T38 or T4
23-12-2009, 08:17 AM
#129
You lot make me laugh 
.
Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night
).
Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).
It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
.Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night
).Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard
), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
Last edited by Mike Rainbird; 23-12-2009 at 08:19 AM.
23-12-2009, 09:28 AM
#132
You lot make me laugh .
Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night ).
Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).
It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
.Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night
).Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard
), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
CheeRS.Lee.
23-12-2009, 01:50 PM
#135
20K+ Super Poster.
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Hence why i mentioned Daves Car in this post of mine Mike ^^^...
I NEVER said T38s were/are crap. just hated my setup which i,ve explained it was Jim who changed from a T4 that he NEVER even fitted after Karl had specced (spelling) the engine for a T4 not a T38...
Be interested in that too Rich...
24-12-2009, 08:26 AM
#139
Dave,
Sadly there are no engine dyno figures for Rich's car, so the above is irrelevant for comparison to his 450bhp. I was hoping you had run yours up on the same rollers as him, so that someone could plot a comparitive curve to see how where one lost pout to the other 
.
Sadly there are no engine dyno figures for Rich's car, so the above is irrelevant for comparison to his 450bhp
. I was hoping you had run yours up on the same rollers as him, so that someone could plot a comparitive curve to see how where one lost pout to the other .
24-12-2009, 09:07 AM
#141
Too many posts.. I need a life!!
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You lot make me laugh .
Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night ).
Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).
It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
.Firstly, STOP confusing LAG with BOOST THRESHOLD, it gets right on my tits (but not as much as that prat Hammond perpetuating the "wastegate chatter" myth on Top Gear the other night
).Secondly, there are two DIFFERENT T38s. One uses a bored out T34 compressor and turbine housing with slightly bigger wheels. This one doesn't make as much torque as a T34, hence why people say it feels "gutless" by comparison - instead of a big mid-range torque spike and the HUGE tail-off you get with a T34, it builds up power gradually and just hangs on to it all the way to the limiter. Therefore, in my opinion this turbo is suited to a track car or a 4x4 running standard transmission (which would last longer with this turbo).
The second T38 is the Turbo Technics one and uses a T4 compressor housing / wheel with a T34 turbine. This flows more air, but has a lot more back pressure and a lower surge-line (due to the bigger mismatch in compressor and turbine sizing). However, it will produce more power and more torque than the smaller T38, but it is almost as expensive as a T4.
Also don't forget that you can't just bolt turbos on and expect them to perform, cams and cam timing plays a BIG part in getting the best out of your choice (and any restrictions in the inlet and exhaust set-ups - from ports to manifolds), as does getting the right person to map it, as the boost curve will be completely different....
Also, in my experience (as in not what I have read or heard
), a roller-bearing core on a T4 only lowers the boost threshold by around 3-400rpm. This may not sound significant and is certainly not the 1000rpm people claim, but that isn't the whole story. A normal T4 feels completely dead below it's boost threshold, whereas a roller-bearing core builds up to it's boost threshold point nice and progressively, so feels much more responsive and lively (and this is born out by the boost gauge. where you can see the boost building).It would be interesting if Mark overlayed Richies GT30 graph with Dave's TT38 (providing Dave has been on the same DD rollers as Richie), as that would give people an idea of how they performed.
I love my T4, but feel that the extra capacity of my engine is obviously helping lower the boost threshold, so I cannot comment what it would be like on a standard size engine.
the man's bang on you can have any sizy turbo you want by boing exhaust housing's there's 3 sizes of t3 turbine wheel's same as comp wheels .t4 wet bearing's all the way.
ball bearing are weak i've seen lot's broke you may be unluky with a bit of spark plug falling off and damage the turbine the turbo will be scrap
http://www.jgstools.com/turbo/50vsgt40.jpg
have a look spool up ect [i know gt3040 not the best ]
Last edited by wilky; 24-12-2009 at 09:09 AM.
02-01-2010, 04:01 PM
#153
ive just swapped from a tt t38 to a gt30 and am a bit dissapointed really i was hoping for a massive difference... am hoping once its mapped properly it will go better..
t38 sounded better too... although i like the screamer noise now..
t38 sounded better too... although i like the screamer noise now..
02-01-2010, 09:58 PM
#155
i havent.. my mate has it on his escort cos.. i was looking at the t4s and couldnt really work out much difference in them . same size front housings and both .63 exhaust only the t4 has the seperate wastegate bit bolted on ...
the t38 was brilliant on mine and i had bd10 cams which people say arent any good..
now has bd14 inlet and gt3076 external wastegate and just feels like it makes boost a little earlier.. im really hoping that it makes a big improvement once its mapped or ill be looking for another turbo again..
the t38 was brilliant on mine and i had bd10 cams which people say arent any good..
now has bd14 inlet and gt3076 external wastegate and just feels like it makes boost a little earlier.. im really hoping that it makes a big improvement once its mapped or ill be looking for another turbo again..
