negative split
Photo Diety
Joined: Mar 2001
Posts: 2,311
Likes: 0
From: Florida
Ok here are the maps. Leading, trailing, and split. I'm into boost by P9. This is one of the reasons I'll probably switch to a Haltech E11 if the car comes back together. It has a larger 32x32 cell tuning map which will allow for much finer tuning in vacuum/boost and I'll still be able to have a 24psi + map.
Map is definitely older than the one I'm currently running but it's only different in a few areas. I can see I was messing around at idle (PFC won't give up idle mixture control) with this map and a bit at highway cruise. But it's mostly the map I run daily. Again, lots of work to be done to it but it seems to work just fine.
Map is definitely older than the one I'm currently running but it's only different in a few areas. I can see I was messing around at idle (PFC won't give up idle mixture control) with this map and a bit at highway cruise. But it's mostly the map I run daily. Again, lots of work to be done to it but it seems to work just fine.
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Joined: Apr 2002
Posts: 1,336
Likes: 2
From: Dayton, OH
Originally Posted by rotorbrain
wow. . . interesting. . . VERY interesting. thats A LOT of negative split!!!!!
thanks!!!
thanks!!!
-ROb
fart on a friends head!!!
Joined: Mar 2002
Posts: 4,104
Likes: 2
From: sheppard AFB, TX
ill keep an eye out for that one as well. . . hmmm. . . maybe i should just take my motor out and have it built like yours (kinda. . . not an RE) at CLR. i could totally use a killer setup. hahaha. bah, i better save cash for the "next generation". hahahaha
Joined: Mar 2001
Posts: 31,796
Likes: 3,210
From: https://www2.mazda.com/en/100th/
Originally Posted by brillo
Since we know that Mazda uses the negative split during idle on my RX8 for economy benefits, I began to wonder why they didn't run negative split accross the board since the car is NA if it really helps the fuel economy.
My guess would be that the lean condition heats the EG up so much that at high RPM's it would burn the cat out to early, and Mazda has already had an issue with cat temps, hence the 11th 1/2 hour ECU flash port campaign as the cars came off the boat.
My guess would be that the lean condition heats the EG up so much that at high RPM's it would burn the cat out to early, and Mazda has already had an issue with cat temps, hence the 11th 1/2 hour ECU flash port campaign as the cars came off the boat.
1. rx8 has higher compression
2. they need to tune it more conservatively, car needs to be reliable for any and everyone.
3. they have a recall for the car melting, higher temps would be bad
Old [Sch|F]ool
Joined: May 2001
Posts: 12,848
Likes: 563
From: Cleveland, Ohio, USA
Originally Posted by Project84
The only way the trailing plug can ignite the next chamber is if the timing is so far retarded that the apex seal is between the leading and trailing plugs when they fire. The leading plug will fire into one chamber, the trailing plug will fire into the following chamber.
It's easy to do, too, just get your trailing wires reversed! Or stab the distributor in 90 degrees off and fail to notice it because you have direct-fire on the leading.
boxed in and drawn out
Joined: Dec 2003
Posts: 555
Likes: 0
From: Bayouself
With the negative split application being under vacume to 0 boost how would it apply to different motors and porting? Under boost and torque load the timing is very engine dependent but even then Steve Kahn admits to using a "safe" timing map for ported and nonported motors alike. (FAQ in Timing).
Could a negative split map be applied in the same way since its is mostly under vacume?
Could a negative split map be applied in the same way since its is mostly under vacume?
Full Member
Joined: Nov 2003
Posts: 192
Likes: 8
From: .
I did this today and could definately feel improved bottom end/midrange. Throttle response and drivability are better also. Engine is a 12a pp with gen1 electronic distributor. I did the same as rotarygod and hooked a vac line to trailing, leading is locked at 22deg btdc and trailing at 20deg btdc no vac. Trailing now advances to around 37deg btdc full vac and ofcourse leading doesn't move. It took 5min and cost me nothing. I expect to use less fuel also.
Originally Posted by cewrx7r1
Thanks RX7TT95 for the negative split maps.
I'll try it after my 1600cc injector install is completed and AFRs retuned.
I'll try it after my 1600cc injector install is completed and AFRs retuned.
Chuck any update on your results/interpretations of negative split?
Very interesting thread thanks guys.
Originally Posted by rotarypower101
Very interesting thread thanks guys.
Full Member
Joined: Nov 2003
Posts: 192
Likes: 8
From: .
Originally Posted by PDF
I did this today and could definately feel improved bottom end/midrange. Throttle response and drivability are better also. Engine is a 12a pp with gen1 electronic distributor. I did the same as rotarygod and hooked a vac line to trailing, leading is locked at 22deg btdc and trailing at 20deg btdc no vac. Trailing now advances to around 37deg btdc full vac and ofcourse leading doesn't move. It took 5min and cost me nothing. I expect to use less fuel also.
Still going fine and fuel economy has definately improved.
just a side note, i'm going to find out if the Megasquirt EMS is able to do negative split, since i will be going to that in the near future. it seems that this might actually have some use for non-turbo cars, so it would be interesting to try out.
Well I'll give this a shot on my daily driven full bridgeport and keep tabs on fuel use. Anything that can help me save some right now would be great. After all whats 5 minutes and 12 inches of vacuum line in comparison to the savings. Gas prices are starting to catch up for us soldiers here in Germany.
Originally Posted by coldfire
just a side note, i'm going to find out if the Megasquirt EMS is able to do negative split, since i will be going to that in the near future. it seems that this might actually have some use for non-turbo cars, so it would be interesting to try out.
yeah, i know that the current MS-1 code for rotary doesn't have it in there, i should have mentioned that, but i do believe someone was going to take a look at it.
it doesn't seem like it would be a very hard modification. i know a bit about the coding, but i have only looked at it briefly so i am not quite sure (i have actually looked more at the MS-2 C code than the assembly of MS-1).
it doesn't seem like it would be a very hard modification. i know a bit about the coding, but i have only looked at it briefly so i am not quite sure (i have actually looked more at the MS-2 C code than the assembly of MS-1).
Originally Posted by rotarygod
No it can't. It only has a range of 0-20 degrees split. If you enter in -1, 21, or any other number, the trailings shut off completely. I've been trying to get someone to change the code for a while now.
Cant be bothered anymore
Joined: Aug 2004
Posts: 465
Likes: 0
From: Norwich UK
I have been having a play with neg split whilst running in my new lsd. i m only at -3 deg neg split at the mo but the car seems a lot quicker through vacum and also strangely a lot more drivable.
I need to go a bit deeper in but in gonna start to try and shape the vacum timing map a little to see what results i get.
So far very good.
Scott
I need to go a bit deeper in but in gonna start to try and shape the vacum timing map a little to see what results i get.
So far very good.
Scott
