Lets speculate on aftermarket performance engine mods
06-23-2003, 07:19 PM
#26
uhhhhh....hello?
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hmmmmmm
what type of gains "used" to be seen on some other rotaries w/o any form of FI?
this will probablu give us a good diea of what is necessary to generate some of the numbers that are seen, well, at least for me, i havent been around as long as you guys have, in terms of messing around with rotaries (or any engine for that matter!)
________
Weed vaporizers
what type of gains "used" to be seen on some other rotaries w/o any form of FI?
this will probablu give us a good diea of what is necessary to generate some of the numbers that are seen, well, at least for me, i havent been around as long as you guys have, in terms of messing around with rotaries (or any engine for that matter!)
________
Weed vaporizers
Last edited by P00Man; 04-16-2011 at 06:18 PM.
06-23-2003, 07:30 PM
#27
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Originally posted by rotarygod
Don't expect gains like the 3rd gens had. You can't compare a turbo to an n/a when you talk about gains.
Don't expect gains like the 3rd gens had. You can't compare a turbo to an n/a when you talk about gains.
) would be attainable from a 3-rotor FI Renesis given that a turbocharged 3 rotor 20B reached about 650 bhp while remaining semi-reliable? Thanks.
06-23-2003, 10:55 PM
#28
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it all depends on how strong the apex seals are. Also it looks like you are going to run into problem with the tertiary (for wakeech) or auxilary (everyone else) ports. Although you may just be able to lock them shut.
06-24-2003, 02:14 AM
#29
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Why in the world would you want to keep the aux. (tertiary) ports closed? There are several important design issues to account for by doing this. First of all you just cut potential airflow down by about a third due to decreased port area. You have also reduced total port timing. This would be less time to shove air into the engine. You have also just done away with the benefit of VDI which is dependent on everything working the way it does. VDI is good for almost the equivalent of a 2 psi boost when naturally aspirated due to a performance increase from acoustic waves. They would still have the same benefit when using FI. The best thing you could possibly do is to figure out how to keep everything working and still add FI. If you left them open like many of the RX-7 guys do, you would lose power below their opening point at 6250.
If you want to get a general idea on how much to expect from boost. 14.7 psi is twice the air as no boost (altitude and weather dependent). The Renesis at 1 bar of boost could get almost double its rated horsepower of 250. In other words 500. Now this assumes 100% efficiency. You will lose some to back pressure through the turbo exhaust wheel and to the intercooler. It would also be dependent upon the correct compressor being used on the turbo. It has to be most efficient at the desired rpm. I would still estimate near 450 hp though. Just a guess. Only time will tell. For a 3 rotor based off of this number it would be 675. I know a few people running 1 bar of boost on the street. Tuning is everything. We still don't know how tough the new engine is though so this may be wrong. Also remember that the high compression ratio of 10:1 is going to be intolerant of high boost before it gets to a detonation point.
If you want to get a general idea on how much to expect from boost. 14.7 psi is twice the air as no boost (altitude and weather dependent). The Renesis at 1 bar of boost could get almost double its rated horsepower of 250. In other words 500. Now this assumes 100% efficiency. You will lose some to back pressure through the turbo exhaust wheel and to the intercooler. It would also be dependent upon the correct compressor being used on the turbo. It has to be most efficient at the desired rpm. I would still estimate near 450 hp though. Just a guess. Only time will tell. For a 3 rotor based off of this number it would be 675. I know a few people running 1 bar of boost on the street. Tuning is everything. We still don't know how tough the new engine is though so this may be wrong. Also remember that the high compression ratio of 10:1 is going to be intolerant of high boost before it gets to a detonation point.
06-26-2003, 02:45 PM
#30
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I've had to go back in time to the 60's to look at some old exhaust system designs that use siamesed exhaust runners. The results are pretty cool. Just taking a guess I feel that a proper header for the Renesis will be really cool looking since we have to account for the different effects in the outer runners than in the middle one. The way I see it, the exhaust header will have to be very similar in design to a try-Y header with proportions matching these systems. In other words, the 2 outer runners will collect at a point in length where they are tuned at the Renesis peak horsepower. The middle port runner will NOT collect here. Rather it should collect at a distance 3 times as long as the first collector. Since I don't know the port timing specs I'll just make a very general example to get the point across. If the outer runners collect at 12" to each other, then the middle runner should join in downstream at a total distance of 36". Again these aren't actual numbers just an example. If we really want to tune for every last little bit then we could take a pipe off of the center one right at the engine that branches off and is a total of 12" long to match the other pipes. The difference here is that this is just a dead end leg attached to the main runner that is sealed at the end. This will cause the center runner to resonate at the same frequency as the outers. The 3 to 1 relationship for runner length is mathematically necessary to arrive at the same tuning. Using this method it wouldn't matter if we have a siamesed center or not. Cool little tricks with acoustics! We'll just have to wait and see who designs the one that works the best. There may be power here after all! FWIW the stock S2000 exhaust has a dead end runner in the system but the aftermarket always seems to remove it. I wonder how much it truly effects the stock exhaust?
Last edited by rotarygod; 06-26-2003 at 02:48 PM.
06-28-2003, 12:58 PM
#31
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Originally posted by B-Nez
I was thinking about porting options the other day...I think once my warranty runs out I'm gonna go nuts. So, maybe someone can give me a clue here. Given the pros and cons of the different porting types used in rotaries, would there be any benefit (and would it even work) to the following scenario:
1. Primary Ports: stock
2. Secondary Ports: street port
3. Auxiliary Ports: bridge port
Obviously the stationary gears would need to be hardened (and a couple other things I forget) and the redline bumped up.
I figure keeping primaries stock would alleviate the idle, streetability, longevity, and low-end torque issues you get with normal bridgeports. At that mid rpm-range the street ports open up real nice, and for the WOT runs a nice bridgeport up to 10 or 11K would be gravy.
I was thinking about porting options the other day...I think once my warranty runs out I'm gonna go nuts. So, maybe someone can give me a clue here. Given the pros and cons of the different porting types used in rotaries, would there be any benefit (and would it even work) to the following scenario:
1. Primary Ports: stock
2. Secondary Ports: street port
3. Auxiliary Ports: bridge port
Obviously the stationary gears would need to be hardened (and a couple other things I forget) and the redline bumped up.
I figure keeping primaries stock would alleviate the idle, streetability, longevity, and low-end torque issues you get with normal bridgeports. At that mid rpm-range the street ports open up real nice, and for the WOT runs a nice bridgeport up to 10 or 11K would be gravy.
btw, i hope this is ok with mrec...
dig the weird port shapes... also, note the (surprisingly) small size of the exhaust side ports... TONS of room to bump out some of these dimensions, create some emissions-passable overlap, and have ports large enough to flow nearing 10k rpm... woooow...
...those tertiary port sleeves would need some pretty clever grinding to work well with a bridge... hmmm...
Last edited by wakeech; 06-28-2003 at 01:01 PM.
07-02-2003, 02:45 PM
#32
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Mazda did some research on port shapes to look at flow through them. The strange shapes are the result of being the most fuel efficient design in testing. It keeps the air just turbulent enough to keep fuel in suspension but not so much that it hurts power.
As a little bit of side info, an exhaust port can be as much as 40% smaller than an intake port and still maintain comparable volumetric efficiency. Don't get this confused with the port timing. The rotary has to change the timing to change the size. A more appropriate example of this fact is to look at piston engines. The exhaust valves are always smaller in area than the intake valves. It would seem that you would want as large an opening as possible but this just isn't so. There are some neat diagrams of this phenomenon in an M.I.T. textbook that I have. (No I didn't go there!) Strange isn't it?
As a little bit of side info, an exhaust port can be as much as 40% smaller than an intake port and still maintain comparable volumetric efficiency. Don't get this confused with the port timing. The rotary has to change the timing to change the size. A more appropriate example of this fact is to look at piston engines. The exhaust valves are always smaller in area than the intake valves. It would seem that you would want as large an opening as possible but this just isn't so. There are some neat diagrams of this phenomenon in an M.I.T. textbook that I have. (No I didn't go there!) Strange isn't it?
07-02-2003, 03:48 PM
#33
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yes, i'm aware that because of the nature of combustion you end up with less gross mols (?sp? it's been a long time since chem), so there is actually less gas to flow out...
my comment about the flow at 10k would be with B-Nez's tertiary bridge port and secondary aggressive port (still lots of room to open up inside the lines, without changing timing much), which would certainly require larger ports, which the block can easily accomodate without effin' up the timing (when you compare the phasing to the p-port exhaust of the 13B).
my comment about the flow at 10k would be with B-Nez's tertiary bridge port and secondary aggressive port (still lots of room to open up inside the lines, without changing timing much), which would certainly require larger ports, which the block can easily accomodate without effin' up the timing (when you compare the phasing to the p-port exhaust of the 13B).
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