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SDI tuning...

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SDI and tuning in the same breath?! If that's even a 'thing'... Just thought I'd update all you non turbo, diesel tuning people out there.

Over the last few months I've been running DLSA150P544 injector nozzles. Same economy on a run, but accelaration torque is way better. Who says you need a turbo? All good, and car 'almost' keeps up with a stock lupo GTi! No access to rolling road at the mo, so no idea what power gain if any. Definitely more torque though. I also adjusted the injection pump quantity adjuster to make it idle at 0.2mg when warm. So a bit more fuelling top end, like 5mg. In theory about 15-20% more fuel. More fuel = more power in a diesel.

But. 

Yesterday my car failed its MOT on emissions. D'oh. Smoke reading when blipped to between 6-7.5. Limit is 0.7 on the plate.

Oh.

Took it on a quick 20 mile blast to clean anything out, along with some purge in the tank (i don't think the stuff works). Retest. No change.

Back to the workshop and had a dig around for some original P745 injectors (0.190mm holes). Chucked em in. Back to tester who was now laughing... Scraped through with an average (after a few tries) of 0.66 smoke. Pass.

Moral of the story- you can have more grunt from an SDI, but it's not gonna be legal...

 

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Dodgy mot!

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Purge in the tank does nothing really. We both know that. Did you not do the full setup like I've said before. That includes running your own independent fuel source from a pop bottle or something?

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Yeah, probably true, but I can't prove it. The good ol' pepsi bottle has been useful for experiments, but I've never conclusively found it to make any difference if running almost neat 'purge fluid' or diluted with a few litres in the main tank. I'll have a chat with one of the guys I know who does the development for BP's fuel additive division half a mile from here. He's told me some interesting stories about fuel additives. Apparently up till recently, Australia was one of the last countries in the world to run 100% pure 'distillate', without any detergents or anything. They know their stuff. Naturally, the BP premium diesel fuel is the world's best... Ever since, I've been using that in the tank (almost empty with just a few litres of the stupidly expensive (like 25p a litre more than regular) diesel just before MOT day. Up till now always good. Apart from I'd forgotten that I'd swapped the injectors over about 10 months ago.

My MOT guy is absolutely straight down the line. My cars are all stock so I like it when he's very critical, because it helps me identify things I hadn't spotted (not often...). The smoke test is interesting because if you test just after a run- like seconds, it's always good. If the car is allowed to idle for 30+ mins (while examined) then tested, the numbers are obviously going to be higher. So I guess, the true reading happens after any soot build up has been blown out of the silencers. I wish I had a smoke tester that I could rig up to a car while driving it to see the actual readings under steady load. My first MOT fail for a very long while. I had to take it in... Woah! :)

 

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