Finally after 2 days of tuning a Rallycross PP engine on a Superflow 901 dyno we finally found 300+ hp Here is some numbers:

6000 rpm 182 hp
6500 rpm 188 hp
7000 rpm 212 hp
7500 rpm 231 hp
8000 rpm 266 hp
8500 rpm 293.6 hp
9000 rpm 309 hp
9300 rpm 314 hp max
9600 rpm 307 hp
9800 rpm 295 hp Max torque was 250 Nm or 184.5 ft/lb@8600 rpm

Between 6000-9800 rpm there was newer below 205Nm or 152 ft/lb.
Average 6300-9800 260 hp! A figure i am very satisfied with

Numbers are STP corrected

My friend Gus FD3s will post some power curves tomorrow

A short set up of the engine
PP housings D port ML Wankeltrim with 45 mm inner dia dysa, Gene Berg 54 mm with 47 mm chokes, 54 mm idia 600 mm long headers, RX/8 rotors coated and balanced, Ianetti 3 mm ceramics,Sequential 4 coil ignition, Aspen 102 race fuel, Motul 300V synthetic oil and so on. Exhaust temp 1480/1520 F. We change a lot on the fuel curve and came up with F7 tubes 270 mail and 100 Air jets. AFR 13.4/13.6. Ran out of time but should have a third day for more tuning

Lasse

 

Congrats on breaking 300hp. I'm surprized on how the hp drops after 9300 rpms cosidering it's a pport. Your exhaust temps seem really low for AFR's in the 13.4-13.6. Where is your egt bungs located? They should be closer to 1700's F with those AFr's

 

The temp probs is about 3" from block. I have ceramic coated the 10:0 rotors and i think the combustion is more complete and hotter, therefore lower EGTs? Also the header is black ceramic coatad and also the aluminium intake. Used 23-24L ignition and -4 split. Did test 0 split but lose some hp. If i should have used distributor, i have seen as high as 1800-1900F on a bridge 12A Would have been nice to do further testing, but it's always a matter of time (and money)

/Lasse

 

 

Did you try more timing? 23-24 is really low especially with 103octane fuel.

 

Are this engine for a swedish or norweigen car ?
Witch class are the going to compete in ?

 

Yeah i did some testing up to 26L but lose power. I use 102 octane and saw more stable fuel curve but little hp gain comparing to V-Power 99

/Lasse

 

The engine is for an Norwegian FB with dog box and 6.12 Volvo axle. Think he will compete in the big 3 litre class.

/Lasse

 

That's wierd. I don't see how more timing could lose power. As long as detonation is not a problem the more timing= more power given the fuel mixture is set right. I'm running over 30L on my motor with 100 octane.

 

Shouldn't you be looking for peak torque and not emphasizing knock readings? Obviously knock readings are crucial for the engine to not die but after peak torque is met why throw in more timing????????

 

More timing does not mean more power. At some point, more advance causes a power drop because the engine is losing power due to trying to compress the expanding gases.

A lot of engines will start to detonate before you can get to the optimal timing, but some don't. N/A rotaries, generally, don't.

I've run over 30 degrees with no problems, other than not making as much power as at 22-24 degrees.

Also you have to figure that octane here isn't the same as octane there. Our 100 octane would be like 103 or so there, their 99 would be like our 96 or so here. Different measuring stick.

 

It all depends on the motor. Every motor is different and will peak at different timing. But usually higher octane fuel and running 11.5 spark plugs you will gain more power at advance between 26-30 degrees.

 

Octane does not determine how fast a fuel burns. It only determines how prone it is to detonation and that is not determined by how fast it burns. You'll also find that an engine running no split can't run as much total timing as an engine running say 10 degrees of split. That's not necessarily a bad thing though.

 

Well...........

The two aren't directly related, no.

But two interesting things...

For pump fuel, generally speaking, the cheapest/easiest (and therefore, what you're likely to get) ways to increase octane, tend to decrease BTU slightly. So higher octane fuel may have less energy in it.

What may bake your noodle though is that the faster you can get the fuel burnt, the less likely it is to detonate in the first place. Think about the condition of the end gases as they have a flame front expanding and compressing/heating them, and it may become clear. It's not magic how modern combustion chambers can tolerate compression that 40 years ago would have engines pinging like a can of marbles on the better fuels we had then...

Not needing as much timing just means the combustion process is happening more efficiently!

I think I should take my timing light with me to the 1320' dyno tomorrow, along with the laptop, and do some datalogging. I know I need to be running less timing but how much, I don't know.

 

Exactly! The higher the VE the less timing required. Look at turbo applications - artificial VE.

Rx4/5 rotors take less timing to make peak power than S5 or RX8 rotors. Why? Better combustion chamber shape, resulting in a faster combustion process. When it comes to N/A rotors the combustion chamber shape seems to be more important than the static compression ratio. Rotor weight is the trade off.

 

[QUOTE=
A short set up of the engine
PP housings D port ML Wankeltrim with 45 mm inner dia dysa, Gene Berg 54 mm with 47 mm chokes, 54 mm idia 600 mm long headers, RX/8 rotors coated and balanced, Ianetti 3 mm ceramics,Sequential 4 coil ignition, Aspen 102 race fuel, Motul 300V synthetic oil and so on. Exhaust temp 1480/1520 F. We change a lot on the fuel curve and came up with F7 tubes 270 mail and 100 Air jets. AFR 13.4/13.6. Ran out of time but should have a third day for more tuning

Lasse[/QUOTE]

Lasse, what coating are you using on the rotors? Have you come to any conclusions comparing coated to non-coated?

Barry

 

Not to totally threadjack, but on the subject of timing, I just got back from the 1320 foot dyno.

I discovered two things today:

My timing was at 22 degrees, not 27.

Going any higher, or any lower, made the car lose MPH, within the bounds of scientific error. (No split, large street port 13B, 87oct R+M/2) I went as high as 25 and as low as 20, making a couple runs at each setting. Putting it back on to 22 degrees got the MPH back.

So, I'd set the timing wrong relative to what I'd wanted, but it turned out to be just right...

 

I use a coating from a Swedish company but don't know the products name right now. As i see it the coating transfoms the heat to more stable and more complete combustion that's why the EGT is so low as 1540F at 9800 rpm. I maybe have a good way to check the the incoming air temperrature before leading ignites the combustion. This is a way of finding how hot the gaseos mixture is if a 3 cycle phase occurs. Hope to have some data in 3 weeks.

/Lasse

 

Damn straight! That's absolutely true.

 

Your timing numbers match what someone else said here a long time ago. I forget who it was but on 87 octane they ran no split and obtained max power at 22* advance. On 92 octane they obtained max power with 27* advance.

 

A 1031 axle with 6.12 gear ratio is to weak so it will probably break.
You need more power and torque for class 3
What is the number from 2500-6000rpm ?
And why is the power dipping at 9K

 

That would be Logan (GTORX7). His setup is a *little* bit different than mine Lots better VE and higher compression. I think the fact that the timing seems to want to be the same is coincidental - every engine is a little bit different.

Which is why I think formulaic "run X timing and Y air/fuel ratio and you're golden" tuning advice is not be-all and end-all. It can get you roughly correct but it will never be ideal except by happy accident.

 

Yeah and at 100 octane around 28-30 and hence the question that I asked about his timing being so low.

 

The porting is going to have alot to do with that. What total advance works best on a streetport isn't going to be the same as a peripheral port with much more overlap and a very different VE range.

 

You bet. The worst advice like this is when people recommend it for turbocharged engines. I always think it's funny when someone says, "you've got too much timing advance" or "you're running too lean". How do you know? That's guessing. What may work on one turbo will be completely different for another. Even at the same pressure levels.