Recipe to Build the Ultimate 13B-REW?
11-29-13, 01:49 PM
#1
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Recipe to Build the Ultimate 13B-REW?
After all these years of people building this motor, from all the trials and tribulations, there has to be some consensus on a proven "formula".
How would you approach putting together an overbuilt motor aimed for mostly street use and can be reliable past the 450RWHP territory.
Use OEM Mazda 2mm 2-piece apex seals?
Pineapple Racing HD Water Seals?
Viton Oil rings?
Turblown Stud Kit?
Balanced Rotating Assembly and Clearanced Rotors?
What other products and tricks can be used to ensure the best of the best build?
How would you approach putting together an overbuilt motor aimed for mostly street use and can be reliable past the 450RWHP territory.
Use OEM Mazda 2mm 2-piece apex seals?
Pineapple Racing HD Water Seals?
Viton Oil rings?
Turblown Stud Kit?
Balanced Rotating Assembly and Clearanced Rotors?
What other products and tricks can be used to ensure the best of the best build?
11-30-13, 12:04 AM
#3
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I think the maintenance and tuning is where the dependability comes from. Meth injection, good ignition, fuel delivery, cooling, and a great tune will take you a long way.
11-30-13, 01:55 PM
#7
Rotary Enthusiast
I like sequential turbos, but many guys seem to advocate single turbo setups at higher power levels.
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11-30-13, 02:36 PM
#9
many ways to skin this cat ...
aside from the apex seal choice (page 1) - and that's just my opinion - here's one iteration of the ultimate.
https://www.rx7club.com/build-thread...-build-845561/
you can find others with a simple search.
aside from the apex seal choice (page 1) - and that's just my opinion - here's one iteration of the ultimate.
https://www.rx7club.com/build-thread...-build-845561/
you can find others with a simple search.
12-01-13, 11:09 AM
#15
547hp at the flywheel
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450-500on a street car is still getting up there. I drive my 500hp FD quite a bit but sometimes its a bit much to handle. a tad too much throttle at the wrong time and the rear end is playing catch up
12-02-13, 02:21 PM
#19
ceramics are bad in a turbocharged rotary engine, even the best current ceramic has less shear strength than even the OEM apex seals do, add in that when they shred they destroy EVERYTHING in that chamber and you have a recipe for bad news.
dowel pinning is also bad, hollow pins do not add much strength to the rigidity of the block, studding it is superior to dowelling. reinforcing an REW is already somewhat redundant anyways, the block is already far more rigid than any other series.
i could go on and on but the first few examples just threw me that the person who wrote that page was just listing expensive modifications based on some builder's recommendation for a $7k engine, which is going to have horrible failure modes.
the REW rotors aren't the best of design since the faces can collapse but there are other alternatives to that if you can either balance the assembly or live with a slightly lower redline.
Last edited by RotaryEvolution; 12-02-13 at 02:29 PM.
12-02-13, 05:22 PM
#20
everyone has their own ideas on the best engine design, unfortunately i disagree with just about everything on that page.
ceramics are bad in a turbocharged rotary engine, even the best current ceramic has less shear strength than even the OEM apex seals do, add in that when they shred they destroy EVERYTHING in that chamber and you have a recipe for bad news.
dowel pinning is also bad, hollow pins do not add much strength to the rigidity of the block, studding it is superior to dowelling. reinforcing an REW is already somewhat redundant anyways, the block is already far more rigid than any other series.
i could go on and on but the first few examples just threw me that the person who wrote that page was just listing expensive modifications based on some builder's recommendation for a $7k engine, which is going to have horrible failure modes.
the REW rotors aren't the best of design since the faces can collapse but there are other alternatives to that if you can either balance the assembly or live with a slightly lower redline.
ceramics are bad in a turbocharged rotary engine, even the best current ceramic has less shear strength than even the OEM apex seals do, add in that when they shred they destroy EVERYTHING in that chamber and you have a recipe for bad news.
dowel pinning is also bad, hollow pins do not add much strength to the rigidity of the block, studding it is superior to dowelling. reinforcing an REW is already somewhat redundant anyways, the block is already far more rigid than any other series.
i could go on and on but the first few examples just threw me that the person who wrote that page was just listing expensive modifications based on some builder's recommendation for a $7k engine, which is going to have horrible failure modes.
the REW rotors aren't the best of design since the faces can collapse but there are other alternatives to that if you can either balance the assembly or live with a slightly lower redline.
-David Guy
12-02-13, 05:25 PM
#21
pasted from a post i made elsewhere, you will also see other people have had the same issues with the late series rotors when detonation occurs at higher levels(high power, over twice factory horsepower levels).
it is because the faces on the late series rotors were thinned out to lighten the rotors(this is something mazda did to raise the redline of the engine at the power it was producing), obviously the compromise was that they aren't exactly ideal in situations which are harming the engine in one way or another. at least the engines will still run but compression obviously suffers.
the series 4 and earlier rotors were less susceptible to this problem but when something's gotta give something WILL give.
this isn't something you would normally see in a factory motor, the stock apex seals would give much earlier than the rotors would cave in. this is also only more of a problem once you start pushing 400+whp.
there's no way to 100% bulletproof an engine, especially a rotary engine. the best you can hope for is minimal losses and build according to that principle. both of the rotors in that engine sacrificed themselves when the secondaries ran out of fuel but only the rotors and nothing else, it was no huge loss because they were milled for 3mm and some slots were beyond spec even at 3mm and were running oversize 3mm seals as it was. i am also not an advocate of 3mm seals in a street driven car, but it was already set up that way before it was rebuilt.
anyways, most people modify their cars otherwise there's no need to talk about upgrading the engine. more power comes with consequences, this is just one possible consequence and is somewhat well known to most who have moderately to highly modified REWs.
it is because the faces on the late series rotors were thinned out to lighten the rotors(this is something mazda did to raise the redline of the engine at the power it was producing), obviously the compromise was that they aren't exactly ideal in situations which are harming the engine in one way or another. at least the engines will still run but compression obviously suffers.
the series 4 and earlier rotors were less susceptible to this problem but when something's gotta give something WILL give.
this isn't something you would normally see in a factory motor, the stock apex seals would give much earlier than the rotors would cave in. this is also only more of a problem once you start pushing 400+whp.
there's no way to 100% bulletproof an engine, especially a rotary engine. the best you can hope for is minimal losses and build according to that principle. both of the rotors in that engine sacrificed themselves when the secondaries ran out of fuel but only the rotors and nothing else, it was no huge loss because they were milled for 3mm and some slots were beyond spec even at 3mm and were running oversize 3mm seals as it was. i am also not an advocate of 3mm seals in a street driven car, but it was already set up that way before it was rebuilt.
anyways, most people modify their cars otherwise there's no need to talk about upgrading the engine. more power comes with consequences, this is just one possible consequence and is somewhat well known to most who have moderately to highly modified REWs.
Last edited by RotaryEvolution; 12-02-13 at 05:43 PM.
12-03-13, 01:09 AM
#22
pasted from a post i made elsewhere, you will also see other people have had the same issues with the late series rotors when detonation occurs at higher levels(high power, over twice factory horsepower levels).
it is because the faces on the late series rotors were thinned out to lighten the rotors(this is something mazda did to raise the redline of the engine at the power it was producing), obviously the compromise was that they aren't exactly ideal in situations which are harming the engine in one way or another. at least the engines will still run but compression obviously suffers.
the series 4 and earlier rotors were less susceptible to this problem but when something's gotta give something WILL give.
this isn't something you would normally see in a factory motor, the stock apex seals would give much earlier than the rotors would cave in. this is also only more of a problem once you start pushing 400+whp.
there's no way to 100% bulletproof an engine, especially a rotary engine. the best you can hope for is minimal losses and build according to that principle. both of the rotors in that engine sacrificed themselves when the secondaries ran out of fuel but only the rotors and nothing else, it was no huge loss because they were milled for 3mm and some slots were beyond spec even at 3mm and were running oversize 3mm seals as it was. i am also not an advocate of 3mm seals in a street driven car, but it was already set up that way before it was rebuilt.
anyways, most people modify their cars otherwise there's no need to talk about upgrading the engine. more power comes with consequences, this is just one possible consequence and is somewhat well known to most who have moderately to highly modified REWs.
it is because the faces on the late series rotors were thinned out to lighten the rotors(this is something mazda did to raise the redline of the engine at the power it was producing), obviously the compromise was that they aren't exactly ideal in situations which are harming the engine in one way or another. at least the engines will still run but compression obviously suffers.
the series 4 and earlier rotors were less susceptible to this problem but when something's gotta give something WILL give.
this isn't something you would normally see in a factory motor, the stock apex seals would give much earlier than the rotors would cave in. this is also only more of a problem once you start pushing 400+whp.
there's no way to 100% bulletproof an engine, especially a rotary engine. the best you can hope for is minimal losses and build according to that principle. both of the rotors in that engine sacrificed themselves when the secondaries ran out of fuel but only the rotors and nothing else, it was no huge loss because they were milled for 3mm and some slots were beyond spec even at 3mm and were running oversize 3mm seals as it was. i am also not an advocate of 3mm seals in a street driven car, but it was already set up that way before it was rebuilt.
anyways, most people modify their cars otherwise there's no need to talk about upgrading the engine. more power comes with consequences, this is just one possible consequence and is somewhat well known to most who have moderately to highly modified REWs.
In my opinion, many people need to worry less about what bits are being put in their engines (obviously if its within spec) and more about what supports/runs their engines such as ECUs that aren't trash (PFC, microtech) and the interesting failsafes you can build in to your tunes (On my SM4 I've built a trim where if it thinks its supposed to be running at X afr in a load table and it begins to run leaner than X boost solenoid duty dumps wide open, among other things) as well as proper wiring which Mazda has been notoriously crappy at.
Either way, I'm not trying to start a fight, I just think that most of the failures I see on these vehicles is due to poor support systems to the engines rather than the engines themselves.
12-03-13, 01:32 PM
#24
did you write that page and list it all? i wasn't trying to jab at anyone but most of what is listed on that page is from 2003, before bendable seals took over the market replacing ceramic, brittle seals and OEM.
there's also many stud kits available now and pinning simply takes too much material off the structural integrity of the irons/housings as well only offers limited shear strength with the hollowed pins.
ceramic seals have their place, but i only feel that place is in a naturally aspirated engine where detonation is minimal to causing damage. the R26B used ceramic seals and showed their strengths, where i believe any metallic seal wouldn't have survived at those revs and duration levels, the housings would have looked like a jenga puzzle half way into the race. clearancing the ceramic also isn't a novice job and i feel clearancing the ceramics is necessary for the best results since they are one piece and offer almost 0 expansion properties, not too many people will have a diamond honing stone set up to precision grind it.
the only experience i have had with ceramics in a turbo engine are with the old pettit FD, which the engine failed and took out half the engine 8 seasons after he purchased it. i rebuilt it and it failed again short of victory, most likely due to a fuel system issue or within the tune(none of which i was commissioned to look at or address). at least if the engine held together as in the above photo the car might have won the race, but i knew little of ceramic seals and their weaknesses 6+ years ago back when these newer seals were barely making a scratch in the market. when competing in races even a single failure will make you look hard at the failure and any alternatives/pros+cons. to me the ceramic is superior for wear and heat absorption(the best hands down for endurance), the weight of the seal is also the best benefit as it eliminates seal chatter(the best again for high revs) but extremely weak with it's tensile strength properties(the worst hands down for detonation) and again extremely weak in it's ability to cope with failure(again the worst as it destroys the rotor, housing and both irons with very little possibility of salvage). the negatives outweigh the pros for a turbocharged engine, unless you have backup engines and deep pockets.
there's also many stud kits available now and pinning simply takes too much material off the structural integrity of the irons/housings as well only offers limited shear strength with the hollowed pins.
ceramic seals have their place, but i only feel that place is in a naturally aspirated engine where detonation is minimal to causing damage. the R26B used ceramic seals and showed their strengths, where i believe any metallic seal wouldn't have survived at those revs and duration levels, the housings would have looked like a jenga puzzle half way into the race. clearancing the ceramic also isn't a novice job and i feel clearancing the ceramics is necessary for the best results since they are one piece and offer almost 0 expansion properties, not too many people will have a diamond honing stone set up to precision grind it.
the only experience i have had with ceramics in a turbo engine are with the old pettit FD, which the engine failed and took out half the engine 8 seasons after he purchased it. i rebuilt it and it failed again short of victory, most likely due to a fuel system issue or within the tune(none of which i was commissioned to look at or address). at least if the engine held together as in the above photo the car might have won the race, but i knew little of ceramic seals and their weaknesses 6+ years ago back when these newer seals were barely making a scratch in the market. when competing in races even a single failure will make you look hard at the failure and any alternatives/pros+cons. to me the ceramic is superior for wear and heat absorption(the best hands down for endurance), the weight of the seal is also the best benefit as it eliminates seal chatter(the best again for high revs) but extremely weak with it's tensile strength properties(the worst hands down for detonation) and again extremely weak in it's ability to cope with failure(again the worst as it destroys the rotor, housing and both irons with very little possibility of salvage). the negatives outweigh the pros for a turbocharged engine, unless you have backup engines and deep pockets.
Last edited by RotaryEvolution; 12-03-13 at 01:49 PM.
12-03-13, 02:12 PM
#25
to add to the dowels i have had numerous come out cracked, others warped and in most all cases the original holes were ovaled out due to stress. you have to consider the pins only extend into the ends of the engine(the actual flex point of the engine) by about 10mm, that isn't very much, even a proper stud can extend into the front iron by 16mm+ and into the rear iron by 40.5mm!
dowels also do not account for stretching and deflection of the tension bolts, studs offer less of both. in the FC build section i am building a engine for my own car with 16 12.7mm studs, which is quite a bit of overkill but to me it was only a few days work with the block and about $200 in materials with another day making the studs. my thoughts were a) the S4 block is the weakest of all the turbo engines and b) i don't anticipate having to tear it down anytime soon. technically it could have done just fine with 6 studs.
in some cases you don't even have a choice in the matter, such as the B code 20b which broke the thick iron. even placing a solid dowel likely wouldn't have salvaged it since the dowel lands had spider cracked in at least 7 positions, enough force and it would just scalp the iron down to the dowel.
you're 100% correct. i just figured the thread covered a wide scope of builds and people should understand the failure modes of each way an FD engine can fail and that was one possibility. 400+ isn't necessarily what i would consider a high horsepower build any longer, perhaps 8+ years ago before you could get a turbo delivered off a freight truck for less than $1k that could break an engine without flinching.
even yet i've still not seen an ECU with enough failsafes or proper setup to save one of these engines. people have tried but in most cases either they were poorly implemented by the owner or the ECU was still too slow to react. IMO the more reliable setups have also been the simplest.
but all that aside, that type of failure will actually rise with the influx of the "unbreakable seals". no one really likes to accept detonation but it quite simply is just a fact of life, no one can ever build a car that will always avoid it.
if you ever do wind up with this sort of failure it actually means you are doing something right, as the rotor faces collapsing is the last in the whole chain of failure modes. cracking irons, to blowing up seals/rotors being the primary examples and actually much easier to accomplish.
dowels also do not account for stretching and deflection of the tension bolts, studs offer less of both. in the FC build section i am building a engine for my own car with 16 12.7mm studs, which is quite a bit of overkill but to me it was only a few days work with the block and about $200 in materials with another day making the studs. my thoughts were a) the S4 block is the weakest of all the turbo engines and b) i don't anticipate having to tear it down anytime soon. technically it could have done just fine with 6 studs.
in some cases you don't even have a choice in the matter, such as the B code 20b which broke the thick iron. even placing a solid dowel likely wouldn't have salvaged it since the dowel lands had spider cracked in at least 7 positions, enough force and it would just scalp the iron down to the dowel.
~500bhp isn't a 'moderately' modified REW. Also Bulletproof != ultimate. You're describing a mode of failure in a system that should never occur unless something is tuned/setup incorrectly or fails.
In my opinion, many people need to worry less about what bits are being put in their engines (obviously if its within spec) and more about what supports/runs their engines such as ECUs that aren't trash (PFC, microtech) and the interesting failsafes you can build in to your tunes (On my SM4 I've built a trim where if it thinks its supposed to be running at X afr in a load table and it begins to run leaner than X boost solenoid duty dumps wide open, among other things) as well as proper wiring which Mazda has been notoriously crappy at.
Either way, I'm not trying to start a fight, I just think that most of the failures I see on these vehicles is due to poor support systems to the engines rather than the engines themselves.
In my opinion, many people need to worry less about what bits are being put in their engines (obviously if its within spec) and more about what supports/runs their engines such as ECUs that aren't trash (PFC, microtech) and the interesting failsafes you can build in to your tunes (On my SM4 I've built a trim where if it thinks its supposed to be running at X afr in a load table and it begins to run leaner than X boost solenoid duty dumps wide open, among other things) as well as proper wiring which Mazda has been notoriously crappy at.
Either way, I'm not trying to start a fight, I just think that most of the failures I see on these vehicles is due to poor support systems to the engines rather than the engines themselves.
even yet i've still not seen an ECU with enough failsafes or proper setup to save one of these engines. people have tried but in most cases either they were poorly implemented by the owner or the ECU was still too slow to react. IMO the more reliable setups have also been the simplest.
but all that aside, that type of failure will actually rise with the influx of the "unbreakable seals". no one really likes to accept detonation but it quite simply is just a fact of life, no one can ever build a car that will always avoid it.
if you ever do wind up with this sort of failure it actually means you are doing something right, as the rotor faces collapsing is the last in the whole chain of failure modes. cracking irons, to blowing up seals/rotors being the primary examples and actually much easier to accomplish.
Last edited by RotaryEvolution; 12-03-13 at 02:39 PM.