Large turbo with low boost or smaller turbo with higher boost?
Large turbo with low boost or smaller turbo with higher boost?
I have been having a look through some turbo compressor maps with regards to choosing a larger single turbo, I have found that the OM606 running at 2 bar of boost at top stock RPM needs around 52lb/min of air. Owing to being in the UK, the Holset turbos aren't the easiest to get hold of - they aren't that cheap for the ones that are for sale. I did have a T88-34D and a TA45 spare in the garage but I sold those on a while back. I am also looking at more budget options such as some of the universal turbos you see for sale - I am aware that they might not last as long as a named brand turbo, however this won't be a daily drive. I have also noticed a fair number of cars running 10s and 11s using universal turbos.
This is where my question comes from, would it be worth getting a larger turbo running a lower boost rather than a smaller turbo - my though is that a lower boost would be less stress on the engine and turbo vs a smaller turbo which would need to spool up more.
I have checked something like a GT45 sized turbo which is should be able to supply enough air at 1 bar of pressure and be right in the middle of the efficiency island vs something smaller like a HX35 at 2 bar.
My thought was also that owing to the fact that I wouldn't need to build a huge amount of boost to be able to give the air flow needed - I am pretty sure a 3 litre engine should be able to spool up a larger turbo as long as I go for a .86 AR turbine housing rather than anything over 1 AR.
Hi all,
I have been having a look through some turbo compressor maps with regards to choosing a larger single turbo, I have found that the OM606 running at 2 bar of boost at top stock RPM needs around 52lb/min of air. Owing to being in the UK, the Holset turbos aren't the easiest to get hold of - they aren't that cheap for the ones that are for sale. I did have a T88-34D and a TA45 spare in the garage but I sold those on a while back. I am also looking at more budget options such as some of the universal turbos you see for sale - I am aware that they might not last as long as a named brand turbo, however this won't be a daily drive. I have also noticed a fair number of cars running 10s and 11s using universal turbos.
This is where my question comes from, would it be worth getting a larger turbo running a lower boost rather than a smaller turbo - my though is that a lower boost would be less stress on the engine and turbo vs a smaller turbo which would need to spool up more.
I have checked something like a GT45 sized turbo which is should be able to supply enough air at 1 bar of pressure and be right in the middle of the efficiency island vs something smaller like a HX35 at 2 bar.
My thought was also that owing to the fact that I wouldn't need to build a huge amount of boost to be able to give the air flow needed - I am pretty sure a 3 litre engine should be able to spool up a larger turbo as long as I go for a .86 AR turbine housing rather than anything over 1 AR.
Duncansport
08-03-2015, 06:54 PM #2The reason for such high boost levels is the fairly poor VE of our engines.
87 300SDL OM606 swapped HE351VE 722.633 swapped, Crower cams, KM valvesprings
76 300TD custom lots of stuff
06 Mercedes CL65 AMG 619 WHP, http://TurboTims.com
And small AR turbos just don't have the leverage to make big boost numbers. It's really a delicate balancing game with our motors. I thought it would be easier but you go big you end up being laggy and you downsize the AR and you can't get big boost before EGB gets out of control.
87 300SDL OM606 swapped HE351VE 722.633 swapped, Crower cams, KM valvesprings
76 300TD custom lots of stuff
06 Mercedes CL65 AMG 619 WHP, http://TurboTims.com
87 300SDL OM606 swapped HE351VE 722.633 swapped, Crower cams, KM valvesprings
76 300TD custom lots of stuff
06 Mercedes CL65 AMG 619 WHP, http://TurboTims.com
Run as small of a turbo to meet your needs and as much boost as you can possibly squeeze out of it.
87 300SDL OM606 swapped HE351VE 722.633 swapped, Crower cams, KM valvesprings
76 300TD custom lots of stuff
06 Mercedes CL65 AMG 619 WHP, http://TurboTims.com
The om-engines are quite asthmatic and flow is almost never our problem. It's pressure... We need to build a lot of boost to make way for our insane levels of fuel.
Cheers / F
F-tune Performance
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I can help you out with all your manual transmission, clutch, flywheel, intake and exhaust manifold issues.
Hi mate. You are thinking both right and wrong here. If the engine could breath that heavy your idea is great but even that big gt45 will boost 2bar with the same amount of air as the hx35 in your example. Reason being the one Duncan is pointing out. The VE is not high enough to "use" the air hitting the engine.
The om-engines are quite asthmatic and flow is almost never our problem. It's pressure... We need to build a lot of boost to make way for our insane levels of fuel.
Cheers / F
F-tune Performance
I can help you out with all your manual transmission, clutch, flywheel, intake and exhaust manifold issues.
Should I be shooting for around 2 bar of boost on these engines? I know that they can take a fair amount more even in stock form but I do also need to balance power with traction as well as other components.
Thanks for the help on this, currently doing a fair bit of research into which turbos would best suit the engine, the car will be used as a project car for drag racing mainly (although still needs to get to the track) - but I am keeping the engine unopened.
Thanks guys, would something slightly smaller like a GT35 be a better size? Looks like the GT3582R runs around the 52lb/min at 2 bar which seems spot on for what I am after. I guess if pressure is the issue then I might look into twin charging or compound turbos then or indeed run a twin turbo setup.
Should I be shooting for around 2 bar of boost on these engines? I know that they can take a fair amount more even in stock form but I do also need to balance power with traction as well as other components.
Thanks for the help on this, currently doing a fair bit of research into which turbos would best suit the engine, the car will be used as a project car for drag racing mainly (although still needs to get to the track) - but I am keeping the engine unopened.
Note that we are moving pretty much insane amounts of air with our engines. We can only make about 2/3rds power of a gas engine with a a similar amount of air. That means that we have to have roughly 50% more airflow to make the same amount of power. Thus the need for huge turbos and high boost pressure.
(08-04-2015, 02:56 AM)Petar Note that we are moving pretty much insane amounts of air with our engines. We can only make about 2/3rds power of a gas engine with a a similar amount of air. That means that we have to have roughly 50% more airflow to make the same amount of power. Thus the need for huge turbos and high boost pressure.
What is the VE of this engine? I have read that the OM603 seems to be at around 70% @ higher RPMs.
(08-04-2015, 02:56 AM)Petar Note that we are moving pretty much insane amounts of air with our engines. We can only make about 2/3rds power of a gas engine with a a similar amount of air. That means that we have to have roughly 50% more airflow to make the same amount of power. Thus the need for huge turbos and high boost pressure.
What is the VE of this engine? I have read that the OM603 seems to be at around 70% @ higher RPMs.
(08-04-2015, 02:11 AM)m1tch Thanks guys, would something slightly smaller like a GT35 be a better size? Looks like the GT3582R runs around the 52lb/min at 2 bar which seems spot on for what I am after. I guess if pressure is the issue then I might look into twin charging or compound turbos then or indeed run a twin turbo setup.
Should I be shooting for around 2 bar of boost on these engines? I know that they can take a fair amount more even in stock form but I do also need to balance power with traction as well as other components.
Thanks for the help on this, currently doing a fair bit of research into which turbos would best suit the engine, the car will be used as a project car for drag racing mainly (although still needs to get to the track) - but I am keeping the engine unopened.
GT3582R or GTX3582R is a really good choice for a single turbo setup.
F-tune Performance
I can help you out with all your manual transmission, clutch, flywheel, intake and exhaust manifold issues.
(08-04-2015, 02:11 AM)m1tch Thanks guys, would something slightly smaller like a GT35 be a better size? Looks like the GT3582R runs around the 52lb/min at 2 bar which seems spot on for what I am after. I guess if pressure is the issue then I might look into twin charging or compound turbos then or indeed run a twin turbo setup.
Should I be shooting for around 2 bar of boost on these engines? I know that they can take a fair amount more even in stock form but I do also need to balance power with traction as well as other components.
Thanks for the help on this, currently doing a fair bit of research into which turbos would best suit the engine, the car will be used as a project car for drag racing mainly (although still needs to get to the track) - but I am keeping the engine unopened.
GT3582R or GTX3582R is a really good choice for a single turbo setup.
F-tune Performance
I can help you out with all your manual transmission, clutch, flywheel, intake and exhaust manifold issues.
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Mercedes 190 -92, om605 Stroker 2.75L, Dieselmeken 7,5mm (160cc) EDC with Baldur DSL1 ECU, Garrett GTX3576R A/R 1.06 without WG, SMF, 716.661 (SG-S370/6) Gearbox
I run my om605 with a GT3582. Dont even need a wastegate. 2,5bars of boost and no black smoke.
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Mercedes 190 -92, om605 Stroker 2.75L, Dieselmeken 7,5mm (160cc) EDC with Baldur DSL1 ECU, Garrett GTX3576R A/R 1.06 without WG, SMF, 716.661 (SG-S370/6) Gearbox
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