Use RX8 Engine Rotors in FD build or other rotor?
11-04-10, 07:58 PM
#1
Use RX8 Engine Rotors in FD build or other rotor?
Doing a pretty big build and wanted some thoughts on possibly using RX8 rotors in my engine build. I previously considered NA 89-91 rotors for their lighter weight an higher compression (more torque). Then I was referred to 86-88 NA rotors, still higher compression (vs FD rotors) and stronger. I was wondering if RX8 rotors are a viable alternative? What are the benefits, costs, and risks for my setup. IIRC they are 10:1 compression.
The vehicle purpose is for autocross racing. I would like to make power reilably till 9000rpm and make torque down low in the rpm range.
The engine build will include:
Street Port
RX8 Eshaft
Balanced rotating assembly
RA Black Apex Seals
OEM gaskets/other seals
Race Clearancing (do I need this if I get the rotating assembly balanced?)
(note: turbo is a T04E with a 60 trim, and will most likely stay unless it's been compromised by the apex seal. peak boost will be around 18psi on 100 octane)
The vehicle purpose is for autocross racing. I would like to make power reilably till 9000rpm and make torque down low in the rpm range.
The engine build will include:
Street Port
RX8 Eshaft
Balanced rotating assembly
RA Black Apex Seals
OEM gaskets/other seals
Race Clearancing (do I need this if I get the rotating assembly balanced?)
(note: turbo is a T04E with a 60 trim, and will most likely stay unless it's been compromised by the apex seal. peak boost will be around 18psi on 100 octane)
11-05-10, 01:49 AM
#5
There are a lot of differences between the Renesis and REW rotors. The Renesis is a much better/modern design for sealing, lower emissions, etc but it is made for side exhaust ports and all the main rotor seals are different:
Source: Ohkubo, "Developed Technology of the New Rotary Engine (RENESIS)," 2004 p. 11
The Renesis rotors also have a cutoff seal which is another thing to deal with. I just don't see enough benefit to using them.
The series 5 9.7:1 rotors would be ideal if you are ok with having a compression ratio that high. The series 4 9.4:1 rotors are heavier so you will need to take steps to balance the assembly. They also have sloppier manufacturing tolerances, and thus the compresison ratio can vary by as much as .3:1 . The combustion recess (bath tub) is cast on series 4. Series 5+ has a machined combustion recess, are 14% lighter than series 4, and have better manufacturing tolerances. Series 4 are generally considered "stronger" rotors but that probably won't matter unless you are building a huge HP monster. They have thicker internal ribbing than the later rotors (3mm vs 2mm on series 5+)
(Source: Matsuda, "New Technology Employed for the Latest 13B-Rotary Engine," 1990 p. 9)
Source: Ohkubo, "Developed Technology of the New Rotary Engine (RENESIS)," 2004 p. 11
The Renesis rotors also have a cutoff seal which is another thing to deal with. I just don't see enough benefit to using them.
The series 5 9.7:1 rotors would be ideal if you are ok with having a compression ratio that high. The series 4 9.4:1 rotors are heavier so you will need to take steps to balance the assembly. They also have sloppier manufacturing tolerances, and thus the compresison ratio can vary by as much as .3:1 . The combustion recess (bath tub) is cast on series 4. Series 5+ has a machined combustion recess, are 14% lighter than series 4, and have better manufacturing tolerances. Series 4 are generally considered "stronger" rotors but that probably won't matter unless you are building a huge HP monster. They have thicker internal ribbing than the later rotors (3mm vs 2mm on series 5+)
(Source: Matsuda, "New Technology Employed for the Latest 13B-Rotary Engine," 1990 p. 9)
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11-05-10, 02:17 PM
#10
Kevin Landers of rotary resurrection may have some. kevin@rotaryresurrection.com
11-06-10, 05:36 PM
#12
Yeah. Car sat solidly between both of you in the final standings, which I was thrilled about. You boys can certainly drive. I had to call out that little glory when djseven bashed my single setup (lol). Regarding the modded turbo, I was just referring to the fact that you modded the wastegate / pre-control system. I am glad to hear that the S5 NA rotors work well without the $$$$lightening$$$$. Where did you get your rotating assembly balanced?
11-08-10, 05:46 PM
#14
^ The REW doesn't have a cut off seal. The cut off seal is a new combustion seal on Renesis engines only, because of the side exhaust port. It's designed to reduce the internal EGR effect by blocking exhaust gas from diluting the intake charge. The reduced EGR allows the Renesis to idle at 14.7:1 AFR normally, with stable combustion.
11-20-10, 05:19 AM
#18
^ The REW doesn't have a cut off seal. The cut off seal is a new combustion seal on Renesis engines only, because of the side exhaust port. It's designed to reduce the internal EGR effect by blocking exhaust gas from diluting the intake charge. The reduced EGR allows the Renesis to idle at 14.7:1 AFR normally, with stable combustion.
https://www.rx7club.com/attachment.p...1&d=1289259971
https://www.rx7club.com/attachment.p...1&d=1289259971
I wouldn't want to use RX-8 rotors in a build that plans to go to 18 PSi due to the higher compression. What is wrong with FD rotors? They're the lightest (excluding RX-8) and are still high boost friendly.
thewird
11-22-10, 11:59 AM
#20
if any one is interested in N/A FD
rx8 rotor with 3mm seals has been done
there is a 12page thread on this forum about it
it was installed in 13B PP N/A FD3S race car .... that made 250 RWHP and they are hoping to make 280 RWHP when its all done
search it and you will fined the thread
as far as boosting on rx8 rotors inside FD engine you should be ok with 10pis max but thats it......- you might as well get a rx8 and slap turbo on it
bout if you wanna go N/A and make some power what i would wanna do is
20b PP with RX8 rotors or ( light weight FC3S N/A rotors) on E85 now that would be SWEET -- i would throw out my current single turbo setup for this
rx8 rotor with 3mm seals has been done
there is a 12page thread on this forum about it
it was installed in 13B PP N/A FD3S race car .... that made 250 RWHP and they are hoping to make 280 RWHP when its all done
search it and you will fined the thread
as far as boosting on rx8 rotors inside FD engine you should be ok with 10pis max but thats it......- you might as well get a rx8 and slap turbo on it
bout if you wanna go N/A and make some power what i would wanna do is
20b PP with RX8 rotors or ( light weight FC3S N/A rotors) on E85 now that would be SWEET -- i would throw out my current single turbo setup for this
11-22-10, 01:03 PM
#21
^ I've tuned an RX-8 to 12 PSi on pump gas which has been running for a little under 2 years now with a few track days. This year he's porting his motor and installing 3mm ceramics and we're gonna add some AI and crank up the boost. Note, there is nothing wrong with the motor, he just wants more p0w3r.
thewird
thewird
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