Author Topic: Car tuning  (Read 6548 times)

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Re: Car tuning
« Reply #15 on: 06 April, 2016, 06:00:17 AM »
Funny,the 'high end' tuners around auckland i spoke to were keen to tune the nismotronics and were very interested learning more because of how advanced the chip is.

Other people who have had issues with tuners not wanting to tune them end up buying an ECU off them for a tune, seems like these tuners only want to tune their ecus for extra profit?

I see the only downfall with Nismotronics is the need of an older ecu, but these are still quite plenty-full, if you know what you are doing the right choice of ecu will net you a couple of bonus in/outputs. EG, S13 DET for 4 ignition outputs, or a US/AUDM ecu for the EGR

Link isn't a bad ecu, but i have yet to see anyone get decent "gains" from switching from a basic piggy back daughterboard to a link in the club. You may have more advanced tuning maps and more tuning features but are these actually needed for our cars? and the end product would still be the same.

The OP might be happy with a basic, US/AUDM ecu with eprom board which is normally more than enough for most people.

« Last Edit: 06 April, 2016, 06:11:01 AM by VET-T4 »

My real name is Lance

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Re: Car tuning
« Reply #16 on: 06 April, 2016, 11:45:50 AM »
All I can say is: once you go Link, you won't go back. :)

How do tuners get more profit from tuning a Link ECU? If anything it would take longer to tune a Nismotronic, and hence they could charge more for labour and make more profit that way.

Don't bag on Link ECUs unless you've owned one. Fiddling with someone else's for 5 minutes doesn't count. A Nismotronic is by far not the "same thing" as a Link or give the "same end product".

Brendan especially you: I would be dubious to use an economy-spec ECU with your engine you've spent $30,000 building. One corrupted tune during a full load pull and the engine's toast - all to save a mere $1500 on a cheaper ECU. May as well have used a DSR turbo and Chinese stainless manifold.
« Last Edit: 06 April, 2016, 11:53:13 AM by My real name is Lance »

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

pTen Developments

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Re: Car tuning
« Reply #17 on: 06 April, 2016, 04:03:54 PM »
I have owned a link ECU before, and have dealt with them loads of times with customers cars and im not bashing link.

Because they will charge you retail for a Link ecu which they get a decent discount (I know cause im a link dealer) and then they will charge you to wire/setup and then obviously tune it.

I am not using a Nismotronic purely because of the cost... as you know from my build I didn't cut corners due to money.
« Last Edit: 06 April, 2016, 04:08:38 PM by VET-T4 »

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Re: Car tuning
« Reply #18 on: 06 April, 2016, 10:03:53 PM »
Link isn't a bad ecu, but i have yet to see anyone get decent "gains" from switching from a basic piggy back daughterboard to a link in the club. You may have more advanced tuning maps and more tuning features but are these actually needed for our cars? and the end product would still be the same.

Are you comparing ECU's based on power output?
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pTen Developments

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Re: Car tuning
« Reply #19 on: 07 April, 2016, 03:17:28 AM »
Link isn't a bad ecu, but i have yet to see anyone get decent "gains" from switching from a basic piggy back daughterboard to a link in the club. You may have more advanced tuning maps and more tuning features but are these actually needed for our cars? and the end product would still be the same.

Are you comparing ECU's based on power output?

Not at all

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Re: Car tuning
« Reply #20 on: 07 April, 2016, 11:04:00 AM »
Are you comparing ECU's based on power output?

Actually, funnily enough you probably would have the potential to make slightly more power on the Link. The NEMU doesn't have real-time barometric compensation (only once at startup), so overall your tune would have to be slightly safer.... probably like half a kilowatt difference though haha

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

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Re: Car tuning
« Reply #21 on: 07 April, 2016, 11:49:23 AM »
Are you comparing ECU's based on power output?

Actually, funnily enough you probably would have the potential to make slightly more power on the Link. The NEMU doesn't have real-time barometric compensation (only once at startup), so overall your tune would have to be slightly safer.... probably like half a kilowatt difference though haha
Thats more than enough to swing most people lol

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Re: Car tuning
« Reply #22 on: 07 April, 2016, 08:45:25 PM »
MAF would provide your barometric correction anyway wouldn't it? Less dense air means less heat extracted from wire and lower reading. Or are you referring to when you use MAP metering?

A thing I have never understood about barometric correction is why do we need to have it, why not just read manifold pressure in absolute pressure, wouldn't that provide all the barometric correction that is needed? Or does the exhaust side pressure create that much of a difference in volumetric efficiency?


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Re: Car tuning
« Reply #23 on: 08 April, 2016, 09:14:52 AM »
MAF would provide your barometric correction anyway wouldn't it? Less dense air means less heat extracted from wire and lower reading. Or are you referring to when you use MAP metering?

Yes, sorry I should've been more clear. I'm referring to when you use MAP metering. MAF metering is fine and has inherent barometric compensation built-in, but professional tuners are "less keen" and less experienced to do MAF jobs, because most people just use a Link or something.

A thing I have never understood about barometric correction is why do we need to have it, why not just read manifold pressure in absolute pressure, wouldn't that provide all the barometric correction that is needed? Or does the exhaust side pressure create that much of a difference in volumetric efficiency?

Ahhh Ha! I wondered this for a while, then I did a whole lot of reading on the internet and figured out that engines are a lot more complicated in that regard than they first appear.

The thing with volumetic efficiency is that one of it's primary influences is throttle position.

More important to understand is why your fuel table should be traversed by RPM and MGP (i.e. in the Link G4), rather than RPM and MAP (as in the NEMU). The requirement for barometric compensation lies in the need to know MGP - the difference between manifold pressure and barometric pressure. The reason for this can be explained by way of an example. Let's also assume a Normally Aspirated car.

Say you're at sea level, 100kPa barometric pressure. At WOT you also have roughly 100kPa in the intake manifold. This corresponds to 0kPa MGP (gauge pressure), and you tune to suit. For example, you tune to 12.5:1 AFR.

Then you close the throttle a little bit, and the pressure in the intake goes down to 75kPa. the barometric pressure remains at 100kPa. The gauge pressure (MGP) is now -25kPa (ie. 25kPa of vacuum). You then tune to suit, say for example 12.5:1 AFR for simplicity.

The key thing here is that volumetric efficiency has gone way down with the slight closing of the throttle. So you need way less fuel to obtain that 12.5:1 AFR reading.

Now, the tune is finished and you drive to the top of a mountain. The barometric pressure is now 75kPa. You put your foot to the floor, what happens? the manifold pressure goes to 75kPa. What's your MGP? That's right, it's still 0kPa, like the sea level example.

Now, because the throttle is wide open, you have maximum volumetric efficiency. Thus, you need proportionally the same amount of fuel as the 100kPa cell from the seal level example, but scaled by 75% (to account for the fact there is less air). This is where it is key to note the difference between "traversing the fuel map" and "the value used in the fuel equation" - two separate things.

However, if you are traversing the fuel map as you would be on the NEMU (i.e. by MAP, rather than MGP), you will be in the 75kPa cell, which was tuned with the throttle slightly closed and hence with a much lower volumetric efficiency (75kPa is also used in the fuel equation, as well as to traverse the fuel map). So your injector pulse width is much narrower...... oh snap! you're miles too lean and just melted a piston!

Now take the Link G4. You are traversing the fuel map based on MGP, so you are in the 0kPa MGP cell (and remember barometric pressure is 75kPa), which translates to the 100kPa MAP cell at sea level. However the Value used in the fuel equation is the barometric pressure, 75kPa. So you're approximately bang on for your volumetric efficiency and fuel requirements - you get the "maximum volumetric efficiency cell" (0kPa MGP), but with less air going into the engine overall (75kPa MAP instead of 100kPa MAP).

I've used kPa in all these examples, but the same applies with psi (which I actually prefer to think about in turbo situations).

Remember the volumetric efficiency changes bugger all with altitude. Is does a little bit, but not much.

In simple words, you do not want the car to step down the fuel map with changes in manifold pressure - you want the car to step down the fuel map with changes in differential pressure with the outside world. This is because the Y axis on your fuel table is not for pressure - it is for volumetric efficiency. The amount of air is only relevant in the fuel equation, not the fuel table.

This also relates back to what you said about exhaust back pressure - if differential pressure between the atmosphere and intake manifold is equal, then exhaust back pressure will be pretty close (ignoring the fact that the amount of fuel burning causes massive changes in the cylinder pressures as the exhaust valves open. Hopefully the ignition timing is tuned properly to avoid this becoming an issue as you head up a mountain)

This is why you would have to tune very safely for MAP on the NEMU, or stick with MAF.

To the contrary, ignition timing is the opposite. When you drive up the mountain in the example above, you are getting less air and less fuel overall, so your burn speed is lower. Thus, stepping down the ignition map (and hence advancing the timing) with MAP is a good thing, and is a better way to do it than stepping down with MGP! This is why the Link G4 software's default settings are:
->MGP as the Y axis on the fuel table (and RPM as X axis). MAP used in fuel equation.
->MAP on the Y axis for the ignition table (and RPM as X axis)

Of course for NA cars, you often get unstable intake manifold pressures - especially when using gargantuan X-Force intakes (or whatever they are called) and high-overlap cams. In this scenario, tuners will often tune using TPS as the Y axis of the fuel table, and barometric pressure as the value in the fuel equation. Wade's car is such an example of this :)
« Last Edit: 08 April, 2016, 09:33:51 AM by My real name is Lance »

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

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Re: Car tuning
« Reply #24 on: 08 April, 2016, 11:59:52 PM »
I like how this thread has gotten carried away

I dont think either ecu offers any benefit in getting a power figure, at the end of the day, both perform the same task, one just has more features than the other.

Link is fantastic, and heavily reputable, in NZ.
Overseas it is still somewhat behind the likes of Motec or Haltech (or so ive heard) but I believe the latest edition is starting to catch up.

Also, just prospecting here, im not sure barometric pressure has as much of an impact here as in other countries. Our country is exceptionally flat really (in altitude), and we dont have vast swings in weather where we go from 45 degrees to -45 degrees.

I completely understand the points of a 20 year old unit vs new, but hardly see this as a reason to avoid an old ecu. cant say i have ever worked on a p10 and found that the ecu had miraculously died.
Whereas i have had lots of new electrical components fail.
It still doesnt feel 'that' fast

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Re: Car tuning
« Reply #25 on: 09 April, 2016, 12:05:07 AM »
also i had my NEMU tuned by Brent at Dynopower in tauranga.
took him all of 5 minutes to figure it out, only issue he had was figuring which keys were quick keys for saving and uploading.

If a tuning shop turns down tuning the NEMU, NEWSFLASH, its a ploy to make you buy their product *cough* LINK.

It is stupidly simple to use especially for a professional tuner
It still doesnt feel 'that' fast

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Re: Car tuning
« Reply #26 on: 09 April, 2016, 05:55:42 AM »
also i had my NEMU tuned by Brent at Dynopower in tauranga.
took him all of 5 minutes to figure it out, only issue he had was figuring which keys were quick keys for saving and uploading.

If a tuning shop turns down tuning the NEMU, NEWSFLASH, its a ploy to make you buy their product *cough* LINK.

It is stupidly simple to use especially for a professional tuner

Bang on the money.

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Re: Car tuning
« Reply #27 on: 09 April, 2016, 09:26:28 AM »
Great post Lance, that fully explains it. I hadn't considered that a change in manifold pressure through closing the throttle would have a different impact to a change in manifold pressure through different ambient conditions.


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Re: Car tuning
« Reply #28 on: 10 April, 2016, 09:28:14 AM »
Great post Lance, that fully explains it. I hadn't considered that a change in manifold pressure through closing the throttle would have a different impact to a change in manifold pressure through different ambient conditions.

Cheers!

If a tuning shop turns down tuning the NEMU, NEWSFLASH, its a ploy to make you buy their product *cough* LINK.

Still waiting to hear how you consider Link to be the tuning shop's product :P

Quote from: Cameron
Darryl, what would it take to RWD SR convert my QG18 bluebird? Ive got a mate with a angle grinder and stick welder, surely it cant be too hard

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Re: Car tuning
« Reply #29 on: 10 April, 2016, 09:35:44 AM »
If a tuning shop turns down tuning the NEMU, NEWSFLASH, its a ploy to make you buy their product *cough* LINK.

Still waiting to hear how you consider Link to be the tuning shop's product :P
[/quote]

Product as in something they sell, they get a decent cut out of the sale.