Dyno results after new Fuel rails... weird? long

[moneypit94]

After i put my new fuel rails on i decided to see if they fixed my lean condition i was having at the top of the rpm band. This dyno facilty i went to was a little different from what im use too. So i don't know how accurate the results are but they seemed to be fairly inline with my previous results.

They strapped me to the dyno and said to take it to 3000 rpms in 3rd and thats how he set the rpms and gear ratio for the dyno? They didn't put the leads on to my spark plug wire to measure rpms? And we did the runs in 3rd. I asked him about this and he said fourth gear is pretty hard on a motor due to the length of the run and that for the most part 3rd was just as accurate. I had my slicks on anyway because i was headed to the track directly afterwards (which it rained and was canceled

But really my whole point of going was to see my air fuel ratio.. And 85 bucks an hour it wasn't bad at all.

Well to make a long story a little shorter. Every run i was taking fuel away. I went from like +25 percent to -20 percent in places with my pms. I ran a flat 10.0 curve and it took forever to get it raised up. So my fuel rails really helped.

But like i said i don't know how accurate these are.. I know the rpms are off a little due to the way he sets it. I took this run to 6200 rpms according to my pms.

These are SAE number.

 

[mytight95]

3rd gear pull's aren't accurate because the transmission isn't at a 1:1 ratio with the engine...........


if you dyno in first for example you will dyno a lot more power than in fourth or even third,...........



i think the above is 100% correct if not someone correct me


jason

 

[moneypit94]

Actually even if you are in 4th witch is a 1:1 ratio at the transmission its not really one to one. Because of the gearing in the rear end.. Rear end gears have no effect on a dyno either.

Just like 1st feels like its got more power but really it doesn't. you just go through the rpms faster... Power goes up real fast but the length of time you have it for goes down just as fast. 1st wouldn't be very effective on the dyno though because you would get too much tire slip.

I have heard of a couple situations were they had to dyno the car in like 5th because they were spinning the tires too much in 4th.