Quote:
Originally Posted by jtbo
My car has 1.9l turbo diesel motor with Garret T2 turbo, these were made with similar sized KKK too, but below 1700rpm there is not much life unless lead foot, 50mph is 1850rpm and any lower rpm would require lead foot to get on boost and to get car going.
Hills would be much easier to climb with more speed as maximum torque is 2250rpm from my memory and it is about where can get max boost.
T2 is tiny turbo, but still boost is coming quite late, this makes me bit skeptical that it would be possible to make good boost at idle without wasting fuel to just make it boost, however I really interested of how such could be done as I would love to get my motor to pull well 500rpm lower than it does now.
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Getting a turbo to boost at idle is impossible because the velocity of the gasses and the lack of heat don't supply enough energy to get the party going, and the turbo you have is a fixed geometry unit. The factory pump settings are to keep it from puffing smoke on initial application of the throttle so fuelling between idle and maximum boost makes the engine feel soft.
The thing I would suggest is to take the car to a chassis dyno ( rolling road ) and find out exactly what the horsepower and torque curves look like, and then based on what you see, decide what would be the most cost effective way to achieve your goals.
The simple things like the piping in the turbo system can have a profound effect on boost response. Look at the factory piping and see about making the piping larger ( you don't have to go overboard on size, just make sure it has great routing with no kinks and smooth bends ), a low restriction exhaust system ( turbos do not like backpressure ) with an upgraded downpipe from the turbo if it has kinks and poor bends.
The main thing with your combination is to remember that a 500 rpm drop is huge with the factory camshaft timing and injector pump calibration. Now comes the time when you have to ask how far do you want to go, because to get there may get expensive. I'll never discourage someone from doing something, just be committed and be wide eyed about the realities.
You need more torque below 2250 rpm, which means either making the fuel come on hard before then by calibrating the pump delivery and timing that way, spooling the turbo ( you do that by flooring the throttle now ) or building more cylinder pressure preboost with a cam swap. Find out if there was a commercial version or industrial version of your engine made and see where the torque peak is because the cam timing is usually milder for these engines and a lower torque peak rpm. If not, you'll have to get something ground that will put peak torque at 1750 rpms. I know someone here that can do something like that, and as long as you can get the info he needs, he'll give you what you want. Maybe Piper or Kent can do the same over in the UK; I am just not familiar with the camshaft specialists over on the Mainland that are closer to you.
If you combine the cam swap and the injection system mods, you will get where you have to go. The increased cylinder pressure will spool the turbo up harder and earlier, reducing lag and increasing fuel efficiency, while at the same time eliminating the need to change turbos. The turbo is optimized for what you have now.