VE of Individual Cylinders
Turbo Mini Forums

I'm making progress with the Siamese Code trials although some of my recent optimism has gone. I'm waiting for a new sensor to double check the results before I publish anything.

It ocurred to me that the injection system assumes equal VE to all cylinders, so it injects an equal amount of fuel for each cylinder. If a cylinder has a lower VE it will run richer because it has less air for the fuel to burn in.

Now on the A series with the centre siamesed exhaust port, do the inner cylinders have a lower VE?

Thoughts would be appreciated as I may be chasing the impossible.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,
You know what I said 2-3 moths ago. Whatever the reason is (wall wetting, VE difference or both, I still believe in wetting) you need a different fuel quantity. Mine is running 15% less on inner. Idle is better with a 17% difference.
Spark plugs are of exactly the same color and I'm unable to make it ping even with 3-5psi boost (but staying rich of course).

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

sorry for the nooby question but what is VE? :$

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

VE = Volumetric efficiency

Stands for Volumetric Efficiency
Means how much the cylinders fill with air/fuel mix.
You'll want to be getting 100% VE bu thats rather fanciful with siamesed ports

Warning:Stig in Training

That is exactly why, in an other thread, I was talking about a full sequential system with individual cylinder fuel trim (basically per-cylinder VE tables). As I said before, this will require a cam sensor to be able to identify the cylinders and 4 injector drivers to allow for staged injectors.

Jean

http://www.jbperf.com/

Isn't the argument behind 'scatter cams' also that it moreover balances out the VE of the engine over a non-scatter cam?
This should suggest that in an 'ideal' world, there will be a need for a difference between inner and outer with a 'non-scatter grind' camshaft...

Don't suppose anyone has a 276SP they want to lend for testing do they LOL.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Changing the cam will take me weeks given my poor health at the moment.

Making a cam sensor and modding the MSII will take a weekend.

Besides, I think the scatter pattern cam would improve the VE of inner and outer cylinders by making more use of the inlet port. Do they scatter the periods on the inner cylinder exhaust port as well?

Just need Rod and Jean to answer the above.

I think that the code is ready to take the cam sensor without mods. There are minimal mods required to the Megasquirt to take the cam sensor output.

I've ordered a hall sensor anyway.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Are you running different spark on the inner/ outer cyls as well Paul?

- the last iteration of my 5 port back in 05 was running different advance curves for the inner/ outer cyls, pulled the torque curve up sooner, held it longer and made a little more at the top end. This was running an MED AGSP cam. The advance curves were dictated by by the balancing of the EGT's.

If Carling made Mini engines
it would probably be like this one!

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I recall an old CCC when Dave walker talked how he fitted two 'twin' wasted spark coils on his XR2 racer, so he could split the inner and outer cylinders - and this is on an 8-port... I recall it was a Very small, but significant improvement (given it's a race car).

John - You were sucking through a weber on the engine you're reffering to aren't you?
As we know a carb doesn't promote perfectly equal mixture distribution, is this not suggesting the injector tweeks were down to optimising the mixture variation?

Edited by turbodave16v on 17th Jun, 2008.

Paul,

Do you really think the siamesed exhaust can make a difference on VE? These pluses are a LONG way apart - admittedly not as long as the outers, but surely long enough than to not cause an issue?

Edited by turbodave16v on 17th Jun, 2008.

Dave - yes the carb was a weber - I still think with FI the distrubution will be a difficult factor to overcome

Wether its related to VE or not - can't say Paul - maybe its time to get the car onto a measuring device for some development?

If Carling made Mini engines
it would probably be like this one!

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,

I'll have to look at the code. It's been a while...

I'll also look to see if it's easy to make a quick hack with the latest MS2/extra code to port the siamese code. That would be time better spent.

Jean

http://www.jbperf.com/

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

It was working in a slightly different way from the current code and using a different cpu pin. That's another reason why it would be good to go with the latest code.

Jean

http://www.jbperf.com/

If it was to a different pin then it wont work with the current code, unless you know what pin it was?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Second trigger was JS7 in the old extra code and is what it should be in the siamese code but I have no idea what would happen if you actually used it with the current code. Again, I'd need to look at the code and do some tests.

http://www.jbperf.com/