Exhaust Porting
02-17-2004, 09:10 PM
#11
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Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Originally Posted by White_FC' date='Feb 17 2004, 06:37 PM
Thanks for the info and pics BDC, very helpful!
How much power did that motor make?
And was it a turbo motor? Would you do things differently for an N/A motor?
Now I know there are always many many differing oppinions on things like this, thats why I want more people to post their thoughts in here
I know theres at lesat someone on this board that likes to take the whole exhaust sleeve out aswell, I think it was Mazdaspeed7(? don't shoot me if im wrong ) what do you think about that BDC? obviously against it from what i've just read in your last post.
So come on people! need more opinions!
How much power did that motor make?
And was it a turbo motor? Would you do things differently for an N/A motor?
Now I know there are always many many differing oppinions on things like this, thats why I want more people to post their thoughts in here
I know theres at lesat someone on this board that likes to take the whole exhaust sleeve out aswell, I think it was Mazdaspeed7(? don't shoot me if im wrong
So come on people! need more opinions!
We're not sure how much that motor has made. It's barely broken in and hasn't even been tuned for high power yet. I've done similar that have barely crested 500rwhp so I suspect this one will do the same unless it explodes into pieces.
On an N/A motor, the exhaust sleeves are different. I'm a believer in just swapping the exhaust sleeve out with a T2 sleeves to remove the 'diffuser' (or whatever they call it) to do a decent port job. It will make the exhaust louder from what I understand, however.
Removing the sleeves? The only two people I've heard of doing that is mazdaspeed7 (as you've mentioned) and Rice Racing. I'm not sure what data they have to compare with and without the sleeve but I'd be interested in hearing about it.
B
02-17-2004, 09:15 PM
#12
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Thread Starter
Join Date: Oct 2003
Posts: 177
Originally Posted by BDC' date='Feb 17 2004, 07:10 PM
Removing the sleeves? The only two people I've heard of doing that is mazdaspeed7 (as you've mentioned) and Rice Racing. I'm not sure what data they have to compare with and without the sleeve but I'd be interested in hearing about it.
B
B
I really don't mind having a really loud exhaust either, so thats not much of a consideration in the whole thing.
I'm thinking about building this motor without the sleeves in and porting everything to match, already done it on a 'junk' housing, looks ok to me, i'll try and grab some pics in the next couple of days so i can show you all what i've done.
I didn't make the actual port much bigger into the housing, just made it open a bit earlier.
Also on a turbo motor an earlier opening would spool the turbo markedly quicker yeah?
02-17-2004, 09:49 PM
#13
Member
Join Date: Jan 2003
Location: Melbourne, Australia
Posts: 48
Originally Posted by BDC' date='Feb 17 2004, 07:10 PM
Hey,
We're not sure how much that motor has made. It's barely broken in and hasn't even been tuned for high power yet. I've done similar that have barely crested 500rwhp so I suspect this one will do the same unless it explodes into pieces.
On an N/A motor, the exhaust sleeves are different. I'm a believer in just swapping the exhaust sleeve out with a T2 sleeves to remove the 'diffuser' (or whatever they call it) to do a decent port job. It will make the exhaust louder from what I understand, however.
Removing the sleeves? The only two people I've heard of doing that is mazdaspeed7 (as you've mentioned) and Rice Racing. I'm not sure what data they have to compare with and without the sleeve but I'd be interested in hearing about it.
B
We're not sure how much that motor has made. It's barely broken in and hasn't even been tuned for high power yet. I've done similar that have barely crested 500rwhp so I suspect this one will do the same unless it explodes into pieces.
On an N/A motor, the exhaust sleeves are different. I'm a believer in just swapping the exhaust sleeve out with a T2 sleeves to remove the 'diffuser' (or whatever they call it) to do a decent port job. It will make the exhaust louder from what I understand, however.
Removing the sleeves? The only two people I've heard of doing that is mazdaspeed7 (as you've mentioned) and Rice Racing. I'm not sure what data they have to compare with and without the sleeve but I'd be interested in hearing about it.
B
In regards to RIce Racing opening up the port with no sleeves, i have copied some of his thoughts from another thread, i had going
rice racing
I just rip the whole exhaust sleeve out ! and make the exhaust port as big as what will fit, not scientific, maybe against convention ?
But when used with one of my turbo headers I have noticed more power with all other variables being the same. These engines have the capacity to make 3 times the output of any Mazda OEM engine so their theories on exhaust port designes may not apply so well ?
I open it up to the maximum that will fit much wider, higher and lower, basically the width is the same as the outer wall minus the sleeve (flush) Port shape is square with small angles on top to be gentler on apex seal (though looks flat !). I just did it to try it basically and now I would not go back to a small port exhaust.
The overlap is greater but I dont find this a problem at all, It has a strong enough feel to it and still makes power around 7.5k rpm with 1k of flat torque peak to boot
Header just needs to be tuned length and of decent size to work with port. I run 2.5" of the motor then step down to 2" ID before turbo inlet, exact lengths and step point I will leave you to figure out but I like it and have not found any negative aspects besides little higher idle required and softer low rpm responce (below 2.5k rpm).
I just rip the whole exhaust sleeve out ! and make the exhaust port as big as what will fit, not scientific, maybe against convention ?
But when used with one of my turbo headers I have noticed more power with all other variables being the same. These engines have the capacity to make 3 times the output of any Mazda OEM engine so their theories on exhaust port designes may not apply so well ?
I open it up to the maximum that will fit much wider, higher and lower, basically the width is the same as the outer wall minus the sleeve (flush) Port shape is square with small angles on top to be gentler on apex seal (though looks flat !). I just did it to try it basically and now I would not go back to a small port exhaust.
The overlap is greater but I dont find this a problem at all, It has a strong enough feel to it and still makes power around 7.5k rpm with 1k of flat torque peak to boot
Header just needs to be tuned length and of decent size to work with port. I run 2.5" of the motor then step down to 2" ID before turbo inlet, exact lengths and step point I will leave you to figure out but I like it and have not found any negative aspects besides little higher idle required and softer low rpm responce (below 2.5k rpm).
What do you guys think?
cheers
Lance
02-18-2004, 12:27 AM
#15
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Thread Starter
Join Date: Oct 2003
Posts: 177
Originally Posted by jspecracer7' date='Feb 17 2004, 10:25 PM
As for sound, I have found that making the port "squarer" makes the exhaust sound louder. Not sure why.
02-18-2004, 01:15 AM
#16
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Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Alright. Most of this has been said before, but its strewn across many posts in a few different threads, so Ill post it all together.
I removed the sleeves from my last 2 engines, and I absolutely love the powerband. I have yet to put a vacuum gauge to my car, to see what kind of vacuum it pulls at idle, but I imagine its not a lot, between the exhaust port and having a large SP 6 port motor with all ports open all the time. When the 6 ports were closed, the engine idled at a nice, smooth 650 rpm. Large exhaust ports are EXTREMELY sensative to backpressure. I finally got rid of my true dual exhaust, and put a good, collected exhaust on, and I noticed a tremendous increase in power and drivability, especially in the low and midrange. I imagine the top end would be even stronger, but the stock ecu is maxed out long before I get to redline. Im working on that, and Ill have some numbers after I get rid of the stock ecu and intake manifold.
The torque builds very quickly from 2000-4000, and then very slowly builds up to the peak. My peak right now is about 5500, but it should be nearly flat from 4000 until around 7500-8000. But by 5500 rpm, the ecu is maxed, and the mixtures start to go lean, and the torque falls. Keep in mind, thats with all 6 intake ports always open, so this engine has A LOT of porting on both the intake and exhaust. Low end will obviously be lower than a stock port motor.
My powerband in 1st feels like a stock turbo TII with exhaust and intake. The power builds in the same way. In the higher gears, there is a bigger difference between on and off boost on the TII, while the difference in my powerband isnt as drastic.
Words do not do justice to how my car drives. Its really something you need to just experience.
Heres the pics. I didnt get a pic of the exhaust port on this engine. This is from my old aux bridge motor. The port on my SP engine was moved about 1/4" down, so it opened and closed earlier. The result was a much stronger low end and midrange, with the torque ramping up faster.
Heres my intake ports. The black is a ceramic coating. Primary and secondary ports are completed, but the aux ports werent quite done.
A few more misc things. Any exhaust porting will make the car louder. With my exhaust port, the exhaust tone is smoother and more mellow than stock ports, but the overall volume is louder. Stock ports have a more distinct, sharp sound to them than my engine(speaking of n/a's, of course). Turbos affect the exhaust sound.
Square exhaust ports make more peak power. Rounded exhaust ports have a broader torque curve.
edit: if the pics still arent showing up tomorrow, Ill fix it then.
I removed the sleeves from my last 2 engines, and I absolutely love the powerband. I have yet to put a vacuum gauge to my car, to see what kind of vacuum it pulls at idle, but I imagine its not a lot, between the exhaust port and having a large SP 6 port motor with all ports open all the time. When the 6 ports were closed, the engine idled at a nice, smooth 650 rpm. Large exhaust ports are EXTREMELY sensative to backpressure. I finally got rid of my true dual exhaust, and put a good, collected exhaust on, and I noticed a tremendous increase in power and drivability, especially in the low and midrange. I imagine the top end would be even stronger, but the stock ecu is maxed out long before I get to redline. Im working on that, and Ill have some numbers after I get rid of the stock ecu and intake manifold.
The torque builds very quickly from 2000-4000, and then very slowly builds up to the peak. My peak right now is about 5500, but it should be nearly flat from 4000 until around 7500-8000. But by 5500 rpm, the ecu is maxed, and the mixtures start to go lean, and the torque falls. Keep in mind, thats with all 6 intake ports always open, so this engine has A LOT of porting on both the intake and exhaust. Low end will obviously be lower than a stock port motor.
My powerband in 1st feels like a stock turbo TII with exhaust and intake. The power builds in the same way. In the higher gears, there is a bigger difference between on and off boost on the TII, while the difference in my powerband isnt as drastic.
Words do not do justice to how my car drives. Its really something you need to just experience.
Heres the pics. I didnt get a pic of the exhaust port on this engine. This is from my old aux bridge motor. The port on my SP engine was moved about 1/4" down, so it opened and closed earlier. The result was a much stronger low end and midrange, with the torque ramping up faster.
Heres my intake ports. The black is a ceramic coating. Primary and secondary ports are completed, but the aux ports werent quite done.
A few more misc things. Any exhaust porting will make the car louder. With my exhaust port, the exhaust tone is smoother and more mellow than stock ports, but the overall volume is louder. Stock ports have a more distinct, sharp sound to them than my engine(speaking of n/a's, of course). Turbos affect the exhaust sound.
Square exhaust ports make more peak power. Rounded exhaust ports have a broader torque curve.
edit: if the pics still arent showing up tomorrow, Ill fix it then.
02-18-2004, 10:51 AM
#17
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Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
I've got a question for you, Adam: Most of the info you're providing here is more 'seat of the pants', which is fine, but when you built this motor, did you also change the intake porting at the same time? What I'm wondering is whether or not the "seat of the pants" feeling can be more attributed to all of the porting work done vs. _just_ the exhaust sleeve removal. If you did do all of this at once, then you may not be able to get a fair gauge on how much effect, either positive or negative, removing the exhaust sleeves and doing that port work had. Is that fair to ask?
B
B
02-18-2004, 02:13 PM
#18
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Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Originally Posted by BDC' date='Feb 18 2004, 12:51 PM
I've got a question for you, Adam: Most of the info you're providing here is more 'seat of the pants', which is fine, but when you built this motor, did you also change the intake porting at the same time? What I'm wondering is whether or not the "seat of the pants" feeling can be more attributed to all of the porting work done vs. _just_ the exhaust sleeve removal. If you did do all of this at once, then you may not be able to get a fair gauge on how much effect, either positive or negative, removing the exhaust sleeves and doing that port work had. Is that fair to ask?
B
B
Im want to give a truly objective review on this porting, and I do my best to not let what the way I want it to be blur how it really is. Feel free to ask me anything.