Dyno tune versus a memcal tune

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Re: Dyno tune versus a memcal tune

Postby vlad01 » Fri Oct 04, 2019 11:57 am

many of the areas in the spark map. 1. you don't have infinite and variable hills. 2. torque output in many areas can't be felt relative to the amount of timing changes input. eg the top plateau of the torque vs spark response curve. One one side of it is safe MBT and the other side is danger territory. Without a dyno its very hard to tell where you are.

This curve depends on the engine itself, some are more peaky and easier to dial in other like my engine were broad and had a large plateau making it impossible to find MBT without a dyno.



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Re: Dyno tune versus a memcal tune

Postby delcowizzid » Fri Oct 04, 2019 3:04 pm

This was the difference on na v6 that 100nm made a huge difference
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Re: Dyno tune versus a memcal tune

Postby Yortt » Sat Oct 05, 2019 10:24 am

vlad01 wrote:many of the areas in the spark map. 1. you don't have infinite and variable hills. 2. torque output in many areas can't be felt relative to the amount of timing changes input. eg the top plateau of the torque vs spark response curve. One one side of it is safe MBT and the other side is danger territory. Without a dyno its very hard to tell where you are.

This curve depends on the engine itself, some are more peaky and easier to dial in other like my engine were broad and had a large plateau making it impossible to find MBT without a dyno.



MBT.jpg

'1. you don't have infinite and variable hills."...…. How do you determine what cell the mapping is going to fall in when you try to duplicate infinite and variable hills on the dyno as compared to the loading on the road.

"2. torque output in many areas can't be felt relative to the amount of timing changes input." …….. This certainly can be logged on the road.

When using 98 octane fuel in the majority of vehicles they are "knock limited" in this case determining the MBT will be just before the knock threshold as determined by the factory knock sensor.

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Re: Dyno tune versus a memcal tune

Postby antus » Sat Oct 05, 2019 12:00 pm

1. you define roller speed on the dyno for the rpm column, and load with your right foot to sweep down the other column to your desired cell. If you cant get it to sit right in one cell, you can land it in a block of 9 cells square, and realtime the lot of them up or down, then know the center point is correct, and smooth the changes out as you tune other areas.

2. I think agree seat of pants tuning can get you in the ballpark, but a hook test can get you right on MBT and you know when to stop before the knock occurs and the engine goes pop. Im sure different people people have different variations and a lot use knock ears rather than the numbers on a hook test so I guess you have options.
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Re: Dyno tune versus a memcal tune

Postby delcowizzid » Sun Oct 06, 2019 5:53 am

I've street tuned for 20 odd years and now the dyno duo is becoming life I love it . I still street tune most first to iron out the bugs and get a base tune been doing a lot of link ecus starting from scratch with no tune at all
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Re: Dyno tune versus a memcal tune

Postby Yortt » Sun Oct 06, 2019 11:00 am

I would be interested in thoughts about dyno "ramp rates". I have always found it interesting that when a car is run up on the dyno the number of seconds it takes to complete the run on the dyno is no where near the time it would take on the road in the same gear. This is a clear indication that the tuning ramp rate loading on the dyno is not the same as it is on the road .... is it not?

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Re: Dyno tune versus a memcal tune

Postby kojab » Sun Oct 06, 2019 3:55 pm

I am pleased you brought the subject of "ramp rates" up. I am sure that many people don't fully appreciate the importance of loading the vehicle with a ramp rate that suits not only the current power of the engine but also
its weight. For those that are not aware of what the ramp rate does on a dyno, its purpose is to allow the car to accelerate on the rollers at the same speed rate it would do on the road at full throttle.
So how does the dyno operator know what the correct ramp rate is? As tuning begins and the engine begins to produce more power the ramp rate will need to be changed again. Will the tuner know what the correct ramp rate will be?
If the ramp rate is not know near the end of tuning it will be very difficult to get the spark timing correct at full power. Fortunately on road or track tuning the ramp rate is not needed or required as the vehicle being tuned is always traveling at its own correct rate.

What’s probably not know is its impossible for dyno operators to know what the true ramp rate is of vehicle they are attempting to tune unless they log the car/vehicle in its true environment which is
on the road/track. There are tools that can do this. An obvious problem then occurs is that at the end of a dyno tuning session to get the correct ramp rate to set up spark timing the vehicle would have to
be logged again on the road to get the correct ramp rate.

You can probably tell I am road/track tuner.
Last edited by kojab on Mon Oct 07, 2019 8:40 am, edited 1 time in total.

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Re: Dyno tune versus a memcal tune

Postby j_ds_au » Mon Oct 07, 2019 8:24 am

I guess going uphill with a full load in the back would also affect the ramp rate.

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Re: Dyno tune versus a memcal tune

Postby kojab » Mon Oct 07, 2019 8:42 am

Spot on Joe

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Re: Dyno tune versus a memcal tune

Postby The1 » Mon Oct 07, 2019 8:57 am

unfortunately nothing will get it all spot on or hit all maps in all the right places in the right conditions even OEM doesn't and never will, hence why they implement things like MAF and MAP sensors and o2 sensors to compensate a few percent.

Like with mine i drive it work and back everyday, so i have the laptop logging and i tune from logs from my drive, so it's tuned to suit. Thankfully also i drive highway and city and WOT and up and down hills, so i get a good general coverage of maps. I do this in Winter and summer so it can be covered in the tune, Just like doing a tune on a freezing cold day on the dyno then run on hot track in middle of summer.. Hope the spark and fuel compensation maps are setup.

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