95 TSI AWD Project VGT Holset no 56k
03-01-2009, 08:43 PM
#241
1.5 BAR
Join Date: Mar 2005
Posts: 723
Re: 95 TSI AWD Project VGT Holset no 56k
Compound boost also means compound heat. A typical turbo & roots SC would be 75%*65%, which is under 50%! When you study the Ideal Gas Law, 40psi at 50% provides LESS oxygen than 25psi at 75%.
Its hard to even find a turbo FLOW MAP that goes down to 50%. I am really not a fan of series twincharging, at least not when you run the SC out of its efficiency. Roger McDaniels did a mostly-parallel twincharged setup 2.0L for his track car, and it worked out very well in the end. His used a JRSC (m62) to increase his low-end & spool the turbo, then his EMS (AEM iirc) gradually phased the blower out once the turbo was cooking. The JRSC doesn't allow for intercooling easily, which is one reason. I think he said his max IAT's were 140F (8psi JRSC, 15-18psi max) vs >200F with just the heatsoaked JRSC at 8psi (no turbo).
I think he said at 14psi the blower was fully bypassed, so there would only be compounded boost up to 14psi at lower RPM, in which the M62 is still fairly efficient. His personal experience (and talks with the Magnuson guys) showed that a bypassed blower that's not compressing doesn't add much heat. Its only when it has to compress the air that it heats it up much. The new setup (owned by H-T's ClemonsHatch??) is insane for a auto-x Honda. It sounds & moves like its just one giant, efficient blower on it.
FYI in the 2nd setup, the one-way really has to be a bypass valve. The compounded boost will always create a pressure differential across that valve (push it closed) and would never open by itself. No bypassing of the SC means the SC is still compressing air, and creating heat. The trick is to use a turbo that's much more efficient, so you can just let the turbo do all the work.
Its hard to even find a turbo FLOW MAP that goes down to 50%. I am really not a fan of series twincharging, at least not when you run the SC out of its efficiency. Roger McDaniels did a mostly-parallel twincharged setup 2.0L for his track car, and it worked out very well in the end. His used a JRSC (m62) to increase his low-end & spool the turbo, then his EMS (AEM iirc) gradually phased the blower out once the turbo was cooking. The JRSC doesn't allow for intercooling easily, which is one reason. I think he said his max IAT's were 140F (8psi JRSC, 15-18psi max) vs >200F with just the heatsoaked JRSC at 8psi (no turbo).
I think he said at 14psi the blower was fully bypassed, so there would only be compounded boost up to 14psi at lower RPM, in which the M62 is still fairly efficient. His personal experience (and talks with the Magnuson guys) showed that a bypassed blower that's not compressing doesn't add much heat. Its only when it has to compress the air that it heats it up much. The new setup (owned by H-T's ClemonsHatch??) is insane for a auto-x Honda. It sounds & moves like its just one giant, efficient blower on it.
FYI in the 2nd setup, the one-way really has to be a bypass valve. The compounded boost will always create a pressure differential across that valve (push it closed) and would never open by itself. No bypassing of the SC means the SC is still compressing air, and creating heat. The trick is to use a turbo that's much more efficient, so you can just let the turbo do all the work.
03-03-2009, 01:21 PM
#243
0.0 BAR
Join Date: Dec 2006
Posts: 34
Re: 95 TSI AWD Project VGT Holset no 56k
Detroit did series compounds on their 2-stroke diesels for decades. They even made V16's with quad turbos and two blowers.
Would this have torque steer? Nah, thats what RWD is for.
1800 HP Detroit Diesel 16V149TI 39.1L, FYI
Would this have torque steer? Nah, thats what RWD is for.
1800 HP Detroit Diesel 16V149TI 39.1L, FYI
03-03-2009, 04:13 PM
#244
0.0 BAR
Join Date: Aug 2007
Location: Okotoks, AB
Posts: 0
Re: 95 TSI AWD Project VGT Holset no 56k
Originally Posted by OM617
Detroit did series compounds on their 2-stroke diesels for decades. They even made V16's with quad turbos and two blowers.
Would this have torque steer? Nah, thats what RWD is for.
1800 HP Detroit Diesel 16V149TI 39.1L, FYI
Would this have torque steer? Nah, thats what RWD is for.
1800 HP Detroit Diesel 16V149TI 39.1L, FYI
03-03-2009, 04:23 PM
#245
0.0 BAR
Join Date: Aug 2007
Location: Okotoks, AB
Posts: 0
Re: 95 TSI AWD Project VGT Holset no 56k
This is something I posted in another thread about 500 posts ago, but it seems to be relevant again here:
"Turbo ratings from the gasser world will not work for the diesel because we have a completely different A/F ratio than them. On the turbine side in a gasser you have a mass flow that's almost proportional to the hp produced. In a diesel you have a mass flow that's close to proportional to boost x rpm, the amount of diesel we inject is comparatively small and while going from 20% throttle to 100% throttle the mass of the exhaust gas doesn't change significantly. The mass flow only starts to change as boost and rpm rise. In a gasser with it's throttle we have an instantaneous reaction in the mass flow as soon as we change the throttle position, and for low throttle situations even a spooled turbo will produce boost against an obstacle so the tuning of a turbine and compressor is quite tricky. In a gasser you will normally not have high pressure ratios and will be interested in a compressor that has a rising efficiency and quick rise of mass flow as the boost is falling due to opening the throttle. In a diesel you want it quite the other way round. You need high pressure ratios, you will want a quick rise of mass flow over a rising pressure ratio when the enthalpy in the exhaust gas rises. So the turbine design for a daily driver will be quite different. For a dyno truck or a puller etc you will be accepting tradeoffs that you couldn't accept in your daily driver. To me tuning a turbo on a diesel is a quest to get the widest powerband possible, with the least amount of lag and the quickest possible transition (to reduce smoke and lag) with as little back pressure as possible and while staying within the EGT limits."
So lets not bring compound diesel into this thread or diesel in general as it has no bearing at all.
I am quite intrigued by this thread, but have nothing else useful to add.
"Turbo ratings from the gasser world will not work for the diesel because we have a completely different A/F ratio than them. On the turbine side in a gasser you have a mass flow that's almost proportional to the hp produced. In a diesel you have a mass flow that's close to proportional to boost x rpm, the amount of diesel we inject is comparatively small and while going from 20% throttle to 100% throttle the mass of the exhaust gas doesn't change significantly. The mass flow only starts to change as boost and rpm rise. In a gasser with it's throttle we have an instantaneous reaction in the mass flow as soon as we change the throttle position, and for low throttle situations even a spooled turbo will produce boost against an obstacle so the tuning of a turbine and compressor is quite tricky. In a gasser you will normally not have high pressure ratios and will be interested in a compressor that has a rising efficiency and quick rise of mass flow as the boost is falling due to opening the throttle. In a diesel you want it quite the other way round. You need high pressure ratios, you will want a quick rise of mass flow over a rising pressure ratio when the enthalpy in the exhaust gas rises. So the turbine design for a daily driver will be quite different. For a dyno truck or a puller etc you will be accepting tradeoffs that you couldn't accept in your daily driver. To me tuning a turbo on a diesel is a quest to get the widest powerband possible, with the least amount of lag and the quickest possible transition (to reduce smoke and lag) with as little back pressure as possible and while staying within the EGT limits."
So lets not bring compound diesel into this thread or diesel in general as it has no bearing at all.
I am quite intrigued by this thread, but have nothing else useful to add.
03-09-2009, 07:52 PM
#250
0.0 BAR
Join Date: Mar 2009
Posts: 2
Aero,
i plan on running a he351ve on my 02 eclipse gt in a rear turbo setup. due to the significantly lower temperatures in the rear of the car do you think it will still be necessary to run coolant to it? i plan on running an oil system with just the turbo, pump, cheap filter, and an oil cooler.
also im sure its been covered more than once but can you recall the size and thread of the oil and coolant inlets/outlets
i plan on running a he351ve on my 02 eclipse gt in a rear turbo setup. due to the significantly lower temperatures in the rear of the car do you think it will still be necessary to run coolant to it? i plan on running an oil system with just the turbo, pump, cheap filter, and an oil cooler.
also im sure its been covered more than once but can you recall the size and thread of the oil and coolant inlets/outlets
