Real Fiero Tech

Here is a sheet from the dyno.

It shows speed instead of rpm due to the fact we were mapping shift points on the other runs. I do have sheets with all the info in data form instead of graphs.

The A/F was almost constant, only changing from a low of 11.1 to a high of 11.4.
The torque curve is like all 4 . 9s in that it starts high and goes down from there. The hp curve is flat from the start of the run till near the end.
The first 3rd gear pull, it had 160.7hp @4800 and 216trq @3800
For the last pull I moved the timing from a base setting of 12 to 16 degrees with the timing control bypassed.
This gave me the days best of 169.6hp@4800 and 218trq @3800.

All the runs ended at 4800rpm in high gear which is 102mph. The factory speed limiter is 118mph. With the change from 2.73 to 3.06 final drive and 24" tires, the computer thinks I am going 118 at an actual 102.

I wish it could have pulled higher because in both cases it made a big hp jump from 4400 to 4800.
It was 7hp in the first pull and 10hp in the last with the advanced timing.

I am now going to send all the data I have to Rocksrawl and get a new chip. I will dyno it when I get it back to see the changes.




Gene

11.1:1

That's rich baby.
Hopefully the new chip will get you to 13:1

Those numbers seem about right.

What does your 160 chart look like?

I'm not saying they are wrong just that with a proper mixture they will improve.

Is your motor stock?

This is the data from the best run which was a 3rd gear pull





This sheet is from one of the runs where we started in 1st and let it shift till the speed limiter cut in at ~101mph. What is confusing to me is the numbers shown in first gear and notice how the a/f ratio is nearer to normal, then drops off. after the shift to second.





Gene

the reason why your a/f's go lean is because the chip is pulling fuel at the shift point. AT least that is my guess.

those charts tell a lot actually.

You have a 160 hp graph?

This is the only one I can find that ends at 160hp
Ignore the coments about CAI and headers/converter. We ran tjhis at a friends shop and did not change the text from the last car.
I have duals with a pair of Supertrapps and no converters.


Gene

The ECM may be seeing a decrease in load during the shift, but it seems unlikely that the it could sense the load change, shorten injector pulse, and have the O2 sensor show the effect of it within one or two tenths of a second, but I suppose it's possible. A log of the MAP sensor could be the answer. More likely the ECM has a torque limiting routine that it uses to protect the transmission during shifts. Since the ECM controls the shift points, it can anticipate the shift and start taking action before the shift even starts.

11.1:1 WOT AFR is pretty normal for a stock chip. I have a dyno chart showing 10.7:1 on a stock 4.9 at WOT. I guess they were thinking better safe than sorry, afterall there's no knock sensor on these babies.

rockcrawl wrote:11.1:1 WOT AFR is pretty normal for a stock chip. I have a dyno chart showing 10.7:1 on a stock Peice of shit at WOT. I guess they were thinking better safe than sorry, afterall there's no knock sensor on these babies.

Could be, but the 3.4l DOHC hits an a:f right at 13:1, from start to finish. But it does have a knock sensor. As enignes become more efficient, DOHC hemi head design with excellent squish areas, with good ECU controlling, it enables manufactorers to move a:f's leaner and leaner, which uses less gas, without the traditional harmful effects of running lean.

scrabblegod wrote:Here is a sheet from the dyno.
The A/F was almost constant, only changing from a low of 11.1 to a high of 11.4.
The torque curve is like all 4 . 9s in that it starts high and goes down from there. The hp curve is flat from the start of the run till near the end.
The first 3rd gear pull, it had 160.7hp @4800 and 216trq @3800
For the last pull I moved the timing from a base setting of 12 to 16 degrees with the timing control bypassed.
This gave me the days best of 169.6hp@4800 and 218trq @3800.



Gene

Isn't that a little light on torque? I thought that 4point9's usually put down about 230-240 TQ...

I felt it was a little low on horsepower, I don't know how people think that could keep up with a 3.4 if that is how they all look :scratch:

The Dark Side of Will wrote:

scrabblegod wrote:Here is a sheet from the dyno.


Isn't that a little light on torque? I thought that 4point9's usually put down about 230-240 TQ...

The torque peak for the 4point9 is at 3000 rpm, so this graph starts almost 1000 rpm past peak.

Gene

Whose brilliant idea was that?

if 87 mph is at 4400 rpm then what is 45 mph at?

It can't be only 4k. Seems like it would be around 3k to me if not lower.