i have an 88 na rx7. im bout to install my super afc and just want to see what power gains were seen from installing it.

 

Installing it, nothing.

Tuning it to run a little bit leaner, minimum.
Cost of tuning far outweighs the gains.

Don't tune the high map yourself if you like your engine in running condition unless you are an experienced tuner with a wideband.

 

FRFC3S doesn't know what he's talking about.

Check out this thread for example

Large gains can be had with tuning; Chris Ludwig tuned an S5 NA with RB header and got an extra 40hp out of it.

 

Seeing (or smelling rather) that the N/A FC runs big rich from factory I could see why you could make such a big gain with leaning it out.

 

I'm sorry, but I don't think that's a fair example. You're comparing a piggyback computer that manipulates the airflow signal to a load cell based timing AND fuel program.

There are gains to be had with tuning an SAFC, sure, but not nearly as much as with the RTEK 2.0 as you used in your example.

 

the RTEK 2.0 seems great. is it difficult to tune fuel mapping? with proper knowledge of cfm and a/f ratio could it be done? i have a stock s4 N/A and i'd love that flatter torque curve and the horsepower up high where it should be

 

Check out the RTEK sub-forum, there is a bunch of information on it. There is also one for the SAFC. I'd take a look around there, probably help out a ton.

 

In the example, it's clearly stated, fuel tuning only, no timing, which is exactly what the AFC does.

 

IMO the SAFCII is the best bang for your buck mod any n/a owner can buy.
Yes, there are better options and ways to make more power but for around $200 and another $150 for an hour w/ a tuner you can make more hp, and save gas.

I haven't put mine on a dyno yet but just by using a milder version of other people's settings I have felt a huge increase in power over stock not to mention better gas mileage and less fumes.

 

Or you can spend $400 plus the dyno time and get a much superior product in the Rtek. Not only do you get full control of timing, which the SAFC doesn't offer, but you also get a TON of other features the SAFC doesn't include. Dollar for dollar the Rtek is superior.

When it comes to power gains from timing that's a big depends. The Rtek ships with a base timing map that is near optimum so there is usually little to gain to be had from changes made to what the Rtek already has programmed. However, timing numbers vary across the range of stock ECUs. We've seen modest power gains from simply swapping the base programmed Rtek in without any sort of fuel or timing tuning over a completely stock ECU. Again, it depends on what ECU you started with.

Also, saying we have picked up 40 hp with a simple header swap and tuning is not really true. On the stock application we posted dyno figures of in the Rtek section we made those large gains in the higher rev ranges where the stock ECU had already signed off an was overfueling to the point of limiting useable revs. Actual peak power gains were in the area of 12 hp, if I remember correctly. And that was from fuel tuning alone...the header had already been added and was used for the "stock" baseline dyno numbers. In the same manner, on a car that was fully optimized with the stock ECU and adjustable fuel pressure regulator we have typically found 6-8 hp from 4500-7000, about 2-4 hp at peak, and as much as 18 hp just past peak.

 

I know what I'm talking about. He did not mention any mods whatsoever. I was assuming he was a bone stock car with ONLY the SAFC on it, because that's all the information he gave.

You referred to an article with a car that had multiple mods. Of course your results would show a gain. Nice try.

Even the poster that you referred to says to expect to see at MOST 5-10 horsepower after spending an hour or two of dyno time. You'll get better gas mileage, but the money to gains ratio there is pretty poor.

 

Multiple mods? Did you even read what was posted?
He had ONE mod, which was a header, and w/fuel tuning only he got those results.
Stop being such a sour kitty.

 

You got me, I thought he mentioned aftermarket cat. I must've skimmed through it too quickly because he says stock cat.

Either way, if you continue on with your purchase and installation of the SAFC, there is a section dedicated to it in the engine management section of the forums.

If you plan to take the better route, the Rtek which should be abused by all S4 owners who arn't on standalones, there is also a section for that in the same section.

 

I picked up 14 RWHP just from a SAFC and tuning on an S5 with 85k miles on it (original motor).

 

NA or turbo? Your sig mentions turbo but you didn't specify in your example. I'm not going to assume this time or I'm going to get more people up my ***.

 

Sounds like an NA, turbos should be making more than 14 whp.

 

That car was an 1990 GTU (N/A). I wrecked it. I now have a turbo II.

The N/A car had an aftermarket exhuast. But that was already on it.

We simply put it on the dyno, did a base run, and it showed 115 RWHP base.

We then tuned it through three more runs and the last run it was 129 RWHP max.

This was a mustang dyno.

Mustang Dyno's are somewhat stingy but as you can tell the engine was tired too.

 

you can get an SAFC for like $100 used and an hour of dyno time for like $100-120. You should be able to get it dialed in in like 5 pulls. SAFC is easy to use once you get used to it.

 

I had to add fuel with my engine on the high map. +3 and up. Higher up top.

I also have a wide open exhaust and intake setup. The exhaust makes the largest difference of all on stock port engines for increasing the amount of air volume for each intake cycle. I would believe that is why I had to add fuel instead of removing like others have done.

 

S4 or S5?

 

Incorrect.

Changing fuel in Rtek has no effect on timing.

With an SAFC, by reducing the airflow signal to lean out the fuel mixture you will be advancing timing because of less calculated load in the ecu. You can't adjust fuel mixture with an SAFC without having a direct effect on timing which in most cases is undesireable. My point still stands that the gains seen with an SAFC are not analogous to the gains seen with an RTEK.

 

My main discourse with your post is that advancing timing is undesireable. With turbos, I would generally agree, however, with NA, advancing timing has been a time-tested crude tuning tool to make more power.

You realize that by advancing timing as a byproduct of using the AFC, you'd be making more power than the Rtek, if it holds timing at the preset point? Stock timing on the leading is 5 degrees ATDC, NA's make power up to 27 degrees BTDC. Advanced timing is desireable up to a certain point. My Rtek has a 31 degree timing advance thru the timing tables.

Using an even more crude example of making most peak power, you could use the CAS and an adjustable fuel pressure regulator to optimize a specific 500 rpm range. You would also show the same peak power as an Rtek fully tuned car, however, everywhere else, your tune would be horrible.

Now, my assumption is that the ECU doesn't advance timing quite that drastically due to the leaning by the AFC., putting it somewhere between 27 BTDC and 5 ATDC. I'll also assume that the ECU will still follow it's preset timing map, and that even with the AFC, you can't go past 24 in Hg vacuum on the lighter load side with the stock ECU. I'll also assume that the Rtek tune that Chris posted had stock timing tables.

Here's what I see happening: The car with the AFC will have less load than the car with the Rtek, rpm for rpm, until a certain point where the stock timing tables hold at a constant value. Up to that point, the timing will be more advanced on the AFC than the Rtek. However, the swept range that the timing goes through will still be between 5 ATDC and 27 BTDC. Therefore, because the timing is more advanced on the AFC than the Rtek with fuel tuning only, you will be making more power at every point where the timing is advanced. This should occur until the timing stays constant and is equal between both the AFC car and the Rtek car.

Of course, with the Rtek, you should be changing timing tables to optimal values, regardless, but this discussion is based on fuel tuning only.

Now, what does all that have to do with my previous post? I believe that the Rtek fuel only tune is making less power than a comparable AFC tune. In other words, the AFC should be making more power than what Chris posted, which makes it a good bang for your buck, if you're interested in fuel tuning only. the Rtek gains are analogous to what an AFC would do, the gains would actually be slightly higher, if my reasoning is correct.

 

I would be curious to hear C. Ludwig's input on this, since we're using his results as the basis of comparison. What was found by advancing the timing afterwards. Gains? I'll take a look at some of his posts.

 

Opps, left that out I guess. Its a Series4 N/A. S5 Intake Manifold.

No AFR Gauge but leaning out the AFR proved horrible engine performance and adding fuel just made the engine pull harder and harder till there was a point of a 1-2% increase that didn't make a difference and any higher just made the engine's performance deminish.

when I had the AFC set before about a month ago, the engine would pull to about 7800rpm on the SAFC (not the stock tach). Now power drops off at around 6500 and only sometimes gets up to about 7500. I have to check my fuel pressure and a few other items.

 

is it the butt dyno telling you or do you have a G-tech/APEX'i RSM to tell you acceleration?