M62tu with SuperSprint headers, SS no-cat connecting pipes, to SS resonator delete

[TriniSpeC]

Take it to jack at MPI for the install.

[Manny G.]

You always want the lowest pressure possible in the relevant branch of the manifold as the exhaust valve opens as this will allow as much of the contents of the cylinder to be ejected as possible before the valve closes, thus allowing more oxygen to be drawn into the cylinder on the next intake stroke.

As I understand it, well tuned NA or SC engine exhausts use the kinetic energy of the exhaust gas from the previous cylinder to create a partial vacuum in the manifold at exactly the right moment (this is called exhaust gas scavenging); this isn't really possible on a turbocharged engine because the turbo restricts the exhaust gas flow too much. Thus in a turbocharged car, you want the air to simply flow as freely as possible to the exhaust outlet; however, for other engines back-pressure is used as part of the tuning technique to align the pulses correctly, so fitting a freer flowing exhaust to a N/A car can actually reduce power.

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Here is some good technical literature based for this topic.. they used an M3 as an example.

http://www.autozine.org/technical_sc...riable-exhaust

[knucklez313]

You always want the lowest pressure possible in the relevant branch of the manifold as the exhaust valve opens as this will allow as much of the contents of the cylinder to be ejected as possible before the valve closes, thus allowing more oxygen to be drawn into the cylinder on the next intake stroke.

As I understand it, well tuned NA or SC engine exhausts use the kinetic energy of the exhaust gas from the previous cylinder to create a partial vacuum in the manifold at exactly the right moment (this is called exhaust gas scavenging); this isn't really possible on a turbocharged engine because the turbo restricts the exhaust gas flow too much. Thus in a turbocharged car, you want the air to simply flow as freely as possible to the exhaust outlet; however, for other engines back-pressure is used as part of the tuning technique to align the pulses correctly, so fitting a freer flowing exhaust to a N/A car can actually reduce power.

You had it until that last sentence, the lack of back pressure not being accounted for creates a lean condition, so when not tuned for correctly yes it causes issues. However that is failure of lack of tuning not the 0 back pressure. The second you adjust the tuning to accommodate the additional air flow allowed into the cylinder then your fine.

Without tuning yes low to no backpressure can cause issues. But it is not the overall problem. Lack of fuel becomes the problem.

[Manny G.]

You had it until that last sentence, the lack of back pressure not being accounted for creates a lean condition, so when not tuned for correctly yes it causes issues. However that is failure of lack of tuning not the 0 back pressure. The second you adjust the tuning to accommodate the additional air flow allowed into the cylinder then your fine.

Without tuning yes low to no backpressure can cause issues. But it is not the overall problem. Lack of fuel becomes the problem.

Ok so now we're arguing about tuning and not the change in back pressure.

Like for like, same tune on the same engine, if you change the exhaust system to be one with 0 back pressure, the tune you had will reduce performance.

You will need to have your tune setup for the adjustment in back pressure drop.

[geargrinder]

What's going on? What all this shouting? We'll have no trouble here!

[Manny G.]

What's going on? What all this shouting? We'll have no trouble here!

LOL no shouting going on, this is a discussion. It never fails though, anytime on any forum that the topic of exhaust back pressure is brought up, it sparks debate.

[knucklez313]

Ok so now we're arguing about tuning and not the change in back pressure.

Like for like, same tune on the same engine, if you change the exhaust system to be one with 0 back pressure, the tune you had will reduce performance.

You will need to have your tune setup for the adjustment in back pressure drop.

Depends on the car and specific ECU, as some can adjust far enough that it wont cause a reduction in power, those that can't, they will see a reduction lol

[Manny G.]

Depends on the car and specific ECU, as some can adjust far enough that it wont cause a reduction in power, those that can't, they will see a reduction lol

Most, not sure if all, BMW's after '96 (OBD2) have ECU's that can accommodate for up to about ~%10 differences in engine performance without tuning... for example with injector lbs. or a cold air intake.

[philly98540]

I think the missing link in this discussion is that changing the exhaust backpressure can impact scavenging. They are intertwined to a certain degree. So if, during a mod to reduce backpressure, you inadvertently screw up the tuned scavenging that the original exhaust provided, you could actually increase the amount of exhaust that is left in the cylinder for the next power stroke.

This can result in a loss in power at those rpm bands where the scavenging was negatively impacted to a greater degree than the backpressure was reduced.

[borii]

The powerband is moved up. The power isn't lost. More air in isn't needed because there is always more coming in than needed. Now, may the car's stock rev limiter fall below where most of the gains are achieved? Sure. Power isn't lost. It's changed. Good headers or a good xpipe will help fix the need to keep low end.

I don't race at 4500 so for me, it serves it's purpose. Need to get some baseline runs in.

[TerraPhantm]

I think the missing link in this discussion is that changing the exhaust backpressure can impact scavenging. They are intertwined to a certain degree. So if, during a mod to reduce backpressure, you inadvertently screw up the tuned scavenging that the original exhaust provided, you could actually increase the amount of exhaust that is left in the cylinder for the next power stroke.

This can result in a loss in power at those rpm bands where the scavenging was negatively impacted to a greater degree than the backpressure was reduced.

Do cross plane V8s even have "tuned scavenging" without using crazy headers? Something like below

[knucklez313]

Interesting. I had wondered about that. I have zero obsession w having to have the M5 / Camaro / Pickituptruck dual-on-either-side look so if a snug dual parallel like that works i might want to consider it for my next exhaust work. Do you have pix posted somewhere Kinkles?

Had it up on the lift this weekend for the Radiator and snapped some pics. Only thing I want to change is the addition of some electric cutouts.

[geargrinder]

Inneressing. Nice setup, very clean. Would look even better w/ the Touring straight-out exit.

I could see doing a quieter version of that setup with a resonator at the first spot where yours is, then the 2-in-2-out flow-through muffler at the rear spot.

[knucklez313]

I like the Touring tip idea. The only issue I currently have is with the HFC's and how low it sits, thats the first thing to scrape, followed by the magnaflow.

[vien]

I like the Touring tip idea. The only issue I currently have is with the HFC's and how low it sits, thats the first thing to scrape, followed by the magnaflow.

i kinda have a similar set up except i have 2 resonators instead of cats but mine go duel like yours to a y pipe then from the ypipe to a magnflow

[1gr8e39]

I am going to run the exact same setup, except I'll have an x pipe where you have the dual in dual out muffler, and a dual in dual out at the back of the car. X Pipe is where its at. nice H pipe setup tho! Share a clip with us! Headers are too expensive, but the rest is easy DIY welding whatnot. MCMNGNS will like this. 2 3/4"
Im no artist.

[extra]

Aaaahhh Florida, no inspections!

Love it here.

[knucklez313]

I am going to run the exact same setup, except I'll have an x pipe where you have the dual in dual out muffler, and a dual in dual out at the back of the car. X Pipe is where its at. nice H pipe setup tho! Share a clip with us! Headers are too expensive, but the rest is easy DIY welding whatnot. MCMNGNS will like this. 2 3/4"
Im no artist.

Not bad at all. I think that should sound great as well.


Cold Start: I wish my phone had a better Mic



Drive OffIncludes my upset son who didn't want me to be in front lol)

[mapleridge]

This is somewhat related but what type of gains can one expect from headers, rear exhaust work and a tune on the m62tu?

[Manny G.]

Ok, so i finally got it all installed.


THIS THING IS LOUD. Not like loud like "hey look at me I deleted my cats and resonator" loud, but like WHAT THE ACTUAL **** loud.

There is video, I will be uploading it soon. The video didnt truly catch the full effect of the sound the exhaust put down.. mostly because the mic on my phone couldnt keep up with it.

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[tptrsn]

WHOA!! What is that exhaust setup now?

[Manny G.]

WHOA!! What is that exhaust setup now?

Supersprint headers for M62/S62 V8 SS PN# - 022 786 801 (Ceramic Coated)
Supersprint front connecting straight pipes (cat delete) SS PN# - 022 786 812
Supersprint Y-Pipe SS PN# - 022 785 912
Supersprint Connecting Pipe (resonator delete) SS PN# - 022 785 953
Dinan M-Sport Free Flow exhaust

[tptrsn]

Dinan M-Sport Free Flow exhaust

So what does this part consist of? Something like a Magnaflow or Borla style straight-through oval body muffler? Sounds WICKED.

[Manny G.]

So what does this part consist of? Something like a Magnaflow or Borla style straight-through oval body muffler? Sounds WICKED.

Yeah, its essentially the muffler with the oval tip.

This is it here: http://www.dinancars.com/product/d66...ries&mid=1048/

[philly98540]

Holy Nascar loud loud. That's wicked. You keeping it like that?