Turbo on RX-8

[mazdamaniac]

Originally Posted by phoenix7

The TII is 160-170whp and with ~1200 bux you can make 300HP

Its already a turbo car. Doesn't count for this comparison. Try making that power that cheaply on the GTU.

Originally Posted by phoenix7

As far as sequentials:
I thought it might help with the top end. I see that the Greddy upgrade in your charts has great low end that tapers off after 6K RPMs in one graph and 7.5K RPMs in the other. Wouldn't a second turbo maintain linear power all the way through the powerband? Similar to the FD setup?

Power tapers in the high-end of the Renesis because of the flow restriction of the exhaust ports.
The Renesis has a very wide power band, but it isn't going to be all at the top like a peripheral port 13b.
Once the gas velocities get really high, the right-angle turn of the exhaust ports becomes a restriction.
The high power output Renesis applications you will see in the future will make their peak tq at 6200 and hp at 7200 max.

Originally Posted by Herblenny

If you could get this system to work for stock turbos and extract as much power potential as you claim (close to 400WRHP), just by the swap, stock FD set up without changing the turbo, you'll hit the market!

The problem with the FD turbos are they don't flow enough air.
You can tune all day, if the air is hot coming out of the turbos (low mass) the power won't happen.

[Herblenny]

Originally Posted by mazdamaniac

The problem with the FD turbos are they don't flow enough air.
You can tune all day, if the air is hot coming out of the turbos (low mass) the power won't happen.

People have made upwards 380ish RWHP sequential via MAP system on stock twins.

99 sequential turbos also made around that HP with quicker spool.

BNR's have made over 400RWHP sequential in MAP system.

So, Are you saying that its the temperature of the air that might cause problem of tuning MAF based system?? Again, I'm not an expert in MAF tuning.. but doesn't air temp gets measured by MAF sensor?? or is there another sensor after TB?? And when running EtOH/Water inj. Do you shoot before MAF or after??

[Whizbang]

i think the problem is the turbos are getting out of their efficiency range when you start getting up there.

[Phoenix7]

Originally Posted by mazdamaniac

Its already a turbo car. Doesn't count for this comparison. Try making that power that cheaply on the GTU.

you got me there. You're right.

Power tapers in the high-end of the Renesis because of the flow restriction of the exhaust ports.
The Renesis has a very wide power band, but it isn't going to be all at the top like a peripheral port 13b.
Once the gas velocities get really high, the right-angle turn of the exhaust ports becomes a restriction.
The high power output Renesis applications you will see in the future will make their peak tq at 6200 and hp at 7200 max.

Makes sense, what exhaust manifold does the MM turbo use?

The problem with the FD turbos are they don't flow enough air.
You can tune all day, if the air is hot coming out of the turbos (low mass) the power won't happen.

[mazdamaniac]

Originally Posted by phoenix7

Makes sense, what exhaust manifold does the MM turbo use?

Its the GReddy cast iron manifold.
Pretty decent piece - the flow cross-section is about equal to the port area.
I've been thinking about an Extrude-Hone to increase flow a bit.

Originally Posted by Low Impedance

i think the problem is the turbos are getting out of their efficiency range when you start getting up there.

Exactly.
Even though the pressure is rising, the mass is holding because the heat is going up.

[Herblenny]

So are you saying that with MAF system can't hit XX Horsepower that MAP system will hit with the same turbo(s)??

[fikren]

can we get a mod to sticky this one, lots of good info coming out maybe useful in the future.

[mazdamaniac]

Originally Posted by Herblenny

So are you saying that with MAF system can't hit XX Horsepower that MAP system will hit with the same turbo(s)??

??
MAF or MAP has nothing to do with it.
You just are limited by the turbos themselves.
The units that come on the FD are dinosaurs.

[Herblenny]

I understand that different turbos have different efficiency and limitation..

Maybe I read it wrong.. But if your turbo makes 400hp top as its limitation on MAF based system and stock REW twin turbo (99s) will make close to 400 as its limitation on MAP.. I'm wondering if using MAF system on REW will produce similar HP...

I guess maybe I got confused when you stated about temp and efficiency being the issue and wondering if thats one of the downfall of MAF based system to so called hitting maximum potential of turbo.

I personally do not think FD units are junk/dinosaurs... Its very responsive and still one of the best sequential systems out there (mazda made FDs til 2002).. Many still prefers it vs. single, not just money but for its performance.. I mean, I still prefer it.. and really money wasn't an issue... I have a gigantic single at home that I could put on and make 500hp (T78BB) if I wanted to... but I know its not all about HP.

BNRSupercar just recently put 99spec (280HP turbos from mazda) and at 14lbs of boost (MAP) on bone stock motor made 321RWHP. Conservative tuning and super responsive (I think full boost at 2300-2500RPM). If FD turbo system is dinosaurs and when compared to Modern Renesis motor and modern BB turbo, why is it that people not putting Renesis in FDs (like person like me with a spare renesis at home and 2x FD)?? is it because of money?? or is it because there is nothing to do with difference between MAF or MAP?? I think that's the bottomline I'm trying to get to.. Is MAF based system so much superior without any catch that even "dinosaur" turbos could be ran better??

[Herblenny]

By the way Jeff, don't take me personally.. I do think MAF system definitely has its advantages... I just don't know its disadvantages...

I hope you understand I'm not trying to argue with you saying MAP is better than MAF.. I just don't know much about the MAF and knew better about MAP.

I'm just trying to learn more by asking stupid questions..

[fikren]

Originally Posted by Herblenny

By the way Jeff, don't take me personally.. I do think MAF system definitely has its advantages... I just don't know its disadvantages...

I hope you understand I'm not trying to argue with you saying MAP is better than MAF.. I just don't know much about the MAF and knew better about MAP.

I'm just trying to learn more by asking stupid questions..

The only stupid questions are the ones not asked......oh and any that phil asks.

[mazdamaniac]

I am, by no measure whatsoever, insulted or offended.
I LOVE people that are inquisitive and I LOVE talking about this stuff.
So, bear with me, because I get side tracked easily and have the memory of a flea, so it takes me a while to get things straight.

[RCCAZ 1]

... yea, Jeff's our little flea, flea

[scotty305]

The Lancer Evo and WRX STI include both MAP and MAF sensors. I won't pretend that I know much about how their stock ECUs work, but they are two good examples of modern turbocharged engines. It would be much cheaper to use only one sensor as opposed to two, so that makes me think that there are enough advantages and disadvantages that the OEMs would want to use both.


It's pretty apparent that a MAP sensor alone doesn't tell you how much fuel to inject: for instance the MAP sensor will measure about 10psi on a bone-stock FD3S that makes about 250hp at the crank. I don't have a specific example in mind, but the same MAP sensor could measure 10 psi with an upgraded turbocharger, ported engine, and free-flowing intake and exhaust setups on a car that could be making over 300 hp at the wheels. The more powerful motor will require a lot more fuel, which is a good sign that it's flowing a lot more air. This is one example of how a MAF sensor could be very useful; a properly calibrated MAF sensor can accurately measure how much air is going into the engine (if properly calibrated) and simplify the tuning process (if you know how to use the data from your properly calibrated MAF sensor). Modern MAF sensors are not much more restrictive than an Intake Air Temperature sensor, you can install them in a bung that fits in any diameter of intake pipe (although you may need to re-calibrate the sensor voltage vs. airflow if you change the diameter of the pipe).


Then again, there's more to tuning an engine than just making sure it runs at your desired air/fuel ratio. I don't know how a MAF sensor would help determine the "correct" ignition timing settings for making power.


As with anything else, the most powerful ECU in the world won't do you much good if your tuner can't use it. You will need to find a tuner who is familiar with MAF-based systems or learn it yourself. Part of learning often involves making mistakes, and we all know how costly mistakes can be when turbocharged rotary engines are involved.



By the way, cool site Mazdamaniac, and thanks for sharing a bit about the RX-8 ECU.



Edit: meant to post this in the "MAF vs MAP tuning" thread in the ECU section. Nonetheless, thanks for sharing about the RX-8 turbo setups.

[rx8man]

Reading some of the posts in this tread, has made me think again... maybe it is worth turboing a rx8???
Good info guys