Dowelling = Waste of money (Except on 1st Gens) ????
05-04-05, 08:01 PM
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Dowelling = Waste of money (Except on 1st Gens) ????
Here's the story:
I've been doing some research on this subject, as I'm about to close my engine. My irons where lapped, but not dowelled. I'm aiming for 350-400whp and the car will be tuned by one of the best Microtech tuners around "Rolo" same dude that tunes Jesus Padillas car.
RiceRacing:
Avenge 13B 8.15 @ 164MPH............. How much HP you think he's making?
http://users.tpg.com.au/users/bsmc/PFtop20drag.htm
Read his post
http://ausrotary.dntinternet.com/fo...t=16792&start=0
Grant Williams 13B 7.81 @ 175mph "NON" Dowelled!!!!!
http://ausrotary.dntinternet.com/fo...=grant+dowelled
Ok, so far so good right?
RXENG: Australia "Microtech"
So my questions is, what can be done to prevent engines from twisting in FB's without dowelling?
Would a torque brace and solid motor mounts help?
http://www.fc3s.org/how_tos/suspensi...ine_brace.html
http://www.banzairacing.net/polyfb_motor_mounts.htm
Or maybe something likes this
Ok fellas............thoughts, answers, flames?
I've been doing some research on this subject, as I'm about to close my engine. My irons where lapped, but not dowelled. I'm aiming for 350-400whp and the car will be tuned by one of the best Microtech tuners around "Rolo" same dude that tunes Jesus Padillas car.
RiceRacing:
In a 13B over 1000bhp...you will not crack the plate.
If detonation occurs you will break anything.
The BMEP can go to around 3 to 4.5Mpa all day, when you have detonation there is a spike in BMEP which can send the pressure in the chamber from the peak of about 20 to 26 Mpa to well over 80 to 100 Mpa !!!
This will break anything, seals/Dowels/rotors.
Correct fuel, right tunning and stay within normal operating conditions of the engine and you will never need to dowel your engine....
This is the hard data, no guesses, or opinions...I have run dowelled and run non dowled. I worked as a machinist and know how hard it is to make these things accuratley (it is near impossible!) half the extra ones you put in end up doing nothing because they take no load due to incorrect clearances and infact all you end up doing is weakining the endplates and rotor housings. I have seen these crack in the "extra" dowel area.
Repeat after me, there is no need for extra dowles...unless of course you like to waste money on mods you do not need. If this is the case then I can do that machining job for you Drop me an email.
If detonation occurs you will break anything.
The BMEP can go to around 3 to 4.5Mpa all day, when you have detonation there is a spike in BMEP which can send the pressure in the chamber from the peak of about 20 to 26 Mpa to well over 80 to 100 Mpa !!!
This will break anything, seals/Dowels/rotors.
Correct fuel, right tunning and stay within normal operating conditions of the engine and you will never need to dowel your engine....
This is the hard data, no guesses, or opinions...I have run dowelled and run non dowled. I worked as a machinist and know how hard it is to make these things accuratley (it is near impossible!) half the extra ones you put in end up doing nothing because they take no load due to incorrect clearances and infact all you end up doing is weakining the endplates and rotor housings. I have seen these crack in the "extra" dowel area.
Repeat after me, there is no need for extra dowles...unless of course you like to waste money on mods you do not need. If this is the case then I can do that machining job for you Drop me an email.
http://users.tpg.com.au/users/bsmc/PFtop20drag.htm
Dowels...who needs them? Never used them, never will. I have never cracked a plate and i have done some seriously stupid things to engines!
If the engine is tuned right you wont need them.
If the engine is tuned right you wont need them.
http://ausrotary.dntinternet.com/fo...t=16792&start=0
Grant Williams 13B 7.81 @ 175mph "NON" Dowelled!!!!!
http://ausrotary.dntinternet.com/fo...=grant+dowelled
Ok, so far so good right?
RXENG: Australia "Microtech"
Most of the American guys run the S6 engines which have the rear plate reinforced under the oil filter around the dowell area which allows them to run that much boost without cracking a plate.
The early S4 engines were extremely thin around this area which became a weak point.Mazda added material to this area on later model S4 engines as well as another strenghening rib to the area on most S5 engines before casting another 10mm or so around it on the S6.
It's not so much the boost that's the problem,It's the amount of horsepower the engine is making.
The problem isn't as bad on the S6 engine either as the engine is mounted from the rear plate.On early model Mazda's the engine is mounted off the front timing cover then there is no support till the rear gearbox mount.The more power an engine makes the more it twists.This twist is multiplied by the fact that the engine is mounted from right at the front.It's the same sort of principle as using a piece of pipe on the end of a spanner.S4 engines are a little better as they are mounted from the centre plate.Not right at the front.
Also add to this the amount the engine & car twists on a launch with a set of slicks & it isn't hard to see how much stress is put on the 4 standard dowells
Tuning does also have a lot to do with it,but at the end of the day if you're not making big power you don't have the problem.Most shops that recommend dowelling do so for a reason.They are all reputable shops that are going fast on the race track & know the conequences of a smashed rear plate.
I'd much prefer a customers engine to be tuned on the safe side with a bit of a safety margin than to try & screw it right up & HOPE that it doesn't break.Most customers & their wallets respect me for this also.
The early S4 engines were extremely thin around this area which became a weak point.Mazda added material to this area on later model S4 engines as well as another strenghening rib to the area on most S5 engines before casting another 10mm or so around it on the S6.
It's not so much the boost that's the problem,It's the amount of horsepower the engine is making.
The problem isn't as bad on the S6 engine either as the engine is mounted from the rear plate.On early model Mazda's the engine is mounted off the front timing cover then there is no support till the rear gearbox mount.The more power an engine makes the more it twists.This twist is multiplied by the fact that the engine is mounted from right at the front.It's the same sort of principle as using a piece of pipe on the end of a spanner.S4 engines are a little better as they are mounted from the centre plate.Not right at the front.
Also add to this the amount the engine & car twists on a launch with a set of slicks & it isn't hard to see how much stress is put on the 4 standard dowells
Tuning does also have a lot to do with it,but at the end of the day if you're not making big power you don't have the problem.Most shops that recommend dowelling do so for a reason.They are all reputable shops that are going fast on the race track & know the conequences of a smashed rear plate.
I'd much prefer a customers engine to be tuned on the safe side with a bit of a safety margin than to try & screw it right up & HOPE that it doesn't break.Most customers & their wallets respect me for this also.
Would a torque brace and solid motor mounts help?
http://www.fc3s.org/how_tos/suspensi...ine_brace.html
http://www.banzairacing.net/polyfb_motor_mounts.htm
Or maybe something likes this
Ok fellas............thoughts, answers, flames?
Last edited by luiml73; 05-04-05 at 08:08 PM.
05-04-05, 08:38 PM
#2
Ok, I have cracked three so far. I can't pin point the main reason because I hear different stories form different people.
I have heard detonation, twisting, raw power, etc. The first time was onthe dyno. I made 400hp at 17psi, I think I detonated at the higher rpm range. Cracked the first plate. Second time on the street. Good conditions, just too much power to the wheels i guess. Boosting at 15psi on the street from first through third, not spinning, just power to the ground. CRACK!
Third time, just the other night. Racing a new BMW coupe. Car pulled good all night, stopped at a light............... My brap,brap,brap went away.. Vacuum went to 4 inches, looked under car, tell tale sign, puddle of oil. Bummer.
All I can reccommend is that you try to get a S5 rear iron and also have it cryo treated. Thats my next step. If this doesnt work for me I promise i'm getting a V8.
Neal
I have heard detonation, twisting, raw power, etc. The first time was onthe dyno. I made 400hp at 17psi, I think I detonated at the higher rpm range. Cracked the first plate. Second time on the street. Good conditions, just too much power to the wheels i guess. Boosting at 15psi on the street from first through third, not spinning, just power to the ground. CRACK!
Third time, just the other night. Racing a new BMW coupe. Car pulled good all night, stopped at a light............... My brap,brap,brap went away.. Vacuum went to 4 inches, looked under car, tell tale sign, puddle of oil. Bummer.
All I can reccommend is that you try to get a S5 rear iron and also have it cryo treated. Thats my next step. If this doesnt work for me I promise i'm getting a V8.
Neal
05-04-05, 08:48 PM
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that you try to get a S5 rear iron
cryo treated
Did a little search on rear irons, and look what I found
https://www.rx7club.com/showthread.p...ight=rear+iron
BTW: What ECU are you using, and who is tunning? If you don't mind.
Last edited by luiml73; 05-04-05 at 08:56 PM.
05-04-05, 08:56 PM
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I don't have anywhere near the experience of the sources, I'm making educated guesses for the sake of discussion.
The part about where the engine mounts is the simplest idea and probably the easiest to test. If the engine is twisting, stuff will break. So is there a way to tie in another mount on the rear iron, probably bolting up along with the bellhousing. I'm talking a proper mount, not just a tourque brace. If it doesnt flex and twist, will things still fail??
If I'm reading this right, detonation causes a pressure spike from 4 to 5 times what the engine is expected to hold. Why is it that the rear iron fails and eats this spike? Why doesn't a housing, seal, rotor, or sparkplug fail and blow out first?? Is there a way to design a collapsable seal (apex, side, between the housings) that would burst and vent the pressure instead of letting the expensive metal parts take the blast??
I assume that since we know what causes detonation that this could be tested out by intentionally allowing a detonation to occur. Of course, I'm also assuming that I'm not paying for the failures and I'm not standing anywhere near a 13b pipebomb.
The part about where the engine mounts is the simplest idea and probably the easiest to test. If the engine is twisting, stuff will break. So is there a way to tie in another mount on the rear iron, probably bolting up along with the bellhousing. I'm talking a proper mount, not just a tourque brace. If it doesnt flex and twist, will things still fail??
If I'm reading this right, detonation causes a pressure spike from 4 to 5 times what the engine is expected to hold. Why is it that the rear iron fails and eats this spike? Why doesn't a housing, seal, rotor, or sparkplug fail and blow out first?? Is there a way to design a collapsable seal (apex, side, between the housings) that would burst and vent the pressure instead of letting the expensive metal parts take the blast??
I assume that since we know what causes detonation that this could be tested out by intentionally allowing a detonation to occur. Of course, I'm also assuming that I'm not paying for the failures and I'm not standing anywhere near a 13b pipebomb.
05-04-05, 09:17 PM
#5
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Mazsport is doing to the motor they are building for me now. I am building a 300hp turbo motor and it is only $350 to have it done. Considering the $3000 plus I am spending on the motor I think it is worth the money.
05-04-05, 09:22 PM
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So is there a way to tie in another mount on the rear iron
05-04-05, 11:01 PM
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does an s5 rear iron bolt onto a 12a block?
i can probably get one, for the 12at im getting but i didnt know if it would bolt right on... im planning on doweling my stock 12a rear iron if not,
i can probably get one, for the 12at im getting but i didnt know if it would bolt right on... im planning on doweling my stock 12a rear iron if not,
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05-05-05, 12:08 AM
#8
Savanna Rx-7
Originally Posted by autopaul
does an s5 rear iron bolt onto a 12a block?
i can probably get one, for the 12at im getting but i didnt know if it would bolt right on... im planning on doweling my stock 12a rear iron if not,
i can probably get one, for the 12at im getting but i didnt know if it would bolt right on... im planning on doweling my stock 12a rear iron if not,
O rings don't match, 12a o ring groove is on the rotor housing, all 13bt's, and 13brew's have the oring groove on the side housings.
kenn
05-05-05, 12:43 AM
#9
FB+FC=F-ME
I dont believe that twisting on the motor mounts is what causes housing failure.
Its more like twisting of the housings against each other within the "sandwich" of plates.
Think about it,the e-shaft rotates within bearings and gears that are supported by the outer iron housings.The irons have to work against the torque being applied to them through the stationary gears.On a piston engine,its easy to make a one piece engine block with webbing and girdles to support the crank.A rotary has to use dowels and long bolts to tie the housings together securely.This setup is inheirently weak since each housing is still an individual part,clamped together with fasteners.Aftermarket doweling is just adding more of what Mazda uses from the factory to strengthen the housing to housing bond.A good idea on very powerful rotaries since its a common failure when you push over 375-400hp.
The rear housing is likely the weakest because it incorporates the most oil passages(open voids) and casting protrusions for the oil filter and oil gallery(stress risers)
Its more like twisting of the housings against each other within the "sandwich" of plates.
Think about it,the e-shaft rotates within bearings and gears that are supported by the outer iron housings.The irons have to work against the torque being applied to them through the stationary gears.On a piston engine,its easy to make a one piece engine block with webbing and girdles to support the crank.A rotary has to use dowels and long bolts to tie the housings together securely.This setup is inheirently weak since each housing is still an individual part,clamped together with fasteners.Aftermarket doweling is just adding more of what Mazda uses from the factory to strengthen the housing to housing bond.A good idea on very powerful rotaries since its a common failure when you push over 375-400hp.
The rear housing is likely the weakest because it incorporates the most oil passages(open voids) and casting protrusions for the oil filter and oil gallery(stress risers)
05-05-05, 01:30 AM
#10
Dowelling (properly) is a great idea on any engine that may at some point be improperly tuned. Otherwise, it is completely unnecessary, and will only do harm if not done correctly.
The lesson: pay better attention to your tuning if you've cracked one of these plates.
The lesson: pay better attention to your tuning if you've cracked one of these plates.
05-05-05, 01:44 AM
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Originally Posted by Islander
Ok, I have cracked three so far. I can't pin point the main reason because I hear different stories form different people.
I have heard detonation, twisting, raw power, etc. The first time was onthe dyno. I made 400hp at 17psi, I think I detonated at the higher rpm range. Cracked the first plate. Second time on the street. Good conditions, just too much power to the wheels i guess. Boosting at 15psi on the street from first through third, not spinning, just power to the ground. CRACK!
Third time, just the other night. Racing a new BMW coupe. Car pulled good all night, stopped at a light............... My brap,brap,brap went away.. Vacuum went to 4 inches, looked under car, tell tale sign, puddle of oil. Bummer.
All I can reccommend is that you try to get a S5 rear iron and also have it cryo treated. Thats my next step. If this doesnt work for me I promise i'm getting a V8.
Neal
I have heard detonation, twisting, raw power, etc. The first time was onthe dyno. I made 400hp at 17psi, I think I detonated at the higher rpm range. Cracked the first plate. Second time on the street. Good conditions, just too much power to the wheels i guess. Boosting at 15psi on the street from first through third, not spinning, just power to the ground. CRACK!
Third time, just the other night. Racing a new BMW coupe. Car pulled good all night, stopped at a light............... My brap,brap,brap went away.. Vacuum went to 4 inches, looked under car, tell tale sign, puddle of oil. Bummer.
All I can reccommend is that you try to get a S5 rear iron and also have it cryo treated. Thats my next step. If this doesnt work for me I promise i'm getting a V8.
Neal
damn neal! hangin out in the 1st gen section! WOOHOOOOO!!!!! yea, his setup seemed to be tuned pretty well from when i rode in it a few times. my god that setup threw me back in the seat with force. sux so bad that it blew that ***** fuggin backplate A G A I N. i hope my damn 12a turbo setup doesnt do this.
05-05-05, 05:54 AM
#13
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The lesson: pay better attention to your tuning if you've cracked one of these plates.
his setup seemed to be tuned pretty well from when i rode in it a few times. my god that setup threw me back in the seat with force.
It blew the next day.
My friends FB made 427whp on the dyno, and blew the the following week at the track.
My point is, just because it makes power or pulls hard for a while, does'nt mean it's tuned properly.
05-05-05, 01:22 PM
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from all the information im seeing.....if u decide to turbo a 12a and u dont push too much boost or try and reach for the 350hp range...then u should be alright?....im asking b/c my turbo project will be starting at the end of this month.....if i need to should i pay the little extra to get it dowelled...or should i just hope for the best?.....thanks....parker
05-05-05, 08:32 PM
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Instead of dowelling, which is bracing it inside, is it possible to brace it outside?
For an extreme race motor, could the housings and end irons simply be welded together as once piece?
For an extreme race motor, could the housings and end irons simply be welded together as once piece?
05-05-05, 11:30 PM
#19
FB+FC=F-ME
Even if you could weld it,the heat would likely torch the seals and youd have the world biggest paperweight.
I have heard of external braces in the works,but nothing solid yet.....
I have heard of external braces in the works,but nothing solid yet.....
05-07-05, 07:40 AM
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Hmmm, as long as we don't have a budget for this discussion...
Right now the outside 'block' of a rotary engine is composed of 5 pieces. 2 housings, 2 end irons, and one intermediate. Why are the end irons and housings not made as one piece?? They'd have to be aluminum (oh drat :P ). Make the rear housing and rear iron as one piece, then the front housing and intermediate iron as one piece, then use a regular front cover. You now have a 3 piece engine, with fewer seals (the rotaries weakness) and fewer parts to twist apart.
Aside from the cost of design and manufacture, why is this a bad idea?
Right now the outside 'block' of a rotary engine is composed of 5 pieces. 2 housings, 2 end irons, and one intermediate. Why are the end irons and housings not made as one piece?? They'd have to be aluminum (oh drat :P ). Make the rear housing and rear iron as one piece, then the front housing and intermediate iron as one piece, then use a regular front cover. You now have a 3 piece engine, with fewer seals (the rotaries weakness) and fewer parts to twist apart.
Aside from the cost of design and manufacture, why is this a bad idea?
05-07-05, 08:32 AM
#21
Bimmer *****
well, i'm not sure why not, but chances are mazda wouldn't be too happy about making the cast irons of aluminim lol, otherwise they would have in the rx8 and the rx7 already i'm sure lol... i'm thinking the reason the cast irons are cast iron is because maybe aluminum is easier to warp from overheating, and the cast irons need to be flat? i dunno... i'm not one of those engimuneers...
05-07-05, 08:50 AM
#22
Savanna Rx-7
Originally Posted by Elysian
well, i'm not sure why not, but chances are mazda wouldn't be too happy about making the cast irons of aluminim lol, otherwise they would have in the rx8 and the rx7 already i'm sure lol... i'm thinking the reason the cast irons are cast iron is because maybe aluminum is easier to warp from overheating, and the cast irons need to be flat? i dunno... i'm not one of those engimuneers...
naw its simple cost effectivness, Racing beat machined up a set of aluminum side and center housings like 8~10 years ago, and they still sell them, for like $1200~1400 apiece. no problems with warping or anything like that, just produciton costs.
kenn
edit: and no they were not one piece with the rotor houseings, but they were aluminum, so its not a warpage issue.
05-07-05, 02:12 PM
#23
If you made it the front and back housings one piece you would run into some serious issues with sleeving the rotor housing portion and probably with machining some of the internal passages. Then there are wear rates on the aluminum sliding surface to consider and the extra cost of higher-dollar-than-standard-nitride coatings to apply to those sliding surfaces.
