how effective is diesel "tuning"?

[gldgti]

just a bit of a throw around topic guys, but i was just thinking...

I've done a little bit of tuning to my old girl over the last couple of years... nothing special, but the list is:

- dynamically adjusted timing to a nice dieselly advanced position
- 2" straight exhaust from the bottom of the dual downpipe back
- enlarged airbox intake to 80mm with cold air intake and open grille
- wound in the fuel screw as far as i could accomodate with my stretched accellerator cable to increase fuel at WOT

Now, i know for a fact that the car goes a lot better, but i've always pondered what kind of gains i've really got. I mean, is it a couple of hp here and there, maybe a little torque.... i know noone can actually tell me unless you are willing to pay for a dyno run (haha) but i really just want to hear your theories. the never ending quest for the lean, clean diesel powermachine is neverending for me, but its a fun underaking. what mods have you guys done?

[imported_brackie]

Re: how effective is diesel "tuning"?

just a bit of a throw around topic guys, but i was just thinking...

I've done a little bit of tuning to my old girl over the last couple of years... nothing special, but the list is:

- dynamically adjusted timing to a nice dieselly advanced position

You must have a dial indicator! That's really the only safe and reliable way of getting the timing right.

- 2" straight exhaust from the bottom of the dual downpipe back

Did you also fit extractors?

- enlarged airbox intake to 80mm with cold air intake and open grille

Got any pics of this?

- wound in the fuel screw as far as i could accomodate with my stretched accellerator cable to increase fuel at WOT

Don't understand the link between your fuel screw (max. fuel control screw?) and your accelerator cable??

Now, i know for a fact that the car goes a lot better, but i've always pondered what kind of gains i've really got. I mean, is it a couple of hp here and there, maybe a little torque.... i know noone can actually tell me unless you are willing to pay for a dyno run (haha) but i really just want to hear your theories. the never ending quest for the lean, clean diesel powermachine is neverending for me, but its a fun underaking. what mods have you guys done?

I haven't done any mods as I'm a "keep it original" sort of guy. But...Anything that improves gas flow both in and out has to be good. Increasing air density (and therefore oxygen content) by drawing cold air is also good. Every diesel (all makes) that I have bought second hand has had the problem of not getting full throttle. This is always the first place I check Usually it's just cable adjustment, but sometimes (depending on the make) it's adjustment or wear on the pump throttle shaft or linkages themselves. With diesels, a fraction of a mm can make a huge difference. As far as the maximum fuel device is concerned, it's a case of compromise. How much smoke can you and the boys in blue tolerate? Wind the screw until nobody complains.
In the US and Canada there are fuel injection shops who pull Golf injection pumps to bits and rebuild them for maximum efficiency. I guess what they are doing is increasing fuel delivery because you can't get something for nothing! They charge to Earth, too. $1k AU or there abouts. You can't really do much with valves and combustion chambers (no chambers!) but you can polish and port the head. I haven't any figures for performance improvement for this but it's got to help. Injectors should be kept in optimum condition. You can get genuine Bosch nozzles very cheaply if you know where and contrary to what the fuel injection shops will tell you, you can fit them youself if you know what you're doing. As timing belts stretch and the teeth wear they incrementally retard both valve and injection timing. Valve timing isn't so bad, but even a fraction of a degree of injection delay can make a huge difference, so replace the belt often. (You must have a dial gauge?? Will you lend it out?)
A lot of what I just wrote has nothing to do with "tuning", I know. But a good place to start is to get the basics right. No point in polishing and porting etc. if the engine isn't basically doing what it should.

[gldgti]

You must have a dial indicator! That's really the only safe and reliable way of getting the timing right.

only way? be careful of saying only... There is a very effective and reliable way of dynamically adjusting the timing (while the engine is running) for the IP which involves loosening pump bolts and turning the pump while the engine is running, listening for engine note etc and snuging bolts back down. testemony to this method is the fact i've had 20,000kms of economical, low smoke running, very low oil consumption and great cold weather starting - so has dad with his golf and a mate and i even performed this on his 2L-T toyota cressida diesel with success. if you look around on http://www.vwdiesel.net you will find details of this method

Did you also fit extractors?

nope. I had the duel downpipe manifold as standard, which by most reports is the best manifold for the diesel golf.

I havn't got any pics of the airbox mod, wish i had a camera. maybe i can arrange something...soon

Don't understand the link between your fuel screw (max. fuel control screw?) and your accelerator cable??

since my cable stretched, i have run out of adjustment to allow pedal to take pump to full throttle when foot on floor. as such, throttle lever can return only a certain way back towards the idle stop. so, if the fuel screw is wound in too far, i will have idle runaway as it will not be able to back off properly. this said, it is probably getting enough fuel anyway...

finally - i have plenty of cold air as i have a custom alluminium grille which has no blocked off parts. thus i have lots of cold air coming into engine bay, and my intake pipe runs 80mm all the way from the airbox to just behind the grille, pointing forwards so as to recieve cold air directly from outside the car. (note, the mouth of the pipe is about 7in behind the grille and points slightly down, so as to avoid too much nasty h20 entering the airbox when its wet.

[Gold-mk1]

Doesn't a fuel pump from a mk2 TD fit on the same block ? if so, won't it pump more fuel ? therefore give more hp ( and smoke ! )

[imported_brackie]

Right on all counts!

Yes...... But we never got the turbos here. All Mk1 diesels were 1.5 NA. Even thought I like to keep my cars original, I would love a 1.6 turbo diesel motor to slot into it. Ah well.... I can dream.

[Gold-mk1]

Re: Right on all counts!

Yes...... But we never got the turbos here. All Mk1 diesels were 1.5 NA. Even thought I like to keep my cars original, I would love a 1.6 turbo diesel motor to slot into it. Ah well.... I can dream.

manifolds and pumps aplenty over here mate !!

[hill billy]

manifolds and pumps aplenty over here mate !!

What sort of price would the manifolds be?

Would you be interested in sending some over to Australia?

Yes, I've read all the warnings about putting a turbo on a non turbo engine.

[Gold-mk1]

manifolds and pumps aplenty over here mate !!

What sort of price would the manifolds be?

Would you be interested in sending some over to Australia?

Yes, I've read all the warnings about putting a turbo on a non turbo engine.

I'll have a scout about to get an idea on price.

ANY engine can be turbocharged. No danger or unreliablility issues AT ALL, provided you don't go mad.....