a friend mailled me this is he talking sense? or wasteing his time ?
his is a 99 spec twin
Decided to go for upgraded internals on this one. Hardened tips etc.
Seeing as i am sticking with stock twins i am just gonna go for more RPM. More RPM = More power. Basic physics, will gas flow turbos tomorrow to check but they will cope easily cos i won\'t need more than 12psi on paper. 11k RPM target is he talking sense? or wasteing his time ?
is he full of sh1t and what should i send back to shut him up?
I\'d say completely. The thing that lets you rev higher is very complex, lighter rotors, dowled engine.......... the list goes on.
If he sticks with the same ports then whats the point, the engine will only make good power at about 6.5k (very roughly) anyway.
There has been alot of threads about getting an engine to rev high on here and rx7club (and no doubt ausrotary) and the list is endless.
I think tim is the best person to quote on this, only person i can think of that revs to that. And thats even on a 12a !
Shaun
i think tim revs his to 12/13k
and i know carl has built engines to rev to 11k ish
matt
this is now what he is saying cant belive its this easy ! got a feeling hes in the clouds
I\'ll be doing it myself, making the engine rev higher i a peice of cake, its just making it stay together that\'s tricky. Just a case of upping the rev limit and making the ecu inject up to higher rpms.
With balanced rotating mass you can gain nearly 1500rpm safely just by reducing the vibration and upping the above. Then it\'s a case of make weak points stronger, but not so strong that you create new weak points. My dad used to make race engines so i have a little advantage.
Don\'t think you need to dowl the engine. That\'s for when you run higher boost to stop the housings from bending. The stationary gears tend to break up at high revs, so he would need stronger ones of those. Also the rotors need to be skimmed for high revs. But if you can move the torque curve further up the rev range, then even without creating more torque, you will get more power.
Quote from: nikpDon\'t think you need to dowl the engine. That\'s for when you run higher boost to stop the housings from bending. The stationary gears tend to break up at high revs, so he would need stronger ones of those. Also the rotors need to be skimmed for high revs. But if you can move the torque curve further up the rev range, then even without creating more torque, you will get more power.
cheers nik ill run that past him he informs me this is his plans
Gasket Kit (obviously)
Atkins Ceramic coated Apex Seals
Apex Seal Springs
Solid Nitrided Corner Seals
Corner Seal Springs
Side Seals
Side Seal Springs
Oil O Ring Vitons
Oil O Ring Seals
Oil O Ring Springs
Front Main Seal
Rear Main Seal
Pilot Bearing and Seal
High flow Thermal Pellet
Torrington reinforced Bearings
Balanced lightened titanium rotors
nikp can this tread be renamed \'higher reving advice\' it might get more interest from tuners ect.
matt
interesting thread :D
http://www.rx7club.com/showthread.php?t=92289&highlight=11k+rpm
Shaun
Quote from: arrouknikp can this tread be renamed \'higher reving advice\' it might get more interest from tuners ect.
matt
Done. Now named - "How to build a high revving rotary engine"
There is loads on this subject, You need a two pc Crank for a start with a center bearing then some real lightening/Balancing of Rotating assembly and the Proper Clearance.
Basically what happens at high RPM is the Crank starts to flex with the weight of a Rotor full of oil being thrown around which in turn screws up the clearance between the Housings and the rotors, You may also want to look into Dry Sumping because at 11k+ things like bearings/Rotor gears will start to walk out.
I suppose it depends on what Power etc you are planning to run, if its NA or Turbo,How long you want to run that high RPM for (ie is it a Track car that runs it for a number of seconds or just being safe if you miss a Gear change) but if you want my Advice this is something that is an Specialist only job, it can be done but you really need to know what your doing.
Quote from: nikpDon\'t think you need to dowl the engine. That\'s for when you run higher boost to stop the housings from bending. The stationary gears tend to break up at high revs, so he would need stronger ones of those. Also the rotors need to be skimmed for high revs. But if you can move the torque curve further up the rev range, then even without creating more torque, you will get more power.
sorry nik dowling what does this consist of??
Here, check this page out: http://www.mazdatrix.com/faq/boost.htm
Basically, run big boost actually forces the rotor housings to get warped out from the pressure of the air which is likely to result in engine failure. Dowl pinning the engine is intended to strengthen the housings to prevent this from happening. That\'s my take on it anyway.
Adding more Dowls. A stock motor has Two Dowls per Rotor and a good machine shop can fit extra Dowls to make it less likly to move about/Twist at high load.
Thats kind of the Old school way of doing it, there is a Newer Method called Studing which involves fitting oversized Studs instead of Bolts which have tight Clearance with the origanal Bolt holes. This is regarded by many to be the best way of doing it becouse there is ver little metal removed from the plates/housings so they have as much meat left round the Hole as poss, its effectivly like fitting a full set of Dowls.
When I build serious engines I allways make the through bolts 14mm dowels too,so they serve a dual purpose.
I have been doing this for around 5 years now.
The center bearing eccentric shaft is also a good thing for higher revving engines.
Lighter rotor weight is essential as is a fully balanced rotating assembly particularly on 13b engines.
The next weak link is the stationary gears.
Regards
Carl
Quote from: nikpHere, check this page out: http://www.mazdatrix.com/faq/boost.htm
Basically, run big boost actually forces the rotor housings to get warped out from the pressure of the air which is likely to result in engine failure. Dowl pinning the engine is intended to strengthen the housings to prevent this from happening. That\'s my take on it anyway.
what kind of boost are we talking? is this 400+? as before i put the engine back 2geather should i do this?
Quote from: LRPBalanced lightened titanium rotors
wtf? Is he mental or has he won the lottery?
Quote from: efinistewtf? Is he mental or has he won the lottery?
not sure if his heads in the clouds or hes dreaming! i do know his ra scooby was very very fast and he built that so????? who knows he hasant joined mrc yet not sure why not?
Quote from: LRPwhat kind of boost are we talking? is this 400+? as before i put the engine back 2geather should i do this?
I believe we are talking very high boost levels. You shouldbe good for 400ish without the need for dowling. but I am not an expert - I am merely someone who has picked up certain levels of information.
Nik, I thought it was Load related rather than HP? if you drag race alot you need some form of Dowl but i know people with more than 400hp with Track cars with stock Dowls and Bolts.
They don\'t have any problem? Saying that i think the story would be diffrent though if they did 20 Drag runs at full wack.
That sounds reasonable.
But I am also on the understanding that [very] high boost levels can cause this effect. Basically, there\'s so much air pressure in the chamber, it causes enough force to physically bend and distort the rotor chamber and/or the rotor. Whether this occurs with continued high usage of a high boost application, or just a few given \'shots\' of high boost, i don\'t know.
Just copy this guy ;)
http://www.rx7club.com/showthread.php?t=554910&page=1&pp=15&highlight=crank
Quote from: nikpThat sounds reasonable.
But I am also on the understanding that [very] high boost levels can cause this effect. Basically, there\'s so much air pressure in the chamber, it causes enough force to physically bend and distort the rotor chamber and/or the rotor. Whether this occurs with continued high usage of a high boost application, or just a few given \'shots\' of high boost, i don\'t know.
I was just going to be cleaver and post a Pic of a Guy i know who smashed a section of his dowled Rotor Housing out when his E-shaft flexed and the rotor made contact at 10k but i guess the Pic\'s on my old Computer.
The Dowls are not your Only problem at high HP/RPM the E-shaft will flex before the Housing moves. If your going to build something that is serious it\'ll have to be all or Nothing don\'t just Dowl it becouse it will be waste of time if you don\'t do the Clearancing and Center bearing.
Quote from: GrizzlyThe Dowls are not your Only problem at high HP/RPM the E-shaft will flex before the Housing moves. If your going to build something that is serious it\'ll have to be all or Nothing don\'t just Dowl it becouse it will be waste of time if you don\'t do the Clearancing and Center bearing.
So I understand it, yes. Fortunately, i\'m not planning this exercise myself! I have enough problems!! Like, why is oil being forced out my pipe that I would use for a catch tank, but only under high and continual load. Otherwise it\'s fine! So, not going for high RPM just yet! :P