Howdy Jkstill, it has to do with the fact that this motor is less efficient with the air it consumes in making power compared to the (roughly) same displacement piston engine by a magnitude of about 30-35%. That's what we've seen, at least. Ever wonder why a "700HP TURBO!" for a piston car only makes about 450-500 on ours?

B

 

while, as Brian mentions, the rotary is less efficient per unit of airflow the rotary can flow MORE AIR so it is capable of making as much power per engine displacement.

the 13B displaces 1.3 liters but should be compared to a 2.6 liter piston motor because it fires every time TDC passes the plug whereas a piston engine fires every other time it reaches TDC... I E the rotary is a 2 cycle and the normal automotive piston engine is a 4 cycle.

drag racing rotaries have made very close to 1100 rear wheel horsepower on methanol.

that's 7.95 flywheel hp per cubic inch!

so, while the rotary VE is approx 77% of a piston engine, due to better airflow ability, it is VERY competitive.

hc

 

Bingo. The flip side of that coin is the power to weight ratio the RE has over a comparable piston motor.

+1 Yep!

 

bumping for great justice and because we got a couple new FD owners

 

this is gospel, subbing so i can find it later.

 

this post is just a smidge off topic but my guess is that we all are quite interested in doing what we can to preserve our motors.

i was talking Cam Worth (Pettit) yesterday and he brought up something that is, IMO, valuable.

as possibly the largest US rotary rebuilder, Cam notes that an awful lot of failed rotaries have the rear rotor as the problem. this is commonly understood and many theories exist. mostly the coolant flowling thru the front rotor housing and getting hotter at the rear... 'probably a factor.

Cam says that the switch to single turbos generally positions the hot turbine assembly very close to the front LIM runners. he thinks this raises the charge air into the front rotor by 100 degrees making it richer than the rear...

the engine is generally tuned for AFR from a combination of the exhaust from the front and rear rotor. if Cam is correct the rear rotor will run lean V the front.

my point is that if you are running a single setup take a good look at where your turbine housing is in relation to the LIM and get busy adding heat shields.

i have a piece of stainless steel, about 6 X 6 inches that mounts on 2 90 degree tabs that key off the UIM/LIM studs. in addition i made a SS curved shield for the turbine. another method would be to buy a turbo blanket. you could attach the reflective/fiberglass sticky stuff to the LIM also...

bottom line is to spend some time removing the heat off your turbine housing.

howard

 

Howard, I have wondered about this topic in the past and a forum members car made me think about it again. He had a NACA duct on the hood for a cold air intake, what if you had something like that that ducted air around the turbo and maybe even a shroud that was a heat shield and released the hot air into the low pressure area under the car....I have not noticed something like this on race cars so it probably wont work. Any body know why?

besides the fact it would be ugly and would make maintenance a pita.

 

The way to get a better idea about that is to use a pair of EGT's and check to see what's going on temp wise between each chamber. That's my take, at least.

B

 

I remember discussing this back in the day with Pineapple Racing, that is why he always suggested dual EGT, one right outside each housing in the exhaust manifold. I know this doesn't give you AFR on both but it will give you a good idea if the AFR is similar on both rotors.

 

What i have noticed with everyone running dual egt's is that pretty much everyone is seeing 100-150 degree difference front to rear with no way of changing it. Even when giving the rear more fuel, the temps stay consistently different.

There was a theory that it was caused by uneven flow in the fd LIM, but even people with equal flowing manifolds have this phenomena. I think if the front rotor was seeing a 100* increase in air temps over the rear that we would see more rotors in the front blow just from the gasoline auto igniting.

Thats not to say heat shielding isn't beneficial, just that i dont think that's what's causing the temp difference. Otherwise adding fuel to the rear would remove the temp difference. Personally, I inject more fuel in the rear for the very reason that it's usually the one that blows, and fuel is usually what saves a rotary.

I also run an aluminum heat shield around my turbine, it's open on the bottom to radiate the heat downward. I noticed a big drop in engine bay temps just by adding this simple shield. Im sure it keeps heat from the manifold too.

 

can you post a pic of your shield please? id just like to get an idea visually on how i should start thinking about it. i am going to get a turbo blanket as well.

 

Here is a rather innovative, and cheap, heat shield:
https://www.rx7club.com/fabrication-250/how-build-turbo-heatshield-775713/

 

When considering a turbo blanket, take a look at your use of the car. If you track the car a lot, I highly suggest you do not run a turbo blanket as you will slowly hurt your turbine housing and increase the chance of warping the flanges and blowing out gaskets.

thewird

 

thanks for the thread/info guys on the heatshield.

thats interesting wird, that a turbo blanket will actually cause damages to the turbo after a period of time. it does make sense tho, since its going to trap in all that heat thus not letting it go anywhere.

 

so heat shield>turbo blanket for track use?

 

I would recommend having the exhaust/hot side ceramic coated for track duty. On that topic, make sure to get a ceramic coat that is NOT a dark color (such as black or blue). Try to get one that is lighter, as it will reduce radiative heat transfer (which will be the dominating heat transfer mode for such a hot part).

 

Yah, I learned it first hand....

thewird

 

calling all chemists-engineers.

i am real happy runing 100% methanol. i expect to be doing a bunch of track events in 2010 and am concerned about getting thru tech. since i run a 4 gallon Jaz cell that isn't a real fuel cell, and it is located in the spare tire well, flammable contents aren't an option as far as tech is concerned.

as long as i run a non flammable liquid i am o k. 50-50 meth water doesn't ignite.

the question is: how much meth can i run %wise w the water and still not have an ignitable mix?

i realise i can figure it out w a few matches and beakers but it is 7 out today and i am curious. and did a bit of searching.

thanks,

howard

 

This might help Howard

http://www.ashland.com/pdfs/technica...sh%20Point.pdf

Dan

 

would it not be wise to run this setup with out their wideband? i like the failsafe idea but if i didnt get it, would i be ok if there was an issue? how about if the boost control is used?

 

Happy New Year to everyone on the thread

as we consider the primary theme of the thread, which is turning the turbo'd rotary into a high output reliable motor, here's another item to consider:

i received the following from K&N Tech...

"Hello Howard,
Thank you for your interest in K&N products. I can determine the CFM of the engine, I will need to know the cubic inch of the engine, maximum RPM, and lbs. of boost (if any). The following part number will flow X amount of CFM at 1.5” of H2O:

RD-1450 = 791.68
RD-1460 = 1,187.52

When replying, please include this email. If you have any further questions, please call our Customer Support Team at 1(800)858-3333. Thank you for writing and have a great day.


Thomas Walden
Technical Support &
Sports Marketing
800-858-3333
ThomasW@KNFilters.com"

i had inquired on the flow capabilities of two straight 4 inch compressor inlet filters.

the first is 6 inches diameter by 7 inches length..

as per K&N, it flows 792 CFM at 1.5 inches of water resistance.

792/1.92 is 412 rw rotary hp. any more flow and you get increasing resistance. sort of like breathing thru a straw.

a GT35r delivers 897 max CFM!

the majority of filters i see on the forum are no larger than this filter if not smaller!

a TO4z/GT500 flows 1056 CFM! yikes!

the RD-1460 measuring 7 inches in diameter by 9 inches in length flows 1,187 CFM and looks like the filter that should be on most single Fds.
1187/1.92 = 618 rw rotary hp.

to be clear, the above filters will (both) flow additional air but at increased resistance which is a negative.

a nine inch filter is alot to fit in an engine compartment.

i am currently designing/fabbing my turbo (GT4094r) manifold. a partial, yet essential aspect of the manifold is that it positions the turbo so the 9 inch filter fits (into an M2 like cold airbox) without making significant bends.

airfilter flow resistance is a significant factor as is getting cold air.

howard

 

HNY to you too.
I have always heard, to put it the biggest filter you can manage to fit in the engine compartment, now I know the reason.
Thanks again Howard.

 

we've run a honda in the last three 25 hours of thunderhill races, and you are exactly correct.

we are getting about 30 hours out of the b18 before its using more oil than gas, with rod or valve failure imminent. (we've had it happen!) the 2008 motor died from detonation

in a sprint race season they last longer, the whole season isn't 25 hours of run time. a drag racing season is 15 minutes.

mazda has entered the rx8 (and mx5's) and they happily run the whole 25...

 

hey howard, you ditching the twins or you have another setup?

 

my twins were placed to a good home and i will make sure they continue to crank out 500 horses.

i bought a GT4094r and am deep into designing and building a unique manifold. my 2010 plan is to run better than 200 mph at the Oct Texas Standing Mile. 7700 rpm in 5th .74 w a 3.90 final drive.

i am flying down for the March event to scope it out.

i am in the middle of adapting a Tremec T56 6 speed for the proper gearing. i also plan to get out ontrack in 2010.

i will be doing a meth V water dyno comparison in March which i will find quite interesting.

it should be a fun year.

hc