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Engine Mods: With a difference

Discussion in 'A4/S4 forum(B5 Chassis)' started by AR-rkon, May 17, 2011.

  1. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 17, 2011]
    A discussion sparked out at work today on what electronic/electrical (no bigger turbo's etc...) mods could be made to an engine (especially the uber-tuneable 1.8T) to increase its maximum wheel HP? (disregarding the obvious... remaps)

    Being an electrical engineer, knowing some software coding and wanting to increase my cars performance, i think this could be manageable.

    Your thoughts?
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  3. Keyser Soze
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    Keyser Soze Member

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    [May 17, 2011]
    Bigger Injectors? Uprated fuel pump? Aquamist injection?

    Addition of an electric motor ala hybrid car stylee?
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  4. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 17, 2011]
    yep those are the kinds of things im thinking (maybe not the motor haha), plus possibly variable inputs (sensors).... im awaiting the ME7.5 manufacture specification from bosch so i can see the limits of these variables and their effect on the ECU base tables/maps
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  5. Keyser Soze
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    Keyser Soze Member

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    [May 17, 2011]
    One potential is an "E-Quattro"!!!!!

    Take one quattro saloon or avant, drop the drive to the rear diff & substitute a motor to the diff et voila, uber tuned 1.8T up front with electric assist at the rear!!!!!

    Regenerative braking to charge up the onboard collection of laptop NiMH batteries and off you go!!!!!!.

    Seriously would dent the kerb weight of the car and you sure as hell would need a mapped K04 or T28 upfront but what the heck, you could wipe the smile of those smug Prius drivers in style!!!! :jester:

    Who says being a hippy tree hugger had to be boring????? :)

    Could well be like the Top Gear Hammerhead Eagle i-Trust perhaps??

    [video]http://youtu.be/WfNfwNWWphI[/video]
    Last edited: May 17, 2011
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  6. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 17, 2011]
    Love it kev...

    Got to consider the kerb weight, it would have to be a pretty damn hefty/torquey motor and have you seen how much tech is involved with regen braking?

    Anyhoo... any feasible suggestions? :jester:
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  7. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [May 17, 2011]
    Problem is a lot of the external factors are tied together.

    If you fit larger injectors, the engine overfuels, lambda notices, ECU cuts fuel back.

    In reality you need more boost, on an AEB/AJL you can fool the ECU into giving more boost by fitting the MAF sensor into a larger housing, and then scaling the injector size by an equivalent amount, because the ECU uses MAF for all its fuelling and boost control.

    Your engine (AWT?) has a dedicated boost sensor, which it uses to control the boost pressure, and the fuels using the maf. If you do the MAF trick, nothing happens as the boost stays the same.

    If you were able to fool the output of the boost sensor by electrically scaling the signal (ie so 8psi IRL appears as 6psi to the ECU), then you'd be able to proportionally increase boost that way, however you then hit another few problems.

    First off the ECU has secondary safety mechanisms which will cause it to cut power if the MAF reading climbs too high. So if you fool the boost sensor into giving a low reading, it will up the boost, realise somethings gone wonky as its now flowing 190hp's worth of air rather than 150 and pop a fault code and cut the power. The aforementioned MAF scaling (using a larger housing and larger injectors) would get round this however.

    Secondly is the issue of timing. To generalise/simplify things, for a given boost pressure/power output you need x degrees of ignition advance. If you increase boost, you typically retard the timing. More boost means more retard. If you've fooled the boost sensor, the MAF, and the injectors, the ECU now thinks its flowing 150hp worth of air, when its infact ingesting 190hp. As a result its running 150hp's worth of timing, which is invariably too much, and will cause the ECU to start cutting the timing back under load using the knock sensor. The ECU can only correct so far though, and controlling det by knock sensors alone is seriously dodgy ground, and because its direct ignition, theres no easy way to change this without changing the ECU's map.
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  8. AndyC
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    AndyC Moderator Staff Member Moderator

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    [May 18, 2011]
    However, its quite interesting when you start playing with OEM maps............ lets just say the manufactures have already tuned the cars at some stage in their development
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  9. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 18, 2011]
    but never to their full safe potential :racer:
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  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [May 18, 2011]
    I think he means the maps indicate that the engine at some point was running MORE power than it was actually shipped with.

    Define "full safe potential"

    With the size of the turbo fitted to the A4 1.8T, 150-165hp is what a manufacturer would define as a safe reliable amount of power. Remember they want that engine to last hundreds of thousands of miles. You want the turbo in its most efficient band, with its shaft speed controlled to a sensible level for longevity.
    They designed the engine for a purpose, which was (at the time) to provide a middle of the range engine choice, which is nicer to drive than a asthmatic 1.8 NA, but without moving into the "high end" luxury choice of a V6. It was never intended in the A4 application to be a performance option, they had the S4 for that.
    An OEM is never going to tune an engine the way people do in the aftermarket. With an aftermarket remap on a 1.8T you've got the turbo working way outside its efficient range of operation, the intercooler becomes insufficent if someone happened to stick their foot down in 5th and leave it there for 20mins, etc etc.

    As a result, the engine, as its installed in an A4 by the factory IS tuned to a safe level.

    They tuned the engine to 225hp in the TT/S3, but the engine isnt identical. They fitted a much larger turbo ofcourse, but they also lowered the compression ratio slightly, added EGT sensing and other similar things, because again they need to ensure its safe. The TT/S3 engine also retained the 20mm wrist pins from the AEB, whereas your AWT engine has 19mm pins for cost saving reasons.
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  11. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 18, 2011]
    Oh no doubt it will have been running more than its forecourt bhp. By "full safe potential", i meant that the peak performance the engine could "in theory" run, wthout eating itself, maybe at the cost of overall longevity and economy.
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  12. Oranoco
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    Oranoco Well-Known Member

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    [May 19, 2011]
    Do you want ideas that will actually work or just theories.

    If it's the later just look on e-bay as there is always things like electric suerchargers and fuel pills and the good old cooker dial power boost valve
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  13. Keyser Soze
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    Keyser Soze Member

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    [May 19, 2011]
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  14. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 19, 2011]
    Ideally the former, Seen all that ebay junk, though have you heen the dyno'ed truck on youtube with the leafblower supercharger :hubbahubba:
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  15. alex-qts
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    alex-qts Member

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    [May 28, 2011]
    Apparently you can diode the MAP sensor on the cars that have them, then using a boost controller you can raise the boost to ~20psi.

    My car does not have a MAP sensor (AJL engine) but I have been running 14-15psi (safe level without MAP sensor - tested) with a Ko4 turbo using a MBC and stock injectors (larger TT type I have been told) and all levels are well within the safe zones (boost does sometimes have to be turned down in certain temperatures).

    I cant remember the links but loads of people on audizine and a few others have done this mod and running 20psi + safely for long periods of time. (google MAP diode mod, i think that's how I found them)

    I know there has been lots of advice to stay away from boost controllers (for good reason) but I decided based on the threads that I found to give it a try and accept all the associated risks.

    It is like driving a different car, boost comes on very hard and fast, only downside is that the accelerator pedal is like an on/off switch now, you either boost it or you dont. It suits me fine.

    I would have done the mod if I had the MAP sensor, but using boot controllers can end very badly from what I can understand!
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  16. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [May 29, 2011]
    Yes I've heard of the diode mod before, and done it on a previous car, it uses a Zener diode across the signal and ground wires on the map to blind the ecu to any pressure over about 17psi and it does work quite safely, but that said you have to be very careful, a boost gauge is a must and if you want to push it to the top end of safe, using software like lemmiwinks or a map to edit the fueling. I have 10x 4.3V 1w zener's on order, as it was the only way to get any, and need to get a good but ideally cheap MBC or EBC and I will be having a play...
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  17. IN 2 Deep
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    IN 2 Deep Hoonigan

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    [May 31, 2011]
    Why not just reduce the losses the stock engine has i.e. electronic water pump, electronic power steering pump or electronic rack swap, ditch the viscous coupled fan and fit an electrical one. Move the alternator to the rear of the car and run it off the propshaft. Fit a lighter battery and locate it in the boot, take your spare wheel out and carry a can of tyre foam instead. Remove all the AC components, we are in England after all, im sure you'll survive those 2 hot days every year without it! Better than blagging your ECU and messing about with lemmiwinks in my opinion. That lot sorted would add up to a fair few horses and remove alot of weight, these A4Q's are damned heavy beasties.
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  18. AR-rkon
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    AR-rkon Midlands regional Moderator Regional Rep

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    [Jun 8, 2011]
    Having recieved my Zener diodes (£3) and a cheap ball and spring type MBC off a friend (free), I fitted them the other night. I set the Diode up on a switch so as to control it a bit, and i installed the MBC in place of the N75.

    And wow... what a difference. the car is peaking at 21 psi and holding 17-19 psi, the power comes on much harder and faster than before. Ran a log on vagcom, F/T are near normal, got no dtc's from the car (unless i had the diode switch in the off position, then it would hit limp due to a 17963 charge pressure maximum limit exceeded fault). Not noticed any driveability issues as yet (ie: part throttle) but i'll report back should issues arise.

    If there are no problems, my next plan is to use a 12v pneumatic solenoid to switch between N75 and MBC control, which will also activate/deactivate the diode bypass via a relay so i can run normally and at the flick of a switch (or a red latching button, james bond style, in the gear shift) have the full MBC power.
    Last edited: Jun 8, 2011
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