STILL MORE READING:
This was one of the most informative tuning posts I've seen on Digi1/2
Originally Posted by "digiracer" from the tex
Who Can Play?: 87-92 Golf, GTI, Jetta, Fox, Cariolet & anything else running on Digifant II
16 Valve Digifant II owners, this is a must do mod IMHO. Near stock or heavily moddified, 16Valve engines can really take advantage of this. Whether you know it or not, your 16 Valve has athsma & this is the cure.
The Point: Significant increases in Horsepower & Torque throughout the entire rev range. I'll have some dyno numbers soon. If you're serious about big horsepower and you've done everything else (cam, intake, chip, exhaust) this is the next step. If you didn't catch that, this should be done last.
1. Airflow Meter: (AFM) found on the 85-88 BMW 535i (most common), 635i, & 735i. It's the K Series Engine, a 3.5 Liter SOHC Inline 6.
New AFMs for these cars are expensive, as high as $450+
Used ones are very cheap from $40-$100 (I only paid $60, shipped to my door) & they can be found @ http://www.car-part.com/
Search for 1987 BMW 535i under Airflow Meter
Mine is from a 1987 BMW 535i it's a Bosch Unit.
The part # is: 0280 203 027
Note: Do not use the BMW AFMS found on the 325i, 328e, 525i, 528e etc. these units are the same size as our stock/OEM units. (they'll work fine, they just won't give you anymore power)
Note: Your engine is not going to pull the vacuum of a 3.5 liter 6cyl. Therefor you need to reduce the spring tension to allow your engine to idle properly. (with my 2.0L ABA/1.8 head I found reducing tension 8 clicks to work best) If you're using a 1.8L I assume you'd need to reduce it more.
Their's no wire splicing or cutting involved, it's a straight plug & play deal, it connects using your Factory Connector.
2. 3 Inch Intake Piping: cut to desired length, I purchased mine @ Summit Racing Equipment & paid too much.
You'll need atleast 2 feet & 3-4 hose clamps.
AT Sears Hardware, I found 3inch Clothes Dryer Ducting in 2 foot sections for only $4.99 a section & it looks identical to the fancy Summit Racing Tubing I spent $60 on.
Sears also has quick release 4" clamps for only $1.09 a piece.
3. 3Inch K&N, ITG Racing Filter or other similar style cone air filter. Again I probably paid too much, I bought my K&N @ Summit Racing for $36.
4. Larger Fuel Pressure Regulator (FPR) depending on your mods, Cam & how well the head flows you'll need atleast a 3.5 bar to a 4.5 bar FPR. The 3.5 bar is a stock Porsche 944S Unit & can be found @ http://www.germanautoparts.com/ for $41.
The part #s for the 3.5 bar FPR is:
Bosch part# 0 280 160 263
Porsche part # 944 110 198 03
'd suggest a 4bar FPR or better yet an adjustable FPR.
Find out more about them in my 4bar/ Adjustable FPR Thread
Ideally you'd want an adjustable FPR & a air/fuel ratio meter to tune it with but again not required.
This is the Adjustable/Rising Rate FPR I'm using:
It's a Malpassi FPR from Bavarian Autosport for BMWs.
It's an excellent unit but fits very tight & is not recomended for use with a G60 Valve Cover or other boxed valve covers.
Depending on how far you go, you'll need bigger injectors.
I'm using these: 24 lb Accels I noticed a nice improvement in throttle response with these. Alot of the 16 valve Digi2 guys are using stock 24-26 lb G60 Injectors.
5. A better chip is suggested but not required.
AMS is by far the best chip currently available.
Increases injector pulse width(more fuel), has agressive timing maps, & raises the rev limit to 7,000 rpm. (with the right mods, you'll make power that high with this AFM)
A cheap alternative is the SNS Cam Chip, it only increases fuel but you'll still have the stock 6,200 rpm rev limit & it does nothing for timing. It's only $39 & better than nothing.
BMW AFM vs VW AFM Size comparison:
The Door measurements:
VW AFM 2" H x 2 1/16"th W /50mm H x 52mm W
BMW AFM 2 9/16"th H x 2" W /65mm H x 50mm W
See Door Measurement for VW AFM
BMW AFM 3" or 75mm in Diameter
VW AFM 2 9/16"th or 65mm in Diameter
BMW AFM 3" or 75mm in Diameter
This is the Inlet Ring that comes with the BMW AFM, so you don't have to deal with using round hose on a square hole.
Chiptuning is also now quite standardized for digifant systems... there's various companies out there that have developed chips.
-VWPilot / Digifast
There is a condition with both digi1 and digi2 systems commonly called "digilag"
digilag is the lag between going WOT and having to wait for fueling to "catch up" this has been fixed with most chiptuning software....
some more links