Howdy folks, some of ya'll might know who I am but most I don't think do. I'm a Mazda rotary Rx-7 guy that's been a customer of Julio's for about 4 years now. I purchased and installed my Alkycontrol setup back in July/August of 2006. I originally used a single M15 nozzle but went to a dual M10 setup in late 2008. I've been undergoing an experiment the past couple of years with a hot-air setup involving a 2.5" pipe that heads straight out of the turbo into the throttle. The turbocharger is a Master Power T70 w/ a P-Trim 0.96 A/R back housing (we have to run large turbine housings on our engines) and using alcohol purely as a charge cooler alongside its high autoignition temperature and anti-knock benefits in the combustion chamber.
This past week I've been messing with the alcohol system and tuning it in to run some pretty heavy duty boost. I had an M10 and an M15 but at the behest of Julio I went back to the M10 on the 2nd nozzle as it was causing a lot of lag in the system due to the Gain setting being only at around 3.2 or so. Right now, aiming for about 10:1 AFR's at 15+psi of boost, the Gain is set to 5.9-6. I've also installed the pair of 10psi check valves and it's completely removed any on-system lag. It's terrific.
I made a post up yesterday on our Rx7 forum in its Auxiliary Injection section (what we place water, alcohol, and whatever injection threads in) and detailed my recent update. Here's the notes from it:
The build thread can be found here:
BDC's FC3S Build Thread (July 2010) - RX7Club.com
The experiment is still the same two-fold endeavour:
1) Try and determine how much boost/power one can make with a heavy ratio of gasoline to alcohol (at least 75/25 respectively)
2) Datalog, graph, and scale intake air temperature relative to alcohol injection to determine if it can be made into an effective charge cooler over and above a standard air-to-air intercooler
I've gotten the motor broken in and have been playing with the car quite a bit the last few weeks. Today I got it up to 27psi of boost. Injector duty cycles, from the only piece of log I was able to get, were at 62% at that boost at just above 6krpm. I suspect I am getting close to the output capability of the turbo and related plumbing setup and may have to go from T4 to T6 architecture. Until I dyno it, however, I'll remain optimistic and shoot for my goal of 30psi of boost (2Bar). I'm currently running low to mid 10's at 15psi and above. My target is ultimately 10 flat:1. This is possible using the amount of alcohol I'm injecting as a replacement to gasoline. I'm assuming a ratio of 75/25 of gasoline to alcohol at 15psi and above but adding excess alcohol to add another point to point and a half (from, say, 11:1 - 11.5:1) to use as both charge cooler and combustion chamber coolant.
The ambient air temps today were between 85-90* at mostly about 90. Cruising IAT's when fully warmed up were approximately 137*F which follows the older discovery from last year that those cruising temps will always be about 45*F above ambient temps. Even though I was alone and had spotty datalogs (for some reason I cannot get the system to datalog well through this new laptop/dosbox setup), I was able to get some IAT vs boost readings:
20psi 110*F
23.9psi 113*F
24.6psi 115*F
25.5psi 118*F
26.4psi 121*F
At 27psi the air temp dialed itself in at 123* and held from what I can tell. So far, I've yet to hit 130* while under boost. It pretty much shows me that part 2 of this experiment is an unexpectedly raving success. The key is to place the alcohol nozzles as far away from the throttle as possible to yield the alcohol enough time to flash from atomized form to vapour. Having them close to the throttle did not work.
1bar of boost IAT's usually hang around at or slightly below ambient temps. Right on!
Attached are two images of the engine bay taken today. They show a close up of the two nozzles on the hot-air pipe along with their newly-installed check valves. These check valves, rated at 10psi, help alleviate the boiling alcohol problem I was having by keeping the system primed once it's been run once. It eliminated all of the on-system lag I was originally having.
I wanted to bring this up here because I'd like to delve more into the science behind using methyl alcohol flashing in an intake pipe as a charge cooler. It's clear to me that it works really damn well but I'd like to know more and know exactly why. Since you guys here seem to use this stuff a hell of a lot more than we do, I figure ya'll might know.
Pictures of the engine bay are linked here:
September 22, 2010 Engine Bay Shots
B
This past week I've been messing with the alcohol system and tuning it in to run some pretty heavy duty boost. I had an M10 and an M15 but at the behest of Julio I went back to the M10 on the 2nd nozzle as it was causing a lot of lag in the system due to the Gain setting being only at around 3.2 or so. Right now, aiming for about 10:1 AFR's at 15+psi of boost, the Gain is set to 5.9-6. I've also installed the pair of 10psi check valves and it's completely removed any on-system lag. It's terrific.
I made a post up yesterday on our Rx7 forum in its Auxiliary Injection section (what we place water, alcohol, and whatever injection threads in) and detailed my recent update. Here's the notes from it:
The build thread can be found here:
BDC's FC3S Build Thread (July 2010) - RX7Club.com
The experiment is still the same two-fold endeavour:
1) Try and determine how much boost/power one can make with a heavy ratio of gasoline to alcohol (at least 75/25 respectively)
2) Datalog, graph, and scale intake air temperature relative to alcohol injection to determine if it can be made into an effective charge cooler over and above a standard air-to-air intercooler
I've gotten the motor broken in and have been playing with the car quite a bit the last few weeks. Today I got it up to 27psi of boost. Injector duty cycles, from the only piece of log I was able to get, were at 62% at that boost at just above 6krpm. I suspect I am getting close to the output capability of the turbo and related plumbing setup and may have to go from T4 to T6 architecture. Until I dyno it, however, I'll remain optimistic and shoot for my goal of 30psi of boost (2Bar). I'm currently running low to mid 10's at 15psi and above. My target is ultimately 10 flat:1. This is possible using the amount of alcohol I'm injecting as a replacement to gasoline. I'm assuming a ratio of 75/25 of gasoline to alcohol at 15psi and above but adding excess alcohol to add another point to point and a half (from, say, 11:1 - 11.5:1) to use as both charge cooler and combustion chamber coolant.
The ambient air temps today were between 85-90* at mostly about 90. Cruising IAT's when fully warmed up were approximately 137*F which follows the older discovery from last year that those cruising temps will always be about 45*F above ambient temps. Even though I was alone and had spotty datalogs (for some reason I cannot get the system to datalog well through this new laptop/dosbox setup), I was able to get some IAT vs boost readings:
20psi 110*F
23.9psi 113*F
24.6psi 115*F
25.5psi 118*F
26.4psi 121*F
At 27psi the air temp dialed itself in at 123* and held from what I can tell. So far, I've yet to hit 130* while under boost. It pretty much shows me that part 2 of this experiment is an unexpectedly raving success. The key is to place the alcohol nozzles as far away from the throttle as possible to yield the alcohol enough time to flash from atomized form to vapour. Having them close to the throttle did not work.
1bar of boost IAT's usually hang around at or slightly below ambient temps. Right on!
Attached are two images of the engine bay taken today. They show a close up of the two nozzles on the hot-air pipe along with their newly-installed check valves. These check valves, rated at 10psi, help alleviate the boiling alcohol problem I was having by keeping the system primed once it's been run once. It eliminated all of the on-system lag I was originally having.
I wanted to bring this up here because I'd like to delve more into the science behind using methyl alcohol flashing in an intake pipe as a charge cooler. It's clear to me that it works really damn well but I'd like to know more and know exactly why. Since you guys here seem to use this stuff a hell of a lot more than we do, I figure ya'll might know.
Pictures of the engine bay are linked here:
September 22, 2010 Engine Bay Shots
B
