Author Topic: 1.6TD Pump on SDI Engine  (Read 2695 times)

April 07, 2023, 05:35:02 am


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1.6TD Pump on SDI Engine
« on: April 07, 2023, 05:35:02 am »
Hi all,

I and have a couple of 1.6TD pumps laying around (all 9mm; 494 code). I also have a GT15 turbo.
So I'm thinking of putting these on a SDI engine which are very cheap here.

I did lots of research there's many topics I stumbled upon (also on this forum)
- many people say it won't have power in the upper revs, and a 300TD / Kia Carnaval 2.9TDI pump should be a better choice.
- 8v-of-fury tried something similar and wasn't satisfied (but unsure why, if he was aiming for big HP, or botched the frankenpump, ..)

I'm trying to understand why;

The AHU/SDI came with a 10mm pump, mine is 9mm, so theoretically mine can provide +-25% less fuel (10^2 / 9^2). But you can squeeze +- 250HP from a stock AHU pump, and I'm only trying to make 100HP (2.5x less), so the 25% in fueling will be insignificant

The only thing I can think of is the DI is more picky about the timing of injection; the cup in the cylinder is only in the right spot a fraction of the time while the whirlchamber is always there. Also the 190bar SDI injectors will have more delay to get up to pressure than the 155bar TD ones. Simply adding "more fuel" will be injected during the wrong time (suboptimal for combustion) and will go out as semi-unburnt black smoke.

So is the "fix" then as easy as;
1. advance timing (say 1.5mm?)
2. swap out cam plate with a more aggressive one (from the SDI pump?)

Reply #1April 07, 2023, 08:12:17 am


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Re: 1.6TD Pump on SDI Engine
« Reply #1 on: April 07, 2023, 08:12:17 am »
Interesting references;

1,34655.0.html  [Seems OK]
Now I have an AAZ pump, with TDI advance mechanism, TDI camplate and 10mm plunger and pump head. Orther than that nothing changed.

2,46444.msg361214.html#msg361214 [Seems OK'ish]
The 1.6TD injection pump will not give decent power on an AHU.

3,46768.msg363949.html#msg363949 [Bad stock, camplate & advance needs changing]
A 1.6TD pump is VERY BAD for a starting point for an mTDI.  The camplate is completely wrong. The advance curve is completely wrong.  There are other less major issues also.

4,19922.msg151294.html#msg151294 [OK-ish]
you can use a 1.6 pump as a base, but then you'll want to put in the tdi cam plate, atleast a 10mm head, find some way to make the timing advance faster.

So I answered the question myself; with the mods described it is possible
« Last Edit: April 07, 2023, 08:19:34 am by chi1337 »

Reply #2April 07, 2023, 08:55:49 pm


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Re: 1.6TD Pump on SDI Engine
« Reply #2 on: April 07, 2023, 08:55:49 pm »
If the SDI is close to the AHU then a cummins 4BT pump might work better.
Tornado red, '91 Golf 4 door,
with a re-ringed, '84 quantum, turbo diesel, MD block

Reply #3April 14, 2023, 06:00:29 pm


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Re: 1.6TD Pump on SDI Engine
« Reply #3 on: April 14, 2023, 06:00:29 pm »
The plunger diameter is only part of the picture for fuel delivery potential.  The camplate profile is another major factor.  Governor spring needs to be correct to be able to reach appropriate rpms.  Dynamic advance needs to be correct to have decent performance throughout the rpms.

The 1.6 pump is a poor choice as a base pump.  AAZ pump is also a poor choice.

The Cummins 4BT would be better but needs internal mods to work well.  The governor spring and rpm range is very limited (4BT runs to ~2,500 rpms) and because of that the dynamic advance is also nowhere near correct.  Those parts can be swapped out but it is not a simple task unless you know what you are doing.  There is also a steep learning curve to tuning one after it is built, even if it is all built correctly.  Doable, but not simple.

Reply #4April 14, 2023, 06:33:24 pm


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Re: 1.6TD Pump on SDI Engine
« Reply #4 on: April 14, 2023, 06:33:24 pm »
hey thanks for the replies.

Some context; I have a Golf mk1 1.6D with original gearbox/engine (with 12mm headbolts) from 1982. I don't want to mess too much with it (e.g. turbo it) because I don't want to push it over the edge.
When it finally dies I want something with more power, say 80-100 HP.

I gave up on the SDI / TDI swap because of the following reasons;
1. Electronics or mTDI (needs expertise in both cases)
2. Needs new gearbox (02A)
3. 100mm driveshafts
4. I won't be able to use all my hoarded stuffs (GT15 turbo, IDI injectors, IDI TD pumps etc)

The AAZ is a much better path, only downside 10-15% more fuel consumption and can reach the power I need easily. It's NA sibling (AEF) is very cheaply available here (100$), with 200mm clutch & freewheel (50$ new or 85$ for the 210mm) for my 020 gearbox. It's actually the same block, same valves, piston oil sprayers, even says 1.9TD on it according to people on this forum.