Rotors
08-07-2008, 02:06 PM
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Rotors
If someone already asked this sorry but i couldnt find the post but i was in my socio's (friends) garage and he had a set of rotors of a 13b-rew and a set of rotors off a renesis. I noticed the rotors off the rew have deeper pockets then the ones of the renesis. So heres my question is it possible to use the rew rotors on a renesis?
Like i said i didnt see any post about this and iv'e searched the whole forum.
Like i said i didnt see any post about this and iv'e searched the whole forum.
08-07-2008, 02:28 PM
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The REW does have lower compression rotors (hence the bigger pockets), but I don't think they will work in a renesis. I'm sure Rotarygod or somebody else can chime in and give all the gory details 
08-07-2008, 02:37 PM
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The problem isn't that the REW rotors can't physically fit in the Renesis. They can. They don't have the wedge shaped side seals which the Renesis NEEDS and there are no cutoff seals. The side seals are also slightly farther out on the Renesis rotors to clear the earlier port opening which will pose support issues with a REW rotor. The REW rotors have been installed and run in a Renesis. It works for a while but longevity isn't there and by that I don't mean 100K+ miles. Try a fraction of that! You WILL lose the motor! There's no if. It's when. It's about as "bulletproof" as a wet paper bag with a stick of dynomite in it.
A rotor needs to be machined with Renesis specific seal grooves if it is to be used in a Renesis block. No exceptions.
A rotor needs to be machined with Renesis specific seal grooves if it is to be used in a Renesis block. No exceptions.
08-07-2008, 03:25 PM
#7
Well, maybe if you could get Rx7 rotors which have not been machined for grooves at all. Then, you could machine the grooves in for the Rx8 seals and not have the extra grooves pertaining to the Rx7 specific features. I don't know if that approach would coincide to how REW rotors are manufactured. I guess it's unlikely seeing as no one is making low compression 8 rotors that I know of.
08-07-2008, 03:32 PM
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Well, maybe if you could get Rx7 rotors which have not been machined for grooves at all. Then, you could machine the grooves in for the Rx8 seals and not have the extra grooves pertaining to the Rx7 specific features. I don't know if that approach would coincide to how REW rotors are manufactured. I guess it's unlikely seeing as no one is making low compression 8 rotors that I know of.
08-07-2008, 04:53 PM
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Nope im just tryna experiment with the renesis. It could have alot of potenial if some work is put into it. Well thats what I think...
08-07-2008, 07:24 PM
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^^RG or someone else could answer this better, but i'm under the impression that you couldnt just dig them out 5mm w/o serious structural consequences. that doesnt mean there isnt a way though...
08-07-2008, 09:13 PM
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The casting thickness of the Renesis rotors is thinner than any other 13B rotor. You'll make them too thin and ultimately instead of a seal or bearing being your weakest link under boost, it'll be the rotor. Don't try it!
Rotors are cast iron that are then machined. The seal grooves are also specially machined. Mazda does not just use a mill and a creative jig to hold the rotor. They have some proprietary machinery designed solely for creating for the intended job.
I deal with a large foundry at work. I've talked to them extensively about casting rotors. Of course we'd have to start with making a mold of one. I brought them a couple of rotors and said I wanted a hybrid. Basically I'd start with the '87-'88 Turbo II RX-7 rotors which had 8.5:1 compression. They had the thickest castings but were also the heaviest. You've got to sacrifice something for strength. Another way to look at it is you need to sacrifice some strength for weight reduction. I would want those rotors cast but the Renesis seals grooves and compression dishes to remain the same. The exception being the apex seals. I want those to accomodate the deeper 13B apex seals.
Through our conversations both on the phone and in person, I was told that it would in fact be possible for them to cast the rotors to my specifications. They could not handle any machining though and unfortunately my shop couldn't either as we are really set up for very large very heavy machinery. The casting process would require what was described to me as 3D radar profiling into a computer program that would then be sent to another machine to cut out the negatives for the mold. Then a positive set would again have to be made. This sounds easy enough but would cost an estimated $3K to do and that was just his best guess! Then we'd have to cast one. They are set up for large order runs of parts so a few here and there isn't going to be cheap. When it is all said and done, I'd probably have somewhere between $5K-$6K into making just the first set of rotor casts. This still has yet to resolve the issue of machining the seal grooves and compression dishes. Older rotors had the dishes cast into them but newer ones are machined for consistency. I see no reason to revert back to inferior methods.
Machining would be very expensive if someone has to design something custom to accomodate the side seal grooves. I'd plan on a minimum machining cost or another few thousand dollars before it's all figured out. Keep in mind that you'll probably ruin a few rotors working all the issues out. Fortunately each rotor, once the casts are made, would only cost about $25 each or so to cast again. If all of the steps were taken, the first working set of rotors could have cost well over $10K to design and build and this isn't even taking into account testing to see strength and longevity. I guarantee the entire rotating assembly will have to be specially balanced along with an as yet unknown set of counterweights. Probably from the '87-'88 13B's. The factory rotors have a special coating on their sides. This too would cost money but this is only after you find someone who will do it. Fortunately I know who to talk to in regards to this.
Now after going through all of this time, effort, and most importantly money, what happens if the rotors fail or don't perform as intended? What then? If you have to redesign them from scratch, repeat the initial costs again. If it's only a machining issue, repeat much of the machining costs. You get the idea. This isn't cheap or easy to do which is why no one in the aftermarket is doing it. The aluminum rotors that someone made from a solid forged piece are not without their difficulties but are limited primarily to machining issues and not any casting issues. A solid chunk of aluminum in the necessary grade isn't cheap though. No matter what making rotors is very expensive and tedious. The first set is always the most expensive. Once you work the issues out, each successive set gets fairly cheap. With the numbers of rotors Mazda makes, it's worth it. For the average enthusiast, it isn't.
Who here would gladly pay $5,000 but possibly much more for a set of lower compression rotors? Keep in mind it would still take the sale of several sets to even break even on the initial investment. I doubt we'll see any takers. Knowing all of this, does anyone really think Speedsource is going to give the average enthusiast the time of day with the question?
Rotors are cast iron that are then machined. The seal grooves are also specially machined. Mazda does not just use a mill and a creative jig to hold the rotor. They have some proprietary machinery designed solely for creating for the intended job.
I deal with a large foundry at work. I've talked to them extensively about casting rotors. Of course we'd have to start with making a mold of one. I brought them a couple of rotors and said I wanted a hybrid. Basically I'd start with the '87-'88 Turbo II RX-7 rotors which had 8.5:1 compression. They had the thickest castings but were also the heaviest. You've got to sacrifice something for strength. Another way to look at it is you need to sacrifice some strength for weight reduction. I would want those rotors cast but the Renesis seals grooves and compression dishes to remain the same. The exception being the apex seals. I want those to accomodate the deeper 13B apex seals.
Through our conversations both on the phone and in person, I was told that it would in fact be possible for them to cast the rotors to my specifications. They could not handle any machining though and unfortunately my shop couldn't either as we are really set up for very large very heavy machinery. The casting process would require what was described to me as 3D radar profiling into a computer program that would then be sent to another machine to cut out the negatives for the mold. Then a positive set would again have to be made. This sounds easy enough but would cost an estimated $3K to do and that was just his best guess! Then we'd have to cast one. They are set up for large order runs of parts so a few here and there isn't going to be cheap. When it is all said and done, I'd probably have somewhere between $5K-$6K into making just the first set of rotor casts. This still has yet to resolve the issue of machining the seal grooves and compression dishes. Older rotors had the dishes cast into them but newer ones are machined for consistency. I see no reason to revert back to inferior methods.
Machining would be very expensive if someone has to design something custom to accomodate the side seal grooves. I'd plan on a minimum machining cost or another few thousand dollars before it's all figured out. Keep in mind that you'll probably ruin a few rotors working all the issues out. Fortunately each rotor, once the casts are made, would only cost about $25 each or so to cast again. If all of the steps were taken, the first working set of rotors could have cost well over $10K to design and build and this isn't even taking into account testing to see strength and longevity. I guarantee the entire rotating assembly will have to be specially balanced along with an as yet unknown set of counterweights. Probably from the '87-'88 13B's. The factory rotors have a special coating on their sides. This too would cost money but this is only after you find someone who will do it. Fortunately I know who to talk to in regards to this.
Now after going through all of this time, effort, and most importantly money, what happens if the rotors fail or don't perform as intended? What then? If you have to redesign them from scratch, repeat the initial costs again. If it's only a machining issue, repeat much of the machining costs. You get the idea. This isn't cheap or easy to do which is why no one in the aftermarket is doing it. The aluminum rotors that someone made from a solid forged piece are not without their difficulties but are limited primarily to machining issues and not any casting issues. A solid chunk of aluminum in the necessary grade isn't cheap though. No matter what making rotors is very expensive and tedious. The first set is always the most expensive. Once you work the issues out, each successive set gets fairly cheap. With the numbers of rotors Mazda makes, it's worth it. For the average enthusiast, it isn't.
Who here would gladly pay $5,000 but possibly much more for a set of lower compression rotors? Keep in mind it would still take the sale of several sets to even break even on the initial investment. I doubt we'll see any takers. Knowing all of this, does anyone really think Speedsource is going to give the average enthusiast the time of day with the question?
08-07-2008, 09:14 PM
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I was under the impression that any pre RX8 engine rotors had the sideseals located closer to the oil control rings and would fall into the intake/exhaust ports on the Renesis irons.
08-07-2008, 10:31 PM
#20
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I personally don't like their compression dish shape. Yes it matters! I also don't see how they can have a completed rotor in those pictures when they aren't hollow. How is oil getting inside to cool them? That was one thing I was always curious about as I see no way for a CNC to get inside to hollow them out. This is why Mazda casts them! Even if they do in fact run, how long will they last? If they work out this way then great. I could get those made. I reserve judgement on them though.
08-07-2008, 10:55 PM
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The casting thickness of the Renesis rotors is thinner than any other 13B rotor. You'll make them too thin and ultimately instead of a seal or bearing being your weakest link under boost, it'll be the rotor. Don't try it!
Rotors are cast iron that are then machined. The seal grooves are also specially machined. Mazda does not just use a mill and a creative jig to hold the rotor. They have some proprietary machinery designed solely for creating for the intended job.
I deal with a large foundry at work. I've talked to them extensively about casting rotors. Of course we'd have to start with making a mold of one. I brought them a couple of rotors and said I wanted a hybrid. Basically I'd start with the '87-'88 Turbo II RX-7 rotors which had 8.5:1 compression. They had the thickest castings but were also the heaviest. You've got to sacrifice something for strength. Another way to look at it is you need to sacrifice some strength for weight reduction. I would want those rotors cast but the Renesis seals grooves and compression dishes to remain the same. The exception being the apex seals. I want those to accomodate the deeper 13B apex seals.
Through our conversations both on the phone and in person, I was told that it would in fact be possible for them to cast the rotors to my specifications. They could not handle any machining though and unfortunately my shop couldn't either as we are really set up for very large very heavy machinery. The casting process would require what was described to me as 3D radar profiling into a computer program that would then be sent to another machine to cut out the negatives for the mold. Then a positive set would again have to be made. This sounds easy enough but would cost an estimated $3K to do and that was just his best guess! Then we'd have to cast one. They are set up for large order runs of parts so a few here and there isn't going to be cheap. When it is all said and done, I'd probably have somewhere between $5K-$6K into making just the first set of rotor casts. This still has yet to resolve the issue of machining the seal grooves and compression dishes. Older rotors had the dishes cast into them but newer ones are machined for consistency. I see no reason to revert back to inferior methods.
Machining would be very expensive if someone has to design something custom to accomodate the side seal grooves. I'd plan on a minimum machining cost or another few thousand dollars before it's all figured out. Keep in mind that you'll probably ruin a few rotors working all the issues out. Fortunately each rotor, once the casts are made, would only cost about $25 each or so to cast again. If all of the steps were taken, the first working set of rotors could have cost well over $10K to design and build and this isn't even taking into account testing to see strength and longevity. I guarantee the entire rotating assembly will have to be specially balanced along with an as yet unknown set of counterweights. Probably from the '87-'88 13B's. The factory rotors have a special coating on their sides. This too would cost money but this is only after you find someone who will do it. Fortunately I know who to talk to in regards to this.
Now after going through all of this time, effort, and most importantly money, what happens if the rotors fail or don't perform as intended? What then? If you have to redesign them from scratch, repeat the initial costs again. If it's only a machining issue, repeat much of the machining costs. You get the idea. This isn't cheap or easy to do which is why no one in the aftermarket is doing it. The aluminum rotors that someone made from a solid forged piece are not without their difficulties but are limited primarily to machining issues and not any casting issues. A solid chunk of aluminum in the necessary grade isn't cheap though. No matter what making rotors is very expensive and tedious. The first set is always the most expensive. Once you work the issues out, each successive set gets fairly cheap. With the numbers of rotors Mazda makes, it's worth it. For the average enthusiast, it isn't.
Who here would gladly pay $5,000 but possibly much more for a set of lower compression rotors? Keep in mind it would still take the sale of several sets to even break even on the initial investment. I doubt we'll see any takers. Knowing all of this, does anyone really think Speedsource is going to give the average enthusiast the time of day with the question?
Rotors are cast iron that are then machined. The seal grooves are also specially machined. Mazda does not just use a mill and a creative jig to hold the rotor. They have some proprietary machinery designed solely for creating for the intended job.
I deal with a large foundry at work. I've talked to them extensively about casting rotors. Of course we'd have to start with making a mold of one. I brought them a couple of rotors and said I wanted a hybrid. Basically I'd start with the '87-'88 Turbo II RX-7 rotors which had 8.5:1 compression. They had the thickest castings but were also the heaviest. You've got to sacrifice something for strength. Another way to look at it is you need to sacrifice some strength for weight reduction. I would want those rotors cast but the Renesis seals grooves and compression dishes to remain the same. The exception being the apex seals. I want those to accomodate the deeper 13B apex seals.
Through our conversations both on the phone and in person, I was told that it would in fact be possible for them to cast the rotors to my specifications. They could not handle any machining though and unfortunately my shop couldn't either as we are really set up for very large very heavy machinery. The casting process would require what was described to me as 3D radar profiling into a computer program that would then be sent to another machine to cut out the negatives for the mold. Then a positive set would again have to be made. This sounds easy enough but would cost an estimated $3K to do and that was just his best guess! Then we'd have to cast one. They are set up for large order runs of parts so a few here and there isn't going to be cheap. When it is all said and done, I'd probably have somewhere between $5K-$6K into making just the first set of rotor casts. This still has yet to resolve the issue of machining the seal grooves and compression dishes. Older rotors had the dishes cast into them but newer ones are machined for consistency. I see no reason to revert back to inferior methods.
Machining would be very expensive if someone has to design something custom to accomodate the side seal grooves. I'd plan on a minimum machining cost or another few thousand dollars before it's all figured out. Keep in mind that you'll probably ruin a few rotors working all the issues out. Fortunately each rotor, once the casts are made, would only cost about $25 each or so to cast again. If all of the steps were taken, the first working set of rotors could have cost well over $10K to design and build and this isn't even taking into account testing to see strength and longevity. I guarantee the entire rotating assembly will have to be specially balanced along with an as yet unknown set of counterweights. Probably from the '87-'88 13B's. The factory rotors have a special coating on their sides. This too would cost money but this is only after you find someone who will do it. Fortunately I know who to talk to in regards to this.
Now after going through all of this time, effort, and most importantly money, what happens if the rotors fail or don't perform as intended? What then? If you have to redesign them from scratch, repeat the initial costs again. If it's only a machining issue, repeat much of the machining costs. You get the idea. This isn't cheap or easy to do which is why no one in the aftermarket is doing it. The aluminum rotors that someone made from a solid forged piece are not without their difficulties but are limited primarily to machining issues and not any casting issues. A solid chunk of aluminum in the necessary grade isn't cheap though. No matter what making rotors is very expensive and tedious. The first set is always the most expensive. Once you work the issues out, each successive set gets fairly cheap. With the numbers of rotors Mazda makes, it's worth it. For the average enthusiast, it isn't.
Who here would gladly pay $5,000 but possibly much more for a set of lower compression rotors? Keep in mind it would still take the sale of several sets to even break even on the initial investment. I doubt we'll see any takers. Knowing all of this, does anyone really think Speedsource is going to give the average enthusiast the time of day with the question?
Last edited by Rotore_787; 08-07-2008 at 10:57 PM.
08-07-2008, 11:29 PM
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08-07-2008, 11:42 PM
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money goes very fast this days man. It might go faster than 10 seconds... Just kidding. Good luck toy you and remember to make sure you dont make a 10 second car for one pass. You need to make it a 10 second car for many many passes. So dont hold back on spending for quality products and We all want to see any of our friends here run those times...
08-07-2008, 11:49 PM
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money goes very fast this days man. It might go faster than 10 seconds... Just kidding. Good luck toy you and remember to make sure you dont make a 10 second car for one pass. You need to make it a 10 second car for many many passes. So dont hold back on spending for quality products and We all want to see any of our friends here run those times...