turbo thoughts......
 

Few things I have been thinking about for me new 617.952.

1. Ability to adjust "throttle" to 1800rpm min when changing gears.
Was thinking about modifying cruise control for this, just no sure how. Biggest Q is how to detect gear change. Speed + neutral/clutch switch?
2. Propane injection, is it as dangerous on IDI engines as they say it is?
3. Turbo cool down shutoff delay.
Was thinking about putting a vacuum delay type valve into the line between the shutoff valve and engine, something that takes a minute or so to kick in.

Any suggestions?

I posted this in another thread too.

1. Why not buy a idle adjustment cable assembly from a 240D and throw it in?

2. Why not turn up the full load?

3. Don't bother. By the time you have slowed to park and are ready to shut off the car the EGTs are already at a safe level.


Edit: The idle adjustment cable is nice for keeping the idle smooth when the engine is cold, however in my experience the idle needs to be all the way down when shifting when the car is warm, otherwise the RPMs do not fall off for a proper smooth shift. Try some shifts with the car fully warmed up and see how it feels. You should easily be able to adjust the way the engine slows when shifting using the idle adjustment screw on the IP and may not even need the idle adjustment cable.

How do the turbos control idle on warm up?

I'll need EGT gauge for both of that

The turbos just rely on the IPs idle governor when cold. The Revs to fall off much faster between shifts when the engine is cold which does make the adjustment nice.

You would need an EGT gauge for propane too. Turning up the full load is free other than the cost of additional fuel.

You don't need an EGT gauge or turbo timer to make it safe to shut down the car. The only time I can conceive of when it would be necessary to cool down the turbo is if you were climbing a mountain pass as fast as you could, then decided to park immodestly and shut the car off at the top. Anyway if you got a turbo timer you would need a big chrome exhaust tip and rubber band tires to go with it. :D

Not necessarily. I have a 20 minute commute going 65mph down the highway. I exit and drive about two miles around 50mph to get to my driveway, which is about 150 feet long. I don't remember where but from reading something on here I gathered that it was best to wait till your egt's are below 400F before you turn off the car. Mine are never there after getting off the highway like that. They're more like 500F and it takes about 30 seconds to a minute for them to come down.

The only time its safe for me to just turn off the car right away is on the opposite end of this commute, going 20 miles to town at 65mph from my house. Then I have a mile or two of driving where I don't get over 35mph and the egt's are around 350-400F when I make it to the parking garage at school.

For keeping the turbo up to speed, you must either double clutch or keep your foot into it on shifting -- this is where an auto beats a manual, since you don't lift your foot for shifting. Otherwise, live with it, this isn't really a performance car anyway.

If you add enough propane to get an ignitable mixture, it will ignite long before TDC on a turbo -- this will rapidly either burn holes in the pistons or over-pressure the rings and ream out the cylinders (or both). Not pretty. If you want more power on a 617, adjust the boost control spring to give 13.1 psi, no more. In the words of my mechanic friend "more and you will greatly reduce the life of the engine".

I always cool the turbo down if I have not been driving at light throttle near idle for several minutes. I live in the country where the speed limit is 40 mph, so don't bother at home, but any time I'm on the highway, I let it idle a couple minutes before shutdown.

Peter

Good grief. I barely get up to 500F on the freeway. I still don't remember the exhaust being that hot, I must have had this intercooler on too long. :dizzy2: