What happens when you fit too big a compressor wheel?
#1
Junior Member
Thread Starter
Join Date: Mar 2010
Location: Glasgow, Scotland, U.K.
Posts: 115
Total Cats: -12
What happens when you fit too big a compressor wheel?
I am thinking of converting my td04L-13t to a 19t is this too big in relation to the turbine? what happens when you increase the size of the compressor without increasing the turbine will this lead to any problems do I need to port the wastegate or is that just for boost creep?
#2
is this the 3 bolt inlet subaru 13t? if so, I've seen some pretty cool results from this upgrade (though on a subaru, not a miata). Basically you give up only a couple hundred rpm worth of spool, but pick up a healthy chunk of torque and quite a bit topend power. something like 30-50 torque if I'm not mistaken. if you do it right and have it balanced, and have the engine to support it (you'll wanna really crank up the boost to see good power increase)
#3
Junior Member
Thread Starter
Join Date: Mar 2010
Location: Glasgow, Scotland, U.K.
Posts: 115
Total Cats: -12
Yes the 3 bolt one. Fitting a 19 in place of the 13 compressor wheel is quite a jump would you not end up with a bit of a mismatched turbo. If the turbo is compressing more than its able to flow through the turbine would that not result in something unwanted?
Last edited by delcbr; 10-16-2013 at 03:42 PM. Reason: Damn predictive text
#7
Junior Member
Thread Starter
Join Date: Mar 2010
Location: Glasgow, Scotland, U.K.
Posts: 115
Total Cats: -12
What I am compressing into the engine has got to come out through the turbine and into the exhaust. So if I am putting in far more air than before surely the turbine won't be able to cope. Will it over spin, will it create excessive boost pressure and heat if the turbine can't flow the increase in air would porting the waste gate help? You see where I am coming from now?
#9
What I am compressing into the engine has got to come out through the turbine and into the exhaust. So if I am putting in far more air than before surely the turbine won't be able to cope. Will it over spin, will it create excessive boost pressure and heat if the turbine can't flow the increase in air would porting the waste gate help? You see where I am coming from now?
you're talking about a baby 19t compressor here, not some mammoth 76r or something.
I doubt you'll choke that turbo up with a 1.8L, but even if you somehow do, all that will happen is a bit of boost taper near redline.
#13
I fitted a larger 60mm compressor to my T2554 turbo making it a T2560
It basically shifted the peak torque and power further up the rev range. Peak power therefore increases as the torque is shifted.
I read somewhere you usually try to keep the diameters of comp and turbine within 25% of each other but this isn't a hard and fast rule as the pitch has a bearing too.
It WILL increase lag a far bit.
On mine a 6mm increase in comp diameter shifted peak torque by about 500rpm
The larger comp will increase load on the turbine so it may even spin slower, its best to improve exhaust breathing to help with turbine gas flow..
It basically shifted the peak torque and power further up the rev range. Peak power therefore increases as the torque is shifted.
I read somewhere you usually try to keep the diameters of comp and turbine within 25% of each other but this isn't a hard and fast rule as the pitch has a bearing too.
It WILL increase lag a far bit.
On mine a 6mm increase in comp diameter shifted peak torque by about 500rpm
The larger comp will increase load on the turbine so it may even spin slower, its best to improve exhaust breathing to help with turbine gas flow..
#15
In order to put the 19t wheel into a turbo that originally came with a 13t wheel you will have to machine the center housing to clear the 19t exducer. This is why I just bought a 08wrx turbo that had a VERY BAD DAY (looks like the compressor nut spun off while the engine was running) for 40 bucks. I'm going to be buying a 19t standard subaru compressor cover and billet 19t comp wheel, STS turbine and shaft and a rebuild kit and slapping that bad boy together. I'm thinking it should reach 300hp in this setup and I'll have pretty much the only td04 with an STS turbine wheel in existence because they literally came out like 2 weeks ago in this size, no subaru people know how to work on cars, and no one is going to pay $900 to buy one completely together because they could just get a 16g instead.
#16
I mean, 18psi seems to know his way around a car or two..
He did have an auto Corvette though so...
Also, why not just VF48 instead of ths swanky td04-19t you're building? I don't know how much money you'll have into a billet comp wheel, STS turbine, and rebuild kit, etc. but it sounds like for about the same money you could have a VF48 that will easily make 300whp and be a whole lot less work. What's all this extra work going to get you? 300rpm better spool?
He did have an auto Corvette though so...
Also, why not just VF48 instead of ths swanky td04-19t you're building? I don't know how much money you'll have into a billet comp wheel, STS turbine, and rebuild kit, etc. but it sounds like for about the same money you could have a VF48 that will easily make 300whp and be a whole lot less work. What's all this extra work going to get you? 300rpm better spool?
#17
I mean, 18psi seems to know his way around a car or two..
He did have an auto Corvette though so...
Also, why not just VF48 instead of ths swanky td04-19t you're building? I don't know how much money you'll have into a billet comp wheel, STS turbine, and rebuild kit, etc. but it sounds like for about the same money you could have a VF48 that will easily make 300whp and be a whole lot less work. What's all this extra work going to get you? 300rpm better spool?
He did have an auto Corvette though so...
Also, why not just VF48 instead of ths swanky td04-19t you're building? I don't know how much money you'll have into a billet comp wheel, STS turbine, and rebuild kit, etc. but it sounds like for about the same money you could have a VF48 that will easily make 300whp and be a whole lot less work. What's all this extra work going to get you? 300rpm better spool?