Author Topic: New Dyno Day at Prather Racing  (Read 13031 times)

Offline 94touring

Re: New Dyno Day at Prather Racing
« Reply #100 on: October 07, 2018, 10:34:20 PM »
And to make it more fun.  Plug in your cars weight and hp to see times.  You will be at roughly 1400lbs according to the miniweight website.

https://robrobinette.com/et.htm

By plugging in my new estimated weight of 1150 I gain nearly 1 second in the 1/4 mile.  By working it backwards and taking my new 1/4 time and using the old weight of 1400lbs, my new equivalent horsepower at a weight of 1150 is 97 to the wheels.  So there was a method to my madness of weight reduction! 
« Last Edit: October 07, 2018, 10:39:13 PM by 94touring »

Offline MPlayle

Re: New Dyno Day at Prather Racing
« Reply #101 on: October 08, 2018, 10:12:05 AM »
The site Bruce posted does not like to calculate for less than 50 hp.  I put in the Moke's 31 hp and it changes it to 50 when clicking the calculate button.


Offline BruceK

Re: New Dyno Day at Prather Racing
« Reply #102 on: October 08, 2018, 10:33:22 AM »
The site Bruce posted does not like to calculate for less than 50 hp.  I put in the Moke's 31 hp and it changes it to 50 when clicking the calculate button.

You just can't get no respect!   ;D
1988 Austin Mini
2002 MINI Cooper S
1992 Toyota LiteAce (JDM)
1992 Honda Beat (JDM)

Offline 94touring

Re: New Dyno Day at Prather Racing
« Reply #103 on: October 08, 2018, 11:37:22 AM »
They're like lawn mowers not welcome!  ;D

Offline 94touring

Re: New Dyno Day at Prather Racing
« Reply #104 on: October 09, 2018, 06:45:58 AM »
Back on the topic of tuning, I figured out what swinging needles my hs4s came with.   After much research and learning myself good on needles and curves, I plotted several out that are in the general neighborhood of what I have.  I know that these needles are divided into 16 segments.   Since I know WOT is spot on air/fuel for the majority of the dyno graph, I used the full throttle segment as a baseline, then corrected the rest of the curves to match.  For example if WOT on needle xyz is 10% more than what I currently have, I deducted 10% across the curve.  This is after seeing what each segment is in relation to my current needle.  Segment 5 may be 10% leaner, but if the full throttle segment is 10% richer, after adjustments segment 5 becomes 20% leaner.  My plan is after the wideband is installed I can see how the air fuel ratios are across 16 various throttle positions throughout the rpm range, and plot the ratios.  I am considering making a spacer with 16 increments to place under the throttle to maintain constant positions.  After I've gone through all segments and see what air fuel is per segment, I can theoretically pick a needle based on all the plotting.

Offline MiniDave

Re: New Dyno Day at Prather Racing
« Reply #105 on: October 09, 2018, 10:01:08 AM »
The needle position will vary not only with rpm but also load, so unless you can keep the exact same load in each position of the throttle, the needle won't stay in the same spot. Remember, when he's doing the run up, he has the throttle wide open the whole time, but the load on the car stays the same (percentage wise) as the rpms goes up - because the dyno adjusts to the input from the wheels. I don't think you can duplicate that on the street, but no question you can get it a lot closer than it is, especially since you know where to start.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline 94touring

Re: New Dyno Day at Prather Racing
« Reply #106 on: October 09, 2018, 10:20:35 AM »
I have a long straight flat road nearby that's perfect for this.  Did the same thing on the rx7, difference is I have a computer to data log to review the map the car is at under load.  So you go out and drive in various rpms and throttle position (my case vacuum to boost too) then adjust the cells accordingly to what the air/fuel gauge reads.  Tedious but you end up nats ass tuned.  There will be some variations on the road as you say, but should get in the ballpark once you start seeing trends at various loads,rpms, throttle positions.  It's even easier to imagine the fuel map of these needles when you plot them out.  I can tell where some cruise rich while others are very lean in relation.  My cruise air/fuel at normal highway speed will narrow the needle down pretty quickly I think.
« Last Edit: October 09, 2018, 10:22:15 AM by 94touring »

Offline Scargo

Re: New Dyno Day at Prather Racing
« Reply #107 on: October 09, 2018, 03:49:26 PM »
Looks like a great day, guys. Nice work putting it together.

If someone would be so kind, I would like to have the contact information for the owner of the red Bugeye.

Thanks.

Offline MiniDave

Re: New Dyno Day at Prather Racing
« Reply #108 on: October 09, 2018, 04:26:11 PM »
PM sent....the Red Bugeye belongs to Gordon Fitch, who also owns the green 63 that went first.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad