Individual combustion chamber tuning
#1
Individual combustion chamber tuning
Has anyone tried individual combustion chamber tunning?
It adds in more complexity and a few more I/O, but the benefits as seen on pistons engines seem to be very much worth it.
At boost creep in Colorado, we just had a stock ej257 in a 2014 STI make 278.4 WHP up from 228 WHP. The only thing done was having individual O2 +EGT + MAF sensor for each cylinder and then a few days worth of tunning. I'll be asking the owner how MPG and drive-ability has changed.
I was told that cylinder temperatures dropped dramatically in cylinder 2 and 4, these two cylinders run much hotter than 1 and 3 because of our unequal length headers.
Moe Greene
It adds in more complexity and a few more I/O, but the benefits as seen on pistons engines seem to be very much worth it.
At boost creep in Colorado, we just had a stock ej257 in a 2014 STI make 278.4 WHP up from 228 WHP. The only thing done was having individual O2 +EGT + MAF sensor for each cylinder and then a few days worth of tunning. I'll be asking the owner how MPG and drive-ability has changed.
I was told that cylinder temperatures dropped dramatically in cylinder 2 and 4, these two cylinders run much hotter than 1 and 3 because of our unequal length headers.
Moe Greene
#2
Super Moderator
iTrader: (1)
Moe,
Take a look at David Hayes' 3 Rotor FD build thread, here: https://www.rx7club.com/build-thread...25733/page184/. He had great success with tuning the EGT from each chamber. You can also reach out to him to get more insight that may not be included in the above thread.
Cheers,
George
Take a look at David Hayes' 3 Rotor FD build thread, here: https://www.rx7club.com/build-thread...25733/page184/. He had great success with tuning the EGT from each chamber. You can also reach out to him to get more insight that may not be included in the above thread.
Cheers,
George
#5
Goodfalla Engine Complete
iTrader: (28)
http://thesensorconnection.com/egt-p...ss_probe.shtml
150ms response, designed for extreme duty (supposedly)
150ms response, designed for extreme duty (supposedly)
Last edited by Monkman33; 12-18-17 at 03:33 PM.
#7
Form follows function
iTrader: (8)
EGT Probe Exhaust Gas Temperature Sensor - Extreme Duty - 1/4" OD
150ms response, designed for extreme duty (supposedly)
150ms response, designed for extreme duty (supposedly)
Trending Topics
#8
Mazzei Formula
iTrader: (6)
Definitely worth doing. Because of the entry angle of the throttle and plenum design, rotor 1 had a 15% air-flow bias. Multiple EGT measurement caught this early on. Now all rotors are within 50* of one another by adjusting fuel trims to each rotor individually. TIming is setup to pull on any rotor that trips 1800F. The 15% difference from 1 to 4 is nearly a full AFR point. So if you imagine wideband reading a 12.0, it could really have been a 12.5 on rotor 1, and an 11.5 on rotor 4. Gives a much greater peace of mind once you equalize rotors as now you can trust your AFR
The 3 rotor favors the middle rotor, because of throttle position
Last edited by Monsterbox; 12-21-17 at 03:12 PM.
#9
10000 RPM Lane
iTrader: (2)
EGT Probe Exhaust Gas Temperature Sensor - Extreme Duty - 1/4" OD
150ms response, designed for extreme duty (supposedly)
150ms response, designed for extreme duty (supposedly)
Thanks, I went ahead and ordered a pair.
.
.
.
.
Last edited by TeamRX8; 12-22-17 at 07:06 PM.
#10
Moe,
Take a look at David Hayes' 3 Rotor FD build thread, here: https://www.rx7club.com/build-thread...25733/page184/. He had great success with tuning the EGT from each chamber. You can also reach out to him to get more insight that may not be included in the above thread.
Cheers,
George
Take a look at David Hayes' 3 Rotor FD build thread, here: https://www.rx7club.com/build-thread...25733/page184/. He had great success with tuning the EGT from each chamber. You can also reach out to him to get more insight that may not be included in the above thread.
Cheers,
George
#12
Definitely worth doing. Because of the entry angle of the throttle and plenum design, rotor 1 had a 15% air-flow bias. Multiple EGT measurement caught this early on. Now all rotors are within 50* of one another by adjusting fuel trims to each rotor individually. TIming is setup to pull on any rotor that trips 1800F. The 15% difference from 1 to 4 is nearly a full AFR point. So if you imagine wideband reading a 12.0, it could really have been a 12.5 on rotor 1, and an 11.5 on rotor 4. Gives a much greater peace of mind once you equalize rotors as now you can trust your AFR
The 3 rotor favors the middle rotor, because of throttle position
#13
So I finally met up with owner of the STI at a local cars and coffee, he noticed a 3mpg gain! The biggest difference he said with the car was city driving, he noticed he was shifting at lower rpms then he normally would, he suspects that the increase in torque under 3k rpm played a massive role in that. The weird thing that was really surprising was when he told me the car sounded a little bit different than before (exhaust note)
#14
RX-7 Bad Ass
iTrader: (55)
IMHO I don't think you will see as much of a gain on a 2 rotor. 3 rotor is a whole 'nuther deal. Same goes for the guy with the STI, he has 4 cylinders to equalize, if you just have 2 it's not as big of a change.
Dale
Dale
#15
rotorhead
iTrader: (3)
I've done it on 8 cylinder cars before using a very expensive setup (individual cylinder EGT and cylinder pressure). Usually there are at least 2 cylinders that burn faster or slower than the others and can really benefit, or they don't breathe as well and need less fuel.
On a 2 rotor the simple way is to go on a dyno, bias one rotor rich or lean in steps (5% richer, 10% richer, 5% leaner, 10% leaner, etc) and see if you pick up any power. The same can be done with spark. You need an ECU can support it.
On a 2 rotor the simple way is to go on a dyno, bias one rotor rich or lean in steps (5% richer, 10% richer, 5% leaner, 10% leaner, etc) and see if you pick up any power. The same can be done with spark. You need an ECU can support it.
#17
Banned. I got OWNED!!!
This is a great thread by the way. I'm doing Exhaust Gas Technologies Analog Kit (because I hate the idea of converting to CAN).
Exhaust Gas Technologies Inc. - Motorsports Catalog
#18
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,805
Received 2,578 Likes
on
1,831 Posts
do not think there is an ecu out there that is capable of doing that. if there was, it would be in the Rx8, stock
#19
Goodfalla Engine Complete
iTrader: (28)
You'd want at least a 60-2 Trigger Wheel and Label Each Rotor by it's Degree Location. Then you have to figure out where on the rotor face is a good point to label that degree location. Tip of Apex Seal? No. Center of Combustion Chamber? Ehh, maybe. The problem is that combustion occurs at different angles as engine speed changes, at least to my understanding.
#20
Eats, Sleeps, Dreams Rotary
iTrader: (17)
Maybe I'm thinking ahead or maybe I have no idea what I'm talking about but couldn't there be a solution where a sensor/ecu combination can follow individual O2, pressure and temperature peaks and valleys along with crank angle and use that info to tune locate the combustion faces?
#21
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,805
Received 2,578 Likes
on
1,831 Posts
So... the combustion event will be at the same "angle" of eccentric shaft rotation for each face. The Eccentric shaft rotates once completely for each rotor face in the epitrochoidal pattern. To track which rotor face is where, would require the ecu to keep track of revolutions. so revolution 1 is face 1, 2 is face 2, 3 is face 3. then it would have to start over. The hardest part of keeping track of this is when the engine is at low speeds (start up and shutdown) where the reluctor may not be getting enough of a signal to reliably count the revolutions all the way to zero motion and back up to idle on the next start up. plus, even a slight amount of interference would knock the running revolution count off, and make the entire process moot (at best). The only way to do this would be to have a method of tracking rotor position within the engine, as the crank position sensor is not a reliable way of doing so.
#22
Old [Sch|F]ool
You'd have to have some sort of trigger wheel driven at a 1:3 ratio relative to the crank in order for the ECU to determine which rotor face was where.
Fortunately, it is not to any benefit. Individual cylinder tuning is a benefit because each cylinder in a piston engine sees different intake tuning, different exhaust tuning, and different cooling system characteristics, for many different reasons beyond the scope of this post. Each rotor face on a given rotor will have the same intake tuning, same exhaust tuning, and same cooling system, so there is no need to go further than individual rotor tuning.
Fortunately, it is not to any benefit. Individual cylinder tuning is a benefit because each cylinder in a piston engine sees different intake tuning, different exhaust tuning, and different cooling system characteristics, for many different reasons beyond the scope of this post. Each rotor face on a given rotor will have the same intake tuning, same exhaust tuning, and same cooling system, so there is no need to go further than individual rotor tuning.
The following users liked this post:
doctorzaius (01-20-18)
Thread
Thread Starter
Forum
Replies
Last Post
H_M
3rd Generation Specific (1993-2002)
22
10-25-16 11:29 AM
cpt_gloval
1st Generation Specific (1979-1985)
5
08-15-01 09:11 PM