What turbo? Subaru EJ20 with 2.5 bottom end.
Discussion
I have to decide on a turbo to fit to my Murtaya. I am wanting about 350 bhp with quick spool. If it can be delivered over a wide power band that would be great. Car will be used as a street car and the odd track day.
The engine is an Ej20 with a 2.5 bottom end and strengthened internals.
VVT heads,
FMIC.
Simtec ECU,
5 speed box.
At the moment I am looking at the following :
Td05 20G
SC 360 (scooby clinic)
IHI vf48 from an 2010 scooby.
Forced performance HTA green.
Anyone know these turbos so I can compare before I commit?
The engine is an Ej20 with a 2.5 bottom end and strengthened internals.
VVT heads,
FMIC.
Simtec ECU,
5 speed box.
At the moment I am looking at the following :
Td05 20G
SC 360 (scooby clinic)
IHI vf48 from an 2010 scooby.
Forced performance HTA green.
Anyone know these turbos so I can compare before I commit?
ScoobieWRX said:
That 20G is capable of c.400bhp, and even on a 2.5 doesn't get spooling till c.3000rpm although it will keep pulling to 7000rpm. You probably don't have the injectors to safely make full use of this turbo, i'm guessing.
If you wanted quicker/earlier spoolup on a 2.5 you would run a VF35(divided thrust), VF34(ball bearing), or TD05 16G(sleeve bearing) turbo. All of these should start spooling from about 2500rpm or sooner on the 2.5 and give you the 350 you're looking for all day long, so long as you have all the right supporting mods and injectors (550cc STi pinks).
I presume your ECU redlines the engine at around 6500-6900rpm (as set by your mapper) which is about 500-1000rpm after these turbos have properly run out of puff so you should be short-shifting at around 5500-6000rpm to make best use of the powerband, ideal for trackday/circuit work.
Your 2.5 should make a shedload of torque from fairly low down on any of these turbos making your Murt an absolute hoot to drive.
If you wanted quicker/earlier spoolup on a 2.5 you would run a VF35(divided thrust), VF34(ball bearing), or TD05 16G(sleeve bearing) turbo. All of these should start spooling from about 2500rpm or sooner on the 2.5 and give you the 350 you're looking for all day long, so long as you have all the right supporting mods and injectors (550cc STi pinks).
I presume your ECU redlines the engine at around 6500-6900rpm (as set by your mapper) which is about 500-1000rpm after these turbos have properly run out of puff so you should be short-shifting at around 5500-6000rpm to make best use of the powerband, ideal for trackday/circuit work.
Your 2.5 should make a shedload of torque from fairly low down on any of these turbos making your Murt an absolute hoot to drive.
Thanks for the info. I do have 550 injectors and the car was originally going to run 400 plus bhp. The gearbox is the weakest link.lol (cant afford £3000 for 6 speed)
If I can save money by going for one of the standard turbos I may just do that. Its got the simtec ecu but it has never been set up as its all still brand new.
If I can save money by going for one of the standard turbos I may just do that. Its got the simtec ecu but it has never been set up as its all still brand new.
You should get good money selling your 20G, you may even be able to do a swap for a fairly new 16G or a low mileage VF34/35 in really good condition.
I played with a 2.5 WRX a month or so ago. This had a TD04 that spooled up from under 2000rpm and was on full boost (19psi) by 2500rpm. Although it properly ran out of puff by just over 4500rpm and the boost rapidly dropped off a cliff, up to that point it made a shedload of torque and was a lot of fun to drive.
A small turbo on a larger displacement engine means instant acceleration, no lag, and goes like the clappers.
I played with a 2.5 WRX a month or so ago. This had a TD04 that spooled up from under 2000rpm and was on full boost (19psi) by 2500rpm. Although it properly ran out of puff by just over 4500rpm and the boost rapidly dropped off a cliff, up to that point it made a shedload of torque and was a lot of fun to drive.
A small turbo on a larger displacement engine means instant acceleration, no lag, and goes like the clappers.
I have just come back from looking at the car in Exeter. I picked up the 20G as well ready to sell.
Interesting that the turbo you mention ran out of power so low down. I would like mine to pull as high as possible yet still give me good low down response.
Out of interest, here is the vf34 on a wrx 2.5 blob eye. Followed by the sc36 on the same car.
[url]
SC36
|http://thumbsnap.com/GLoHl0SV[/url]
Interesting that the turbo you mention ran out of power so low down. I would like mine to pull as high as possible yet still give me good low down response.
Out of interest, here is the vf34 on a wrx 2.5 blob eye. Followed by the sc36 on the same car.
[url]SC36
|http://thumbsnap.com/GLoHl0SV[/url]Edited by SA boy on Sunday 3rd April 13:49
I'm afraid you can't have your cake and eat it unless you spend a lot of money on your turbo. The sc36 is a lot more money than a standard VF34/35 because it's a custom turbo developed for the Impreza. You'll find VF turbos on many jap cars.
330 from a VF34 is still well below it's full potential despite a TMIC. On a car with TMIC it should still make 350+. On a 2.5 it should pull really well to 5500rpm and then drop off fairly swiftly after that. On a 2.0L it will pull all the way to 6000-6200rpm before properly starting to drop off. You shouldn't need to rev your 2.5 any further than 6500rpm so short-shifting is the way forward to keep your engine in the sweet spot where you're seeing most torque.
I keep saying this on my posts but only because it's true....Don't get hung up on bhp figures from a rolling road, it's just a guesstimate. You should be more hung up on how much Torque you're making and Wheel horsepower figures (the amount of power you're putting down on the road/rollers) as that's all that really matters in the real world. Torque is what makes a quick car, not bhp. Next time you take your car on a rolling road ask for uncorrected wheel Horsepower figures.
ETA... Looking at those graphs it would seem the VF34 makes more peak torque than the sc36 and the graphs only go up to 6500rpm in any case so actually there isn't a lot between them. A decent remap would see that VF34 doing as well if not better than the SC36's peak bhp figure.
It's all relative.
330 from a VF34 is still well below it's full potential despite a TMIC. On a car with TMIC it should still make 350+. On a 2.5 it should pull really well to 5500rpm and then drop off fairly swiftly after that. On a 2.0L it will pull all the way to 6000-6200rpm before properly starting to drop off. You shouldn't need to rev your 2.5 any further than 6500rpm so short-shifting is the way forward to keep your engine in the sweet spot where you're seeing most torque.
I keep saying this on my posts but only because it's true....Don't get hung up on bhp figures from a rolling road, it's just a guesstimate. You should be more hung up on how much Torque you're making and Wheel horsepower figures (the amount of power you're putting down on the road/rollers) as that's all that really matters in the real world. Torque is what makes a quick car, not bhp. Next time you take your car on a rolling road ask for uncorrected wheel Horsepower figures.
ETA... Looking at those graphs it would seem the VF34 makes more peak torque than the sc36 and the graphs only go up to 6500rpm in any case so actually there isn't a lot between them. A decent remap would see that VF34 doing as well if not better than the SC36's peak bhp figure.
It's all relative.
Edited by ScoobieWRX on Sunday 3rd April 17:38
Speaking of selling, i've got an Andy Forest 20G still attached to my 2.0L WRX wagon that's done very little mileage, and that i would like to sell or ideally swap for an 18G or a VF34 (even better) 
IHI VF48, standard 08 STi turbo, perfect for the 2.5L. Strong midrange and topend. Should make 300-310whp (wheel Horsepower) which is about 360-370bhp, very similar in performance to an 18G although will spool earlier than the 18G.
A used VF34 would be cheaper, and spool earlier still so almost every bit as good as the VF48 and will make 350bhp no problem, although it will run out of steam before the VF48 does in terms of rev range. It's not often you want to use the whole rev range anyway, and with Subaru's generally you're better off short-shifting, even in a Murt.
VF48 will make more power but it's only useable from midrange and up. A VF34 on a 2.5L should be spooling pretty early on, maybe even as low as a TD04 on a 2.5, baring in mind the ball bearing nature of the VF34.
350bhp in an STi is a lot of grunt and will propel you very quickly from zero and onto a silly top speed. In a Murt 350bhp should be a shedload of grunt and enough to scare you bloody silly although it's so much nicer if that power is available from low down.
What does the Murt weigh??
Edited to add...If you're really keen on 400bhp and early spool and have the money perhaps instead of the HTA Green have a look at an MD321H from Lateral Performance. That will spool from low and pull all the way to the redline but it will cost you. Equally you'll need to have a look at your injectors for 400bhp. If you can squeeze enough fuel through your 550's without them leaking through the fuel rail seals, using a good quality fuel pressure regulator at 4bar+, and running solid mid AFR's(11.5) to the redline you might just get there.
IHI VF48, standard 08 STi turbo, perfect for the 2.5L. Strong midrange and topend. Should make 300-310whp (wheel Horsepower) which is about 360-370bhp, very similar in performance to an 18G although will spool earlier than the 18G.
A used VF34 would be cheaper, and spool earlier still so almost every bit as good as the VF48 and will make 350bhp no problem, although it will run out of steam before the VF48 does in terms of rev range. It's not often you want to use the whole rev range anyway, and with Subaru's generally you're better off short-shifting, even in a Murt.
VF48 will make more power but it's only useable from midrange and up. A VF34 on a 2.5L should be spooling pretty early on, maybe even as low as a TD04 on a 2.5, baring in mind the ball bearing nature of the VF34.
350bhp in an STi is a lot of grunt and will propel you very quickly from zero and onto a silly top speed. In a Murt 350bhp should be a shedload of grunt and enough to scare you bloody silly although it's so much nicer if that power is available from low down.
What does the Murt weigh??
Edited to add...If you're really keen on 400bhp and early spool and have the money perhaps instead of the HTA Green have a look at an MD321H from Lateral Performance. That will spool from low and pull all the way to the redline but it will cost you. Equally you'll need to have a look at your injectors for 400bhp. If you can squeeze enough fuel through your 550's without them leaking through the fuel rail seals, using a good quality fuel pressure regulator at 4bar+, and running solid mid AFR's(11.5) to the redline you might just get there.
Edited by ScoobieWRX on Sunday 3rd April 22:41
£900 for a VF34....Someone is having a laaaarf!!! 
I think i've seen the same VF48's for sale on eBay at around £550. So long as they are not the cheap chinese copies that flooded the market sometime back and they've been manufactured in Japan you should be OK.
IMHO, and if money is not an issue, i would go for an MD series turbo every time. Mark at Lateral Performance does some lovely turbos that have been properly tested and run successfully in competition on many top performaing Subaru in the UK and abroad. I would give him a serious look on the turbo side.
Equally he could also modify your injectors to get them flowing a lot more fuel than standard to cope with all the extra air your engine will be consuming. Internally they'll be like brand new and I think he can get somewhere around 810-830cc flow from a set of 550's, plus they'll be properly flow matched too. Fuelling is important when you're chucking on a more efficient turbo.
Just don't drive your car with extensive modifications until you get it remapped, or at least drive it for very short distances and very gently. There are a small handful of very good mappers around that will do you proud.
Note...I didn't say reputable mappers as good reputations aren't always deserved.
Edited to add....1012Kg
350-400bhp will keep you reliable and is more than ample to seriously run rings around much more powerful Subarus. I'd love to know what it does on a 1/4mile. Nice one!! 
I think i've seen the same VF48's for sale on eBay at around £550. So long as they are not the cheap chinese copies that flooded the market sometime back and they've been manufactured in Japan you should be OK.
IMHO, and if money is not an issue, i would go for an MD series turbo every time. Mark at Lateral Performance does some lovely turbos that have been properly tested and run successfully in competition on many top performaing Subaru in the UK and abroad. I would give him a serious look on the turbo side.
Equally he could also modify your injectors to get them flowing a lot more fuel than standard to cope with all the extra air your engine will be consuming. Internally they'll be like brand new and I think he can get somewhere around 810-830cc flow from a set of 550's, plus they'll be properly flow matched too. Fuelling is important when you're chucking on a more efficient turbo.
Just don't drive your car with extensive modifications until you get it remapped, or at least drive it for very short distances and very gently. There are a small handful of very good mappers around that will do you proud.
Note...I didn't say reputable mappers as good reputations aren't always deserved.
Edited to add....1012Kg
350-400bhp will keep you reliable and is more than ample to seriously run rings around much more powerful Subarus. I'd love to know what it does on a 1/4mile. Nice one!! Edited by ScoobieWRX on Monday 4th April 08:41
A previous Murt with 320bhp did 0-60 in 3.4 and I think 100 in 7.8sec. I need to find the link again to be sure.
The chap mapping mine is Steve Simpson who developed the simtec ECU. He should be pretty good mapper. I see the SC360 is good for 428bhp on a 2.5. Interesting for later upgrade of gearbox. I can have Steve set up 2 maps one with 350 bhp the other with 400.
The chap mapping mine is Steve Simpson who developed the simtec ECU. He should be pretty good mapper. I see the SC360 is good for 428bhp on a 2.5. Interesting for later upgrade of gearbox. I can have Steve set up 2 maps one with 350 bhp the other with 400.
You're in safe hands then
Pop a 6spd box in and unlikely you'll break it till you start nearing 600lbft torque. It will add a little more weight to the car but you can soon offset that with a mild hike in power plus the 6spd ratios will probably suit you better.
In the meantime 400 in yours should be about the same as 600 in an STi. Similar power to weight ratios etc... Whatever way you look at it, it will be fecking quick!!
I look forward to seeing an in-car video of your first track day. Good luck with it!!
Pop a 6spd box in and unlikely you'll break it till you start nearing 600lbft torque. It will add a little more weight to the car but you can soon offset that with a mild hike in power plus the 6spd ratios will probably suit you better.
In the meantime 400 in yours should be about the same as 600 in an STi. Similar power to weight ratios etc... Whatever way you look at it, it will be fecking quick!!
I look forward to seeing an in-car video of your first track day. Good luck with it!!
t like an FP green on it!
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