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Mk1 Build Thread

MK1 Build Thread

12-Correction factor koni front shock Breakfast run Idle screw Stickers It gives me great joy to customise my car's appearance and performance to suit my taste .  :grin:
This is another topic I researched. I found it strange that on turbo car's dyno graphs I saw NA correction factors being used. I found the articles below on the internet. Interesting reading which confirms my suspicions. Turbo cars using NA correction factors give generous readings My question: Should turbo cars and NA cars use the same ambient correction factor? I'm very interested in this topic. So I did a little reading:

http://forums.nasioc.com/forums/archive ... 73912.html

"The notion of the use of some kind of ‘correction factor’ is based on original work by many different standards bodies to inject some amount of reproducibility in power measurements. In the US, SAE is certainly the most well known, but among the rest of the world, standards from ISO and DIN have equal penetration into the engineering mindset. Lest we Americans think not the world revolves around us. ;)

The concept of having a correction factor is derived from both the changes in engine operation due to atmospheric differences, but also testing procedures, steady state and dynamic efficiencies, and of course repeatability. Most people referring to “SAE Corrections” in the US are talking about SAE1349, which is the current and most updated and recognized industry standard. Like all standards, it is VERY easy to talk about with an air of authority without actually TALKING about it. I took the time to read the standard and much to my surprise it was VERY easy reading. This document is nothing like the usual standards body work in both obfuscation and terminology. I highly recommend it for any professional tuner. "

While SAE prevents publication of the document itself, US Copyright fair use provisions do allow quotation and analysis of the document. There are several interesting factors used in the SAE correction, but the “Power Correction Factor” is what most people here would be interested in. Let is take a quick look at the following text:

http://www.pdxtuning.com/nasioc/SAE-exp1.jpg

This section describes the corrections used for non standard atmospheric conditions. There are three critical things to get from this text...

(2) Turbocharged cars need not apply. The use of the standard SAE air density corrections for turbocharged applications is plain wrong. As stated in the standard, without any need for additional clarity, “For example, boosted engines with absolute pressure controls shall not be corrected for ambient barometric pressure”. It need not be any clearer. You will notice by the way that all of the PDXTuning posted data is non corrected. Further in the document, the use of intercoolers is discussed, and there are changes to the air temperature corrections based on the efficiency of these intercoolers."



Some more interesting reading:


http://www.max-boost.co.uk/max-boost/in ... tuning.htm

Dynos Don't Lie. Or Do They?
By Shiv S. Pathak

Altitude

...While this correction amount is reasonably accurate in some cases, it is notoriously optimistic in the case of turbocharged engines. In such engines, power output rarely falls as dramatically in response to air density reduction. This is due to their turbo control systems that combat air density reductions by allowing for higher boost pressures. These increased boost pressures can almost completely offset the ambient pressure reduction and make the "altitude correction" almost completely unnecessary. However, I have yet to see a high-altitude tuner come forth and not apply the positive correction factor when displaying their grossly optimistic dyno results.

Humidity

Similar issues arise with changes in humidity...However, as with altitude, not all cars react to humidity changes the same way. For example, a naturally aspirated car may behave as predicted by the smarty-pants that derived the correction technique. But a heavily turbocharged may behave exactly opposite to the rule. Turbocharged cars, unlike naturally aspirated cars, often operate right up to their knock (also known as detonation) thresholds. When humidity rises, the extra water content in the air charge actually acts as a passive cooler of sorts, lowering in-cylinder temperatures just enough to allow for a few more degrees of ignition advance without the presence of detonation. In other words, whatever engine output is lost through the reduction in oxygen content is gained (and then some) through a significant bump in thermal efficiency (caused by operating with more ignition advance). Voila-another improperly applied correction factor!

Temperature

...Turbocharged cars may, in fact, make less power when ambient temperatures drop beyond a certain point. This is often caused by lean-run conditions induced by the increase in air density. Running with the leaner air/fuel ratios, a turbocharged car may run into detonation, which will result in spurious knock sensor activity. Before you know, it several degrees of ignition advance is yanked out and power suffers measurably. This situation is not uncommon in cars, like the WRX, that have their intake temperature sensors placed before the turbo (in the Mass Air Flow sensor) and not just before the throttle body. Latter placement provides a much more accurate indication of in-cylinder air temperatures, allowing the engine management computer to respond with proper fuel and timing compensations.
So the shipment of shocks arrived late in this week and I got my shocks installed today. I got the KONI Sport shocks for the front (861919 spt inserts with casings) and a Powerflex bump rubber on each shock. My shocks are black because I couldn't wait for the yellow powder coating (another 4 days of waiting), I only had 1 functioning shock which was dangerous! I'm very impressed with Steve and his team. They are honest, friendly, go the extra mile and are extremely knowledgable. I recommend them for suspension upgrades! Thanks again Steve for helping me out. My car handles like a dream:grin:. I snapped some pics of Steve's beautiful Scirocco too which was in the process of getting a Caractere body kit and KONI suspension upgrade.:drool:Please excuse the quality of the pics as I took them with my phone.



















































































Breakfast run






























A pic of my new battery.






























As I'm sure you have all noticed that I'm a "sticker - whore", so when I had my car recently tuned at KAR Performance I decided to add more stickers

























































As I wrote in the tech section. My car started being jerky on pull off and idled poorly in heavy traffic (1km in 40 minutes). Shane from KAR performance diagnosed that for me and he tweaked my map
The 5mm hole that my mechy drilled.
The screw to to set idle to 950 rpm instead of the 750 rpm it was on.






























He used a grub screw, threaded screw without a head, only with a nut (stopping it from going through the hole) and it has a grove at the end of the screw which he adjusted with a screw driver. The both of the ends of the screw are flat, so it doesn't dig into the black plastic "disk" that the throttle cable is attached to and opens and closes the throttle plate






























I've always wanted to put a sticker on my airbox, so I got another one when I was at KAR the other day. I'm a firm believer in OEM these days and have opted to stick with an OEM air filter, so no K & N sticker etc.






























So thanks to Torker I went to Volkspares and bought one of their lower strut braces / bars. I thought I would have issues fitting it because my car is old and I was in an accident so I went to my mechy Jacque to fit it. It turns out it fitted like a dream. My handling has greatly improved. Jacques said because of my 2.0i power my chassis legs flex outward under acceleration so now my traction will improve which I can feel too. I sprayed the brace black with high heat paint (gets hot by branch) as it was bare steel.





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