370z Forced Induction for Noobs...

Infidel · 12-22-2013, 04:02 PM

11:1

theDreamer · 12-23-2013, 08:25 AM

Quote:

Originally Posted by stiggy

It does look small. Is there a known safe psi, given the stock engine compression ratio of 9.0:1? I think.

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Get Even...

Forced Induction Finished Builds
Take a look at a lot of the finished builds, many guys well into the 500 with the 1.5 GTM kit and very safe. I am not running that much power, but I have the stage 1 SC from GTM with over 50k miles on the kit (71k miles total car) and around 400whp.

JWillis72 · 12-23-2013, 08:35 AM

Quote:

Originally Posted by theDreamer

Forced Induction Finished Builds
I have the stage 1 SC from GTM with over 50k miles on the kit (71k miles total car) and around 400whp.

Wow thats great you have that many FI miles. Any problems so far?

theDreamer · 12-23-2013, 08:43 AM

Quote:

Originally Posted by JWillis72

Wow thats great you have that many FI miles. Any problems so far?

Nope, just have a solid tune, good install, and keep up with maintenance.
The VQ37VHR is a very solid motor for boost it seems like, which is very good, you just have to monitor it for any odd occurrences.

JWillis72 · 12-23-2013, 06:22 PM

Quote:

Originally Posted by theDreamer

Nope, just have a solid tune, good install, and keep up with maintenance.
The VQ37VHR is a very solid motor for boost it seems like, which is very good, you just have to monitor it for any odd occurrences.

Glad to hear it since we are right around the same HP!

1slow370 · 01-15-2014, 10:42 PM

I posted this in another thread but it should be here too. An explanation of why headers and superchargers don't agree with each other. In a naturally aspirated engine with stock exhaust, the valve overlap on the engine allows the exhaust volume moving out of the head to scavenge the cylinder better allowing a greater intake volume to be pulled into the cylinder, it is timed up so that the valve closes before the intake charge begins to leave the exhaust valve. When you put headers on an NA car you improve the scavenging of the exhaust improving the intake charge to the point that just a little intake volume goes into the exhaust before the valve closes but the cylinder is filled with more intake charge regardless so it makes more power. On a supercharged car the intake charge is pressurized so that once the exhaust has vented enough that the cylinder pressure is equal to the intake pressure intake charge begins to flood out the exhaust valve long before it is closed, with a restrictor like a factory cat, or running a smaller exhaust diameter(2-2.5") with test pipes you allow manifold pressure to rise right at the critical point where the intake charge would over pressure the cylinder and flood out the open exhaust valve so the manifold back pressure holds the charge in.

This has been true for long before the 370z even came out, every supercharger kit manufacturer will warn about headers causing a loss in boost pressure, the fact is with a supercharger and the locked in cam timing the Z will make more power per cfm pumped into the engine with a restrictive exhaust. headers plus cam timing the way it is the engine wastes a large percentage of intake charge, so the header manufacturer tells you to get a bigger blower so that even though 10% of the intake charge is flying out the exhaust you will get your power back by shoving more in. The supercharger manufacturer tells you to put a more restrictive exhaust on the car so you waste less and get more pressure and power for the amount you spin the charger. In the end the both do the same thing you just have to pick whether you want headers and a more wasteful setup or a smaller setup that's more efficient.

Now if you can change the valve timing, grab your self some headers and turn the overlap down and enjoy the best of both worlds. Like I said none of this is new it's neither companies fault it's just the way it is, thats why back in the 60's a thing called a blower cam was invented.

SS_Firehawk · 01-15-2014, 10:49 PM

Exactly why I was scared at first with my PPE's. (I think) My exhaust setup helps keep some needed back pressure. I still have a cat and the Tanabe is 2 3/4 at the Y.

1slow370 · 01-15-2014, 10:52 PM

so when are you going to pulley that thing down and shoot for 6XX haha

SS_Firehawk · 01-15-2014, 11:00 PM

When I have the balls and money to build the motor

It has a 92mm's and there are 84mm's available. That'd be an extra 100whp I'd imagine. I accept donations for any that are curious :P

1slow370 · 01-15-2014, 11:04 PM

Quote:

Originally Posted by SS_Firehawk

When I have the balls and money to build the motor

It has a 92mm's and there are 84mm's available. That'd be an extra 100whp I'd imagine. I accept donations for any that are curious :P

I think they can down to a 72 if you really want to push it

Boosted Performance · 01-16-2014, 02:57 AM

Quote:

Originally Posted by 1slow370

I posted this in another thread but it should be here too. An explanation of why headers and superchargers don't agree with each other. In a naturally aspirated engine with stock exhaust, the valve overlap on the engine allows the exhaust volume moving out of the head to scavenge the cylinder better allowing a greater intake volume to be pulled into the cylinder, it is timed up so that the valve closes before the intake charge begins to leave the exhaust valve. When you put headers on an NA car you improve the scavenging of the exhaust improving the intake charge to the point that just a little intake volume goes into the exhaust before the valve closes but the cylinder is filled with more intake charge regardless so it makes more power. On a supercharged car the intake charge is pressurized so that once the exhaust has vented enough that the cylinder pressure is equal to the intake pressure intake charge begins to flood out the exhaust valve long before it is closed, with a restrictor like a factory cat, or running a smaller exhaust diameter(2-2.5") with test pipes you allow manifold pressure to rise right at the critical point where the intake charge would over pressure the cylinder and flood out the open exhaust valve so the manifold back pressure holds the charge in.

This has been true for long before the 370z even came out, every supercharger kit manufacturer will warn about headers causing a loss in boost pressure, the fact is with a supercharger and the locked in cam timing the Z will make more power per cfm pumped into the engine with a restrictive exhaust. headers plus cam timing the way it is the engine wastes a large percentage of intake charge, so the header manufacturer tells you to get a bigger blower so that even though 10% of the intake charge is flying out the exhaust you will get your power back by shoving more in. The supercharger manufacturer tells you to put a more restrictive exhaust on the car so you waste less and get more pressure and power for the amount you spin the charger. In the end the both do the same thing you just have to pick whether you want headers and a more wasteful setup or a smaller setup that's more efficient.

Now if you can change the valve timing, grab your self some headers and turn the overlap down and enjoy the best of both worlds. Like I said none of this is new it's neither companies fault it's just the way it is, thats why back in the 60's a thing called a blower cam was invented.

Sorry to say it, but this is kind of backwards. Without getting in to too much detail (it is too late for an old man like me), you will loose boost pressure by opening up your exhaust, that is true. However, you will gain power due to efficiently scavenging all the exhaust gases out of your combustion chamber. This will allow you to run cooler, and advance timing therefore making more power.

On a more common platform that uses supercharges such as Ford Mustangs, the upgrade to LTH and a free flowing exhaust will cause a 2psi drop, but at the same time will cause a 10-15whp increase, especially in the top end.

Remember, boost pressure is resistance to flow.

1slow370 · 01-16-2014, 03:34 AM

My note is more application specific that is why it is in the 370z FI for noobs not the other FI for noobs. That is exactly what happens on the Z. Yes a free flowing exhaust does increase scavenging but on our cars the cam timing and duration cause this to happen. What you say about muffstains is true I have seen that, but as for camming on the mustang the overlap is much less aggressive and the head flows like **** to start with so it is a totally different platform. And the reason turbos don't run into this issue on our cars is one turbo's generate the back pressure to keep the boost in the motor and they do it proportionally to the amount of intake pressure so that as boost pressure rises so does back pressure(that is main reason manifold temp and pressure skyrocket on a turbo car and egt's become that much more important), and two the turbo will spool up to the set boost pressure regardless of head flow. Boost pressure is pressure in the intake pipe nothing more nothing less, so wether you are losing two psi because the cylinder is scavenged better and needs more intake charge to fill or you lose 2 psi because it blows right out the exhaust valve the gauge is still gonna read 2psi lost but the dyno will show the difference. SOOOO sorry to say this but while your statement is grounded in truth and i acknowledge that, it does not work on our application, I even stated it in a for noobs way at the end of my post, you fix the valve overlap and you can get the better scavenging of the LTH's without wasting the intake charge by blowing out the exhaust.

Subnote:The cams in the 370z are pretty much optimal for it's NA size and use thats why jun needed to go .030 over and bump the compression to get a big result out of theirs this means that a F.I. longtube which pretty much taps the car out NA, has way to much flow for the cams overlap and lift for the engines bore size and leads to boost wasting

Va_gunguy · 01-26-2014, 04:14 PM

This is just the info I was looking for! However from a maintenance point of view which is easier to take care of over the long run. Supercharger or turbo? or would they both be about the same?

1slow370 · 01-26-2014, 06:58 PM

the superchargers are usually lower maintenance because the kits are simpler and are less stressful on the engine when work needs to be done it is usually easier to take the supercharger kit apart to do the work. also because of the temperatures involved and the internal lubrication supercharger units themselves are less prone to failure

elperuano · 01-26-2014, 07:19 PM

BP kit would make maintenance very simple as well.

01-15-2014, 10:42 PM	#36 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	I posted this in another thread but it should be here too. An explanation of why headers and superchargers don't agree with each other. In a naturally aspirated engine with stock exhaust, the valve overlap on the engine allows the exhaust volume moving out of the head to scavenge the cylinder better allowing a greater intake volume to be pulled into the cylinder, it is timed up so that the valve closes before the intake charge begins to leave the exhaust valve. When you put headers on an NA car you improve the scavenging of the exhaust improving the intake charge to the point that just a little intake volume goes into the exhaust before the valve closes but the cylinder is filled with more intake charge regardless so it makes more power. On a supercharged car the intake charge is pressurized so that once the exhaust has vented enough that the cylinder pressure is equal to the intake pressure intake charge begins to flood out the exhaust valve long before it is closed, with a restrictor like a factory cat, or running a smaller exhaust diameter(2-2.5") with test pipes you allow manifold pressure to rise right at the critical point where the intake charge would over pressure the cylinder and flood out the open exhaust valve so the manifold back pressure holds the charge in. This has been true for long before the 370z even came out, every supercharger kit manufacturer will warn about headers causing a loss in boost pressure, the fact is with a supercharger and the locked in cam timing the Z will make more power per cfm pumped into the engine with a restrictive exhaust. headers plus cam timing the way it is the engine wastes a large percentage of intake charge, so the header manufacturer tells you to get a bigger blower so that even though 10% of the intake charge is flying out the exhaust you will get your power back by shoving more in. The supercharger manufacturer tells you to put a more restrictive exhaust on the car so you waste less and get more pressure and power for the amount you spin the charger. In the end the both do the same thing you just have to pick whether you want headers and a more wasteful setup or a smaller setup that's more efficient. Now if you can change the valve timing, grab your self some headers and turn the overlap down and enjoy the best of both worlds. Like I said none of this is new it's neither companies fault it's just the way it is, thats why back in the 60's a thing called a blower cam was invented. SS_Firehawk, warpeacelove, KratikosG37 and 1 others like this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

01-15-2014, 10:49 PM	#37 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	Exactly why I was scared at first with my PPE's. (I think) My exhaust setup helps keep some needed back pressure. I still have a cat and the Tanabe is 2 3/4 at the Y. __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

01-15-2014, 10:52 PM	#38 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	so when are you going to pulley that thing down and shoot for 6XX haha SS_Firehawk likes this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

01-15-2014, 11:00 PM	#39 (permalink)
SS_Firehawk Premium Member Join Date: Oct 2011 Location: Tampa Posts: 4,142 Drives: 13' Magma Red Nismo Rep Power: 7335	When I have the balls and money to build the motor It has a 92mm's and there are 84mm's available. That'd be an extra 100whp I'd imagine. I accept donations for any that are curious :P __________________ Old Car:GTM TSC'd 550whp / 410lbft tq @ 11.88PSI New Car: Under Construction

01-16-2014, 03:34 AM	#42 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	My note is more application specific that is why it is in the 370z FI for noobs not the other FI for noobs. That is exactly what happens on the Z. Yes a free flowing exhaust does increase scavenging but on our cars the cam timing and duration cause this to happen. What you say about muffstains is true I have seen that, but as for camming on the mustang the overlap is much less aggressive and the head flows like ** to start with so it is a totally different platform. And the reason turbos don't run into this issue on our cars is one turbo's generate the back pressure to keep the boost in the motor and they do it proportionally to the amount of intake pressure so that as boost pressure rises so does back pressure(that is main reason manifold temp and pressure skyrocket on a turbo car and egt's become that much more important), and two the turbo will spool up to the set boost pressure regardless of head flow. Boost pressure is pressure in the intake pipe nothing more nothing less, so wether you are losing two psi because the cylinder is scavenged better and needs more intake charge to fill or you lose 2 psi because it blows right out the exhaust valve the gauge is still gonna read 2psi lost but the dyno will show the difference. SOOOO sorry to say this but while your statement is grounded in truth and i acknowledge that, it does not work on our application, I even stated it in a for noobs way at the end of my post, you fix the valve overlap and you can get the better scavenging of the LTH's without wasting the intake charge by blowing out the exhaust. Subnote:The cams in the 370z are pretty much optimal for it's NA size and use thats why jun needed to go .030 over and bump the compression to get a big result out of theirs this means that a F.I. longtube which pretty much taps the car out NA, has way to much flow for the cams overlap and lift for the engines bore size and leads to boost wasting warpeacelove and KratikosG37 like this. __________________ ANSWER PRICE LIST** Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50 Last edited by 1slow370; 01-16-2014 at 04:00 AM.

12-22-2013, 04:02 PM	#31 (permalink)
Infidel Enthusiast Member Join Date: Mar 2013 Location: Central Florida Posts: 457 Drives: 2013 GM 6MT Rep Power: 14	11:1

01-26-2014, 04:14 PM	#43 (permalink)
Va_gunguy Base Member Join Date: Jan 2014 Location: Virginia Posts: 22 Drives: 2009 Nissan 370z Rep Power: 11	This is just the info I was looking for! However from a maintenance point of view which is easier to take care of over the long run. Supercharger or turbo? or would they both be about the same?

01-26-2014, 06:58 PM	#44 (permalink)
1slow370 A True Z Fanatic Join Date: Aug 2009 Location: In the D Posts: 3,732 Drives: v8 74 260z ;) Rep Power: 7251	the superchargers are usually lower maintenance because the kits are simpler and are less stressful on the engine when work needs to be done it is usually easier to take the supercharger kit apart to do the work. also because of the temperatures involved and the internal lubrication supercharger units themselves are less prone to failure KratikosG37 likes this. __________________ ANSWER PRICE LIST Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50

01-26-2014, 07:19 PM	#45 (permalink)
elperuano A True Z Fanatic Join Date: Oct 2011 Location: Southwest FL Posts: 1,374 Drives: G37S Rep Power: 29	BP kit would make maintenance very simple as well. Dzel likes this.

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