Turbo Specs

[TNT ANDY]

Not really powerful glasses, but the specifications of Turbo's.

I'm not getting anywhere searching the treads for info, I could do with some guidance on what size turbo is good for a 220 - 240bhp 5 with a 285 cam.

I know about the T28 etc, but I could do with a bit more than that, I think that my turbo may be struggling at top end and.

This is what I have

T3 Compressor (.42AR) with a .49 turbine housing.

The compressor wheel as viewed from the front is 43mm and the turbine wheel diameter is 43mm.

What kind of specs are people running to get between 220bhp - 240bhp

I can't get to the turbo to fully measure it until Sunday so I'll work out the trim on Sunday.

[Logg]

Well if you believe rolling roads my lill blower made 227@22psi last year run got aborted at the very top end as it got a little lean.. Garrett GT2056

https://www.rtoc.org/boards/album.php...pictureid=3997


_________Cmpressor___________________________Turbi ne_______________
Ind Whl Dia(mm)___Exd Whl Dia(mm)__Trim___A/R____Whl Dia(mm)__Trim___A/R
41.50____________56.00___________55____0.53____47. 00_______72___0.46

[BluntyR5GTT]

hi andy i have the following

t3 comp housing with pulsar comp wheel, t2.63 exhaust housing with pulsar t28 shaft/turbine machined into it.

this made me 230bhp at 23psi on a very rich few runs (10.5-6 afr)

its a great turbo full boost by 4k and pulls like a train, would be even better with mappable ignition, which you of course have with efi

[TNT ANDY]

Cheers guys, food for thought.

[TNT ANDY]

Cheers guys, food for thought. It looks like my turbine housing may be too small and choking up at top end.

[TNT ANDY]

Right - I've measured everything now and worked out trim etc.

This is what I have

Compressor

T3 Housing - 42 AR
Inducer - 42.75mm
Exducer - 60.00mm
Trim - 50.7mm



Turbine

T25 Housing - 49 AR
Inducer - 52mm
Exducer - 41.50mm
Trim - 63.69mm

What do you reckon this will put out with a 285?

[Logg]

That turbo Andy should be more than man enough for what your asking from it.

[HAndy]

Right - I've measured everything now and worked out trim etc.

This is what I have

Compressor

T3 Housing - 42 AR
Inducer - 42.75mm
Exducer - 60.00mm
Trim - 50.7mm



Turbine

T25 Housing - 49 AR
Inducer - 52mm
Exducer - 41.50mm
Trim - 63.69mm

What do you reckon this will put out with a 285?

230 bhp+
i think your .49 ar turbine housing is killing the power, try a .64 housing, as i can only assume your compressor is out flowing your turbine, if those measurements are correct also get that tubby manifold on and help the flow

had a quick look in the shed, but have not got a .63 t25 to give you to try

[TNT ANDY]

That turbo Andy should be more than man enough for what your asking from it.

Lovely, that's what I like to hear.

[TNT ANDY]

230 bhp+
i think your .49 ar turbine housing is killing the power, try a .64 housing, as i can only assume your compressor is out flowing your turbine, if those measurements are correct also get that tubby manifold on and help the flow

had a quick look in the shed, but have not got a .63 t25 to give you to try

Cheers Andy - I don't think that's the problem fella, Ross has a .49 rear with 220bhp, slightly bigger trim though (5mm) and a tubby manifold, I'm sure it will free it up somewhat but at the sacrifice of lag. Ross has a .63, but would I need to re-map before maxing it out???

[TNT!hammond]

Cheers Andy - I don't think that's the problem fella, Ross has a .49 rear with 220bhp, slightly bigger trim though (5mm) and a tubby manifold, I'm sure it will free it up somewhat but at the sacrifice of lag. Ross has a .63, but would I need to re-map before maxing it out???

Andy I never had the manifold on when on the rollers , I'm sure my trim is 55 on the front rather than your 50 . As people have said I'm sure your turbo is upto flowing more than 200hp , the rear housing I have as a spare for mine Is a .64 not the .63 , it's also machined to match my rear wheel which I also think is a larger trim to yours , we could always look though as I'm not 100%. If I remember right you hated the lag mine had when that was fitted , no boost till near 5k really so I'd keep looking else where on your setup rather than the blower

[TNT ANDY]

Andy I never had the manifold on when on the rollers , I'm sure my trim is 55 on the front rather than your 50 . As people have said I'm sure your turbo is upto flowing more than 200hp , the rear housing I have as a spare for mine Is a .64 not the .63 , it's also machined to match my rear wheel which I also think is a larger trim to yours , we could always look though as I'm not 100%. If I remember right you hated the lag mine had when that was fitted , no boost till near 5k really so I'd keep looking else where on your setup rather than the blower

Yo fingers LOL - I've checked everything bar the exhaust back pressure now, Check out my other post for details.

[HAndy]

the reason i mentioned the bigger housing was to give you something to try thats fairly cheap and easy to do first that could flow a bit more through the exhaust, and release more bhp/ftlb from the engine, rather than jump straight in the deep end and have the expense of having a turbo pulled apart just to have a very slightly bigger trim ratio upgrade, and have the costly expense of a rebuild /balanced. just to find it might still not be enough you are pushing through a 40mm throttle body now not a 25mm venturi ,and you have had the head flowed also, you will have lost flow restriction, would be a bit of difference between ross and your c1j set up

why not pm mr ipswich and get him to shuffle around his shed, im sure he has a bigger exhaust housing you could try for free first


book a local rolling road, do a run as it is now, get a print out then change the exhaust housing first and try again will give you more of an idea which direction you have to go and how much without the large expense.

[TNT ANDY]

the reason i mentioned the bigger housing was to give you something to try thats fairly cheap and easy to do first that could flow a bit more through the exhaust, and release more bhp/ftlb from the engine, rather than jump straight in the deep end and have the expense of having a turbo pulled apart just to have a very slightly bigger trim ratio upgrade, and have the costly expense of a rebuild /balanced. just to find it might still not be enough you are pushing through a 40mm throttle body now not a 25mm venturi ,and you have had the head flowed also, you will have lost flow restriction, would be a bit of difference between ross and your c1j set up

why not pm mr ipswich and get him to shuffle around his shed, im sure he has a bigger exhaust housing you could try for free first


book a local rolling road, do a run as it is now, get a print out then change the exhaust housing first and try again will give you more of an idea which direction you have to go and how much without the large expense.

Andy, that's a fantastic idea, I'LL see what OLI HAS KICKING AROUND.

[TNT ANDY]

Look at post number 6 chap.

Can you do a run down of how you're working this stuff out. You did tellme once, but I'm a really slow learner and I need to do stuff a number of times before I get it.

[TNT ANDY]

Ok on a more serious note what are your power goals and do you want to future proof it in case you want more**also do you want to run lower boost levels ie use a bigger turbo and have some lag or do you want to run a higher boost level and still have it very responsive with as small a unit you can get away with**also what spec turbo do you currently have and I would like compressor size and turbine size I can work all the trims out with that info and it gives us a good base to work from**plus also we know what turbos work on the c1j we can compare them to what you have*

You can see my turbo specs above, I would like 230 BP with a minimum of lag. See what you can do.

[Os8472]

Your running a .49 right turbine housing which is what I was running, it should flow enough for 220, well mine did at least but if you want a .63 turbine housing to try I have 2 sat in my garage

[TNT ANDY]

Your running a .49 right turbine housing which is what I was running, it should flow enough for 220, well mine did at least but if you want a .63 turbine housing to try I have 2 sat in my garage

Dig em out for us fella, I'll see you when I drop jp's ecu off, be worn a shot. What size is the turbine wheel which used to live in there?

[HAndy]

Your running a .49 right turbine housing which is what I was running, it should flow enough for 220, well mine did at least but if you want a .63 turbine housing to try I have 2 sat in my garage

your forgetting this turbo is not the same spec you had , it went back to cr turbo for modification ,ie 200bhp and fast spool, which it is at a push.


compressor diameter is ok but could do with more trim, to maximise air flow,

but your turbine is small diameter and to smaller trim, as i thought, your just bottle necking all the exhaust gasses

and to be honest by the time youve had this turbo altered it would be just as well to sell it , and buy a new item
gtx28rs(53.86 turbine wheel diameter/74 trim) with 60mm compressor wheel, .63 exhaust housing....... will give you the power you want without lag.

although if it were me i would still get the internal wastegated gtx3071r,55.6mm turbine,and 71mm compressor, for bigger bhp output 250+

[Os8472]

Dig em out for us fella, I'll see you when I drop jp's ecu off, be worn a shot. What size is the turbine wheel which used to live in there?

They were off my old 200sx turbos, I used one on my T28 when I first did the f7r conversion and I did notice a difference. Ill measure the wheel size for you when I get 5 minutes.

[TNT ANDY]

This is what CR Turbos suggested


Compressor – Re-Profiled

T3 Housing - 42 AR – T3 Housing 0.60 A/R
Inducer - 42.75mm – 47.22mm C/w
Exducer - 60.00mm – 60mm
Trim - 50.7mm – 62 Trim

Turbine – Re-Profiled

T25 Housing - 49 AR – 0.49 A/R
Inducer - 52mm – 53mm
Exducer - 41.50mm – 47.1mm
Trim - 63.69mm – 76 Trim

This would produce the power you require without the need for changing the associated plumbing on the fitment of the unit.

[Dave Reed]

your forgetting this turbo is not the same spec you had , it went back to cr turbo for modification ,ie 200bhp and fast spool, which it is at a push.


compressor diameter is ok but could do with more trim, to maximise air flow,

but your turbine is small diameter and to smaller trim, as i thought, your just bottle necking all the exhaust gasses

and to be honest by the time youve had this turbo altered it would be just as well to sell it , and buy a new item
gtx28rs(53.86 turbine wheel diameter/74 trim) with 60mm compressor wheel, .63 exhaust housing....... will give you the power you want without lag.

although if it were me i would still get the internal wastegated gtx3071r,55.6mm turbine,and 71mm compressor, for bigger bhp output 250+

I still say the .63 housing is too big.. You see my power and that was a .49 as I keep saying.. That was 250+ (which I also keep mentioning lol).

You could always ask Jesus to have a measure up..

[TNT ANDY]

I still say the .63 housing is too big.. You see my power and that was a .49 as I keep saying.. That was 250+ (which I also keep mentioning lol).

You could always ask Jesus to have a measure up..

I'm getting to grips with this now, It makes sense that a 50mm trim (turbine) is going to be restrictive trying to get megga amounts of gas through a 50mm hole just aint gonna go, like having a 2inch exhaust. Keeping the A/R to a .49 seems like a good way to keep the turbine speed up as best it can be without restriction. I'm gonna go down this route now.

Jesus - if you're reading this is it possible or have you already measured the wheels on Dave's ol turbo?

Cheers Dave

[Logg]

I remember when Tony (fish head) looked at your turbo Dave he said it looked like the gt28RS but with a .49 turbine housing.

[Dave Reed]

I remember when Tony (fish head) looked at your turbo Dave he said it looked like the gt28RS but with a .49 turbine housing.

That sounds about right Logg.. As I say I'm
Not a turbo expert and just phoned up td, told them what I wanted and they said ok that'll be £1300 quid lol (or whatever it was) and I gave them my credit card no

But what I do know is it was a wiled turbo without much lag and seemed to make good power.. Don't get me wrong with a .63 housing it probably would've made even more, however as I used to cruise around the streets a lot I decided it would be best left alone.

[fishead]

I remember when Tony (fish head) looked at your turbo Dave he said it looked like the gt28RS but with a .49 turbine housing.

2554

[rs250nut]

2554

****, alright burt where you been hiding

[TNT ANDY]

2554

Oddly enough, I've been working out about which is the best suited etc, and I've narrowed it down to just this one also.

[TNT ANDY]

OK - specing turbo's

There are a few things you need to know, Firstly how much air your engine will get going through it at a certain rpm etc, and its also worth working this out for a few rpm ranges also, as you will be able to see if the turbo you are specing will reach full boost by your lower rpm limit. So I'll be looking at 3500 rpm (as this is where I would ideally like to see my turbo on full boost by as a maximum) and also 7000 rpm which is where possibly I think I'd like to see my trusty C1J pushed to.

The equation to use for calculating how much (cfm - cubic feet per minute) is :-

CFM=L x rpm x VE x pr
---------------------
5660

L = Liter of engine, so that's 1.4

rpm = at what rpm you want to find out how much air is being shifted

ve = Volumetric efficiency of engine, this is the really grey area in all of this, but there are a few rules of thumb which suggest the following :-

Stock 2-valve = 85%
Stock 4-valve = 90%
Street modified = 93%
Competition = 105%


I've gone with 90% as I have a modified 2 valve engine and this seems to be the most conservative option.

Pr = the amount of boost you want to run which is derived from the following:-

Pr = 14.7 + amount of boost
-----------------------------
14.7 This gives you the absolute pressure the turbo will be dealing with.

So for the lower threshold we will do

1.4 x 3500 x 90 x 2.36
-----------------------------
5660

= 183.88 cfm or 12.89 lb/min (divided 183.88 by 14.27 to get lbs which is the unit of pressure Garrett use on there maps)

So that's the minimum rpm,

Max rpm =

1.4 *7000**90*2.36
--------------------------
5660

=367.76 cfm or 25.77 lb/min



Once we have these we can looks at the maps for turbo's and see how well they suit our needs.

I believe this theory to be relatively accurate, and from what I'm seeing it seems to make sense. please please please point me in the right direction if you see any glaring mistakes, as this is hopefully going to make sense of the black art.

I'll post up, what to do with this info later.

[Logg]

Wow your really getting into this Andy. makes my turbo choice seem rather simple.

I just looked at for the smallest turbo that could supply around 200bhp at 20psi, as this is what a c1j normally floats around but had scope for more boost and flow in the compressor map.

Good luck in your search mate.

[JP Racing]

If you are using the info to read compressor maps then you have to take it with a pinch of salt. When using the same technique for my engine and putting it to a compressor map it came back as being able to run lots bigger turbos with less lag than I thought they should have. So in my opinion it's only a rough idea of what to go for but a good start if you go on garretts web page they have compressor maps for all their turbos so that's handy

[TNT ANDY]

If you are using the info to read compressor maps then you have to take it with a pinch of salt. When using the same technique for my engine and putting it to a compressor map it came back as being able to run lots bigger turbos with less lag than I thought they should have. So in my opinion it's only a rough idea of what to go for but a good start if you go on garretts web page they have compressor maps for all their turbos so that's handy

Yeh, that's what I've been looking at. Looking at my data and similar spec turbo, it all makes sense.

Throw 1 of those Chinese turbo's up for me to look at and I'll see what's what.

[TNT ANDY]

OK - specing turbo's

There are a few things you need to know, Firstly how much air your engine will get going through it at a certain rpm etc, and its also worth working this out for a few rpm ranges also, as you will be able to see if the turbo you are specing will reach full boost by your lower rpm limit. So I'll be looking at 3500 rpm (as this is where I would ideally like to see my turbo on full boost by as a maximum) and also 7000 rpm which is where possibly I think I'd like to see my trusty C1J pushed to.

The equation to use for calculating how much (cfm - cubic feet per minute) is :-

CFM=L x rpm x VE x pr
---------------------
5660

L = Liter of engine, so that's 1.4

rpm = at what rpm you want to find out how much air is being shifted

ve = Volumetric efficiency of engine, this is the really grey area in all of this, but there are a few rules of thumb which suggest the following :-

Stock 2-valve = 85%
Stock 4-valve = 90%
Street modified = 93%
Competition = 105%


I've gone with 90% as I have a modified 2 valve engine and this seems to be the most conservative option.

Pr = the amount of boost you want to run which is derived from the following:-

Pr = 14.7 + amount of boost
-----------------------------
14.7 This gives you the absolute pressure the turbo will be dealing with.

So for the lower threshold we will do

1.4 x 3500 x 90 x 2.36
-----------------------------
5660

= 183.88 cfm or 12.89 lb/min (divided 183.88 by 14.27 to get lbs which is the unit of pressure Garrett use on there maps)

So that's the minimum rpm,

Max rpm =

1.4 *7000**90*2.36
--------------------------
5660

=367.76 cfm or 25.77 lb/min



Once we have these we can looks at the maps for turbo's and see how well they suit our needs.

I believe this theory to be relatively accurate, and from what I'm seeing it seems to make sense. please please please point me in the right direction if you see any glaring mistakes, as this is hopefully going to make sense of the black art.

I'll post up, what to do with this info later.

OK from here we need to use a map to base our findings on, so we will use a compressor map as follows




On this we we plot the results of our calculations. The first of which is the amount of air we our engine will flow @ 20psi which was 12.89 lb/min

Then next we need to plot that against how much pressure we will be running


As we can see on this plot @ 3500rpm, we are just to the left of the surge line which means it will not be fully on at this point, but it's very close, not too laggy. Next we want to see if this turbo will cope with 20psi higher up the rev range. so again we will need to put our 7k calculations on this map----

Here we can see that @ 20psi and @ 7000rpm its all rosy, in fact there is a few more psi that can be run on this turbo with it still being within the map.

Hope that helps a bit, but remember that as others have pointed out, use these only as a guide and also that we are only guessing at the engines VE, so there can be variance there.

When I ran these calculations on on a similar turbo that's on my car, running over the 16psi which was the very right of the map @ 6.5k my intake temps went crazy, suggesting that it was pumping very hot air out and into my engine. dropped it back to 16psi and everything was good, she felt crisp and lively, good afr's and a steady but respectable intake temp.

[TNT ANDY]

Sorry about the massive gaps, I can see why thias has happened, but I don't know how to sort them out.

[HAndy]

glad your getting the idea

[TNT ANDY]

glad your getting the idea

[Dave Reed]

Well what do you know, there's a turbo that is the same as mine in the classifieds.



https://www.rtoc.org/boards/showthread.php?t=32188