skc supercharger build
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
It is just such a pain to install and uninstall. You can't just snag one part, or check one seal.
I would love to go fix everything but I have decided that would require a complete redesign. I would weld the dogbone into the manifold and just have a pipe with silicone coupler to it. Literally cut the whole bypass off and do a traditional bypass on the supercharger exhaust. Unfortunately that requires some sort of pre-blower manifold which in the Hymee unit is only a 1/8th inch spacer between the throttle and plate. Also, having the lay-shaft submerged in oil (due to orientation) makes the front seal constantly leak, and there is no way to refill the oil in the super with it on the car, or and way to check the level.
Honestly I am going to give the mounting plate to my machinist to take measurements, then somewhere down the line do something on my own, just for me.
The constant chase doesn't bother me as much as each time I need to do a complete tear-down of the kit, which on my schedule is at least 3 free nights. So I am going without it for a week at a time. I already have a 85 RX-7 I'm restoring, I don't need this.
I would love to go fix everything but I have decided that would require a complete redesign. I would weld the dogbone into the manifold and just have a pipe with silicone coupler to it. Literally cut the whole bypass off and do a traditional bypass on the supercharger exhaust. Unfortunately that requires some sort of pre-blower manifold which in the Hymee unit is only a 1/8th inch spacer between the throttle and plate. Also, having the lay-shaft submerged in oil (due to orientation) makes the front seal constantly leak, and there is no way to refill the oil in the super with it on the car, or and way to check the level.
Honestly I am going to give the mounting plate to my machinist to take measurements, then somewhere down the line do something on my own, just for me.
The constant chase doesn't bother me as much as each time I need to do a complete tear-down of the kit, which on my schedule is at least 3 free nights. So I am going without it for a week at a time. I already have a 85 RX-7 I'm restoring, I don't need this.
It took me four engines to get here 
Glad to see you are still at it SKC, My kit is sadly still up for sale. The intended buyer has been a bit short of cash lately so I may not get to see it running locally.
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
So my engine is doing well. The only issue I have is an oil leak at the crank which is common at this age.
I usually change my oil and filter every 5000km and always drive it hard. I have also done close to 100 track days which also helps keep carbon at bay.
I have also been spraying brake cleaner into the LIM and letting it sit until the next drive. I believe this also helps keep carbon at bay. I notice that my vacuum improves slightly when I use this trick.
I started using this technique when I was experiencing hesitation around 5000rpm and the brake cleaner helped loosen up the valve and it worked perfectly afterwards.
I think it also helps the springs on the apex seals as well.
I have to be careful as too much brake cleaner will cause the car to flood.
Not sure if anyone else does this however, it works for me.
I usually change my oil and filter every 5000km and always drive it hard. I have also done close to 100 track days which also helps keep carbon at bay.
I have also been spraying brake cleaner into the LIM and letting it sit until the next drive. I believe this also helps keep carbon at bay. I notice that my vacuum improves slightly when I use this trick.
I started using this technique when I was experiencing hesitation around 5000rpm and the brake cleaner helped loosen up the valve and it worked perfectly afterwards.
I think it also helps the springs on the apex seals as well.
I have to be careful as too much brake cleaner will cause the car to flood.
Not sure if anyone else does this however, it works for me.
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
Added a one way check valve to the jet air line. Also re routed the line directly to the intake as per stock configuration.
The original set up had the jet air connected to the vacuum lines. It did not make sense so I changed it and hopefully it will not upset things.
The theory behind the one way chech valve is that under boost the jet air port is a source of potential boost leak
Hope it works
The original set up had the jet air connected to the vacuum lines. It did not make sense so I changed it and hopefully it will not upset things.
The theory behind the one way chech valve is that under boost the jet air port is a source of potential boost leak
Hope it works
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
After the initial successful run I will be taking it to the red line as I did not encounter and hiccups.
The rerouting of the vacuum pipe is subtle so I was not expecting any major issues however, it is best to approach every change with caution.
The rerouting of the vacuum pipe is subtle so I was not expecting any major issues however, it is best to approach every change with caution.
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
Car ran well in full boost however when I got home the oil leak at the back of the supercharger was really bad.
I reverted back to the original layout and added the check valve to the system and it works just as well without the leak issue
I reverted back to the original layout and added the check valve to the system and it works just as well without the leak issue
I misunderstood what you were saying earlier. Both the jet air and OMP lines should be connected to a filtered atmospheric air source with check valves. They should not have either vacuum or boost. However, you could technically argue that the jet air could be plugged or removed entirely on an FI application. I recall that OD removed it on his Pettit set up.
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Last edited by TeamRX8; Apr 18, 2015 at 09:32 AM.
Ok, forgive my ignorance here, but why not a pre TB boost source? That's how I have mine set up and I've seen no issues. They both give a slight TB bypass, but that's the same as stock setup, and I vaguely remember someone claiming to have lowered oil consumption in boost with a ATM source for the OMP line.
It actually doesn't matter . Pre TB is fine for jet air . I've also seen pre TB for OMP (on a rear mount setup) with no ill effects .
Thread Starter
rev it up
Joined: Feb 2004
Posts: 1,590
Likes: 11
From: Brisbane Australia
My omp goes directly to the intake pipe and gets fed fresh metered air.
When I had the jet air nozzle connected to the intake the car seemed to have more power however, it was causing the engine to get pressurised which in turn caused the oil leak from the weak point in the supercharger. I intend to get this fixed soon.
The rest of the vacuum system was under pressure and the vacuum was being provided by the jet air nozzle. As I had capped the line the air could not vent.
Now that I have added the check valve to the original system it works just as well and the key difference is that it holds boost to the maximum and it stays there until I let go of the throttle. Previously, I noticed the boost gauge slowly loosing boost and I had to apply more throttle to get it back.
My dyno also shows a tapering to torque and power in the higher RPM range.
I will hopefully get the supercharger leak and bypass valve done soon and get a retune on the dyno for comparison.
When I had the jet air nozzle connected to the intake the car seemed to have more power however, it was causing the engine to get pressurised which in turn caused the oil leak from the weak point in the supercharger. I intend to get this fixed soon.
The rest of the vacuum system was under pressure and the vacuum was being provided by the jet air nozzle. As I had capped the line the air could not vent.
Now that I have added the check valve to the original system it works just as well and the key difference is that it holds boost to the maximum and it stays there until I let go of the throttle. Previously, I noticed the boost gauge slowly loosing boost and I had to apply more throttle to get it back.
My dyno also shows a tapering to torque and power in the higher RPM range.
I will hopefully get the supercharger leak and bypass valve done soon and get a retune on the dyno for comparison.
I recalled that from the early MM turbo days, but maybe it was wrong. I can see how jet air could be pre-TB, but am not sure if it matters. I thought Mazda kept boost off the OMP nozzles on the FD3TT, but again that is an old fuzzy memory.
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Joined: Apr 2015
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Took the car to the track today as everything was working well. However, as soon as I got on the track one of the seals blew out causing hesitation above 5000 rpm. Drove the car in at the end of the session and discovered the seal had popped out.
Also of concern is that oil was being blown out of that same location. This would mean that oil is traveling through the inter cooler and then into the engine. People reported seeing black smoke on gear changes.
It was a very hot day with ambient at 95F and the oil peaked at 230F.
Also of concern is that oil was being blown out of that same location. This would mean that oil is traveling through the inter cooler and then into the engine. People reported seeing black smoke on gear changes.
It was a very hot day with ambient at 95F and the oil peaked at 230F.
Got the same problem with my setup.. After replace the o-ring the engine wont start.. Only by pulling the car by another car (to tow) and starting by releasing the clutch..
have a look at this video, where you can see, how the engine is working:
www.youtube.com/watch?v=nCpO0jeVHB0
maybe the ignition coils and plugs needs to replace?
thanks for your help!
