now that we have a n/a section

who is running 0 degrees of ignition split on there n/a engines either efi or carb.

 

Whats the benefit in this?

 

supposedly more power but i never dyno that car because bearing damage from ruptured oil cooler line

 

That sucks, i had that happen to me before.

but i havent heard of anyone making more power from this.

 

You'll find areas in the stock ecu timing map where 0 split is used. Basically during WOT.

 

I dont understand anything much about timing, but i wanna change it. Im sure its stock because its a little rich (thats normal right?) do i advance or retard the timing? and can someone PLEASE help me with my vacuum?

 

when you say zero split i assume you mean both leading and trailing firing at the same time? because i've read that many NA 20b and some of the new zealand NA 4 rotor engines are running their ignition like this

 

Zero split, or even very low split (1-3 degrees) will give higher torque and power. I use it on almost all n/a setups at full load.

 

are emissions the only compromise, or is there more?

 

I never tried emissions testing with the zero, or near zero split. On a side note, which I dont have two setups side by side with thousands of miles to compare, but I think zero split wears out plugs slightly faster. Possibly due to the hotter flame front?

 

that is one consideration

the rx8's timing map goes from negative split @idle and low load to a very low split in light to medium split situations to running about 10 degrees of split @wot

also to be considered is cross fire, if you fire em all at once, then cross fire cant hurt.

 

what plugs are you using?

 

I am.

One MSD box, two coils through the distributor.

Why? Too cheap for two boxes and I *want* a functional rev limiter.

Downside is that fuel economy suffers a little. (25ish MPG instead of 27-30)

 

25 mpg?!?
I wish I could get that....
mine is anywhere from 11 - 15
It's really driving me to sell my rex.

 

There is no reason to be getting fuel economy that horrible unless your tuning is way off (not enough low load advance/running full power fuel mixtures in the low load region) or you're just driving like an animal.

There used to be some FD guys in Columbus who'd get 30mpg in their turbo cars, your higher compression setup has no excuse.

 

If we retain stock ECU, corrections force us to average around 14.7:1. That's why my car averages 22 mpg. If I had a standalone, could definitely use the lean burn feature.

 

i get 20 on the highway, 14-15 in the street. It might have something to do with a large streetport and Aux bridge, but I could be wrong.

As for selling your rx7 because of gas mileage: If you get 20 mpg with the Rx7 and drive same 90 miles a day, versus getting 30 mpg and driving 90 miles per day you are talking about 3 gallons vs 4.5 gallons. That $5 a day, roughly. Multiplied by 30 days a month your new car payment would have to be less than $150 a month for it to make financial since, assuming you dont have a car payment on the RX7, which most of us dont. If you do have a car payment then you would have to figure that into your costs. If your payment is $100 ($3k financed over 3 years) a month then your new car payment would have to be under $250 a month before selling your RX7 would make save you anything.



BC

 

Under WOT, I'm at 13:1 afr. During cruising, I'm anywhere from 14 - 16 afr depending upon where I'm at in vacuum. I'm only getting 15mpg when I really baby it and try and keep from going past 3500 rpms and 50% throttle. Overall, I still seem to maintain my usual 11 - 12 mpg. My typical driving habit consists of shifting at 3 - 5k at 35 - 75% throttle. I checked my compression and I'm still getting 90 psi all around (give or take 1 or 2 psi). My ignition map is pretty decent and I'll try and put up a pic or a link. I got to drive my brother's 03 celica for a week while he was in Alaska and being able to get 30 - 35 mpg made me quite jealous. 150 miles in his car cost me around $15, whereas 120 miles in my 7 cost me around $39.

 

It REALLY sounds like you need a tune up man. Try new plugs, wires, fuel filter and have the injectors cleaned. May only net you a few mpg, but 11-15 is pretty bad. I get a 15 city pretty easily. I dont see anywhere near 11 unless I beat the **** out of the engine.

Worst I ever got was a touch under 8 mpg up at The Dragon last April.


BC

 

have new plugs (bur9eqp), have new wires, a new fuel filter, a mallory hyfire, and my 550 and 680's were professionally cleaned before I put them in about 800 miles ago.
I've been thinking about it today and maybe my fuel enrichment settings are too rich during warmup. Most of the time, it doesn't reach full operating temp (about 160) until I reach my destination which is usually within 10 miles. It takes alot longer to reach that temp because it's been soo friggin cold in PA. Even at that, when it is warmed up, I see 15mpg at best.

 

thats about the same mileage i got with the 3 rotor, tuned to 14.7

 

back on topic.

I tried 6 split and got the WOT to 13.1 then lowered the split to 2 degrees ( would of tried zero split, but with the haltech didnt want to take a chance and it negative spliting at WOT ). and noticed I needed to add more fuel to get back to 13.1 . So assuming more fuel to make the same afr means its making a litte more power.

Never went to dyno, but im going to assume at wot smaller split will yield better power.

System: haltech e6k egt was aprox. 1350-1380 If i remembe correctly ( but this can be off).

 

https://www.rx7club.com/showpost.php...8&postcount=79

 

Peejay, what did you do to get the "zero" split?

Do you use vac. adv. at all (I thought I read somewhere that you did)?

 

Jumper wires from the leading coil to the trailing coil. The MSD is an awesome piece of equipment.

Absolutely.