My search for more NA power (Dyno time)

Well, to get a better understanding of how much the manifold-back section of the exhaust is doing, you could always do a dyno run with just the exhaust manifold. I'm not positive on this, but I've always felt like everything after the exhaust manifold did little in terms of performance, and that being the reason why most formula and le mans prototype exhaust manifolds look the way they do.

For some reason I think that the biggest limitation is the software, which from my understanding is just a basic Jim Conforti Shark Injector tune?

Originally Posted by ETA

What I'd like to change if it was mine is the two 90 degree bends and they are real close to each other. 90's slow the flow. the oem exhaust shows 45's.

but on the other hand the increase in size may make up for it?

didnt you increase the throttle body as well, or did you dyno with the other exhaust sorry i missed it

The bend radius of the 3" tubing is much larger than the bend radius of the 2" tubing, and needs to turn a little more to compensate.

cool video of f1 exhaust i found
http://vids.myspace.com/index.cfm?fu...ideoid=2313546

Will JC make a tune for an m54 with cams? If not what about ESS? I think with a proper tune you could get 10 to 15hp. Not to get OT.. You can really see how the gases pulse out of the motor.

Originally Posted by hoveringuy

I am also learning that one cat gets hot as a mofo.

Yes, and running too hot is also bad. I've seen already melted down cats.

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Now, if it goes about stock Y-pipe in M54. Put this # 18301733901 into your realoem, and tell me what you got.

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OK, once again about pipe merging. I hope, it will be the final proof to confirm I'm right about my pipe diamater ratito theory.

Check this -> http://www.supersprint.com/USP00bmwE4626.asp

Supersprint offers 63,5mm pipes for headers back exhaust. Now, you can also choose something like this:



diameter? 76mm

what do we get than? 76 / 63,5 = 1,1968

period.

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Iceman00, could you explain the relation beetwen stepped headers and merging several pipes into one (creating Y-pipe). I agree that stepped headers work. Stepping helps in cylinder scavenging. But why than, for example, supersprint do not offer whole exhaust stepped, but just the headers? That's because it's only benefical when gases are travelling very fast, which happens just at the cylinder head.

Now about the situation farther from the head.

Question:
You have a pipe, 10 feet long, 2" dia. Is it going to flow more water if you make one end of the pipe 4" ?
Answer is no. Because you still have a 2" restriction on the other end, which just can't flow more.

So, what is the point of using big pipe diameters at the end of exhaust? None.
Doing so just hurts low end torque, due to no backpressure.

And for now, I don’t want to judge anything from AA and BW graphs, unless we have some proper info about dyno’ed cars.

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For low end torque you need a system with proper backpressure,

For high end torque you need big flowing system,

With stock setup you get nearly optimal balance for wide torque curve. Nearly because they are limited by emissions, noise levels and costs.

And what AggieE46 has? Definitely a big flowing exhaust. Low end torque is down, but where is his top end? Nowhere, because he is now limited by stock head. That’s why bigger bored throttle didn’t help either.

Originally Posted by beemka

For low end torque you need a system with proper backpressure,

For high end torque you need big flowing system

I think for low-end torque, you need a system that's properly sized for low-end torque. That system will usually have some back pressure at higher rpms. Backpressure is never a good thing, it's just that you can't have it properly sized for low-end torque AND high-end power at the same time. I think it's a misnomer to say you need backpressure for low-end torque.

Totally agree, you just said it much better than me, but this is what I wanted to say.
proper is not good word there.

it all really depends on what your doing as well. A car that lives on the track at 3.5K plus RPM all the time, doesnt need low end torque. It needs as much as it can get at the high end.

Sorry, I haven't had to much time to sit down, and respond (and I'm at work now, so This will not be a complete response)

Originally Posted by beemka

Now, if it goes about stock Y-pipe in M54. Put this # 18301733901 into your realoem, and tell me what you got.

Tried it, nothing came up. I googled the part number, and it looks like whatever it is, it came on M52tu equipped cars, and not M54 cars. There is NO CROSSOVER ON M54 cars.
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OK, once again about pipe merging. I hope, it will be the final proof to confirm I'm right about my pipe diamater ratito theory.

Check this -> http://www.supersprint.com/USP00bmwE4626.asp

Supersprint offers 63,5mm pipes for headers back exhaust. Now, you can also choose something like this:



diameter? 76mm

what do we get than? 76 / 63,5 = 1,1968

period.

I'm not sure I follow. You posted an image of a SuperSprint Y pipe and measurements compared to a twin pipes. Are we comparing cross sectional area? It's hard to follow your post, and furthermore, what does it prove? **************

Iceman00, could you explain the relation beetwen stepped headers and merging several pipes into one (creating Y-pipe). I agree that stepped headers work. Stepping helps in cylinder scavenging. But why than, for example, supersprint do not offer whole exhaust stepped, but just the headers? That's because it's only benefical when gases are travelling very fast, which happens just at the cylinder head.

You are arguing in cricles with no real point. I've already established that stepped headers are used to broaded the powercurve by keeping exhaust gas velocity, without to much of a sacrifice to higher rpm power. This is not case with Y back exhaust, and as explained before, there is nothing to be gained with an exhaust after the Y/merger. You can lose power by creating a disruption in flow (backpressure) by sizing the pipe to small, but you can't go to large. (That is how a exhaust cut out works)
Now about the situation farther from the head.

Question:
You have a pipe, 10 feet long, 2" dia. Is it going to flow more water if you make one end of the pipe 4" ?
Answer is no. Because you still have a 2" restriction on the other end, which just can't flow more.

So, what is the point of using big pipe diameters at the end of exhaust? None.
Doing so just hurts low end torque, due to no backpressure.

And for now, I don’t want to judge anything from AA and BW graphs, unless we have some proper info about dyno’ed cars.

I'm at work, but I have quite a few that I can post up. Keep in mind, we are arguing theory here. I have supported my theory with opinion and testing of many others who are more experienced and educated on this subject than I am.
That being said, I'm not sure what you're arguing, that a single 3 inch pipe is too large?
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For low end torque you need a system with proper backpressure,

For high end torque you need big flowing system,
Back pressure is never good. Exhaust gas velocity might be the term you are looking for.

With stock setup you get nearly optimal balance for wide torque curve. Nearly because they are limited by emissions, noise levels and costs.
The stock exhaust configuration has nothing to do with Emissions, and everthing to do with packaging.

And what AggieE46 has? Definitely a big flowing exhaust. Low end torque is down, but where is his top end? Nowhere, because he is now limited by stock head. That’s why bigger bored throttle didn’t help either.

I already told him ahead of time that he wouldn't gain anything meaningful on the ported throttlebody. The intake manifold out flows the head at this point. As for the exhaust, theoretically speaking, his peak power should remain the same unless there is a restriction (Y pipe)

Guys, this has NOTHING to do with optimizing back-pressure. Too many have read "internet facts" without questioning the physics of what's really going on. This is about optimizing velocity in relation to pulse frequency.

The merge collector shape and location is where the power is made.

Originally Posted by PEI330Ci

Guys, this has NOTHING to do with optimizing back-pressure. Too many have read "internet facts" without questioning the physics of what's really going on. This is about optimizing velocity in relation to pulse frequency.

The merge collector shape and LOCATION is where the power is made.

I've been saying this all along. IMO the Y pipe needs to be moved back. It's not going to be easy to find the right location. If you have a welder at your house. Who cares what it looks like start cutting/welding to find the proper placement. Best muffler is no muffler the best cat is no cat. It will always be this way imo. No reso's nothing pipe it from the headers back without any garbage in between. If performance is number one, sound shouldn't even be considered. Hope I made sense here

Originally Posted by xixixi

I've been saying this all along. IMO the Y pipe needs to be moved back. It's not going to be easy to find the right location. If you have a welder at your house. Who cares what it looks like start cutting/welding to find the proper placement. Best muffler is no muffler the best cat is no cat. It will always be this way imo. No reso's nothing pipe it from the headers back without any garbage in between. If performance is number one, sound shouldn't even be considered. Hope I made sense here

I said this before many times. PEI didn't say anything I haven't.

Well, I finally got the runfiles. I must say, I was pleasantly surprised to see my best run. Although the low end torque drop still bothers me, it wasn't as far into the RPM range as I thought, and I actually made more midrange power and torque than I remembered from the quick view I got of the pull.

In blue is the run I did this summer after I replaced my drop-in with my cone filter inside the airbox. Green was the run from a couple weeks ago with the throttle body. And red is the incomplete pull from the exhaust. You can see that I lose torque up to about 3300, but then I make more torque from about 4200 on. Same with power. I'm actually amazed. The car doesn't really feel like it made gains. I guess the sound throws me off.

Discuss.

Originally Posted by Iceman00

To be honest, the major benefit you should be looking for is more mid range power than peak. Though even so, I don't expect a large change in peak power.

Can I say I told you so? And FYI, your power peak is normally 6800rpm. While it isn't the wild success I was hoping for, this project is not a failure. Time for the next step.

Sure, but I didn't realize I had made it Never got a close look at the run!

Originally Posted by Iceman00

Can I say I told you so?

I wish they had taken it to redline, I would have loved to see what we were working with, but I don't believe you lost that much low end torque. Looks like they started a full throttle run a bit later than before, that's all.

I really wish they had, too.

Well, all 3 of the pulls were like that with the low end torque. They stabbed the throttle all the way after letting the RPMs fall.

Originally Posted by Iceman00

I wish they had taken it to redline, I would have loved to see what we were working with, but I don't believe you lost that much low end torque. Looks like they started a full throttle run a bit later than before, that's all.

So, with this dyno, aside from using a different muffler and/or resonator, I'm pleased. The drop in torque makes it easier for daily driving (stoplights) and I'd never be in those RPMs at the track or strip.

Time for some tuning!

Originally Posted by aggieE46

So, with this dyno, aside from using a different muffler and/or resonator, I'm pleased. The drop in torque makes it easier for daily driving (stoplights) and I'd never be in those RPMs at the track or strip.

Time for some tuning!

I still believe a proper Y pipe would improve power all through the powerband, but if you're happy, so am I.

Grats man. I mean unless your on the track you generally dont live above 4K constantly. so i mean you do serious "race" mods you will shift your power curve higher. But like iceman said. if your happy brady, I am happy for you.

And I may still look into one

Originally Posted by Iceman00

I still believe a proper Y pipe would improve power all through the powerband, but if you're happy, so am I.