Nissan 370Z Forum - View Single Post

1slow370 · 01-16-2014, 02:34 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

01-16-2014, 02:34 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: 7250	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 __________________ ANSWER PRICE LIST** Answers - - - - - - - - - - - - - - - - $0.75 Answers (requiring thought) - - - - $1.25 Answers (correct) - - - - - - - - - - $12.50 Last edited by 1slow370; 01-16-2014 at 03:00 AM.