slash128

QFT. Last week I pulled the WG spring to do some 0psi logs. Boost gauge was reading 0ps avg-1psi peak but my logs showed calc load over 150%. Even with the WG wide open this thing picks up quite a bit of pep just from the additional flow with little pressure increase. Airflow peaked at 339.6g/s... at atmosphere!

logalinipoo

Thats why i upped my ve on the upper end a bit.

slash128

Sounds similar to what I have. VE peaks around 4KRPM, drops down from there to about 6K then slopes back up to the end. The VE table is where I do the bulk of my boost tuning. I set the gear fuel tables where I wanted, scaled the injectors as best I could no boost, then did all the boost tweaking in the VE table...

logalinipoo

I've got a pretty reliable 3 PSI boost and have it lined out to a okay 11:1 anything in boost. I'm still smoothing it out some.

I'm thinking of making some DET PHONES and wiring them into the radio for testing and tuning.

logalinipoo

I just took a little look at your maps. The 430WHP map doesn't look like you did much, in there.

I'm currently looking for trends and trying to get the fuel injectors and MAF about as close as I can then I'm going to tweak the VE If I see anything specific to rpm and load. I've already tweaked it a bit just before the SSV opens and the APV valves to remove the spikes form them.

slash128

It doesn't take much of a change in the VE map to change things. For me it is fine tuning. I set my gear fuel tables where I want and tweak the VE table to dial it in. I also Virtual Dyno quite a bit as a tuning aid. I would overlay my logs in VD and see if my previous changes led to a relative increase or decrease in power and further adjust VE accordingly.

logalinipoo

Things are looking good at 4 psi, 125% load I'm maintaining 11.5:1.

Timing is way retarded. Im about to start working that up a bit, but its what scares me the most. Im still working on my compilation of timing maps I've found.

slash128

Nice work man how's it feeling?

9krpmrx8

iTrader: (46)

Kanes motto, "Just add fuel",

logalinipoo

It's not much, but it's noticeable in the lower rpm. Anything over 20 MPH and as Soon as I floor it I'm at full boost(4 PSI Manifold). I'm still really retarded up top. over 1 Load I'm at 0 Leading and -10 Trailing. But I'm still working out everything. I've got a homemade det phone going togther. I'm waiting on parts right now. I'm going to try soldering an Aux input into my radio and running it there.

I know my timing is crazy retarded, I'm just trying to be very careful with it.

logalinipoo

I'm thinking of going a bit of another direction with my timing then most I see.

Less Split, Less advance, Less fuel. Why? Well Zoom Zoom Boom.

slash128

Careful of retarded timing and EGTs

Hows your transition fueling looking? Got any logs?

logalinipoo

I've got a EGT gauge and I've been keeping an eye on it to get use to where it likes to be. Here is a CSV that's named Zip of a pull I did yesterday. I haven't drove it today with the updated timing. I also stretched the VE map last night from 1.25 Max to 2.5. I'm just doing one map at a time then driving it a bit to see how things are going.

Transition is not too bad, I just adjusted the VE a little for the lean spike at 6000 RPM and 100-125% load. It did something a little strange and went lean in the middle but went back to 11.5 on the final gear. All my Air/Fuel maps read exactly the same.

slash128

Zip file seems corrupt?

logalinipoo

not a zip. rename it .csv

slash128

Oh duh, didn't catch that

logalinipoo

All three of these combined should increase power and might make it safe at the same time.

I'm not joking about this for a timing strategy. I'm thinking of aiming for the 12.2:1 AFR range. With some pretty low splits like 5Deg maybe less. Then see where timing needs to be. It will be obviously less than people with more split.

I know that for best power you want the highest cylinder pressures sometime after TDC. I think 15-20 Degrees. This is hard to attain because you have to advance ignition then run into knock from having ignition too early. Most people throw more fuel at it to give it more advance, but the extra fuel costs some power also. There is almost no difference in power from MBT of 13.2:1 and RBT of 12.2:1. But we’re talking fuel levels down to 10 I’m seeing. I’m Aiming for 12.2 Since It’s going to be safer then 13 with little to no power loss.

Any advance above TDC is starting to push backward(taking away power) and causing a drastic increase in chamber pressure before you reach TDC. On the other side of TDC you are using your charge in a more efficient place, which nets you more power than it costs you. If you can get a faster burn with less timing advance then you should gain the power that is lost from that backward push. I also think knock is happening before TDC, Not after. Reducing the pressure should greatly decrease the chance of knock. It will also reduce temperatures making pre ignition less likely.

Less damage from knock? If knock happens before TDC then pressure is still increasing and it’s like hitting something head on with a strong impact. If it happens after TDC with the chamber volume increasing it will reduce the impact. Like getting rear ended it shoves you forward but is no where near as violent as the head on hit at the same speed difference.

By reducing split I’m effectively advancing timing. I am thinking that one degree in reduced split is more than one degree in advance. It looks like most people between 8 club and 7 club are running around 12-15 Degrees of split. There are a few people on 7 club that reported running 0 split( no posted maps). It looks like a lead timing in the teens is best for power but has a strong risk of knocking. If I can reduce split to 5 Degrees then lead timing would be down around TDC.

The less I advance ignition the less chamber pressure there will be when it reaches TDC. That 10 Degree reduction caused by using less split could reduce Chamber pressures BTDC very dramatically. It might be half or more. That would allow for more boost maybe a lot more.

logalinipoo

Anyone with some insite on that strategy, or see any big holes let me know. I'm always up for thinking things out.

Brettus

iTrader: (2)

let me know what happens when you hit 15psi .................

logalinipoo

I will also have water injection. Im sure it will be required. My plan is to tie the water injection into my boost controller so if it is not working then my boost drops pretty low.

Harlan

iTrader: (3)

Running more trailing timing (less split) will reduce required timing and reduce knock, BUT if you start to go lean it's like pushing more and more trailing timing. That's why people run higher splits 15deg+ in boost, it's not for power it's a safety measure.

The peak pressure point for power on a rotary is about 45deg, and it's due to the rate the combustion pocket expands and the leverage it causes on the e-shaft. Knock comes not from having the ignition to early, but from having the in cylinder pressure get high enough to cause detonation. Detonation is unavoidable once the fuel reaches a certain pressure determined by the octaine of the fuel and an ignition source is present. Since peak pressure happens at 45degATDC that's when knock happens. Knock won't happen before 45deg unless something is VERY wrong. This is where you get into preignition and that causes more knock and engine destruction rapidly. Preignition can (will) cause knock, and knock can (if it goes on long enough) cause preignition. This cycle is what I believe causes engine damage.

Ignition before or after TDC doesn't mater, it's the area of the pressure curve on either side. The piston (rotor) is always fighting a little bit of pressure from combustion (and most of the pressure from compression). If adding timing puts more area of the pressure curve before TDC than after you lose power.

Again, ruining low split is safer right up until you go lean, then it's a recipe for disaster. I don't recommend it. When I started testing lean burn I figured out some of these interesting quirks.

Harlan

iTrader: (3)

I guess I wasn't that clear. When the engine starts to lean out the leading plug is sitting in a mix close to what the ecu commanded, lets say 12.5:1, the trailing plug is sitting in something much richer lets say 10:1. As the mix goes leaner the leading plug sees 14.7:1 while the trailing plug sees 12.5:1 this change in mixture is like advancing the trailing plug while retarding the leading. If the plugs had equal worth then this would be no big deal, but because of how the combustion pocket squishes the trailing plugs advance is actually worth much more than the leading. So it ends up like you are running much more advance than intended.

But until something causes your engine to go lean everything is golden. You could even run negative split in boost if you set the timing right, and the power would be higher.

Here is a good WI link, some of the info is outdated like extreme problems using fuel injectors, but most of it is solid info.
https://www.rbracing-rsr.com/waterinjection.html

Brettus

iTrader: (2)

Where did this info come from ? Never heard this before .

Harlan

iTrader: (3)

The information is out there, but you have to read a bit between the lines or experiment yourself. The reason why lean burn works well on a rotary is the rich pocket of fuel around the trailing plug, it's also one of the reasons why Mazda went with side port exhaust. The side port exhaust prevents the excess fuel pushed along by the trailing apex seal from going straight out the exhaust unburnt. This lowers HC emissions and raises fuel economy. It also causes flooding to be a bigger issue.

The trailing plug is always washed in this rich mixture, even when you read 14.7 going in and 14.7 going out. The unburt fuel kinda hangs out, and each cycle a little gets added and a little gets burnt. I ran minor (5-10deg) negative split for lean burn which ran fine with a stock AFR, but as I started leaning out weird things started happening. It started acting like it had WAY too much advance, and as I pulled advance (especially trailing) everything fell back into place with EGTs lower than original and no increase in ECT. I would have continued, but before I could figure out what was happening I was installing the turbo and had other things to think about. It's the kinda thing that makes a lot of sense in retrospect.

I plan on continuing with lean burn after I get the electronics working. But enough derailing the thread, I gotta go back to cleaning out my garage.

logalinipoo

No derailing here thats the stuff im intreated in. Ive been running negative split in my low load for quite a while. Im not at the moment since i started this tune form scratch but ill be going back to it. Although i haven't done lean burn.

My brain is still turning about what you first said. Let me stew on that for a while.