I'm not sure anyone else got the joke.


the screws/plugs are a dead giveaway.

 

That thing sounds great, I'm surprised it took someone this long to finally do it. I see more of them being built in the near future.

 

It uses smaller valves because the engine is small. They simply had no choice.
My point was, that you can still achieve reasonable performance even if flow was restricted.

Besides, increasing dynamic compression ratio, doesn't reduce flow.

And again, since the Renesis has no port overlap, any exhaust restriction is of less importance, as fresh gases do not have the opportunity to scavenge any remaining exhaust gases anyway.

 

I'd Just Feld In Love Again ,first With My 8 And Now With This Engine
Thanks !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

No, but it allows you to get away with smaller exhaust valves so that you can fit larger intakes for more power, there's a trade off between the two that bias toward the intake valve the more compression you have.
Not really a problem with a rotary as the intake ports don't get in the way of the exhaust ports, so it's not really relevant, besides, it's the shape of the ports that makes them restrictive, not the size.

 

Since the engine is small both intake as well as exhaust valves are small. Besides you don't take into account, that the VW engine actually does have a valve overlap and the Renesis doesn't.


Size is important. The pressure loss through any opening is proportional to the flow velocity. And the flow velocity is inversely proportional to the cross-section of that opening.
Needless to say that an exhaust valve has a worse aerodynamic coefficient than a brick and the Renesis has none.

 

Any opening with a constant cross section with no turns or twists that is, you seem to be forgetting that the rotary has two 90* bends one right after the other which creat a huge disruption and boundary area, especially the sharp SSRs.
Valve overlap helps with power, so that makes your point even less valid, especially given that the engine runs at a pressure ratio of 1.5+, it has a huge amount more pressure available to flow air through that port.

The exhaust ports and flow on the VW has basically no similarities to the Renesis, it's not a valid comparison at all.

 

So, I guess Carl now needs to start the 20B GB thread...?

 

1. As said a valve is not shaped in any aerodynamically favorable way either. And the cross section around the valve and its exhaust opening is not constant nor is it particularly straight.

2. Regardless: Size is still more important. If the cross-section area is 4 times larger the flow is also reduced by a factor of 4. And again the pressure loss is always proportional to the flow velocity squared - regardless of shapes and twists.
If the flow velocity is quadrupled one ends up with 16 times the pressure loss for a given shape.

http://www.engineersedge.com/fluid_f...ssure_drop.htm


Large flow restrictions one does indeed obtain if the opening of the exhaust pipe (header) is significantly larger than exhaust port facing it. But this does not seem to be the case.


Again, the point is that with an overlap one can scavenge the combustion chamber and pressure loss through the exhaust valves becomes an important factor.
If there's no overlap as with the Renesis, scavenging is simply a no-option and pressure loss through the exhaust port is of less importance.
Because whatever you do to reduce that pressure loss: You can never scavenge the remaining exhaust gases from the exhaust chamber even with 30 psi of boost pressure.

 

just been talking with a guy here in NZ that has built 2 x3 rotor renesis motors already and is now building a 4 rotor renesis for a guy in the US to put into an RX8..........

oh - and no BS calls please - this is the guy that built the engine for the 6second RX8 from Pueto Rico .

 

Sweet!

 

Lets see what Alec Bell has done in pics please.
Regards
Carl

 

He lives a 100km away - but did say I was welcome to come and have a look so I may do that soon .

 

u know someone could bring there housings from there renisis to flow the outer ports compared to the inner ports and then we would really know how that middle rotor is doing!

 

sick and subscribing.

 

thanks carl for joining and sharing !

 

How much for you to make another one of those shipped to Louisiana, USA?

Failing that, how about a step by step construction process mapped out with photographs? I have access to a machine shop, but don't really have the expertise in engines to go into this cold.

 

Nice! What happened to the Renesis timing cover?

Cheers,
Hymee.

 

I noticed that you are running single length intake runners. Any thought to a variable length setup like the OEM renny? I know this is a big improvement for N/A rotaries.

 

I'd imagine they'll be in a fairly short rpm range most of the time, so it'll provide no benefit for a lot more weight and complexity.

 

I agree it's complex and I don't know much about optimizing for drifting but I do know it was a key component to the Lemans team win in 1991 with their 4 rotor car.

 

This engine pulls hard from low rpm right through the rev range,we are at 8250 rpm at the moment and it still has not stopped pulling hard.
Regards
Carl

 

I think a lot of lookers have been pulling hard as well after seeing this

Cheers,
Hymee.

 

what does he do with the exhaust ports?
OD

 

Agreed. I think I need to invest in Jerkins lotion after this thread.