January it's only money and you cant take it with you right ? :)

hopefully will be able to get on as long as it doesn't snow

Can't wait to see this build start progressing again, ...my mate had a similar thing with his Impreza re; the turbo.

 

Bought a turbo that was just way to big for what he needed so ended up selling it and getting a smaller one which generated power much lower down & is still good for silly horse power. B)

Yea i should have looked into it in depth before i started but there just isn't the information out there to allow you to choose a turbo for a rear mount setup because it's not what the manufacturers thought we were going to do with them as i said before if you do the math the turbine has less than half the gas volume you would expect with a standard setup so you'd spec the turbine to suit an 1800cc and the compressor to suit a 3500cc which says you need somewhere between a gt22 to gt28 for the turbine and gt30 to gt37 for the compressor which makes an ideal hybrid even more difficult as the gt22-28's are t25 and the gt30 to 37's are t3's so you can't just swap over the compressor housing and wheel like i'm going to with my gt35

just had to go and answer the door my turbo's here already 5 days from Hong Kong ok enough rambling gotta go open the Z's Christmas prezzi :teeth:

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Can't wait for this build to come together😎 good job and tech stuff to keep us entertained.

 

I really admire your DIY attitude but if I had your skill I would have gone with the mid mount setup and substantially reduce the issues with turbo selection, plumbing etc.

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Edited by GT4 Zed
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Can't wait for this build to come together😎 good job and tech stuff to keep us entertained.

 

I really admire your DIY attitude but if I had your skill I would have gone with the mid mount setup and substantially reduce the issues with turbo selection, plumbing etc.

Subscribed.

Glad to hear my ramblings don't bore you all to tears i shall try to keep you entertained :yahoo:

i think the plumbing on the mid mount is harder due to the lack of space i did a mid mount many years ago on a 2.8 capri the heat inside in the summer was unbearable plenty of space no heat problems on rear mount also has the novelty/rarity factor which was the decider in this case since i'm just playing Yes this is what i do for fun :wacko:

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Well my day just keeps getting better had lots of comms via email when i ordered my new turbo from the manufacturer in Hong Kong was trying to get a turbo with the correct turbine and compressor the extremely poor English didn't help

(theirs not mine) so in the end they were just going to send me the .48 A/R turbine and i was going to put my compressor housing and wheel from the GT35 on to it so i open the box and it's got a complete turbo in it :wacko:

my first thought was they've got it completely wrong but as it happens they got it 100% right even the right anti surge compressor housing and wheel they said they couldn't do. the compressor housing A/R is .70 same as the gt35

the wheel is slightly smaller but the GT35 is capable of 600+hp this slightly smaller wheel wont have a big impact still more than enough for my requirements

i'm sure you can guess from how shiny it is which one is new

 

IMAG0572_zps966c9cdb.jpg

 

you can see the big differance in exhaust housing size here

 

IMAG0570_zpsf124c66c.jpg

 

 

the turbo came with an internal wastegate and v band fitting already removed so will require some mods to fit

 

IMAG0569_zps644eec33.jpg

 

IMAG0573_zpsfdd8ba8b.jpg

 

IMAG0574_zps87c54000.jpg

 

IMAG0576_zpsb0ec8a90.jpg

 

 

 

dual pump speed controller ready to fit to control the oil feed and scavenge pumps

 

IMAG0575_zps9eb8dca1.jpg

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cant believe it one of the neighbours collared the missus when she came home and squealed on me for having a little play in the garage today " I don't think he should be doing that dear he's still not well " She says interfering old biddy :rant:

I got a right ear full, god it was only a bit of spanner-ing no grinding no welding

Any way that's my little rant :)

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New turbo look's cool Andy and sorry the old lady grassed you up to the Mrs but I guess her heart was in the right place. :thumbs:

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New turbo look's cool Andy and sorry the old lady grassed you up to the Mrs but I guess her heart was in the right place. :thumbs:

yea but she's still an old bag :)

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Still keeping an eye on this, glad to see you back in business with the build, from my limited knowledge of turbo positioning, given the fact that that as the exhaust to turbo length increases, the gas temp and so gas speed decreases with it, so I would imagine that in order to make the best use of whats available, you would not only need a smaller hot side housing and turbine, it would also need to be designed to make more use of the lower gas speed, IE different spacing and pitch on the turbine if that makes sense.

 

I think the oil scavenging is going to remain you biggest problem though, unless you can actually use a pull through pump system to both feed and return the oil.

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Still keeping an eye on this, glad to see you back in business with the build, from my limited knowledge of turbo positioning, given the fact that that as the exhaust to turbo length increases, the gas temp and so gas speed decreases with it, so I would imagine that in order to make the best use of whats available, you would not only need a smaller hot side housing and turbine, it would also need to be designed to make more use of the lower gas speed, IE different spacing and pitch on the turbine if that makes sense.

 

I think the oil scavenging is going to remain you biggest problem though, unless you can actually use a pull through pump system to both feed and return the oil.

 

sorry haven't been keeping up with my own thread only just seen your post some one offered me a gt35 rebuild kit really cheap £15 since i ran it dry a couple of times while trying to get the oil system to work properly seemed like a good idea

 

IMAG0594_zps7e5cb6af.jpg

 

having stripped down the old turbo today other than the compressor O ring getting damaged when i removed the cover it's good as new but lots of oil has been getting past the seals so I've decided 100% to go with a scavenge pump and separate pump to supply oil to the new turbo :)

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Excuse my ignorance but have only just hooked onto this topic by default.

Amazing determination and attention to detail against the odds.

Keep up the good work.

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Excuse my ignorance but have only just hooked onto this topic by default.

Amazing determination and attention to detail against the odds.

Keep up the good work.

Thanks it is a bit of a labour of love otherwise i would have given up by now was hoping to have it all ready to go by now but life threw a couple of spanners in the works

but hopefully as long as no more spanners come my way i'll be back on track by the end of February :)

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thought I'd stop moping (that's what my wife calls it) over the stuff I cant do and get on with what I can

having tried several different electronic speed controllers for the oil feed and scavenge pumps I've decided not to waste any more money on them as they won't do exactly what I want them to do

so I'm going to build an all singing all dancing one with a few added extra's

this controller will be dash mounted and will

 

1) control the speed of the oil feed and scavenge pumps so maintain steady oil pressure

2) raise the oil pressure if the turbo temperature gets too hot to increase cooling

3) give a warning if oil temp or pressure are not normal

4) display oil pressure and temperature

5) allow easy adjustment of all of the above

6) display and allow adjustment of boost pressure

 

Yes I know I'm very demanding. this shows most of the stuff I will be using to achieve this and my progress to date (I did only start today)

 

IMAG0599_zps1350b036.jpg

 

IMAG0607_zpsf642c497.jpg

 

IMAG0604_zpsfd8147bd.jpg

 

IMAG0611_zpsd1133f2c.jpg

 

also purchased a little gift for the Z to help with the engine oil temp when the turbo's fitted

 

IMAG0598_zpsd008a31e.jpg

 

IMAG0597_zps03408091.jpg

 

:)

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This really is very impressive stuff, y'know.

 

Good on you mate, really enjoying this :)

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This really is very impressive stuff, y'know.

 

Good on you mate, really enjoying this :)

Thanks for the vote of confidence much appreciated my missus has been calling me nerd all day and asking me if i shouldn't be wearing sandals and a tank top :blush:
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