Question about 1996 Volkswagen Jetta
I want to do a turbo conversion to my mk3 and i have the turbo set up but i want the reinforced equipment from a tdi because of strength and torque.
i'm sure i can use the internals of the bottom end but im curious about the head. Can i use the tdi cam valves springs and retainers?
You are probably better off using aftermarket gear meant for the car. Remember that a diesel uses extremely high compression ratios (as high as 17:1), and that is created partially by the head's deck height and combustion chamber dome, and partially by the rod length. Very high compression ratios are not desirable for a turbo engine unless it's extremely fine-tuned (by a pro on a dyno, using standalone mapping to set up all the individual timing and fuel maps for partial throttle vs full throttle activation, boost-dependent timing ******, etc). Trying to piece together a high compression turbo setup and controlling its operation with an off-the-shelf turbo chip is a recipe for mulching the internals of your engine. As far as valve springs and retainers, it'll depend on the size of the valves relative to the size of your engine's valves, and the cam would definitely be wrong to use - diesels are designed for large amounts of low-end torque and a low rev limit, whereas a gas turbo engine depends on higher RPM for spool and power production. The lobes of a diesel cam are optimized for low-end operation and won't run well at higher revs (since they were designed for an engine that will never see those higher revs - the diesel will hit redline shortly after the RPM point at which the gas engine really starts to build boost). You may even find that the OEM cams are fine for use on a turbo setup - usually it isn't until you really start pushing that you NEED cams. Even the stage 3 kit from C2 that I've seen uses OEM cams, and that's set up for a base tune close to 500hp on the VR6 (not your engine, but still, making 500hp on an engine that was designed at 170ish hp, and still using stock cams, shows the potential for high-end breathing of OEM gear). I'd do the turbo setup and get it working great, and then start upping the boost and upgrading further components, like the cams, as needed.
Keep in mind too, that building a turbo setup, you're not going to want to use used internals, and the price of OEM tdi internals is likely to rival the cost of aftermarket parts - you are better off going with the aftermarket parts that are intended for a gas-engine turbo setup, and the additional benefit to that is, as long as you're tuning for power/boost levels similar to the output of the kits from places like C2 or APR, you will probably be able to use one of their in-stock tuned chips and fine-tune with an Apex'i S-AFC as needed.
Posted on Oct 19, 2008
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Posted on Jan 02, 2017
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