yah you've got a baby face

My little birdie told me that MNAO ran a Renesis up to 25 PSI. Does anyone else have insider info on this? I think a 10 PSI Blower will work just fine Richard. Does higher pressure make it longer by adding stages?

As others have mentioned before...it's not necessarily the pressure that determines what happens...we are looking for mass flow and proper tuning. Detonation at 25lbs boost will kill an engine...but it will at no boost as well ( maybe not quite as quick though :D: ). A dead engine is just that....dead...so we need to rely on proper tuning and a dose of reality...to end up with a reliable engine that produces the power we want. Personally I want a 280 to 300WHP car that is reliable...not a dyno queen, or a track race monster that needs to be rebuild often cause it is running on the ragged edge.

This isn't what everyone wants...hence why there are different kits out there.

Come on Richard...I like what I hear from this project..................

Yes, lots of air at 10 PSI :)

Not old but young with long flowing golden hair. ;)

Temperature at max compression mainly depends on initial temperature.
T2=T1*(V1/V2)^0.4
You just have to make sure that the temperatures don't rise significantly after the compressor (intercooler, water injection, low boost and/or efficient compressor).

This old mans ears are still ringing from the test bench this morning. I mean I just got back home from the shop where we ran a 4 stage Rx8 size blower.
From this old mouth I can tell you 10psi with 85%+ efficiency. :ylsuper:
I say conservative on the eff because the ambiant was higher by the time the tests got done then it was when I pluged the number into the calcs and I forgot to look at the later number.
8psi will give you about 76 degree temp rise. That's about what we plan on giving the Ren. That way there will be extra headroom for later development of the engine.

To answer a question, yes to get higher presures it takes more stages. Each stage adds .700 to the blower. But it isn't that simple, you have to design the stages together to get the best off design performance.

Notice I said Rx8 size blower not shape. The new parts are not yet built so don't start asking for pictures. It still looks the same. Only the compressor section carries over to the new design.

RP
I'm still here by the grace of God and moonshine. I'm still following the development. 10lbs would be enough except for the diehard drivetrain blowers. We would just need a good tune with that with maybe some porting?. I still love the concept dude. Any news about the possibility of reflashing our on ecu? You know I got to thinking (which is dangerous and self limiting) but too much power would really un-balance this car for me. Heck we do pretty good on the track the way we are--just need a LITTLE more omph.
Take care you old bastard and yea I remember the Bonneville salt flats in the 60's. I was too young to drive but we where racing micro midgets in the central ga area and we helped open the 1st 1/2 mile circle figue 8 suicide dirt track also. I remember Hot Rod magazine featuring a lot of Bonneville cars. Beadlowe or something like that was holding the unlimited record.
Ah the memories--now where is my damn glasses?
Olddragger

I don't think I've seen that equation before. I've given the formula before but I'll do it again. Of course it depends on initial temp but mainly the only difference you can make is with efficiency.

100% eff (which you can get the same day I get Bo Derick) is thus:

Pr^.283-1 is your y factor
Y x degrees R (amb + 460) -460 is your rise over ambiant at 100%
100% over eff=your rise

Therfore if your 100% number is 65 and your eff is 50% then your rise is 130.
If your eff is 75 then your rise is 86 degrees. And so on.

Forget those damn ear plugs again? Who need them - hell I can't hear a damn thing right now :)

OK, you could be my Dad along with Olddragger - does not matter, I'm going to wait for you to finish - got faith in old age and treachery I guess.

Now, with what dannobre says, we need CFM at low boost - I have to ask, "If we force too much air thru the Renesis, it acts as a pressure drop, so have you caculated a "system curve" for the engine block? I remeber that old second order system curve nonsense, "It takes four times the pressure to force twice the flow thru the same diameter pipe". Does this only work for non-compressible fluids?

PS: Have you been involved in http://landspeed.com/ ??

I the posted the stock air flow measurements (at WOT) of the RX-8 engine ages ago, and Richard has a copy of that. Good tool that sCANalyser ;)

Cheers,
Hymee.

Nemesis,
I have patients at the hospital that have intestional problems that will validate the second order system curve nonsense you speak off! They realy get red in the face!
olddragger

If you want to put more CFM in it has to be with more pressure. Now if you want more MASS then you can get that with efficiency. IE cooler discharge. See above equation. :doh:

All the rambling on about turbos that have bigger comp sections so they will give you more CFM at X psi is out of context. The maps are true but you have to figure out what size hole your putting it into. If you put more mass into the hole it has to be with more pressure or cooler air. I've posted equations for this way back at the start of this thread.

If a vender is telling you he has a bigger blower so he gets more air in for a given pressure beware. The exception to that is if his compressor operates in a higher efficiency range. Then that is the unit you should be running in the first place.
Someone somewhere on the forum has shown this with specific turbo numbers. You could search Rotarygod, but that might be alot of reading. :evil_laug

I have this equation from a physics book. T1/T2=(V2/V1)^0.4
It's valid if you compress dry air adiabatically (assume no frictional losses = 100% efficiency) which is still close to what goes on during the compression cycle in a IC engine.
It simply prooves that not boost pressure but temperature (after the compressor) is mainly responsible for knocking issues.

This is great! And would be reason to buy a RX-8 just be able to use your compressor.

Whooo, the adiabatic efficiency of the piston otto cycle engine is about 36%.

I'll play with your equation for a few minuites.

That's the efficiency of the whole thermodynamic otto cycle.
I was just looking at the compression part, which is of course more than 36%. An air compressor (not otto cycle) has a higher efficiency than 36%.

The reason why a piston or a rotary engine should have a relatively high compression efficiency is because they seal better than for instance a roots blower. (Although they would take more space and be heavier if simply used as compressors).
What's interesting and I believe most people don't know is that the Swiss Engineer Bernard Maillard patented a double acting 'Wankel'-compressor 1943 already. Unfortunately for Maillard he didn't realize that he could easily adapt this compressor design to create a 4-cycle engine. (See link - it's German but the pictures are self explanatory).
http://www.rx-7club.ch/pdf/Geschichte-Wankelmotor.PDF
What's also interesting is that James Watt came up with a compressor design 1759 which looks very similar to a Honeywell compressor design, that was talked about in the 80's. I wonder what happened to it?

You guys are too smart for me, but I do know that I'll wait for RP kit to become a reality. I really want one of these on my rotary.

Richard, given all this talk about efficieny I guess I'll ask a layman's question. I recall before you expressed the want to run your SC without an intercooler.

At the rate of efficiency you're achieving, does that still leave you on track to not need one?

Is there a simple guideline to how much extra heat, like a farenheit base temp, that you can push into the engine without worrying about detonation?

Do we actually know when this kit will be fully developed?
What are the sticky points of the project?
Asking these questions to try and help out or to understand what problems are still to be overcome.

After the tests we ran last weekend I'm very confident that our goals are met.
As for a limit I had heard and RotaryGod confermed that A mazda study of several years back claimed 180 f as a safe limit for intake charge. I think this study is still available someplace.

What are the problems left to solve?
First there is the redesign of the housings to fit the engine compartment and the ECU. That's it. Also the intake manifold but that has to come after the new housings are done.

Biggest problem is that we have no budget for this it has to be done around making the shop pay for itself.

Thanks Richard. We're all pulling for you!

Do we have a target price in mind then, and how was the dyno runs??(in theory)

I have the plug and play engine mangement (Interceptor-X) and would really like to see your product on the market! How can I help? Scott

No kidding!

I was going to ask RP about that. All I need is manifold pressure and temperature sensors, right. I have the LC1 afr sensor already. All three could hook up the the -X right?

This way, I could benefit from the -X right now, then add the SC later :)