GT Motorsports: 370Z Supercharger system development

RCZ · 02-19-2010, 09:05 AM

Alright so after reading a bit from reputable sources. AKA Garrett from the stuff that Silo showed us.

Bigger turbos make more power per the same psi for two main reasons:

1) Bigger turbo will put less heat into the air and therefore the air is denser. More air = more power

2) The actual CFM of the turbo is meaningless. What matters is how much of that air is actually going into the engine and being used. There are restrictions that keep all the air from getting to the combustion chamber, the main one being backpressure from the exhaust housing of the turbo. The smaller it is the more backpressure, the less air that can flow through the engine, the less air that can flow INTO it in the first place and therefore less power. So bigger exhaust housing means less backpressure, meaning more air in, meaning more power.

The logic seems to be that it doesnt matter if the turbo can flow an infinite cfm, if the engine can't make use of it. The less backpressure, the more the engine can use, the more power it can make.

So how does this all apply to the SC vs TC dilemma?

I would say its the same thing, more flow through the engine means more power. So why do manufacturers recommend sticking with 2.5" piping rather than 3" piping on an SC? Because the sc doesnt flow enough in the first place to cause a 2.5" exhaust to become an obstruction??

Zsteve · 02-19-2010, 10:26 AM

Quote:

Originally Posted by RCZ

Alright so after reading a bit from reputable sources. AKA Garrett from the stuff that Silo showed us.

Bigger turbos make more power per the same psi for two main reasons:

1) Bigger turbo will put less heat into the air and therefore the air is denser. More air = more power

2) The actual CFM of the turbo is meaningless. What matters is how much of that air is actually going into the engine and being used. There are restrictions that keep all the air from getting to the combustion chamber, the main one being backpressure from the exhaust housing of the turbo. The smaller it is the more backpressure, the less air that can flow through the engine, the less air that can flow INTO it in the first place and therefore less power. So bigger exhaust housing means less backpressure, meaning more air in, meaning more power.
The logic seems to be that it doesnt matter if the turbo can flow an infinite cfm, if the engine can't make use of it. The less backpressure, the more the engine can use, the more power it can make.

So how does this all apply to the SC vs TC dilemma?

I would say its the same thing, more flow through the engine means more power. So why do manufacturers recommend sticking with 2.5" piping rather than 3" piping on an SC? Because the sc doesnt flow enough in the first place to cause a 2.5" exhaust to become an obstruction??

This makes sense, with my 4 cyl turbo, when we just upgraded theintake and Down Pipe we saw huge gains as more air was flowing in and out. When I chipped the ECU I also went 3 in TBE and with the small turbo on the car I hit full boost @ 2500 rpms and actually had more TQ than HP on the car. I had over 300 TQ and about 260 HP on a 4 cyl FWD car, it was fun to feel all that TQ. Since the turbo does create its own back pressure we could go larger on the exhaust (to a point of no return of course) but I guess NA cars use the exhaust to create the back pressure.

Togo · 02-19-2010, 03:29 PM

Quote:

Originally Posted by RCZ

Alright so after reading a bit from reputable sources. AKA Garrett from the stuff that Silo showed us.

Bigger turbos make more power per the same psi for two main reasons:

1) Bigger turbo will put less heat into the air and therefore the air is denser. More air = more power

2) The actual CFM of the turbo is meaningless. What matters is how much of that air is actually going into the engine and being used. There are restrictions that keep all the air from getting to the combustion chamber, the main one being backpressure from the exhaust housing of the turbo. The smaller it is the more backpressure, the less air that can flow through the engine, the less air that can flow INTO it in the first place and therefore less power. So bigger exhaust housing means less backpressure, meaning more air in, meaning more power.

The logic seems to be that it doesnt matter if the turbo can flow an infinite cfm, if the engine can't make use of it. The less backpressure, the more the engine can use, the more power it can make.

So how does this all apply to the SC vs TC dilemma?

I would say its the same thing, more flow through the engine means more power. So why do manufacturers recommend sticking with 2.5" piping rather than 3" piping on an SC? Because the sc doesnt flow enough in the first place to cause a 2.5" exhaust to become an obstruction??

If I had to take a guess, and yeah thats what I'm doing with this post, I'd say the SC doesn't make enough power to bog down a 2.5" exhaust. The turbo's turbine housing would be causing some back pressure relatively close to the engine so I'd suspect the 3" turbo back exhaust would help elevate the back pressure by creating a lower pressure area aft of the turbines. The low pressure area would help increase the flow over the turbines due to a relatively high pressure zone pre-turbine. I don't think that a 500RWHP TT setup produces more exhaust than a 500RWHP SC setup so the 3" exhaust might just help to lower the pressure pre-turbine by moving those gases over the turbine blades faster and more efficiently.

KEVTEX · 02-19-2010, 09:23 AM

Yes, we know sc's have higher internal parasitic losses than turbo's. The majority of the power drawn from the engine is used to to compress the air, not toovercome parasitic losses.
None of this discussion should have any impact on one's decision to buy a GTM supercharger. I've had a turbo before and would prefer the torque curve provided by a a supercharger for a daily driver.

Buddy Revell · 02-19-2010, 09:33 AM

Quote:

Originally Posted by KEVTEX

Yes, we know sc's have higher internal parasitic losses than turbo's. The majority of the power drawn from the engine is used to to compress the air, not toovercome parasitic losses.
None of this discussion should have any impact on one's decision to buy a GTM supercharger. I've had a turbo before and would prefer the torque curve provided by a a supercharger for a daily driver.

But if the turbo is sized just right, the midrange torque is really good. I had a turbo kit on my old Toyota Celica, and the response was very quick. That also looks like the case for the TT kits available for the 370, judging from the dynos of those TT systems.

RCZ · 02-19-2010, 09:51 AM

Yeah, once I post why, we are all experts and knew all along, but before then no one could give me a specific answer as to why.

budakai · 02-19-2010, 10:05 AM

Ya know what I just realized...There is no easy way out......I just need to pick a HP goal for my car....If the SC can do it then I should get it...If the SC can't do it then I should buy the TT kit...

shumby · 02-19-2010, 10:50 AM

tell me again how discuessing turbo's for the last 3 pages is on topic to this thread?

Buddy Revell · 02-19-2010, 11:38 AM

Quote:

Originally Posted by shumby

tell me again how discuessing turbo's for the last 3 pages is on topic to this thread?

Because the compressor side of a turbo and a centrifugal supercharger are pretty much the same, unlike a roots-type/twin-screw supercharger. Understanding one will give you a greater understanding of the other.

StillenZ · 02-19-2010, 11:01 AM

lol.. I was waiting for you to say something shumby! lol... Thanks for the education though guys... I'm definitely learnin' here. lol

shumby · 02-19-2010, 11:06 AM

MOds/admin. please move the turbo posts to there owen thread. There is useful info here but all these posts will take away from the point of this thread. (GTM's SC) makes it hard to search and find info in this topic

budakai · 02-19-2010, 01:03 PM

Quote:

Originally Posted by shumby

MOds/admin. please move the turbo posts to there owen thread. There is useful info here but all these posts will take away from the point of this thread. (GTM's SC) makes it hard to search and find info in this topic

I think it's all useful information for vets and noobs. Shoot 70 pages of this thread alone is just filled with us begging GTM for information on the SC kit. They should remove that before moving this useful information.

Buddy Revell · 02-19-2010, 01:28 PM

Quote:

Originally Posted by budakai

I think it's all useful information for vets and noobs. Shoot 70 pages of this thread alone is just filled with us begging GTM for information on the SC kit. They should remove that before moving this useful information.

Haha, agreed. Also, complaining about turbo/centrifugal sc info on this thread yet not about the random fat guy pics here makes no sense to me, lol.

BRUSSO · 02-19-2010, 12:37 PM

to me the point is simple..... if you are making a small amount of boost(3-5lbs) the stock exhaust and cats can handle the amount that is trying to be pushed out. However, the more boost you make (8-10lbs) the more trouble the stock exhaust has . So by removing the restrictions in the exhaust you will see higher gains with higher boost levels.

roplusbee · 02-19-2010, 01:29 PM

Quote:

Originally Posted by Zsteve

This makes sense, with my 4 cyl turbo, when we just upgraded theintake and Down Pipe we saw huge gains as more air was flowing in and out. When I chipped the ECU I also went 3 in TBE and with the small turbo on the car I hit full boost @ 2500 rpms and actually had more TQ than HP on the car. I had over 300 TQ and about 260 HP on a 4 cyl FWD car, it was fun to feel all that TQ. Since the turbo does create its own back pressure we could go larger on the exhaust (to a point of no return of course) but I guess NA cars use the exhaust to create the back pressure.

That is the same result that I saw when upgrading the intake and exhaust on my S13 Fastback (CA18DET). It seemed as if I was at full boost sooner, but I had no way of really telling for sure. I also installed a Power FC the next day and spent like 2.5 weeks and 5 50 liter fillups (sucked) tuning it (mostly DD efficiency). When I upgraded from the T-2-Small to 2871, all I could say was WOW. And it was a bolt on affair.

Quote:

Originally Posted by shumby

MOds/admin. please move the turbo posts to there owen thread. There is useful info here but all these posts will take away from the point of this thread. (GTM's SC) makes it hard to search and find info in this topic

The next quote pretty much sums it up, but everyone is entitled to their take on things.

Quote:

Originally Posted by Buddy Revell

Because the compressor side of a turbo and a centrifugal supercharger are pretty much the same, unlike a roots-type/twin-screw supercharger. Understanding one will give you a greater understanding of the other.

Well put.

Quote:

Originally Posted by BRUSSO

to me the point is simple..... if you are making a small amount of boost(3-5lbs) the stock exhaust and cats can handle the amount that is trying to be pushed out. However, the more boost you make (8-10lbs) the more trouble the stock exhaust has . So by removing the restrictions in the exhaust you will see higher gains with higher boost levels.

Sounds like something that I can agree with, but I have never increased boost pressure in my setups. I have only swapped out turbos for more efficiency for my application and driving habits.

02-19-2010, 10:50 AM	#8 (permalink)
shumby Captin Canuck Join Date: Dec 2008 Location: with your mom Age: 45 Posts: 6,288 Drives: your sister Rep Power: 237	tell me again how discuessing turbo's for the last 3 pages is on topic to this thread? __________________ Originally Posted by SAM@GTM Engine detonation is not normal and it should never never happen, and whoever told that need to do something else for living . Sam

02-19-2010, 11:01 AM	#10 (permalink)
StillenZ Enthusiast Member Join Date: Oct 2009 Location: Indiana Posts: 283 Drives: 09 Nissan 370Z Red M Rep Power: 16	lol.. I was waiting for you to say something shumby! lol... Thanks for the education though guys... I'm definitely learnin' here. lol __________________ Stillen Dual Exhaust / Stillen Gen 3 Intake / Stillen Headers / Eibach Pro-Kit / Euro Fog Lamp / 1000W JL Audio Amp / 2 - 12' JBL P1222's / Pioneer In-dash Nav

02-19-2010, 11:06 AM	#11 (permalink)
shumby Captin Canuck Join Date: Dec 2008 Location: with your mom Age: 45 Posts: 6,288 Drives: your sister Rep Power: 237	MOds/admin. please move the turbo posts to there owen thread. There is useful info here but all these posts will take away from the point of this thread. (GTM's SC) makes it hard to search and find info in this topic __________________ Originally Posted by SAM@GTM Engine detonation is not normal and it should never never happen, and whoever told that need to do something else for living . Sam

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02-19-2010, 09:05 AM	#1 (permalink)
RCZ A True Z Fanatic Join Date: Nov 2008 Location: Miami Posts: 6,403 Drives: '09 370Z Rep Power: 1119	Alright so after reading a bit from reputable sources. AKA Garrett from the stuff that Silo showed us. Bigger turbos make more power per the same psi for two main reasons: 1) Bigger turbo will put less heat into the air and therefore the air is denser. More air = more power 2) The actual CFM of the turbo is meaningless. What matters is how much of that air is actually going into the engine and being used. There are restrictions that keep all the air from getting to the combustion chamber, the main one being backpressure from the exhaust housing of the turbo. The smaller it is the more backpressure, the less air that can flow through the engine, the less air that can flow INTO it in the first place and therefore less power. So bigger exhaust housing means less backpressure, meaning more air in, meaning more power. The logic seems to be that it doesnt matter if the turbo can flow an infinite cfm, if the engine can't make use of it. The less backpressure, the more the engine can use, the more power it can make. So how does this all apply to the SC vs TC dilemma? I would say its the same thing, more flow through the engine means more power. So why do manufacturers recommend sticking with 2.5" piping rather than 3" piping on an SC? Because the sc doesnt flow enough in the first place to cause a 2.5" exhaust to become an obstruction??

02-19-2010, 09:23 AM	#4 (permalink)
KEVTEX Base Member Join Date: Nov 2009 Location: Montgomery, TX Posts: 119 Drives: 2010 370Z 7at sp pg Rep Power: 16	Yes, we know sc's have higher internal parasitic losses than turbo's. The majority of the power drawn from the engine is used to to compress the air, not toovercome parasitic losses. None of this discussion should have any impact on one's decision to buy a GTM supercharger. I've had a turbo before and would prefer the torque curve provided by a a supercharger for a daily driver.

02-19-2010, 09:51 AM	#6 (permalink)
RCZ A True Z Fanatic Join Date: Nov 2008 Location: Miami Posts: 6,403 Drives: '09 370Z Rep Power: 1119	Yeah, once I post why, we are all experts and knew all along, but before then no one could give me a specific answer as to why.

02-19-2010, 10:05 AM	#7 (permalink)
budakai Base Member Join Date: May 2009 Location: PA Posts: 57 Drives: g37 Rep Power: 17	Ya know what I just realized...There is no easy way out......I just need to pick a HP goal for my car....If the SC can do it then I should get it...If the SC can't do it then I should buy the TT kit...

02-19-2010, 12:37 PM	#14 (permalink)
BRUSSO Base Member Join Date: Nov 2009 Location: SO CAL Posts: 21 Drives: 370z Rep Power: 16	to me the point is simple..... if you are making a small amount of boost(3-5lbs) the stock exhaust and cats can handle the amount that is trying to be pushed out. However, the more boost you make (8-10lbs) the more trouble the stock exhaust has . So by removing the restrictions in the exhaust you will see higher gains with higher boost levels.