I'm racing a dezert car with very little weight. I'm also building a new car that's even lighter with a redline performance 13brew in it's rear.
Dezert racing is a big mix of understeer and Scandanavian flick. I need a reasonable amount of engine braking in order to flick the back end out and I understand the rotary to be not the best in this regard.
Is there anything or any technique that I can use to assist in engine braking?

 

For those of you interested, the car is to be of this type.

 

The draconian post laws require me to do this. My apologies gentlemen.

 

The draconian post laws require me to do this. My apologies gentlemen.

 

iF you're not turning right at all you could try installing a left front brake. you could go into the corner higher, stab the brake and turn left lol. Idk man. I used to race a mini sprint and those things are always sideways going into the corner. Try a different rear shock damper.

 

going from a tie-down and adjusting towards an easy up shock could cause the rear to slide out a little more.

 

Change flywheel weight? I know can help slow revs

 

I may say a stupid thing but ... if you need the engine to brake to rotate the car, can't you just use an hydro e-brake ?

 

The car will run a cutting brake. Effectively a hand controlled hydrolic brake that is applied to either of the rear wheels. IE, turn left or right on the brake.

But that is not the issue. I'd rather pull the back end around under decel than setup the car on the cutting brake.

 

A reduction in flywheel weight may slightly effect a road car, but the reduction in rotating mass when I'm running 35" mud tyres and heavy beadlock rims is negligable if anything.
It's already running an aftermarket lightweight, KEP flywheel.

 

Car already runs a cutting brake (independant rear hand brakes) however it takes a split second to use and makes a process that it automated (ie back end comes around off throttle) something manual. It also stresses a rear braking system that's already taxed. I'm limited to 12 inch rotors by the 15 inch rims and 6 pot calipers.

 

Could I simply put a flapper valve in the exhaust that closes at idle speeds?
Issues with hot side temp?

Or what about closing the throttle entirely while on decel. IE closed to the point where it won't maintain idle. When RPM drops below 3k enable an idle bypass.
Apex seals okay with a load in reverse to what they were designed for?

 

What about softer springs in the front for more dive?

 

Dive will allow me to throw more weight forward, after braking, which is not the effect I was after. It's about engine braking the rear to pull the back end around. An instantaneous change in attidude given a removal of power, not application of brake.
Allowing more weight transfer will also affect control with large polar mass movements being difficult to adjust for.

The front end will be softly sprung (it's hard not to with 21 inches of travel), but also incorporates anti-dive in the A-Arm geometry.

 

Idk about 13brew my n/a 13b and 12a's engine break like fn champs

 

clutch kick? LOL I dont really get if you just want the engine braking to help with deceleration or with making the car rotate ..

 

so you don't get it, sit back and let someone else talk?

OP. i havent driven one of these types of "cars" before, but if you can change ur gearing it may help. i do know that you can't engine break into a drift in an fc unless ur doing it in 2nd gear(maybe 1st at a low speed). i know a few "drifter guys" that engine break into corners and then power over.. which to me, is quite violent... but driving style is a preference. the rotary has great engine braking capability, but you'll get the most by having the rpms in the 4-5ks when you shift down, really the higher the better. if you can adjust your tire size or gears, you may find what you're looking for.

 

With a redline of 8K RPM, running small 33 inch tyres.

Gear, Redline km/h, RPM in new gear
1st 95 0
2nd 131 5778
3rd 170 6176
4th 204 6674
5th 240 6800
6th 276 6957

I know the top speed isn't high, but it is on dirt. 1st is purposely set high to try and get a good pull from the start line and also have a useable gear for slow speed cornering.

 

Near as I can tell you are wishing to use a technique that is more common to front wheel drive rally cars while you have a rear wheel drive. From my experience; if you are trying to make good time you need a bit of over-steer and do your setup by turning into the curve with enough throttle to drop the rear out , then counter steer and steer with the throttle to get through the corner. Use anything available as a "berm shot" just like a bike. set the car up for over-steer and a tad much caster seemed to work for me. My preference is for a little de-camber in the rear. Run up on corner, back off, turn into corner, stand on it, let up as back comes out or better still counter steer to keep car where you want it while staying on the power. perhaps a little smoother than I have explained.

 

add more rotors then you will have more compression braking from a rotary engine.

 

Engine braking is a technique that I (and almost everyone else I've seen on dirt) use very sucessfully in both of my rally cars and also my 800hp Cosworth/Nissan Jimco offroad race car. It's worked very well for me in the last 22 years of racing.
It sounds like you are unknowingly using the same technique anyway. By braking then standing on it you're unloading the rear end before planting power. Without braking the rear end free (under braking) you end up with the potential to push heavily into the corner and blow very wide.
I also accent this process with a Scandanavian flick where possible. And yes, I both berm shot and kerb hook in corner.

By de-camber you're talking of neg camber?

 

Tempting... very tempting.
However I'm limited by the FIA multiplication factor and local class regs to two rotors. I'm also restricted by the necessity to run a very light engine package with about 450hp. It's an estimate based on the amount of power I can get to the ground with my Cosworth/Nissan power plant. Hence the selection of the 13b in the first place.

 

Yes negative camber. and truthfully i raced old school with a mid engine 250hp corvair and just drove around the corners. With a good handling car there is no push. Just set up with steering and control with throttle to achive maximum speed.

 

I apologize for prior posts. the topic is engine braking. under deceleration You are turning an engine into an air compressor and the horsepower (braking power} required to run a compressor is -- volume X pressure but in an engine the power stroke after compression gives that power back, early exhaust opening will help, but a compression release right after top dead center (dirt bike) would be ideal (principal of the diesel "jake brake") suggest that you read the recent post on "wasted spark" it is possible that a solenoid activated pressure relief valve or a stand alone activated valve in the housing like a 3rd plug. or perhaps run one plug and use the other opening. Meanwhile cutting fuel and or ignition during deceleration and closing intake completely should help. engine braking is more natural for the driver and is part the natural slowing down and if brakes are not used the foot is right on the accelerator for quick corrections.

 

Jake brake may be a little agressive for what I require. But a good idea.
If I do have problems with engine braking I'll try closing the throttle plate and run a soleniod that I'll open at 3k RPM (to allow me to idle).