Lower Compression Rotors for the REnesis
12-21-2010, 08:40 PM
#51
Oh Damn--sorry Easy--- My brain is a twirling around all this and I got crosseyed.
This is a good read Easy++ thanks!
My AIT's are measured on the lim and uim junction and that is post w/m injectors. Most of the time they are only just a little above ambient,, it has seen 140 on a 90+F track day. It does build lap by lap and the a/w intercooler starts to show its weakness---may be time for an ice chest on the front seat during track days in the summer down south.
I will guarantee that NA track cars are seeing 140+ ait in the lim areas. Heck they are probably seeing it on the street. I can see 120--130F on the street without going into any boost, by just doing city driving on a 95+F day. Thats with w/m system OFF.
Eric Meyer has posted that he has even seen 180F temp of his FUEL at the fuel rail site.
The maf temps bear no comparison to the temps on the other side of the engine. My maf temps will be only 5 degrees above ambient.
Course turbo guys have a different set up. But if yall think that the maf temp is about what you are getting at the intake ports then you are sadly mistaken.
I did learn something tonight. Our OMP lines ------did yall know that the engine side fitting also has a 1 way valve in it? Not the nozzles which has their own valve, but the omp banjo type fitting that goes to the nozzle. So that is TWO one way valves in the omp lines. If you try to blow through the line after you remove it from the nozzle and omp you will never be able to do it until you open that valve.
OD
This is a good read Easy++ thanks!
My AIT's are measured on the lim and uim junction and that is post w/m injectors. Most of the time they are only just a little above ambient,, it has seen 140 on a 90+F track day. It does build lap by lap and the a/w intercooler starts to show its weakness---may be time for an ice chest on the front seat during track days in the summer down south.
I will guarantee that NA track cars are seeing 140+ ait in the lim areas. Heck they are probably seeing it on the street. I can see 120--130F on the street without going into any boost, by just doing city driving on a 95+F day. Thats with w/m system OFF.
Eric Meyer has posted that he has even seen 180F temp of his FUEL at the fuel rail site.
The maf temps bear no comparison to the temps on the other side of the engine. My maf temps will be only 5 degrees above ambient.
Course turbo guys have a different set up. But if yall think that the maf temp is about what you are getting at the intake ports then you are sadly mistaken.
I did learn something tonight. Our OMP lines ------did yall know that the engine side fitting also has a 1 way valve in it? Not the nozzles which has their own valve, but the omp banjo type fitting that goes to the nozzle. So that is TWO one way valves in the omp lines. If you try to blow through the line after you remove it from the nozzle and omp you will never be able to do it until you open that valve.
OD
Last edited by olddragger; 12-21-2010 at 08:47 PM.
12-21-2010, 09:43 PM
#53
I'm going to sound like a dick here but
this is exactly the kind of response you'd expect from a forum for a platform like this. So few people here can produce a dyno sheet (even from a generous dyno) for 350+ rwhp on any turbo car they've ever owned. I'm talking about a no bs pump gas setup. methanol injection if you have to. There are lots and lots of theories in this thread and very few results... but most of you forget that the overwhelming majority of port injected turbo engines making serious power (at least 350rwhp) run between 8:1 and 9:1 compression. piston or rotary. Turbo engines almost always come with compression ratios like this from the factory (direct injection is an exception). This is indisputable.
Do you really think you know better than all the OEM engineers who choose run much lower compression ratios than the Renesis on their turbo engines? and that's why Rx-8's get bashed for being slow... the people who know enough and care enough to make serious power get frustrated with the platform and leave. the prevailing mentalities here are not helping.
300whp isn't jack today. 10:1 compression is mostly a dead end unless you run E85.
this is exactly the kind of response you'd expect from a forum for a platform like this. So few people here can produce a dyno sheet (even from a generous dyno) for 350+ rwhp on any turbo car they've ever owned. I'm talking about a no bs pump gas setup. methanol injection if you have to. There are lots and lots of theories in this thread and very few results... but most of you forget that the overwhelming majority of port injected turbo engines making serious power (at least 350rwhp) run between 8:1 and 9:1 compression. piston or rotary. Turbo engines almost always come with compression ratios like this from the factory (direct injection is an exception). This is indisputable.
Do you really think you know better than all the OEM engineers who choose run much lower compression ratios than the Renesis on their turbo engines? and that's why Rx-8's get bashed for being slow... the people who know enough and care enough to make serious power get frustrated with the platform and leave. the prevailing mentalities here are not helping.
300whp isn't jack today. 10:1 compression is mostly a dead end unless you run E85.
Last edited by arghx7; 12-21-2010 at 09:49 PM.
12-22-2010, 12:03 AM
#55
"Preignition (actually, "autoignition" as you mean it) requires a substantially more hostile environment than what OD is experiencing.
12-22-2010, 08:51 AM
#56
OD,
You cannot compare N/A AIT's and FI AIT's. I think you would see better results if you can get them down in the 125 area or even lower would be better. The air will be even hotter once it gets to the motor after going through the LIM as we all know how close it sits to the exhaust mani. I would bet a good chunk of money that you lost the last motor to preignition and not detonation w/ the numbers you are talking about.
You cannot compare N/A AIT's and FI AIT's. I think you would see better results if you can get them down in the 125 area or even lower would be better. The air will be even hotter once it gets to the motor after going through the LIM as we all know how close it sits to the exhaust mani. I would bet a good chunk of money that you lost the last motor to preignition and not detonation w/ the numbers you are talking about.
12-22-2010, 08:53 AM
#57
MM are you saying that the NA guys are cooling the air more as it passes through the runners? Am I understanding that correctly?
Please elaborate and I dont understand that ar all.
Our lim has such a large footprint on the engine itself--you cannot stop it from heat soaking. I tried a true phenolictic gasket, multi exhaust header heat shields etc
It would be good if they could make the lim out of the same material as the uim.
i am thinking about coating mine.
Argh--thats my thinking also. Not for power but for the safety and realiability.
I already know where there are 2 A rotors that have been machined for the extra oil seal but they were also machined for the 3mm apex seals and I am not sure about that.
Please elaborate and I dont understand that ar all.
Our lim has such a large footprint on the engine itself--you cannot stop it from heat soaking. I tried a true phenolictic gasket, multi exhaust header heat shields etc
It would be good if they could make the lim out of the same material as the uim.
i am thinking about coating mine.
Argh--thats my thinking also. Not for power but for the safety and realiability.
I already know where there are 2 A rotors that have been machined for the extra oil seal but they were also machined for the 3mm apex seals and I am not sure about that.
12-22-2010, 09:50 AM
#58
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I'm going to sound like a dick here but
this is exactly the kind of response you'd expect from a forum for a platform like this. So few people here can produce a dyno sheet (even from a generous dyno) for 350+ rwhp on any turbo car they've ever owned. I'm talking about a no bs pump gas setup. methanol injection if you have to. There are lots and lots of theories in this thread and very few results... but most of you forget that the overwhelming majority of port injected turbo engines making serious power (at least 350rwhp) run between 8:1 and 9:1 compression. piston or rotary. Turbo engines almost always come with compression ratios like this from the factory (direct injection is an exception). This is indisputable.
Do you really think you know better than all the OEM engineers who choose run much lower compression ratios than the Renesis on their turbo engines? and that's why Rx-8's get bashed for being slow... the people who know enough and care enough to make serious power get frustrated with the platform and leave. the prevailing mentalities here are not helping.
300whp isn't jack today. 10:1 compression is mostly a dead end unless you run E85.
this is exactly the kind of response you'd expect from a forum for a platform like this. So few people here can produce a dyno sheet (even from a generous dyno) for 350+ rwhp on any turbo car they've ever owned. I'm talking about a no bs pump gas setup. methanol injection if you have to. There are lots and lots of theories in this thread and very few results... but most of you forget that the overwhelming majority of port injected turbo engines making serious power (at least 350rwhp) run between 8:1 and 9:1 compression. piston or rotary. Turbo engines almost always come with compression ratios like this from the factory (direct injection is an exception). This is indisputable.
Do you really think you know better than all the OEM engineers who choose run much lower compression ratios than the Renesis on their turbo engines? and that's why Rx-8's get bashed for being slow... the people who know enough and care enough to make serious power get frustrated with the platform and leave. the prevailing mentalities here are not helping.
300whp isn't jack today. 10:1 compression is mostly a dead end unless you run E85.
we're not at the e85 part of this discussion yet
quit jumping the gun. ( but just for kicks go look at the number of e85 stations that are available to OD 
)
12-22-2010, 09:50 AM
#59
Nobody is ignoring 13B history. It is not only well documented, but a few of us have the inside track to people that all of your 13B knowledge equates to only a pimple on their @ss. The reality is you are an unproven Renesis theorist at best and all of your theories are based on 13B experience, not any actual Renesis experience. You are mired in the 13B past and cannot see beyond it, which coupled with your complete lack of direct Renesis knowledge and experience, relegates you to being nothing more than an amateur on the subject. While you may be a rook or a bishop on the RX7Club chess field, you are merely a pawn here. Your continued insistence to be taken seriously based on nothing more than that insistence only serves to further belittle yourself.
Not only do low compression rotors fail to address the ultimate limitation of the Renesis engine, they will push you to that limit sooner. Reliable FI Renesis power up to that limitation will be had either at the expense of lower boost (street)or higher quality fuel (track unless you have E85 access). You neither know this or are capable of understanding it because you cannot think or demonstrate anything outside of your own self-imposed 13B history box.
Last edited by TeamRX8; 12-22-2010 at 09:55 AM.
12-22-2010, 11:06 AM
#60
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I am posting from my experiences which does include renesis work. I have decided to remove my posts and refrain from posting in these topics anymore as I get frustrated how ideas are shared and life is too short to get frustrated over the internet.
I will continue w/ what I do and I am sure others will continue the same way.
Good luck.
Brad
12-22-2010, 11:27 AM
#61
The only reason anyone gives a **** what my opinions are is because I refuse to go away.
Even then, I am probably merely tolerated around here.........
12-22-2010, 11:32 AM
#62
Not only do low compression rotors fail to address the ultimate limitation of the Renesis engine, they will push you to that limit sooner.
Reliable FI Renesis power up to that limitation will be had either at the expense of lower boost (street)or higher quality fuel (track unless you have E85 access).
There's also a reason why an STi on pump gas can make nearly 400wtq with a bolt on turbo upgrade and stock intercooler. They can safely run over 20psi on pump gas only provided that the timing isn't too aggresive. STi's have compression ratio below 9:1 . This is not a coincidence.
12-22-2010, 11:36 AM
#63
2) The combustion chamber on rotary engines poses unique challenges that piston engines do not.
12-22-2010, 11:46 AM
#65
2) The combustion chamber on rotary engines poses unique challenges that piston engines do not.
12-22-2010, 12:30 PM
#67
^ so show me a 400whp or 600 grams/sec Renesis at 10psi manifold boost pressure then.
1) you can't feasibly change the intake manifolds due to cost
2) you can't gain much from porting the intake and exhaust ports due to the casting
3) you do have limited choices in exhaust manifold and intercooler design but there's only so much that accomplishes
again, theory vs practical results. Show me a powerful Renesis running 10psi, 93 octane pump fuel only, and 10:1 static compression. They don't exist. thousands and thousands of dollars spent, and you might 320-340 on a dynojet if you're lucky. That's weak given the dollars spent and the weight of the car. It's not going to cut it.
1) you can't feasibly change the intake manifolds due to cost
2) you can't gain much from porting the intake and exhaust ports due to the casting
3) you do have limited choices in exhaust manifold and intercooler design but there's only so much that accomplishes
again, theory vs practical results. Show me a powerful Renesis running 10psi, 93 octane pump fuel only, and 10:1 static compression. They don't exist. thousands and thousands of dollars spent, and you might 320-340 on a dynojet if you're lucky. That's weak given the dollars spent and the weight of the car. It's not going to cut it.
12-22-2010, 12:32 PM
#68
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Our lim has such a large footprint on the engine itself--you cannot stop it from heat soaking. I tried a true phenolictic gasket, multi exhaust header heat shields etc
It would be good if they could make the lim out of the same material as the uim.
i am thinking about coating mine.
It would be good if they could make the lim out of the same material as the uim.
i am thinking about coating mine.
12-22-2010, 12:43 PM
#70
Very valid point, it actually has been done, but the set-up was definitely not street friendly. Well not at 10PSI, at 14 I think.... been a while.
The thing is, if you are shooting for 400-500WHP, then lowering compression ratio would be a valid option on the table, and part of the system which would include turbo selection etc.
For 300-350WHP, it's not worth the drawbacks.
Edit to add: Either way, OD's compressor sure as hell isn't getting any more efficient with more boost....so you lower compression in order to put in hotter intake air, not really a good trade.
Last edited by Kane; 12-22-2010 at 12:52 PM.
12-22-2010, 12:52 PM
#71
well we could, but the turbos you need to make power don't wake up until well past 10psi. you can slice it any which way, using whatever units you like, but with 10psi boost you are going to have thousands of dollars spent and not much to show for it by today's standards.
maybe so, but 10psi (on any turbo really) is still holding back this engine no matter how you frame the discussion. it's a wall that's not going to be broken in a convenient manner (pump gas only) with 10:1 compression. There's only so much mass airflow you can achieve at 10psi no matter what you do. only engines you see making power at this boost level are big displacement, whether they are 3 rotors or V8's.
maybe so, but 10psi (on any turbo really) is still holding back this engine no matter how you frame the discussion. it's a wall that's not going to be broken in a convenient manner (pump gas only) with 10:1 compression. There's only so much mass airflow you can achieve at 10psi no matter what you do. only engines you see making power at this boost level are big displacement, whether they are 3 rotors or V8's.
This is why I keep focusing on two things; the fuel we are expected to use (or assume for the sake of discussion) and the amount of mass airflow we are expected to shove in the engine.
Last edited by Charles R. Hill; 12-22-2010 at 12:55 PM.
12-22-2010, 02:49 PM
#73
ok so that's 70 lb/min if you use a calculator like this one: http://www.gordonengland.co.uk/conversion/feedrate.htm . and you're never going to get 70 lb/min flow at 10psi boost on a 2 rotor. it's not going to happen. if you put in a turbo that's big enough to flow that, you'll just hit the surge line. the displacement is too low. you have to crank up the boost, and 10:1 rotors makes that inpractical. 10psi boost won't cut it.
ok so if that's true... how does this information mean that I can achieve 550 grams/sec at 10psi boost with a 10:1 static compression ratio.
again, you can use whatever units or calculations you want to use... with 10:1 rotors and only 93 octane fuel you are going to have knock preventing you from achieving real power. Real power can only be made with more boost than what almost all of the Renesis turbo engines are currently running. Otherwise you're still spending thousands and thousands of dollars and barely keeping up with a V6 mustang.
the reason why there aren't many Renesis engines out there making real power is because the turbos are too small and/or the boost is too low. you can explain that in whatever terms you want to explain it (insufficient grams/sec or whatever), but that's the crux of the matter.
Static Compression is 10:1, Dynamic compression would be like 18 or 20:1 I think....
again, you can use whatever units or calculations you want to use... with 10:1 rotors and only 93 octane fuel you are going to have knock preventing you from achieving real power. Real power can only be made with more boost than what almost all of the Renesis turbo engines are currently running. Otherwise you're still spending thousands and thousands of dollars and barely keeping up with a V6 mustang.
the reason why there aren't many Renesis engines out there making real power is because the turbos are too small and/or the boost is too low. you can explain that in whatever terms you want to explain it (insufficient grams/sec or whatever), but that's the crux of the matter.
Last edited by arghx7; 12-22-2010 at 02:56 PM.
12-22-2010, 03:07 PM
#74
arghx7 i think that you're missing the point. You moved from discussing Denny's goals to talking about putting down serious power with our platform.
In his particular case it is not a practical option, there are other points of concern that need to be addressed.
Talking in general lowering the compression is an option, ok. What do you need huge power for though? The power curve of a renesis makes up for the loss in top-end power. Remember that some of the world's finest rx7 also don't have more than 420hp, they simply don't need it.
There are other aspects of a car that are often undervalued.
I would love to see a chart that compares power vs boost needed in a 10:1, 9:1 and 8:1 engine with a turbo that flows 60lbs\min. That would be a good starting point to make comparisons.
In his particular case it is not a practical option, there are other points of concern that need to be addressed.
Talking in general lowering the compression is an option, ok. What do you need huge power for though? The power curve of a renesis makes up for the loss in top-end power. Remember that some of the world's finest rx7 also don't have more than 420hp, they simply don't need it.
There are other aspects of a car that are often undervalued.
I would love to see a chart that compares power vs boost needed in a 10:1, 9:1 and 8:1 engine with a turbo that flows 60lbs\min. That would be a good starting point to make comparisons.
12-22-2010, 03:10 PM
#75
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Not only do low compression rotors fail to address the ultimate limitation of the Renesis engine, they will push you to that limit sooner.
I dont always agree with your posts, but I think likely understand better than this and probably just had a
moment(or hell maybe I did, I'm pretty fucked up still
)