A6 C5 Quattro oldschool V8 engine conversion advice/guideance
11-28-2016, 03:53 PM
#1
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A6 C5 Quattro oldschool V8 engine conversion advice/guideance
Hey Guy's
I brought a MY98 A6 2.8 Quattro and shortly after I bent some valves after the sump was punctured, long story short is I think the car is too nice to wreak and I came up with the idea to do an old school (carb/distributor etc) engine and gearbox conversion making it RWD only.
Last night I removed the engine and gearbox in preparation to receive the 253 CI V8 and gearbox I have purchased.
My idea is to have as many of the cars electrical and gauge systems working as possible and that when the ignition key is turned to ON things like lights, indicators, stereo etc work and I setup some relay's on the "ON" circuit to allow a push button start on my V8.
I would also like to setup the cruise control system onto the carby.
The hub ends of the front drive shafts with speed sensors will remain.
I am hoping to disconnect the motor's loom from the computer tho I hope to fit temp/oil sensors to the new setup.
I am hoping the speedo will still work???
I'm wondering if possible to setup the standard tacho to my motor, its a coil and points V8.
I assumed the fuel pump would operate with the ignition in the ON position but am not sure now.
display and alarms, I'm not sure what will happen here and is it possible if alarms do come up to use vagcom to alter alarms and display messages???
I have tried looking for wiring diagrams and thought for sure there would be some available for free online but am yet to find and.
Hoping some well educated members may be able to shed some light on possible issues and solutions so in the cab at least it all works like standard or as close as possible.
I brought a MY98 A6 2.8 Quattro and shortly after I bent some valves after the sump was punctured, long story short is I think the car is too nice to wreak and I came up with the idea to do an old school (carb/distributor etc) engine and gearbox conversion making it RWD only.
Last night I removed the engine and gearbox in preparation to receive the 253 CI V8 and gearbox I have purchased.
My idea is to have as many of the cars electrical and gauge systems working as possible and that when the ignition key is turned to ON things like lights, indicators, stereo etc work and I setup some relay's on the "ON" circuit to allow a push button start on my V8.
I would also like to setup the cruise control system onto the carby.
The hub ends of the front drive shafts with speed sensors will remain.
I am hoping to disconnect the motor's loom from the computer tho I hope to fit temp/oil sensors to the new setup.
I am hoping the speedo will still work???
I'm wondering if possible to setup the standard tacho to my motor, its a coil and points V8.
I assumed the fuel pump would operate with the ignition in the ON position but am not sure now.
display and alarms, I'm not sure what will happen here and is it possible if alarms do come up to use vagcom to alter alarms and display messages???
I have tried looking for wiring diagrams and thought for sure there would be some available for free online but am yet to find and.
Hoping some well educated members may be able to shed some light on possible issues and solutions so in the cab at least it all works like standard or as close as possible.
11-29-2016, 06:02 PM
#3
Wow. I don't want to discourage you...but the plan you have proposed would be quite challenging to pull off - not impossible. Basically you are going to toss the Motronic computer in the trash and then try to get the rest of the systems up and running.
Almost every system you mention will require some sort of clever workaround and/or adaptation.
Not to mention a huge amount of custom fabrication. Motor mounts. Transmission mounts. Radiator and fan of sufficient capacity + custom hoses. Custom driveshaft. Custom exhaust system. You will probably want to adapt the Audi alternation to the SBC and definitely the PS pump and AC compressor. Custom hoses for both. My head is starting to hurt.
Fuel pump receives input from Motronic, not key, so this requires modification. Plus remember you will need to regulate the pressure down to say 7psi. I'm not sure the stock high pressure pump will be happy delivering fuel straight to a carb with no return. You could also just go with a mechanical engine driven pump.
Tach receives signal from Motronic so this will require some work - not to mention it is a 6cyl tach and you are now 8 cyl.
Depending on what your transmission speedometer sender looks like this may be fairly simple - adding a gear reduction?
Temp sensor - maybe adapt the Audi temp sender to the SBC or find a sender with same resistance sweep that will fit the SBC.
Oil temp - same
Cruise should be easy assuming yours has a throttle cable and not drive by wire.
Idiot lights will be a nightmare. For example as I recall the oil pressure system uses 2 senders - one for low pressure at idle and a second for high pressure.
You will definitely need the factory wiring diagram.
Good luck. This could be a full season of one of those reality TV shows.
Almost every system you mention will require some sort of clever workaround and/or adaptation.
Not to mention a huge amount of custom fabrication. Motor mounts. Transmission mounts. Radiator and fan of sufficient capacity + custom hoses. Custom driveshaft. Custom exhaust system. You will probably want to adapt the Audi alternation to the SBC and definitely the PS pump and AC compressor. Custom hoses for both. My head is starting to hurt.
Fuel pump receives input from Motronic, not key, so this requires modification. Plus remember you will need to regulate the pressure down to say 7psi. I'm not sure the stock high pressure pump will be happy delivering fuel straight to a carb with no return. You could also just go with a mechanical engine driven pump.
Tach receives signal from Motronic so this will require some work - not to mention it is a 6cyl tach and you are now 8 cyl.
Depending on what your transmission speedometer sender looks like this may be fairly simple - adding a gear reduction?
Temp sensor - maybe adapt the Audi temp sender to the SBC or find a sender with same resistance sweep that will fit the SBC.
Oil temp - same
Cruise should be easy assuming yours has a throttle cable and not drive by wire.
Idiot lights will be a nightmare. For example as I recall the oil pressure system uses 2 senders - one for low pressure at idle and a second for high pressure.
You will definitely need the factory wiring diagram.
Good luck. This could be a full season of one of those reality TV shows.
