M-TDI with top end issues

[MichaelBuck]

I've got an AHU, 4Bt pump (by Karl - timed .9mm), pp520s, K03/04 II turbo in my Vanagon Syncro.  I rebuilt top to bottom (head, bearings and rings) and added an AWIC from siliconeintakes.com for thrills.  Compression test 465, 480, 450, 460.  The engine seems to run alright in the mid range but has issues in the top end.  As soon as I approach an incline of any size vehicle speed immediately begins to drop often requiring the downshift slog to carry it and the family over the hills.  I forgot to mark the new TDC to correspond to the the Vanagon diesel BH and may have had the timing off by a bit but have since found what I believe to be an accurate TDC with a dial indicator through an injector hole.  Since then it may run a little better but still not right.  What else could be causing this top end problem?  Injectors improperly set, maybe?  I haven't done a leak down test could that cause the top end to lack?  I'm stumped and really would like to be able to pull the passes like other Vans say they can?  Please advise.  TIA

Michael

[jtanguay]

timing it to .9?? TDI's like their advance.  who is Karl?

[boxer246]

I'm certainly no expert. but your post interested me because I am building the exact same motor right now, for my '88 Westfalia and so I will be interested in how things shape up for you.

I believe though, first and foremost, we will need a bit more info to try to narrow down what's going on.  Here's a couple questions that come to mind:

1. Do you have a boost guage, and if so, what pressures are you seeing both in straight line driving, and under heavy load, as you describe.  A boost leak is possible.

2. Are you noticing much smoke, again during straight line and under load?

3. Is .9mm where Karl (I assume Mullendore) told you to set the timing?

4. Have you ruled out all the obvious fuel plauges for ANY diesel....such as air in line, dirty filter or screen, etc.?

5. I assume your turbo is in good shape....is the wastegate set too low?

6. Do you have an EGT guage...and if so, what temps are you seeing?


THere's lots more questions for sure, but those should get things started.

[Tintin]

It's very simple, the 4BT pump do not give enough timing for hight RPM engine, these pump are for low rev engine (2000-2500RPM at the redline), that take over 10-12mm of travel from the timing piston to allow 20deg of timing, but a cummins pump are only 4-5mm of piston travel...  not enought.

Initial timing with dial gauge is for the cold starting.

[MichaelBuck]

I'm certainly no expert. but your post interested me because I am building the exact same motor right now, for my '88 Westfalia and so I will be interested in how things shape up for you.

I believe though, first and foremost, we will need a bit more info to try to narrow down what's going on.  Here's a couple questions that come to mind:

1. Do you have a boost guage, and if so, what pressures are you seeing both in straight line driving, and under heavy load, as you describe.  A boost leak is possible.

2. Are you noticing much smoke, again during straight line and under load?

3. Is .9mm where Karl (I assume Mullendore) told you to set the timing?

4. Have you ruled out all the obvious fuel plauges for ANY diesel....such as air in line, dirty filter or screen, etc.?

5. I assume your turbo is in good shape....is the wastegate set too low?

6. Do you have an EGT guage...and if so, what temps are you seeing?


THere's lots more questions for sure, but those should get things started.

Ash, Thanks for interest!  I should mention the 4bt came from Karl Mullendore, who had this pump on his Van for several thousand miles. For him it was making his van run with no issues, no lack of power, or lack of RPM range.  The only difference between our set ups is he is running a GT1548 turbo.

1.  I had trouble generating enough boost in the beginning but saw it increase when I increased fuel thus increasing velocity.  That said, it likes to cruise at around 15 psi and when I'm able to get the RPMs up to 4k+ I see 18-22.  I've had the fuel adjustment all over the place - actually backed off a bit right now so max boost seems a bit less.  This is my first turbocharged engine so I don't fully understand boost.  However, I would say I don't see boost increase with load, boost increases with RPM increase.  I contacted the turbo builder and he explained that the objective they were after in building this turbo was to maximize flow with keeping pressure (or back pressure) to a minimum.  He said this would give the performance of higher pressure without the power robbing heat associated with higher boost.  This seems consistent with theory in literature and opinion of others I asked.  As for a leak: I don't think there's a leak but I'm not positive.  How do I become positive of leaks?

2. No smoke at anytime.

3. .9mm is where Karl told me to set the timing.

4. I was having a fuel issue that I believed to be a clogged filter.  At high speed and WOT it would pull a vacuum bubble and die.  Bleed the air and it would start and run for a while.  Anyway, I replaced the stock filter with a Stanadyne fm-100 w/ a 5 micron filter.  So I know I have a good filter but I don't know about the air in the line or the etc. part.  I had assumed I had the air out of the line because it runs and runs pretty OK except for the lack of high end hill climbing power.  How would I know if there's air in the system?

5. Turbo is brand new rebuilt.  I have a boost valve w/ 22-28psi spring, from boostvalve.com.  So at the boost levels I'm seeing the wastegate should not be seeing any pressure to open.  Not positive on that but is what I believe is happening.

6. EGT gauges shows 900F max.

[westyman]

The pump is 4BT but as in all of my pumps the timing advance has been modified to duplicate that of the TDI pump. The throttle/governor spring has been changed as well to achieve 4400 rpm redline.

It's very simple, the 4BT pump do not give enough timing for hight RPM engine, these pump are for low rev engine (2000-2500RPM at the redline), that take over 10-12mm of travel from the timing piston to allow 20deg of timing, but a cummins pump are only 4-5mm of piston travel...  not enought.

Initial timing with dial gauge is for the cold starting.

[westyman]

I think that with these two answers we can tell that something is restricting max fuel availability. Perhaps we will need to shorten the small pin that in that the aneroid controls.

2. No smoke at anytime.

6. EGT gauges shows 900F max.

[MichaelBuck]

red herring UPDATE:  I went and added more fuel (a bunch more) and I'm getting happier.  There is still no or not much smoke.  Mostly just a puff of smoke when I bump the throttle and the Van is standing still.  The only concern at this point is that EGT climbed to 1150+ and that is unloaded and ascending a rather mild East Texas hill.  Loaded and climbing through the Rockies I can imagine problems with EGTs. What is a safe maximum EGT for this setup?  Interestingly, I had not seen the engine temperature come up to normal range, until today, and had assumed I had a defective thermostat. Two things I need to deal with before I back off the main fuel screw.  First, I don't have a fan on my AWIC heat exchanger (radiator) and noticed the IC was quite hot after the test runs.  The fan I received with the kit was DOA and I just got the replacement and need to install it.  I want to have the fan come on as the coolant in the AWIC system reaches a certain temperature.  Anyone have input on what AWIC coolant temperature is advisable to use as the point to trigger the heat exchanger fan? Secondly, I had previously screwed the LDA spring seat down tight to get more fuel at high boost levels and I'm wondering if the higher EGTs are due to the increased fuel at High boost and hill ascension.

I feel much better after almost two months of wrangling with this thing.  I was so frustrated because I was so careful during the engine assembly and component selection.   Not to mention I spent so much on the project only too run way below par.  The trip from Oregon to Texas was tedious and very stressful.  I need to make a run to Austin, TX in the next couple days and will know much better if things are getting dialed in.

Thanks for looking/responding and I still could use input on anything that seems out of place.

Michael

[boxer246]

Michael,
Its been several weeks I was wondering how your van is running now.  Were you able to turn up the fuel to get more power without your EGT's going through the roof?  What about the IC issue....got it straightened out?  Sometime I would like to see some pics of your setup....maybe even look at it in person if possible....I'm in Houston, sounds like you get through here sometimes.

[jtanguay]

Anyone have input on what AWIC coolant temperature is advisable to use as the point to trigger the heat exchanger fan?

really depends on how much power draw you want on your electrical system.  lower temps are better.  i would say somewhere around 45C-60C depending on your goals.  lower for more power, and higher for less draw on the system.  a high flow water pump will also be beneficial (a multi-speed pump would further help reduce electrical load on the system as well)

i really want to attempt an AWIC setup as i firmly believe they are superior, but are more complicated.