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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Motronic's turbo conversion thoughts?

We are lucky to have and Protomotove to support converting 3.2 Carrera's and C2's to turbo. Such conversions seem to work well and can make a huge amount of HP

However, I am wondering if the following ideas make any sense or have potential.

On the fuel side:

For something like running .4 bar (6psi) with a stock 3.2, we could get more fuel by increasing the fuel delivery with a stock style higher pressure fuel pressure reg (stock 3.2 is 2.5bar) or change to larger injectors with the goal of increasing fuel delivery about about 40-50%.

Then to balance, tune and adjust for this by tightening the spring in the AFM so it progresses about 30-40% slower.

On top of this we can also play with the fuel quality switch to add 3.1 or 6.3% more fuel or subtract 3.9% of the fuel delivery.

On the ignition side the stock chip is pretty conservative. Also, with a blow through AFM, temp sensing is at the AFM and I believe can retard timing up to about 3 deg with heat. One could also use the Fuel Quality Switch on the ECU to retard timing 2 deg.

There is also the Calif/Japan brown jumper at the ECU that leans part throttle fueling and retards timing 3 deg. This might be a good fit with such a strategy.

A 3.2 running about 1.4 boost should make about 340fwhp.

As to a 3.6 (89-95 w AFM's) one would probably need to cut the dome's off the pistons or run J&E's. I believe that cutting the stock pistons down can get us to about 8.5/1 cr.

With this one might be able to run up to 1.7 bar for about 440fwhp.

With the 3.6 we would probably have to add injectors that flow some 70-80% more. Not sure if we can slow down the AFM flapper valve that much.

Increasing fuel deliver at the same duty cycle and slowing the AFM meters rate to a percentage of this is key to this concept.

On the ignition side, the 3.6 is timed for 11.2/1 compression already. If we stay at .7 bar and set the compression to 8.5/1 we will have about the same effective compression rate on boost as the stock N/A motor.

On top of that the 3.6 has knock sensing ability. If we do not get to carried away we may not need to worry much about the spark side on a 3.6. If they have a fuel quality switch, we could pull timing back a bit just to be safe.

Of course the best approach is to convert to a fully programmable system or go the with a Raising Rate fuel pressure reg and or Protomotive chip.

Dose anyone else think this might work or see any big holes in such an approach.

Last edited by 911st; 01-26-2010 at 09:34 AM..
Old 01-26-2010, 09:22 AM
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