Trigger angle alteration for 36-2-2-2 (MS3-PRO)

[muythaibxr]

The first tooth after the extra tooth on a stock 2nd gen rx7 CAS is at 5 deg BTDC. So this pretty much proves that Haltech isn't using the same concept of trigger angle as us. In any case none of that really matters, we can make it work, it just requires testing.

[Peter Florance]

I think there are two different RX8 wheels, early and later. The wheels match up with with different sensor locations. somewhere I think I have photos.
Was it due to oil line placement on later motors?

[spyrstas]

Huh, you might be right about that! I do recall the 2009 S2 RX8 having the oil filter pedastal on the front cover, but I;'ve never checked it out.

[Peter Florance]

Huh, you might be right about that! I do recall the 2009 S2 RX8 having the oil filter pedastal on the front cover, but I;'ve never checked it out.

This was not on a MegaSquirt but a MoTeC M4 on Formula Mazda Renesis Protype. The owner replaced older 4 port with 2009 6 port. We found this troubleshooting some other issues: the trigger angle (CRIP in MoTeC speak) changed. Motor still made about 190 RWHP on the Trailing plugs (the mode MoTeC chose for the M4 did not support splits between L and T).

Ken may remember the phone call I made to him...

There were several issues with the car (Bosch Motosports coils didn't play well with M4 and fuel starvation) and some other dead ends, but finally it did about 225 rwhp and 158 tq!.

[bcrx7]

Well the split between leading and trailing is a mute point on a N/A engine. The only reason I sometimes do it to make sure the ignition latency doesn't cause an early fire. On a turbo car obviously that is a different story.

[muythaibxr]

I disagree about split not making a difference on NA engines. You can gain good improvements in fuel economy by making use of negative split. Running 0 split helps power at full throttle.

For the NA rotaries I've been involved in tuning, we made the split as high as we could make it without hurting power (for the same reason we make things as rich as we can without hurting power, added safety margin).

Ken

[Peter Florance]

I disagree about split not making a difference on NA engines. You can gain good improvements in fuel economy by making use of negative split. Running 0 split helps power at full throttle.

For the NA rotaries I've been involved in tuning, we made the split as high as we could make it without hurting power (for the same reason we make things as rich as we can without hurting power, added safety margin).

Ken

Do you remember that call? We pulled the ignitor connectors from the leading plugs and it ran the same...

[muythaibxr]

Yeah, that didn't make any sense at all. Any rotary I have ever seen on trailing only ran like crap if at all. Leading only however ran fine. I remember thinking you guys had leading and trailing mixed up.

[Peter Florance]

Yeah, that didn't make any sense at all. Any rotary I have ever seen on trailing only ran like crap if at all. Leading only however ran fine. I remember thinking you guys had leading and trailing mixed up.

So did I until I realized that ignition mode had no split.

[muythaibxr]

Yeah, but even with no split, the plugs are located in different places and will have a different effect on how the engine runs if you're only using trailing vs if you're only using leading.

My experience with trailing only has been things like:

1) Low power and misfires
2) Glowing exhaust manifold (very high EGTs)
3) Poor fuel economy

My experience with leading only has been that power was a little lower and fuel economy was a little better.

Granted all this experience has been on 2nd-gen or frankenstein engines and not on the Renesis.

Ken

[bcrx7]

I disagree about split not making a difference on NA engines. You can gain good improvements in fuel economy by making use of negative split. Running 0 split helps power at full throttle.

For the NA rotaries I've been involved in tuning, we made the split as high as we could make it without hurting power (for the same reason we make things as rich as we can without hurting power, added safety margin).

Ken

We have dynod 330+HP N/A engine (2-rotor) with zero split and there was no gains to be made. These are race engines and this was both on megasquirt and Motec. Fuel ratio around 13.3.

[muythaibxr]

We have dynod 330+HP N/A engine (2-rotor) with zero split and there was no gains to be made. These are race engines and this was both on megasquirt and Motec. Fuel ratio around 13.3.

If all you're looking at is max power, then sure I agree. When you're not at full throttle there are benefits to running other than zero split.

Ken

[spyrstas]

Ok, so now seeing that there is also a variance on the stock S1 to S2, it's probably a better idea to make it adjustable for a wide range degree scale. It's actually in the same position that I have it! http://www.rx8club.com/attachments/seri ... filter-jpg

[muythaibxr]

We were already planning to make it adjustable, it was just a matter of when.

[Peter Florance]

Ok, so now seeing that there is also a variance on the stock S1 to S2, it's probably a better idea to make it adjustable for a wide range degree scale. It's actually in the same position that I have it! http://www.rx8club.com/attachments/seri ... filter-jpg

But remember if you have the trigger wheel that matches the front cover, the trigger angle should be the same. Our wheel was custom MoTeC wheel so we had no choice.

[spyrstas]

I wouldn't say that trigger wheels(rotary) are matched to front covers. The front covers mostly just have a timing mark on them and on the pulley wheel. There's a bunch of different combinations as different generation rx's had different bolt patterns on the hubs and pulley wheels. As long as the pulley and hub are matched there's only a set timing mark on the pulley, and on the front cover(-5,-10, L or T) according to which it was.

[spyrstas]

So has this feature been added into any firmware update???

[jsmcortina]

Did you determine whether your wheel and sensor are misphased from standard?

James

[spyrstas]

Hey James, well full function made me a new wheel clocked in a different position similar to the stock S1 rx8, offset came out to +12degrees. I also have a guy here with a S2 renesis engine-stock setup, turbod-but his is sensor is at the 3' o clock position.

[spyrstas]

Btw, yes it's misphased by ~40degrees in total.