Like the title says, how far is too far if you wanted to purposely advance the timing and use high octane gasoline to compensate? I'm contemplating doing this when I get my AFC Neo and tuning the car. Possibly using both the piggyback and the sensor to gain more power by advancing the timing. How many degrees could I move the CAS before it gets too radical and starts affecting things like drivability and idle?

 

You should have a professional tune your engine if you don't know what you are doing.

 

Right, which is what I'm planning on doing, I just wanted to know the range of feasible timing advances.

 

Feesible range = anything short of grenading the keg

Don't set up your timing in a crude manner such as setting the CAS ahead. All of the timing throughout the entire rev and load range will be screwed all up.

Generally speaking, when people refer to advancing the timing (in reference to tuning) they are motsly talking about the high load portion of the map. The timing at idle and in vac would still be the same. By changing the position of the CAS, you throw the entire shabang out to lunch by the amount you moved the sensor.

Why are you thinking of doing this? More power? The marginal amount you'll squeeze out (of your N/A I'm guessing?) isn't worth the risk of destroying a running engine.

 

yup, squeezing a drop or two more of power would be nice. You would recommend setting the CAS to spec and using the piggyback to advance timing instead?

 

Good! That is what the top race car drivers do.

None.

Most piggybacks control the fuel but not the timing. Screwing with the CAS will just make the engine run worse, and possibly damage it.

There is a reason why the higher-performance RX-7's have a professionally-tuned standalone EMS.

 

Usually, the most you can advance it without having to change from 87 octane is 10 degrees advanced ATDC at 750 RPM idle. I've got my car at this right now just using the CAS, and it's got a little more power without sarcrificing fuel milage.

 

Ah, I had thought the AFC Neo could directly adjust timing, but I was mistaken, apparently, it only does it indirectly like the other SAFC's did, but moving you into other maps. Oh well, back to the drawing board. I'm surprised that even a 1 degree advance is considered infeasible.

I'm worried that, even with a switch to 93 octane, exceeding 10 degrees advance would end up ruining other parts, such as driveability and idle. Has anyone even attempted a radical advance using higher octane gas to compensate?

 

PowerFC will do your timing as well from what I hear.

 

power FC is a standalone, isn't it? If so, I already have a Haltech lying around, I'm just too lazy to install it.

 

Is this car turbo or nonturbo? On a turbo car you better have your CAS dead on. DO NOT mess with it.

On a nonturbo you can rotate the CAS and gain hp definately. I did it on my 172rwhp GTU on 87 octane. I made about 4 rwhp but it confused the ECU a bit and it wouldn't run richer than mid 13's at high RPM no matter how much SAFC correction I gave it (I only got it to richen up a year later when I set the CAS back to stock). I did it two years ago and i have the dyno sheet somewhere on paper (not scanned). It made the idle slightly rougher, but it was barely noticeable, and this was on a street ported motor.

Oh, and there's not a chance in hell you will detonate it either unless your timing is insanely off. I don't remember how many degrees mine was advanced, but it was probably around 7+. Just keep advance it until you stop making more power. I have never met anyone who has ever noticeably detonated an N/A, although I don't doubt that people have done it before. I daily drove my car like that for over a year and at least 10,000 miles with no problem. I ended up putting the CAS back to stock though like I said because I could never figure out why it wouldn't richen up.

And you won't make any meaningful (at least, compared to the time and hassle) gains from a standalone on an N/A. Been there, done that too, made the exact same power even though the AFR's were dialed in even better... I have dyno sheets for that as well (scanned on my computer). I mean technically you will get more control over timing but there's only a few hp to be gained from that anyway on a nonturbo.

In summary: if it's a turbo, do not touch your CAS and make sure it is perfectly set to stock. If it's a nonturbo, in my personal experience you can gain a few hp by advance it somewhat and you won't detonate it, even on 87. It may not help your overall engine life though (although I drove it like that for 10k miles), and the gains are small enough that you're not missing out by leaving your CAS alone.

 

He wouldn't, and you didn't, but somebody who knows what he is doing would gain a lot of performance from a standalone EMS on a non-turbo engine. Peak hp maybe wouldn't change very much without porting, but the torque curve and response can be improved a great deal.

I do not know of one good NA tuner who uses AFR as a primary tuning tool. There is only so much you can accomplish with this method, and unfortunately it takes a greater amount of skill and experience to tune by other methods.

 

Who are the good NA tuners in your area?

 

i'm not going to get into a big debate about this.

I will just end my input in this thread by saying that you have got to know when to quit with an N/A. Each successive hp becames harder and harder to extract in terms of time and money. All the while each hp you make after the first easy 30-40 has little noticeable difference in the actual performance of the car.

 

St. Louis sucks. All of my tuning was done in the Southeast. The good RX-7 NA tuners there are Rick Engman (Motec), Gregg O'Brien (carbs), and Scott Neville (Wolf). Mandeville Auto Tech is also a good resource for tuning and just about anything else.

 

Any N/A will not make any more power with the timing advanced past 27 degrees ATDC. There is no need to run higher octane to run this timing either.

 

stock is 20 ATDC on the trailing, so that's about a 7 degree advance? How's the drivability, idle, etc. compared to stock?

 

If you're looking for more power and reliability - you answered your own question right ther - standalone.

But if you're too lazy to install it then no one can help you.

 

Like its really hard or something..

 

more like I'm trying to sell it and buy another standalone instead......

Anyone have any opinions on the drivability and idle after advancing the timing?

 

I meant 27 degrees BTDC. 27 degrees ATDC is very retarded. It was the end of a 20 hour day.

 

I had thought that 27 ATDC was retarding it 7 degrees off the trailing, then I'm thinking that it's set off the leading. 27 BTDC, that's like what, a 32 degree advance? Isn't that kind of ridiculous to do? Wouldn't setting the CAS for that much advance really ruin the drivability and idle and other things?

I'm thinking you meant setting the timing with a standalone. What would be the furthest that you would go with just the CAS?

 

put it on the dyno and keep advancing it until it stops making more power

that's what I did. It was two years ago though and I cannot recall how much I ended up advancing it. Again, you will not have any noticeable driveability problems in my experience, and you will not need higher octane.

 

Digital Tuning's RTEK-7 2.0 is supposed to be released for your model "real soon now".

It will allow you to adjust both fuel and timing maps, as well as secondary activation point and more. I just ordered the S4 NA version, which they'll start installing soon. S5 NA is next.

http://www.pocketlogger.com/?pid=rtek7

NA feature list:

Rtek7 for S4 NAs (N326 & N327 ECUs only) Stage 2
User Adjustable Fuel Correction Map [details] 14 x 14 (196 Points)
User Adjustable Timing Maps (x2) 21 x 19 (399 Points)
Primary Injector Size Presets 460cc, 550cc
Secondary Injector Size Presets 460cc, 550cc, 720cc
Adjustable secondary staging RPM
Software Idle Fuel Control
Datalogging Port
No wires to splice, no "black box" clutter
Extends engine life by defeating the Accelerated Warmup System (AWS)
Easily clear an engine flood without opening the hood
Palm PDA Based Programming and Datalogging Software
Diagnostic Check Codes and I/O Viewer
ATP Input as External General Purpose Loggable Analog Input
VarRes Input as External General Purpose Loggable Analog Input
EGR Output as RPM Controlled switch

 

I am referring to the maximum advance achieved at WOT. How you achieve it is up to you. Generally, a stand-alone is easiest.

I simply stated that in the first place to point out that jamming the timing way advanced will not make any more power. The stock ECU maps, with the stock CAS positioning, the ECU pretty much runs right around there at WOT anyway. There's not much power to be gained from touching the CAS... 3-4 degrees at the most.