25 replies to this topic

[Funracer]

Tomorrow is my first trip to a dyno.

Installed the Advance Autosports FPR on the 94 1.8 in the spring.
Since then we haved moved to another state and I have misplaced (lost) the instructions
that came with the unit.

Can someone that has the same setup remind me which screw/bolt to turn to adjust the fuel pressure,
and in which direction?

While your at it, any recommendations for an A/F ratio setting to shoot for on the 1.8? I have an Innovate guage installed also.

Thanks

Happy Thanksgiving!

Go Dolphins!

[FTodaro]

In the front of the unit it has a nut with an allen/hex screw inside it, you losen the nut and I think you turn the hex clockwise to lean it out. I have a 99 not sure what will work for you but I run about 14 degrees timing and about 51psi.

[Funracer]

In the front of the unit it has a nut with an allen/hex screw inside it, you losen the nut and I think you turn the hex clockwise to lean it out. I have a 99 not sure what will work for you but I run about 14 degrees timing and about 51psi.

Thanks

[Ron Alan]

It will be up to your dyno tuner to find the sweet spot...I think we ended somewhere around 37-38psi. Made great HP at 35psti but a little to lean for comfort!

[Danny Steyn]

Ron - IMHO if you are running 37/38 psi then I suspect something is wrong with your FP guage. Yes you can run at that level (marginlal in my experience), but you will lose so much TQ that your car will be really slow out of the corners..

50-52psi seems to be the consensus, but at certain tracks where Hp is critical, you can go leaner. Where Tq is more important, go richer.

important to calibrate FP guage against known, reliable FP guage

[Tom Sager]

Ron - IMHO if you are running 37/38 psi then I suspect something is wrong with your FP guage. Yes you can run at that level (marginlal in my experience), but you will lose so much TQ that your car will be really slow out of the corners..

50-52psi seems to be the consensus, but at certain tracks where Hp is critical, you can go leaner. Where Tq is more important, go richer.

important to calibrate FP guage against known, reliable FP guage

'94 - '97 run at a much lower pressure than a '99. We've set ours both with and without vacuum attached and I can't remeber the numbers but mid-upper 30's is in the ballpark depending upon vacuum and idle settings. I believe clockwise increases fuel pressure. A/F reading on dyno will guide you. With a '94 you'll probably find that slightly richer after finding peak HP will be optimal as you'll be much leaner than you want to be at 4500RPM - 5500RPM when you tune only for peak. Get it near 12.6 - 12.8 between 6000 and 6900 and you'll be close. Tune from there. The next key is to figure out how to adjust the FP for weather. We find that the swing from a 50 degree day to a 90 degree day may require as much as 5PSI in adjustment and if you miss on this setting and the car is too lean, the power really suffers especially at lower RPM. An onboard AF guage is really a must IMO. Also you need to compare your on-board guage to that of the dyno. Even a 2/tenths difference between the two is meaningful. Without all this you're guessing to an extent at the track.

[FTodaro]

Tom are you saying that generally, that the cooler temps may require MORE fuel pressure to compensate?

[Ron Alan]

'94 - '97 run at a much lower pressure than a '99. We've set ours both with and without vacuum attached and I can't remeber the numbers but mid-upper 30's is in the ballpark depending upon vacuum and idle settings. I believe clockwise increases fuel pressure. A/F reading on dyno will guide you. With a '94 you'll probably find that slightly richer after finding peak HP will be optimal as you'll be much leaner than you want to be at 4500RPM - 5500RPM when you tune only for peak. Get it near 12.6 - 12.8 between 6000 and 6900 and you'll be close. Tune from there. The next key is to figure out how to adjust the FP for weather. We find that the swing from a 50 degree day to a 90 degree day may require as much as 5PSI in adjustment and if you miss on this setting and the car is too lean, the power really suffers especially at lower RPM. An onboard AF guage is really a must IMO. Also you need to compare your on-board guage to that of the dyno. Even a 2/tenths difference between the two is meaningful. Without all this you're guessing to an extent at the track.

Ditto...not a 99 Danny. I want to say stock was somewhere around 45psi? Tom, at 12.6 to 12.8 are we pushing the leanness envelope to much? My car was set at 13 and told not to go lower than that...anyone can chime in on this.

[Jim Drago]

Ditto...not a 99 Danny. I want to say stock was somewhere around 45psi? Tom, at 12.6 to 12.8 are we pushing the leanness envelope to much? My car was set at 13 and told not to go lower than that...anyone can chime in on this.

The lower the number, the richer the mixture. So above 13.0 is leaner, below is richer

[BrianZ]

the answer to your question is if you turn the allen screw clockwise it will raise the fuel pressure, and like wise if you screw it out it will lower the fuel pressure.

[Ron Alan]

The lower the number, the richer the mixture. So above 13.0 is leaner, below is richer

Thanks Jim...guess I was not paying attention in school that day Actually I realize now my memory is faulty...we started at a higher number and he said we need to come down...which we did and it was to much so he went back up. I just remember the 12.9-13.0 range. What A/F ratio would you consider to lean in the power band? Tom...your comment on temp makes sense. Will the car go leaner or richer as the temp increases? I would assume altitude would also affect this?

[Jim Drago]

Ron
It depends on the RPM range... in a perfect world. we would start around 12.5-12.7 at 4500 and work up to about 13.1 or 13.2 at red line.. Unfortunately our curves for the most part go the other way. They're typically leaner around 5000 and get richer at the high RPM.

On my 99 for example, 5000 is usually mid 13's and 6500-6800 is about 12.7-12.8. You have to compromise one way of the other.

[Ron Alan]

Great info...as always thanks! So it sounds to me like if your a little lean at the bottom, this will affect torque, if you rich-en to get torque you take away from peak HP by being to rich.

[Funracer]

Back from the dyno this morning. As reported here turning the screw clockwise increases
fuel pressure which richens the mixture and lowers the A/F number.

In my case the first pull showed an A/F of low 10's at 6000 RPM - too rich.
We turnd the allen screw counterclockwise to decrease FF gradually over the next 5 pulls.

HP started at 109 on first pull and reached 116.23 HP by the 6th pull with final A/F of 13.1 at 6000 RPM.

Considering we did no other changes (timing, parts swaps etc) I was pretty happy with my first dyno tune experience.
I also got a cool set of charts with different color lines on them to puzzle over.

Thanks again for all the input.

[Ron Alan]

Back from the dyno this morning. As reported here turning the screw clockwise increases
fuel pressure which richens the mixture and lowers the A/F number.

In my case the first pull showed an A/F of low 10's at 6000 RPM - too rich.
We turnd the allen screw counterclockwise to decrease FF gradually over the next 5 pulls.

HP started at 109 on first pull and reached 116.23 HP by the 6th pull with final A/F of 13.1 at 6000 RPM.

Considering we did no other changes (timing, parts swaps etc) I was pretty happy with my first dyno tune experience.
I also got a cool set of charts with different color lines on them to puzzle over.

Thanks again for all the input.

Based on your numbers it sounds like you got our chart

[Danny Steyn]

Back from the dyno this morning. As reported here turning the screw clockwise increases
fuel pressure which richens the mixture and lowers the A/F number.

In my case the first pull showed an A/F of low 10's at 6000 RPM - too rich.
We turnd the allen screw counterclockwise to decrease FF gradually over the next 5 pulls.

HP started at 109 on first pull and reached 116.23 HP by the 6th pull with final A/F of 13.1 at 6000 RPM.

Considering we did no other changes (timing, parts swaps etc) I was pretty happy with my first dyno tune experience.
I also got a cool set of charts with different color lines on them to puzzle over.

Thanks again for all the input.

The fact that you got 7HP is pretty awesome

And your experience pretty much explains why so many of us use the dyno so extensively - in a "spec" class there is so much to be had by tuning and tweaking on the dyno. My "AHAH moment" came at the the 2010 runoffs watching Gorilla book the track dyno before every qalifying and race session (weather conditions change on the hour at Road America in Sept) and DDG religiously on the dyno before each session switching out AFM and other sensors trying to get the most out of the car.

[Tom Sager]

Thanks Jim...guess I was not paying attention in school that day Actually I realize now my memory is faulty...we started at a higher number and he said we need to come down...which we did and it was to much so he went back up. I just remember the 12.9-13.0 range. What A/F ratio would you consider to lean in the power band? Tom...your comment on temp makes sense. Will the car go leaner or richer as the temp increases? I would assume altitude would also affect this?

My car gets richer on cooler days so we have to reduce FP comapred to warmer days, but it's not a perfectly linear excercise. Humidity I think also plays a role but we haven't got a good handle on that yet. In the past when we couldn't adjust we simply ran the car and on some days you got good A/F numbers and on other days you didn't. Now you can drive yourself nuts adjusting for each session as a day gets warmer or cooler and if you don't have a good idea how to adjust for conditions BEFORE YOU GET ON TRACK it's too late. I think the '94 - '95 has the worst engine management among all the cars so it's the most challenging to dial in for conditions and the A/F curve varies more top to bottom than the other cars even when adjusted as best it can be.

[Ron Alan]

My car gets richer on cooler days so we have to reduce FP comapred to warmer days, but it's not a perfectly linear excercise. Humidity I think also plays a role but we haven't got a good handle on that yet. In the past when we couldn't adjust we simply ran the car and on some days you got good A/F numbers and on other days you didn't. Now you can drive yourself nuts adjusting for each session as a day gets warmer or cooler and if you don't have a good idea how to adjust for conditions BEFORE YOU GET ON TRACK it's too late. I think the '94 - '95 has the worst engine management among all the cars so it's the most challenging to dial in for conditions and the A/F curve varies more top to bottom than the other cars even when adjusted as best it can be.

So lets say you dyno at 70 degrees, if you get to the track and it is 45 degrees, odds are you will be running rich...leaner if it is 100 degrees out...correct? So in theory, if you dyno on a really cold day and a month later run the car on a really hot day(maybe 60 degree swing)could you run lean enough to hurt the car?

[Muda]

Colder air = more oxygen per unit volume, requires more fuel. If you don't add fuel you will be LEANER than you were when it was warmer. Warmer air, you run richer.
Unless it's different on this coast.

The dyno allows you to set the "best" a/f ratio under those conditions. You need to adjust for conditions at the track that day. To do that you need a wide band O2 sensor and you need to have calibrated it before the dyno run and observed it during the run. Adjusting the a/f at the track takes a few seconds and is really helpful when the temperature swings are significant, like in the Spring & Fall. It's a pretty worthless exercise without the O2 sensor.

[Ron Alan]

Muda.....So if I'm reading this correct...you are saying the opposite of Tom?? Oh man i'm confussed