side seal clearance, high HP application
01-09-09, 12:38 PM
#1
side seal clearance, high HP application
What are most of you turbo guys running for side seal clearance? I'm about to spec out my side seal clearance and decide whether I am going to get new ones and cut them. The number I hear most often is .002" , and some say .003" . This motor has to be able to make 450rwhp (meth injection) , rev to 8000 (which isn't that high really), and pull 100-110psi compression with good condition used housings. These are 8.5:1 rotors with new corner seals and springs and new apex seal springs.
01-10-09, 03:11 PM
#4
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If you want those compression numbers I think new housings would be a better choice. I had an engine built with great condition used housings and it never came close to getting those compression numbers. It can probably be done with used housings, but you may be disappointed.
01-10-09, 04:26 PM
#5
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My method of clearancing side seals scares most people but always seems to work fine. I build tight engines that don't spew oil under boost.
I grind the seals until they fit. That's it. I just slowly grind until the seal just slides up and down.
The engine I have in Tina (my turbo-NA) car is clearanced this way.
I grind the seals until they fit. That's it. I just slowly grind until the seal just slides up and down.
The engine I have in Tina (my turbo-NA) car is clearanced this way.
01-10-09, 06:24 PM
#6
^so you are running effectively zero clearance? I was going to follow this video from Pineapple Racing: http://www.rebuildingrotaryengines.c...ing_Side_Seals . he just recommends grinding them down with 400 grit sandpaper. I have heard of other methods.
as far as the rotor housings go, well I spec'd these out very carefully. they had basically no edgewear, and hardly any grooves in them. the chrome surface is pretty good. two new housing just isn't in the budget. If it doesn't make that compression, oh well. It ran pretty strong before even when my front rotor housing was almost out of spec in terms of edgewear.
oh and I just checked the clearance. It was around .005" , so it's time for new side seals.
as far as the rotor housings go, well I spec'd these out very carefully. they had basically no edgewear, and hardly any grooves in them. the chrome surface is pretty good. two new housing just isn't in the budget. If it doesn't make that compression, oh well. It ran pretty strong before even when my front rotor housing was almost out of spec in terms of edgewear.
oh and I just checked the clearance. It was around .005" , so it's time for new side seals.
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01-16-09, 09:36 PM
#8
how freely should these side seals be springing up and down when I push on them? It seems like when I cut them for tight clearance (trying my best to get an accurate measurement of .002" here) they are binding against the corner seals when I push them down but are still kind of springy in the middle. I imagine that would result in a stuck seal.
getting these seals to my exact target spec is even harder than I imagined. I am filing them down with 400 grit per Pineapple Racing's video, and it seems like they go from too long/too tight to way too loose/too short just from scratching the seal against the sandpaper three or four times. I am trying to maintain the angle of the factory cut the best I can.
the way I have the spring installed is this: \/\/\/\/\/\/ . that's right isn't it? it doesn't seem like there is much spring pushing back on the edge of the side seals though, where they meet the corner seals. maybe that's why they aren't springing back as much as they are in the middle, and i'm worried about nothing.
getting these seals to my exact target spec is even harder than I imagined. I am filing them down with 400 grit per Pineapple Racing's video, and it seems like they go from too long/too tight to way too loose/too short just from scratching the seal against the sandpaper three or four times. I am trying to maintain the angle of the factory cut the best I can.
the way I have the spring installed is this: \/\/\/\/\/\/ . that's right isn't it? it doesn't seem like there is much spring pushing back on the edge of the side seals though, where they meet the corner seals. maybe that's why they aren't springing back as much as they are in the middle, and i'm worried about nothing.
01-17-09, 11:12 AM
#14
Stupid question - but when you're measuring your clearance - you ARE pushing down the center of the side seal, then sitcking in the feeler, yes?
The last one I built ran .003 to .0035ish on a couple. I re-used the side seals in that engine and just touched up the clearances on a few (some were .002, so I just went a bit wider to make them all the same) and it still runs fine. No smoke, good compression (barely 100psi though)
IMO as a completely novice builder though, the side seals need to be checked for their movement all the way across the seal, or by pushing down the entire seal with many fingers. Otherwise its just binding in the slot from un-even forces. But when checking the clearance you MUSt push down *only* the center of the seal completely, then check it against the corner seal with a feeler.
The last one I built ran .003 to .0035ish on a couple. I re-used the side seals in that engine and just touched up the clearances on a few (some were .002, so I just went a bit wider to make them all the same) and it still runs fine. No smoke, good compression (barely 100psi though)
IMO as a completely novice builder though, the side seals need to be checked for their movement all the way across the seal, or by pushing down the entire seal with many fingers. Otherwise its just binding in the slot from un-even forces. But when checking the clearance you MUSt push down *only* the center of the seal completely, then check it against the corner seal with a feeler.
01-17-09, 02:14 PM
#15
In the Pineapple Racing video http://www.rebuildingrotaryengines.c...ing_Side_Seals
at about 1:20 or so, it doesn't look to me like he is applying pressure to the center of the seal as he is measuring. He just evenly places the seal in the groove and tries to check for side-to-side movement as he slides the feeler gauge in. That's kind of the method I have been using.
When I apply a little pressure to the middle of the seal as you are saying, the factory machined end of the side seal feels like it has a little more clearance than when I follow the video's method.
Maybe I am really just overthinking this.
at about 1:20 or so, it doesn't look to me like he is applying pressure to the center of the seal as he is measuring. He just evenly places the seal in the groove and tries to check for side-to-side movement as he slides the feeler gauge in. That's kind of the method I have been using.
When I apply a little pressure to the middle of the seal as you are saying, the factory machined end of the side seal feels like it has a little more clearance than when I follow the video's method.
Maybe I am really just overthinking this.
01-20-09, 09:56 AM
#16
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You need to make sure to file the slant so it matches up with the corner seal. One side should be cut at an angle from the factory, then you have to make the angle on the other one.
As for how they feel, an even push should move the seal with only a slight drag on the corner seals.
As for how they feel, an even push should move the seal with only a slight drag on the corner seals.
01-20-09, 12:41 PM
#18
It turns out that the one seal that was binding when I pushed on it I had cut unevenly. It was the first one I had attempted. I managed to screw a couple of the new ones up so I ordered some replacements from Ray Crowe.
The weird thing is, these side seals I got have an angled edge on both the finished and unfinished sides, as I mentioned before. Maybe mazda is machining them differently now? In the FSM pic one side is definitely square.
The weird thing is, these side seals I got have an angled edge on both the finished and unfinished sides, as I mentioned before. Maybe mazda is machining them differently now? In the FSM pic one side is definitely square.
01-20-09, 05:12 PM
#20
used rotor housings(they are almost new)new OEM corner seals( rubber inserts only on the center plate HBP motor)FD corner seals springs,OEM apex seals and springs,OEM FD side seals springs and OEM side seals clearance to 002 and i had 120psi turning the motor with the starter and that was before the motor even ran,i have 2k on the motor now and i have not taken the compression yet but it should be around 125psi
01-20-09, 05:15 PM
#21
My method of clearancing side seals scares most people but always seems to work fine. I build tight engines that don't spew oil under boost.
I grind the seals until they fit. That's it. I just slowly grind until the seal just slides up and down.
The engine I have in Tina (my turbo-NA) car is clearanced this way.
I grind the seals until they fit. That's it. I just slowly grind until the seal just slides up and down.
The engine I have in Tina (my turbo-NA) car is clearanced this way.
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