pump mods

vwmike

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« on: July 14, 2005, 04:27:33 pm »

So, I think we've mostly covered 2 different modifications - The governor mod, and the timing piston mod.

Here are some peices I have put together for my car.

I think I've only seen one fuzzy picture of the governor mod, but I'm pretty sure I have it right as that is the spring that would be compressed when throttle effort is opposed by the governor weights.

On the timing cover I have cut a recess around the spring seat to allow further timing piston travel. I think my only concern may be the strength of the cover after cutting this, but it seems like a problem would be unlikely. I plan to use the 1.5 spring to allow advance to happen sooner rather than trying to extend the rev range (I'd have to port the head to even think about taking advantage of that). So, there will be more advance, sooner, and more total advance available.

I also have a 10mm pump head sitting around that I was thinking of throwing on there at the same time, but I think my primary concern is flexibility in fueling. What I mean by that is I want tons of fuel on the top end but relatively little at lower speeds and when cruising. So, right now I'm just trying to get the best of both worlds. Anyone have anything to add?

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fspGTD

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« Reply #1 on: July 14, 2005, 05:58:28 pm »

If you want to maintain full fueling until high RPMs, you should ditch that intermediate spring, or at least "disable" it so it won't compress. Although it is hard to tell from the pic if it has been disabled and is just along for the ride, or not. It looks to me like you've added a huge stack of spacers on the governor main spring, but not disabled the intermediate spring.

Short of trying the machined timing advance cover, I wouldn't mess with the timing advance curve at all. Dyno testing has shown timing @ 1.00mm is ideal until very high RPMs like 5500-5750 RPM (when by that point in theory the piston has hit the wall.)

General tip: if you are doing an experiment, hold all other factors equal. Test it scientifically otherwise you will probably have a hard time making sense of what is causing what.

But anyway, you can try what you've got there too, it's just my advice... definitely ditch that intermediate spring. What looks to me there right now is a 2-stage revv limiter, first stage set (intermediate spring) set very low at the stock setting, and next one (the main spring) set very very high. How high exactly I do not know but I can tell you it's higher than I have tried.

If you are of the mindset that "more must be better" and really want to revv your motor out, perhaps you should try shimming the whole governor capsule solid.

Funny, to see this coming from a guy who doesn't believe diesels can revv.

Good luck!

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Jake Russell
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« Reply #2 on: July 14, 2005, 10:17:58 pm »

Quote from: "fspGTD"

If you want to maintain full fueling until high RPMs, you should ditch that intermediate spring, or at least "disable" it so it won't compress. Although it is hard to tell from the pic if it has been disabled and is just along for the ride, or not. It looks to me like you've added a huge stack of spacers on the governor main spring, but not disabled the intermediate spring.

I guess I'm just not up on the names for the springs. I shimmed the lighter spring and left the other alone. I thought about what you had said before with the LDA and no spring causing things to get bent, and you're right about that so I left a very small amount of travel in the spring.

Quote from: "fspGTD"

Short of trying the machined timing advance cover, I wouldn't mess with the timing advance curve at all. Dyno testing has shown timing @ 1.00mm is ideal until very high RPMs like 5500-5750 RPM (when by that point in theory the piston has hit the wall.)

Has anyone actually tried using the 1mm static advance but increasing the total advance? What I mean is that yes the car made good power with stock timing, but did you have something with a modified timing curve to compare it with?

Quote from: "fspGTD"

General tip: if you are doing an experiment, hold all other factors equal. Test it scientifically otherwise you will probably have a hard time making sense of what is causing what.

This is true, but some things are likely to happen at the same time like the governor mod and the pump head since both require disassembly.

Quote from: "fspGTD"

But anyway, you can try what you've got there too, it's just my advice... definitely ditch that intermediate spring. What looks to me there right now is a 2-stage revv limiter, first stage set (intermediate spring) set very low at the stock setting, and next one (the main spring) set very very high. How high exactly I do not know but I can tell you it's higher than I have tried.

So,....are you saying to disable the small (lighter) spring entirely?

Quote from: "fspGTD"

If you are of the mindset that "more must be better" and really want to revv your motor out, perhaps you should try shimming the whole governor capsule solid.

That's not exactly what I had in mind. I figure that it is beginning to take fuel away relatively early, so I do want to extend max fueling to the end of the engines useful working range. If in the process I enable the engine to rev past that point then sobeit.

Quote from: "fspGTD"

Funny, to see this coming from a guy who doesn't believe diesels can revv.

I never said that diesels can't rev. I just think the 1.6 D/TD is extremely handicapped in this scenario. The ports and valves are quite small, not to mention the danger of piston/valve contact if the valves float even a little bit. The camshaft is way too small and upgrading it really isn't possible unless you increase the valve releifs in the pistons which would lower the compression ratio, etc, etc...To me, it's not worth the extra risk when you consider how expensive it can be if you do bend the valves and/or trash the engine. Instead, I'd rather work on increasing the power output in the mid-range where most diesels really shine.

Quote from: "fspGTD"

Good luck!

Thanks

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Maarten

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« Reply #3 on: July 15, 2005, 02:38:57 am »

Nice mods

I've got a 2nd pump (from a RA/SB GTD) which I'm going to use as my tuning pump.. the original is for the yearly check (APK overhere). I was planning to do the governormod this week so I popped off the lid and noticed that I was missing the spring on the left on your pic). If I remember ok, that one is for idling?

I'd like to see the results on the timing cover, can you get a printout of the rev/timing somehwere?

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« Reply #4 on: July 18, 2005, 01:52:08 am »

This picture should clarify the springs I am talking about:

Edit: and if you are wondering about any of the other parts...

For more info on this mod, study this thread on the old forum where it was developed:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/4037/t/242

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« Reply #5 on: July 18, 2005, 06:19:06 pm »

Quote from: "fspGTD"

This picture should clarify the springs I am talking about:

Edit: and if you are wondering about any of the other parts...

For more info on this mod, study this thread on the old forum where it was developed:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/4037/t/242

I think one of the most helpful posts out of that thread was actually this post by you, Jake:

Quote from: "fspGTD"

"OK guys... back on topic of increasing the revv-limiter. Today I got the chance to open up my governor cover and have at it.
What I ended up doing was removing the governor spring assembly. Here's a picture of what it looks like:

...and here's where it fits into the grand scheme of governor things:

Then I examined it closely and decided how I would go about modifying it. Here you see 2 springs: the governor main spring and the part load spring. The part load spring is a really high-rate spring that has very little travel. The governor main spring has tons of travel, is lower-rate, BUT is pre-loaded so it doesn't even start working until the part load spring has compressed until it sits on stops. There are precision shims in part load spring that "tuned" it so the governor main spring would start working just at about the exact moment that the part load spring collapsed it's stop.

What I did was yank the part-load spring and replace it with shims. one 1/16" washer, to be exact. This pre-loaded the main spring a tiny bit, which is all I needed, I figured, to make a very significant change to when it kicks in. Also, I made a conscious decision I wanted to try eliminating the action of the part-load spring. There was also a stock shim also in place there which I didn't remove.

I took some force readings using a bathroom scale (not very accurate, but better than nothin')

Stock:
force when part load spring begins to compress: 1lb
force when part load spring hits stop and main spring starts to compress: 3.0lb
force when main spring hits end of it's travel (probably never hits this in real life): 10lbs

Modified:
part load spring removed and 1/16" shim installed in it's place (in addition to stock shim.)
force when main spring starts to compress: 4lbs

Here's the result from the G-tech: (note: use this to compare the change in the shapes of the hp and torque vs rpm curves, not absolute values):

Note that the g-tech only plots up to 5750 rpm in this plot, but it was recording decent hp numbers all the way to 5920 RPM. During the test, the revv limiter was not kicking in at all, and I felt the RPMs were getting quite high so I withdrew the accelerator at 5920 RPM. At that point I backed off the accelerator pedal! (I plan on next setting my max-RPM screw so it doesn't go any higher than that.)

I had to remove the screw to remove the governor cover, as well as the idle stop screw, so I probably have not reset these exactly how they were before. Specifically, it seems like it smokes a bit less than before, so the full load screw probably didn't get turned in as far as it could.

Anyway, I was really pleased to see all the extra meat in the powerband all the way up to the upper 5000 RPM area. What this tells me is that the high-spring rate "part load" spring was prematurely limiting fuel up there beforehand, making for sort of a very "soft" revv limiter. By removing the spring and installing shims in it's place, the revv limiter has become much more quick acting. I LIIIIKE!

This will be a perfect compliment to my new, lower-profile racing rubber. Can't wait to take it to SCCA nationals.

I just hope I don't stretch a rod or something beforehand! Anyone know how heavy these diesel pistons weigh vs a gas-engine VW piston?"

In reviewing this post it seems like I'd be wise to remove/shim/replace the part load spring. I didn't think that spring would even have much effect because it compresses so easily which totally takes it out of the picture. But, apparently every little bit makes a rather large difference in this case. I will probably remove some of the shims from the other spring as well since it seems like overkill.

When I finally do take the pump apart for this I'll be sure to document everything so that I can make everything clear for the others who may follow. Maybe it's just because I'm still fairly new to this board (in comparison to some of you), but it feels like pump tuning is sort of a "black art" which nobody really talks about in specifics. I'm not quite sure why that is, only I get the picture that a few of the more knowledgable people have left and taken some of this in-depth information with them and may not want to talk about what has become "trade secrets".

I haven't yet decided if I want to go with a 12mm pump head. That sort of seems like it might be a bit much and as I've heard from the TDI guys it can be somewhat RPM limiting. That is, they're not meant to be spun as high as the IDI spins. Nevertheless, I may give it a try. It largely depends on what my supplier has to say when he gets back to me though. Has anyone tried the 10? I know Deo or Blake had a 12, but I'm not sure what effect that had on driveability or mileage.

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« Reply #6 on: July 19, 2005, 02:24:26 pm »

As you have found, there is a lot of information in the archives on the governor mod. Spend more time using the search to uncover the juicy bits, and I believe you will find all the information is there, and that there is no conspiracy to withhold secrets - at least for most of us up here, myself included! If you still have questions at that point, shoot. In my view, we are here to help each other push the boundaries of diesel performance together.

Back to your pump situation - personally I would make changes iteratively and measure/test in between each step. If you are planning on trying all the mods you listed to your pump, I would first start off while you have the pump removed from the car with ONLY the 10mm plunger mod, which I think if it was installed right, could make a very nice improvement. That is also the only mod out of everything you listed that requires that the pump be disassembled to change. The governor and timing advance cover and timing advance spring are all fairly easily accessible with the pump installed on the car. And of course there is the whole plethora of external adjustments and LDA adjustments you can make without opening up the fueling system. Please do let us know the findings of any experiments you run!

VE pump external adjustments and LDA mods are pretty well known, easy to change, and well documented up here (Smog FAQ) as well as on other web sites. Governor mods are also tested and documented, IE: above referenced thread. Although I would love to hear some other people's results. Timing advance cover has been spelled out pretty well what the idea is, but results have yet to be quantified / documented. I will work on trying it and documenting it when I have some time, but it just has not been my priority as of late. 9mm -> 10mm plunger conversion, I would love to know how to do, particularly hear the gory details of how to install it, and also hear some results. I have a 10mm plunger pump sitting in the garage I would love to know how I can utilize in my GTD autocrosser.

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« Reply #7 on: July 19, 2005, 03:36:45 pm »

Quote from: "fspGTD"

9mm -> 10mm plunger conversion, I would love to know how to do, particularly hear the gory details of how to install it, and also hear some results. I have a 10mm plunger pump sitting in the garage I would love to know how I can utilize in my GTD autocrosser.

I've actually done that one already, albeit to a pump I have yet to install. It's pretty straight-forward. I just put the pump in the vice, belt side down and unbolt the pump head.

Be sure to lift the pump head off slowly and carefully. If you lift it up stright then the springs should stay upright and everything.

Here is what's inside. That is the plunger right there in the middle.

Here is a comparison shot of the 9mm vs 10mm plungers.

When reassembling, be sure to put the spring guides back into the pump head and then lower them through the springs. It's very difficult to do in the reverse order. Also, there are a couple of springs in the pump head that act as a throtle return, be sure that those are reinstalled.

Here is a pic with the 10mm pump head installed (not really all that interesting).

At the same time I was playing with that I figured I'd try and cut down the timing piston in a spare pump.

.

I chucked it up in the drill pressed and greased around the timing piston to keep metal shavings out. I think I could have found something better to use, but it was like 2 AM when I was doing this so I used a griniding stone I had around. It worked though, and I shaved about 2mm off of it.

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« Reply #8 on: July 19, 2005, 04:24:18 pm »

These are great pics, thanks!

Got a few questions along 10mm plunger head swap lines -

Does the governor and/or governor cover need to be removed in order to remove the plunger?

Does the camplate need to be swapped along with the plunger, or can the original camplate just stay in the pump and then mate properly with the 10mm plunger?

Are those two plunger return springs any different between the 9mm and the 10mm pumps? Are the delivery valves different between 9mm and 10mm pumps? Anyone know if they should be changed for a plunger enlargement?

Thanks for the info. It almost looks too easy to try!

PS - my 10mm pump came off of a mid-80's mitsubishi pickup truck.

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« Reply #9 on: July 19, 2005, 04:46:10 pm »

Quote from: "fspGTD"

These are great pics, thanks!

Got a few questions along 10mm plunger head swap lines -

Does the governor and/or governor cover need to be removed in order to remove the plunger?

Nope, the pump head is totally seperate from the timing section.

Quote from: "fspGTD"

Does the camplate need to be swapped along with the plunger, or can the original camplate just stay in the pump and then mate properly with the 10mm plunger?

The cam plate fit fine with the 10mm plunger. The indexing on the shaft was the same.

Quote from: "fspGTD"

Are those two plunger return springs any different between the 9mm and the 10mm pumps? Are the delivery valves different between 9mm and 10mm pumps? Anyone know if they should be changed for a plunger enlargement?

I don't beleive the springs were any different. I can't really recall which springs I used, but dimensionally they were the same. I left the 10mm delivery valves on, but I probably ought to check to see if they're any different. I see no reason why they would be.

Quote from: "fspGTD"

Thanks for the info. It almost looks too easy to try!

PS - my 10mm pump came off of a mid-80's mitsubishi pickup truck.

The whole thing was pretty simple. This pump head was off of a Peugeot 505 TD, but I'm also trying to get my hands on some new pump heads. In some of the literature which I beleive was on Roger Browns page they referenced a power increase by going to the 10mm pump in factory development. Of course, my "more is better" attitude makes me think of going even bigger....depending on what I can get my hands on.

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SMOKEYDUB

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« Reply #10 on: July 19, 2005, 10:00:12 pm »

While you were in there did you change the cam plate? I was wondering is there any other more common cars that use a 10 mm pump like a 1.9 td or something like that because there is next to no peugeots around here and i only know of one ranger diesel. I took a spare pump apart today Its easier then it looks well for me anyway. anyways thanks

Jeff

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« Reply #11 on: July 20, 2005, 12:54:09 am »

I haven't tried the governor mod yet.

Quote

What I did was yank the part-load spring and replace it with shims. one 1/16" washer, to be exact.

You removed the whole part load spring and replaced it with one 1/16" washer?
I must be reading that wrong. A bunch of 1/16" washers right?

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« Reply #12 on: July 20, 2005, 01:59:37 am »

Nope, you are reading correctly. See in the cross-section diagram of the governor capsule how deep the intermediate spring seats are, especially the one between intermediate and main governor spring? The intermediate spring is designed to collapse, spring seat on spring seat, with only a small amount of travel. But due to the high rate of the intermediate spring, it collapses over a relatively broad RPM range. This gives the revv limiter a "soft" or "progressive" characteristic and it takes noticeable steam out of the power band before the main governor spring kicks in.

There are usually precision spacers factory installed between the intermediate spring seats. If you had enough of those on hand, you could just use them to fill up the gap, at which point the intermediate spring is useless, and it can just be removed. I can add that the washers I use turned out are aluminum backup washers for 3/16" aluminum pop-rivets.

They are a suitable ID and OD, and are about 1/16" thick. You can buy a package of them for cheap at the hardware store.

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Jake Russell
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Northern RD

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« Reply #13 on: July 20, 2005, 12:46:10 pm »

Any idea of just how much you removed with the grindstone? I`m thinkin` I could do it on the lathe but I`m not sure of how far I can go before I run into trouble.
Thanks,
N.

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vwmike

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« Reply #14 on: July 20, 2005, 01:06:25 pm »

Quote from: "Northern RD"

Any idea of just how much you removed with the grindstone? I`m thinkin` I could do it on the lathe but I`m not sure of how far I can go before I run into trouble.
Thanks,
N.

Who? me? I trimmed about 2mm off of the timing piston. The most difficult part with getting an accurate reading was being able to hold the piston in place consistantly.

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