4-Rotor FC Build
Rotary Enthusiast
Joined: Aug 2004
Posts: 1,326
Likes: 9
From: Australia - Perth
I don't really see the point of an electric waterpump, sure it isn't driven by the crank so it saves a tiny bit of power but I would have to run a larger alternator and there would be more strain on it. It's also less reliable, and I don't think any of them will actually pump more water than the S4 one I'm using, maybe at lower engine rpm's. I personally would only use one if I ran into fitment issues of some sort.
+ we all have seen how badly the stock unit cavitates at high RPM.
And at low you wont get the required amount.
I've not had a issue yet with my EWP setup, if anything its to cold that i've had issues with (and been out in the hills thrashing about on 105 F. days (41 Degres for the rest of us)
for reference, a -10an 19 core unit (so only about 200x200 or so) runs about 10deg cooler then my stock FC unit. Id never go back to the old tech FC unit.
Senior Member
Joined: Nov 2003
Posts: 533
Likes: 3
From: Sweden
Then, we don't have that temperature-problem in Europe that some have in USA for example.
I don't know how you having it down in netherlands, but here up in Sweden, the highest we got is about 25-30degres celcius.
At my S4 Turbo with 420hp I hade 27dgr celcius intake-temp on a sunny day
I don't know how you having it down in netherlands, but here up in Sweden, the highest we got is about 25-30degres celcius.
At my S4 Turbo with 420hp I hade 27dgr celcius intake-temp on a sunny day
Rotary Enthusiast
Joined: Aug 2004
Posts: 1,326
Likes: 9
From: Australia - Perth
I know, I been to Sweden a few times and lived in the UK for many years so I know its not hot like down here at times. But if he plans to track it, well he knows it will keep up with his requirements.
I suppose i would have to agree on the EWP.
I've had cooling problems in my S4 turbo on track days at only 25deg C.
It's your project and do with as you will, just saying, i agree with the others comments.
I've had cooling problems in my S4 turbo on track days at only 25deg C.
It's your project and do with as you will, just saying, i agree with the others comments.
Drawing air through the oil cooler and then the radiator may not be a good idea john.
On my previous i had about the same setup, fan drawing air through the oilcooler and then the radiator.
Oil temps were a bit lower, but i could notice a slight raise in water temp
Putting a shroud in between lowered oil temp by 5-10 degrees, but the watertemp went up by about the same amount.
Adding ducting to make sure the air could not get passed the radiator without going through it, lowered the overall temps bij maybe 5 degrees.
But because the passing air gets superheated by the multiple cores, the cooling efficiency drops and the engine bay itself will become far too hot if there is no proper ducting to get it out of the engine bay.
I could not touch my strutbrace because of the heat...
Having your intake above the engine in a superheated engine bay will give insane high intake temps.
Now with the new setup and ducting, everything is cool to the touch
On my previous i had about the same setup, fan drawing air through the oilcooler and then the radiator.
Oil temps were a bit lower, but i could notice a slight raise in water temp
Putting a shroud in between lowered oil temp by 5-10 degrees, but the watertemp went up by about the same amount.
Adding ducting to make sure the air could not get passed the radiator without going through it, lowered the overall temps bij maybe 5 degrees.
But because the passing air gets superheated by the multiple cores, the cooling efficiency drops and the engine bay itself will become far too hot if there is no proper ducting to get it out of the engine bay.
I could not touch my strutbrace because of the heat...
Having your intake above the engine in a superheated engine bay will give insane high intake temps.
Now with the new setup and ducting, everything is cool to the touch
Joined: Mar 2001
Posts: 31,835
Likes: 3,233
From: https://www2.mazda.com/en/100th/
i think they were referring more to the cost/danger of shipping a 4 rotor Eshaft from europe to the US and back than there being anything wrong with Roger.
Thread Starter
Joined: Oct 2010
Posts: 605
Likes: 13
From: The Netherlands
I disagree. The pump isn't about getting extra HP, its about reliability and having the flow there when you need it (not depending on the RPM your doing)
+ we all have seen how badly the stock unit cavitates at high RPM.
And at low you wont get the required amount.
I've not had a issue yet with my EWP setup, if anything its to cold that i've had issues with (and been out in the hills thrashing about on 105 F. days (41 Degres for the rest of us)
for reference, a -10an 19 core unit (so only about 200x200 or so) runs about 10deg cooler then my stock FC unit. Id never go back to the old tech FC unit.
+ we all have seen how badly the stock unit cavitates at high RPM.
And at low you wont get the required amount.
I've not had a issue yet with my EWP setup, if anything its to cold that i've had issues with (and been out in the hills thrashing about on 105 F. days (41 Degres for the rest of us)
for reference, a -10an 19 core unit (so only about 200x200 or so) runs about 10deg cooler then my stock FC unit. Id never go back to the old tech FC unit.
Electric waterpump have their advantages, but I've seen multiple engines die because of a failing fuse, pump or wiring. I'm going to try the mechanical pump first, and if I get problems with water temperatures then I'll concider it. I am going to take your advice about the oil coolers though.
Drawing air through the oil cooler and then the radiator may not be a good idea john.
On my previous i had about the same setup, fan drawing air through the oilcooler and then the radiator.
Oil temps were a bit lower, but i could notice a slight raise in water temp
Putting a shroud in between lowered oil temp by 5-10 degrees, but the watertemp went up by about the same amount.
Adding ducting to make sure the air could not get passed the radiator without going through it, lowered the overall temps bij maybe 5 degrees.
But because the passing air gets superheated by the multiple cores, the cooling efficiency drops and the engine bay itself will become far too hot if there is no proper ducting to get it out of the engine bay.
I could not touch my strutbrace because of the heat...
Having your intake above the engine in a superheated engine bay will give insane high intake temps.
Now with the new setup and ducting, everything is cool to the touch
On my previous i had about the same setup, fan drawing air through the oilcooler and then the radiator.
Oil temps were a bit lower, but i could notice a slight raise in water temp
Putting a shroud in between lowered oil temp by 5-10 degrees, but the watertemp went up by about the same amount.
Adding ducting to make sure the air could not get passed the radiator without going through it, lowered the overall temps bij maybe 5 degrees.
But because the passing air gets superheated by the multiple cores, the cooling efficiency drops and the engine bay itself will become far too hot if there is no proper ducting to get it out of the engine bay.
I could not touch my strutbrace because of the heat...
Having your intake above the engine in a superheated engine bay will give insane high intake temps.
Now with the new setup and ducting, everything is cool to the touch
Update
Made some progress on the cooling system today. I tried fitting the FC oil coolers, but that didn't go too well. They didn't fit as well as I thought they would, the mounting points weren't in the right location (can't weld new mounting points on them) and the coolers weren't in great condition, lots of bend fins and just tired. So I'm not going to use the FC coolers, I ordered a pair of 19-row coolers. Those will work and fit way better. While waiting on those I started with the ducting.
This is where one of the oil coolers wil live, a 19-row one should fit well in here. You can also see that the ducting matches the front bumper, so air entering in this part of the bumper is forced to the oil cooler.
Just found this build, & its insane!
I just wanted to add, that you couldn't run wasted spark for all the leading plugs off of a single coil/output, since with a 4 rotor 90* spacing, every time you have one rotor close to TDC for combustion (when you'd want to spark), you'll have another that is in the middle of compression, very ignitable, and exposed to the leading plug, so you'd end up lighting off 2 rotors. Wasted spark would only work the leading spark (since it's positioned further down the housing - later in the cycle) on pairs of rotors that are 180* out of phase.
In addition, I'd say that you really must run spark to the trailing, even if its phased the same as the leading, because the chamber is really too long & thin for just a single plug to ignite it all, especially when that plug is offset to a lower position that assumes a trailing spark will be occurring at the other end of the chamber. The addition of the 3rd plug only adds 2-3%, but in most cases the addition of the 2nd plug adds more like 15-20%, and greatly helps with the stability.
Its already been established that you shouldn't try to use a single coil for leading & trailing on a single rotor. Since the air/fuel mix at both plugs is pressurized & thus harder to ionize, you'll either only end up firing one of them anyway (but won't get to choose which), or you'll fire both but with half the power.
With all this in mind, the minimum number of individual coils you could use, without suffering from a very weak spark described above, is 6, with 6 individual signals. This would have the leading plugs in rotors 1 & 2, and in rotors 3 & 4 firing wasted spark (2 coils & signals for all leading, while each trailing spark would have its own signal and coil (4 coils & signals for all trailing), bringing us to 6 total coils & signals.
Alternatively, if you didn't mind firing the leading & trailing at the same time, you could use 4 signals from the ECU (one for each rotor), with each routed to a pair of coils, with each coil firing a single plug, for a total of 8 coils. This is b/c you can't do wasted spark with the trailing plugs, since they are higher up the housing and get exposed to the gas in the next rotor face much earlier than the leading plugs. This is the way you'll have to go if your ECU only has 4 spark outputs, or can only output sparks evenly at a single timing (no split-timing control)
I just wanted to add, that you couldn't run wasted spark for all the leading plugs off of a single coil/output, since with a 4 rotor 90* spacing, every time you have one rotor close to TDC for combustion (when you'd want to spark), you'll have another that is in the middle of compression, very ignitable, and exposed to the leading plug, so you'd end up lighting off 2 rotors. Wasted spark would only work the leading spark (since it's positioned further down the housing - later in the cycle) on pairs of rotors that are 180* out of phase.
In addition, I'd say that you really must run spark to the trailing, even if its phased the same as the leading, because the chamber is really too long & thin for just a single plug to ignite it all, especially when that plug is offset to a lower position that assumes a trailing spark will be occurring at the other end of the chamber. The addition of the 3rd plug only adds 2-3%, but in most cases the addition of the 2nd plug adds more like 15-20%, and greatly helps with the stability.
Its already been established that you shouldn't try to use a single coil for leading & trailing on a single rotor. Since the air/fuel mix at both plugs is pressurized & thus harder to ionize, you'll either only end up firing one of them anyway (but won't get to choose which), or you'll fire both but with half the power.
With all this in mind, the minimum number of individual coils you could use, without suffering from a very weak spark described above, is 6, with 6 individual signals. This would have the leading plugs in rotors 1 & 2, and in rotors 3 & 4 firing wasted spark (2 coils & signals for all leading, while each trailing spark would have its own signal and coil (4 coils & signals for all trailing), bringing us to 6 total coils & signals.
Alternatively, if you didn't mind firing the leading & trailing at the same time, you could use 4 signals from the ECU (one for each rotor), with each routed to a pair of coils, with each coil firing a single plug, for a total of 8 coils. This is b/c you can't do wasted spark with the trailing plugs, since they are higher up the housing and get exposed to the gas in the next rotor face much earlier than the leading plugs. This is the way you'll have to go if your ECU only has 4 spark outputs, or can only output sparks evenly at a single timing (no split-timing control)
Thread Starter
Joined: Oct 2010
Posts: 605
Likes: 13
From: The Netherlands
Just found this build, & its insane!
I just wanted to add, that you couldn't run wasted spark for all the leading plugs off of a single coil/output, since with a 4 rotor 90* spacing, every time you have one rotor close to TDC for combustion (when you'd want to spark), you'll have another that is in the middle of compression, very ignitable, and exposed to the leading plug, so you'd end up lighting off 2 rotors. Wasted spark would only work the leading spark (since it's positioned further down the housing - later in the cycle) on pairs of rotors that are 180* out of phase.
In addition, I'd say that you really must run spark to the trailing, even if its phased the same as the leading, because the chamber is really too long & thin for just a single plug to ignite it all, especially when that plug is offset to a lower position that assumes a trailing spark will be occurring at the other end of the chamber. The addition of the 3rd plug only adds 2-3%, but in most cases the addition of the 2nd plug adds more like 15-20%, and greatly helps with the stability.
Its already been established that you shouldn't try to use a single coil for leading & trailing on a single rotor. Since the air/fuel mix at both plugs is pressurized & thus harder to ionize, you'll either only end up firing one of them anyway (but won't get to choose which), or you'll fire both but with half the power.
With all this in mind, the minimum number of individual coils you could use, without suffering from a very weak spark described above, is 6, with 6 individual signals. This would have the leading plugs in rotors 1 & 2, and in rotors 3 & 4 firing wasted spark (2 coils & signals for all leading, while each trailing spark would have its own signal and coil (4 coils & signals for all trailing), bringing us to 6 total coils & signals.
Alternatively, if you didn't mind firing the leading & trailing at the same time, you could use 4 signals from the ECU (one for each rotor), with each routed to a pair of coils, with each coil firing a single plug, for a total of 8 coils. This is b/c you can't do wasted spark with the trailing plugs, since they are higher up the housing and get exposed to the gas in the next rotor face much earlier than the leading plugs. This is the way you'll have to go if your ECU only has 4 spark outputs, or can only output sparks evenly at a single timing (no split-timing control)
I just wanted to add, that you couldn't run wasted spark for all the leading plugs off of a single coil/output, since with a 4 rotor 90* spacing, every time you have one rotor close to TDC for combustion (when you'd want to spark), you'll have another that is in the middle of compression, very ignitable, and exposed to the leading plug, so you'd end up lighting off 2 rotors. Wasted spark would only work the leading spark (since it's positioned further down the housing - later in the cycle) on pairs of rotors that are 180* out of phase.
In addition, I'd say that you really must run spark to the trailing, even if its phased the same as the leading, because the chamber is really too long & thin for just a single plug to ignite it all, especially when that plug is offset to a lower position that assumes a trailing spark will be occurring at the other end of the chamber. The addition of the 3rd plug only adds 2-3%, but in most cases the addition of the 2nd plug adds more like 15-20%, and greatly helps with the stability.
Its already been established that you shouldn't try to use a single coil for leading & trailing on a single rotor. Since the air/fuel mix at both plugs is pressurized & thus harder to ionize, you'll either only end up firing one of them anyway (but won't get to choose which), or you'll fire both but with half the power.
With all this in mind, the minimum number of individual coils you could use, without suffering from a very weak spark described above, is 6, with 6 individual signals. This would have the leading plugs in rotors 1 & 2, and in rotors 3 & 4 firing wasted spark (2 coils & signals for all leading, while each trailing spark would have its own signal and coil (4 coils & signals for all trailing), bringing us to 6 total coils & signals.
Alternatively, if you didn't mind firing the leading & trailing at the same time, you could use 4 signals from the ECU (one for each rotor), with each routed to a pair of coils, with each coil firing a single plug, for a total of 8 coils. This is b/c you can't do wasted spark with the trailing plugs, since they are higher up the housing and get exposed to the gas in the next rotor face much earlier than the leading plugs. This is the way you'll have to go if your ECU only has 4 spark outputs, or can only output sparks evenly at a single timing (no split-timing control)
Tonight I did this:
The big hole is obviously for a hood vent. Aluminium ducting will be inserted between the radiator and the hood to guide the air outwards. I tried leaving as much as stiffening ribs on the bottom side of the hood to keep most of it's structural integrity but the hood still became very wobbly and flimsy. This was partly because the removed material, but also because the remaining stiffening ribs are now only attached to the top side of the hood with a few spotwelds. So I started boxing up the bottomside of the hood. Only did a part of it at the moment but this already makes a huge difference.
The inserted sheet metal is only tackwelded to the top side of the hood to minimize distortion, but it will still need some bodywork later. I wish I would've used a steel hood, that would be a bit easier. ah well, no fun doing things the easy way I guess.
Last edited by John Huijben; Jun 5, 2012 at 05:30 PM.
Most of that is already covered on the bottom of the previous page. Different coil configurations will be tested on the dyno to see what works and what doesn't work. By the way, don't just wire multiple coils on one ignition output without knowing what your doing, you can possibly blow up your ecu like that.
Anyhow, awesome job
