Advice on uprating the STi turbo, please
03 December 1999, 11:18 AM
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Dear all,
Have any of you guys swapped your standard STi turbo for an aftermarket one? Either larger, or smaller. If so, what were the results, changes in performance, lag etc.?
I am thinking of doing this to my STi5, but I'm not too sure of what the results might be.
Any input on the subject would be of great help.
Regards, Tim
[This message has been edited by TimK (edited 03-12-1999).]
Have any of you guys swapped your standard STi turbo for an aftermarket one? Either larger, or smaller. If so, what were the results, changes in performance, lag etc.?
I am thinking of doing this to my STi5, but I'm not too sure of what the results might be.
Any input on the subject would be of great help.
Regards, Tim
[This message has been edited by TimK (edited 03-12-1999).]
08 December 1999, 02:37 PM
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As I have a lowly MY94 WRX (not STi) I am interested in any comment son this subject as well. Tim, if you get any decent replies pls let me know! BTW are you the Tim from the Reading meet??
Cheers
Pilch
Cheers
Pilch
08 December 1999, 02:50 PM
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Pilch,
Good to see that it's not JUST myself that is interested in aftermarket turbos!
In answer to your question - no it wasn't me at the Reading meet.
Looking forward to some replies on this post from Firefox, Scoobymania, Bob Rawle and Quattro.
Here's waiting.
Regards, Tim
Good to see that it's not JUST myself that is interested in aftermarket turbos!
In answer to your question - no it wasn't me at the Reading meet.
Looking forward to some replies on this post from Firefox, Scoobymania, Bob Rawle and Quattro.
Here's waiting.
Regards, Tim
08 December 1999, 04:27 PM
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Then wait no longer. 
Tim.
This is quite complicated but I'll have a go. Your STi 5 has a reasonably sized turbo, this will spin up quicker than a 'larger' one from low revs, but will also run out of puff far earlier than a larger one.
A higher flow rate 'bigger' turbo usually will not initially spin up as fast, (not quite a hard & fast rule) but when it does, its ability to move air will greatly exceed your smaller turbo. A 350 BHP Turbo is bigger and will meet your needs without going silly on the lag front.
With any modifications that you do, your turbo will be hard pushed to give big(ish) increases.
The benefits gained from a larger turbo will be big increases in mid range to redline. This is where the majority of 'going for it' or 'spirited' type driving is done anyway.
It is likely that you will see no discernible loss in the bottom end at all, combined with huge differences from 3,200RPM (ish) upwards.
That is it VERY simply put, if you want to discuss it further, phone Ben on 0118 981 0832.
Pilch.
How you doin?
LOWLY 94 WRX?????
<B>LOWLY!!!!!!</B>
I've got one of those! They are far from lowly, they had fitted probably the largest of Turbo's ever fitted to any Impreza, somebody will now probably tell me i've got the model No. wrong (it will probably be J.) but I believe that it should have a TD05H.
You shouldn't need to uprate/upgrade that at all unless it needs overhauling.
You would see bigger gains faster by doing the same as above but without having to buy a bigger turbo.
Mike.
[This message has been edited by Mike Tuckwood (edited 08-12-1999).]
Tim.
This is quite complicated but I'll have a go. Your STi 5 has a reasonably sized turbo, this will spin up quicker than a 'larger' one from low revs, but will also run out of puff far earlier than a larger one.
A higher flow rate 'bigger' turbo usually will not initially spin up as fast, (not quite a hard & fast rule) but when it does, its ability to move air will greatly exceed your smaller turbo. A 350 BHP Turbo is bigger and will meet your needs without going silly on the lag front.
With any modifications that you do, your turbo will be hard pushed to give big(ish) increases.
The benefits gained from a larger turbo will be big increases in mid range to redline. This is where the majority of 'going for it' or 'spirited' type driving is done anyway.
It is likely that you will see no discernible loss in the bottom end at all, combined with huge differences from 3,200RPM (ish) upwards.
That is it VERY simply put, if you want to discuss it further, phone Ben on 0118 981 0832.
Pilch.
How you doin?
LOWLY 94 WRX?????
<B>LOWLY!!!!!!</B>
I've got one of those! They are far from lowly,
they had fitted probably the largest of Turbo's ever fitted to any Impreza, somebody will now probably tell me i've got the model No. wrong (it will probably be J.) but I believe that it should have a TD05H.You shouldn't need to uprate/upgrade that at all unless it needs overhauling.
You would see bigger gains faster by doing the same as above but without having to buy a bigger turbo.
Mike.
[This message has been edited by Mike Tuckwood (edited 08-12-1999).]
08 December 1999, 06:21 PM
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Hi Tim
A straight turbo swap rated at 350bhp and you are looking at maybe extra lag for 100rpm. As you are running the same boost you won't see any more than 10bhp gain and no extra torque. Boost gets you the torque.
The chances are the engine will run leaner as the turbo is pushing more air in and the air/fuel ratio starts to go the wrong way.
As a result, since the STi5 has a fuelling issue at revs then it would be prudent to remap the car at the same time.
You are already aware that a 3" exhaust system will remove the heat and gasses better for you at these horsepowers as a 2.5" struggles and starts to present back pressure which is the antithesis of the turbocharged angine as those turbines need to have as little restriction as possible.
The STi ball bearing jobbie is one option and I am still chasing to get the very best spec and price for a Garrett alternative.
Kind regards
Ben
A straight turbo swap rated at 350bhp and you are looking at maybe extra lag for 100rpm. As you are running the same boost you won't see any more than 10bhp gain and no extra torque. Boost gets you the torque.
The chances are the engine will run leaner as the turbo is pushing more air in and the air/fuel ratio starts to go the wrong way.
As a result, since the STi5 has a fuelling issue at revs then it would be prudent to remap the car at the same time.
You are already aware that a 3" exhaust system will remove the heat and gasses better for you at these horsepowers as a 2.5" struggles and starts to present back pressure which is the antithesis of the turbocharged angine as those turbines need to have as little restriction as possible.
The STi ball bearing jobbie is one option and I am still chasing to get the very best spec and price for a Garrett alternative.
Kind regards
Ben
08 December 1999, 06:54 PM
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TimK - Before u do anything wit ur car.... can u provide me wit ur turbocharger spec.
U can check the compressor housing for the spec.... wat is wrong wit the original unit??
Before u upgred anything... make sure u know wat u want from the tc .... by changing it to a bigger unit does not make it any better... if it does not meet ur requirement.
Find out from the tc seller... wat spec is their tc and wat different does it make compare to the original unit in ur car.
U dont want to make any mistake. Make sure U know ur engine and ECU limit too. I know Subaru is still new in UK. So do some research first.
Cheers.
U can check the compressor housing for the spec.... wat is wrong wit the original unit??
Before u upgred anything... make sure u know wat u want from the tc .... by changing it to a bigger unit does not make it any better... if it does not meet ur requirement.
Find out from the tc seller... wat spec is their tc and wat different does it make compare to the original unit in ur car.
U dont want to make any mistake. Make sure U know ur engine and ECU limit too. I know Subaru is still new in UK. So do some research first.
Cheers.
Trending Topics
08 December 1999, 10:10 PM
#8
Ecu Specialist
Tim, Dynt has a great deal of knowledge about the different turbos fitted to our cars. The important thing to consider is the ultimate objective. Your turbo should be a VF28, if you look at the aluminium compressor housing (part of the turbo that the air intake is connected to), you should find the model designation. Check and post the info or email Dynt. A larger turbo will negate the benefits that you have gained so far with your SS exhaust items.
A larger turbo delivers air volume for volume at lower boost pressure but, as it takes longer to spool up, it also means that torque takes longer to build up. The best option for the "ultimate" performance combination of torque and power is a "hybrid" which combine's the best exducer with the best impeller. there will be lots of opinion on this ... take advice from a "real" expert (no offence to anyone intended) who can offer the actual best combination to achieve your requirements.
The turbo is only one part of the chain, a larger turbo is no good if the exhaust/airfilter are not suitably uprated to cope, the engine internals also have to be considered as does the intercooler.
Pilch, if you have a TD05H then join the lucky ones as its considered to be one of the best, its a Mitsubishi not an IHI and has a floating sleeve bearing system thats far more robust than ball races. Definately not necessary to upgrade IMHO.
Bob
A larger turbo delivers air volume for volume at lower boost pressure but, as it takes longer to spool up, it also means that torque takes longer to build up. The best option for the "ultimate" performance combination of torque and power is a "hybrid" which combine's the best exducer with the best impeller. there will be lots of opinion on this ... take advice from a "real" expert (no offence to anyone intended) who can offer the actual best combination to achieve your requirements.
The turbo is only one part of the chain, a larger turbo is no good if the exhaust/airfilter are not suitably uprated to cope, the engine internals also have to be considered as does the intercooler.
Pilch, if you have a TD05H then join the lucky ones as its considered to be one of the best, its a Mitsubishi not an IHI and has a floating sleeve bearing system thats far more robust than ball races. Definately not necessary to upgrade IMHO.
Bob
08 December 1999, 11:03 PM
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Hi guys...
Bob is right regarding the TD05.. it is far more robust...
Regarding hybridising an IHI, forget it... you are quite limited... The cores arrive complete..with wheels...you cant dismantle them (you can take the shaft/turbine wheel and compressor wheel off).. but they do come pre-balanced...
The RHF Series of IHI turbos (thats the roller bearing type to most people) have a top operating temp of 950 for gasses... The bearing core is the weakest part....
But they do spool up quicker than the oil sleeved type..if you are after a good, robust, easily obtainable (and fixable) turbo.. get a Mit TD05.. they are real common.. and plenty of variety about...
You have to sort out the air flow... air filter.. intake pipe... down pipe..exhaust...even flowing the heads/ports.... equal headers (waits for Bro to comment)... its pointless having the best turbo if it cant do its work. An intercooler should have only a few PSI back pressure through it..anymore and it will need changing fro a better flowing one.
One thing to think about... is what DYNT said... why do you want to change your turbo ? have you reached its limit on flow or boost ? I doubt it.... so why change ? Try fitting a new ECU, or a boost controller that will maintain the boost or "bring it on sooner"....
The reason I changed is because I needed a higher flowing turbo...
Anyways.. I have to go and pack...
tara
J.
Bob is right regarding the TD05.. it is far more robust...
Regarding hybridising an IHI, forget it... you are quite limited... The cores arrive complete..with wheels...you cant dismantle them (you can take the shaft/turbine wheel and compressor wheel off).. but they do come pre-balanced...
The RHF Series of IHI turbos (thats the roller bearing type to most people) have a top operating temp of 950 for gasses... The bearing core is the weakest part....
But they do spool up quicker than the oil sleeved type..if you are after a good, robust, easily obtainable (and fixable) turbo.. get a Mit TD05.. they are real common.. and plenty of variety about...
You have to sort out the air flow... air filter.. intake pipe... down pipe..exhaust...even flowing the heads/ports.... equal headers (waits for Bro to comment)... its pointless having the best turbo if it cant do its work. An intercooler should have only a few PSI back pressure through it..anymore and it will need changing fro a better flowing one.
One thing to think about... is what DYNT said... why do you want to change your turbo ? have you reached its limit on flow or boost ? I doubt it.... so why change ? Try fitting a new ECU, or a boost controller that will maintain the boost or "bring it on sooner"....
The reason I changed is because I needed a higher flowing turbo...
Anyways.. I have to go and pack...
tara
J.
09 December 1999, 09:56 AM
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Bob, Firefox, Scoobymania & Dynt,
Thanks for your input on this - God!, you guys know a lot of "stuff".
My main objective with my STi is to increase the torque available, to tarmac ripping proportions.
The STi5 does have a smallish turbo and this helps it spool up quicker (bringing in more torque, further down the rev range) and this is something that I would like to capitalise on, as it makes the car far more drivable.
I am of the firm belief that for "real world" driving (90% on the road + 10% on the track) TORQUE is King.
Having taken on board all of this advice, I have decided to do the following :-
1) Sort out the inherent problems with the STi ECU mappngs. I will be going for a Possum Link. The car will be mapped for 97RON and with low down torque, as the major objective.
I should get good results, as I have a straight through Scoobysport exhaust, so I'm pretty excited.
2) I will be trying to get the turbo / downpipe, HPC / ceramic coated, to reduce the under bonnet temperatures and keep the heat in the pipe (so aiding speed of gas flow).
3) Fit a water spray kit for the intercooler, to reduce the charge temperature under higher boost conditions.
4) Uprate my brakes even further
5) Change to Leda 'C' suspension.
6) Plead & beg to my Bank Manager!!
Looking forward to seeing some of you at the PE Dyno day on Saturday!
Regards,
Tim
[This message has been edited by TimK (edited 09-12-1999).]
[This message has been edited by TimK (edited 14-12-1999).]
Thanks for your input on this - God!, you guys know a lot of "stuff".
My main objective with my STi is to increase the torque available, to tarmac ripping proportions.
The STi5 does have a smallish turbo and this helps it spool up quicker (bringing in more torque, further down the rev range) and this is something that I would like to capitalise on, as it makes the car far more drivable.
I am of the firm belief that for "real world" driving (90% on the road + 10% on the track) TORQUE is King.
Having taken on board all of this advice, I have decided to do the following :-
1) Sort out the inherent problems with the STi ECU mappngs. I will be going for a Possum Link. The car will be mapped for 97RON and with low down torque, as the major objective.
I should get good results, as I have a straight through Scoobysport exhaust, so I'm pretty excited.
2) I will be trying to get the turbo / downpipe, HPC / ceramic coated, to reduce the under bonnet temperatures and keep the heat in the pipe (so aiding speed of gas flow).
3) Fit a water spray kit for the intercooler, to reduce the charge temperature under higher boost conditions.
4) Uprate my brakes even further
5) Change to Leda 'C' suspension.
6) Plead & beg to my Bank Manager!!
Looking forward to seeing some of you at the PE Dyno day on Saturday!
Regards,
Tim
[This message has been edited by TimK (edited 09-12-1999).]
[This message has been edited by TimK (edited 14-12-1999).]
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