26 vs 30 mm oil pump

gatorjos · Posted: Thu May 19, 2005 7:50 pm Post subject: 26 vs 30 mm oil pump

hey all,

I'm building a 1776 from my tired 1600 dp. I'm full flowing the case, and I would like to install a bigger oil pump. I'm a little confused about which one to get though. What's this flat cam vs dished cam thing. My car si a1972 with (I think) the original engine. my old oil pump has a flat piece coming out the back where it hooks into the crank. Is that the flat cam?

thx

Jos
_________________
1977 Westfalia Weekender Berlin "The Kitebus" aka " Colonel Mustard"

Previous romances:
1972 Ghia cabriolet (full body-off restoration -- stolen after five years of ownership)
2004 Passat 1.8T (manual)

http://21stcenturyhobo.com

RUI FARIA · Posted: Fri May 20, 2005 12:17 am Post subject:

Firstly the oil pump is run off the cam not the crank, a dished cam is a later model & the flat cam is the early model. All the performance cams I have seen (Engle etc.) are flat early type cams. Your motor in standard form should have the later dished cam. As for the pump the 26mm should be ok but I always use a 30mm Shadeck pump, a little insurance never hurts, especialy when things have worn out a bit.

[email protected] · Posted: Fri May 20, 2005 11:00 am Post subject:

26mm. Most engines will run hotter with a 30mm pump.

John
Aircooled.Net Inc.

gatorjos · Posted: Fri May 20, 2005 12:51 pm Post subject:

Why does an engine run hotter with the bigger pump? The added flow doesn't offset the extra work the engine is doing to turn the pump?

I did know the pump is driven by the crank, I just don't see how the type of cam you have affects the choice of oil pump (since it doesn't hook up to it). I'm going to run a Scat c35 cam, so I guess I should get the flat cam style oil pump by RUI's comments.

Damn, I'm getting more confused! Help!
_________________
1977 Westfalia Weekender Berlin "The Kitebus" aka " Colonel Mustard"

Previous romances:
1972 Ghia cabriolet (full body-off restoration -- stolen after five years of ownership)
2004 Passat 1.8T (manual)

http://21stcenturyhobo.com

gatorjos · Posted: Fri May 20, 2005 12:52 pm Post subject:

By the way John -- Nice Nuts

Laughing

_________________
1977 Westfalia Weekender Berlin "The Kitebus" aka " Colonel Mustard"

Previous romances:
1972 Ghia cabriolet (full body-off restoration -- stolen after five years of ownership)
2004 Passat 1.8T (manual)

http://21stcenturyhobo.com

[email protected] · Posted: Fri May 20, 2005 2:13 pm Post subject:

Ever see a diagram of the Beetle Oiling System? The way it works is when the oil gets hot, it gets thinner and pressure drops, and when it drop below a certain point the temp relief piston routes the oil thru the stock cooler.

The problem with THICK oil and/or big pumps, is pressure can be too high, and the engine thinks the high pressure oil means COLD OIL, so it never goes to the cooler.

If you look at a diagram of the system it will make sense. But running a huge pump and thick oils is a sure fire way to excessive oil temps. Not to mention pumping the oil back to the pressure relief only to get dumped into the sump again is a complete waste of power and mpg.

You do not need more then a 26mm pump, the EXCEPTION is a turbocharge engine where a 30mm is not a bad idea. I have a 26mm pump on an 8k RPM 2332. Many racing guys run 21mm pumps to decrease pumping losses.

John
Aircooled.Net Inc.

gatorjos · Posted: Fri May 20, 2005 3:46 pm Post subject:

That makes sense. I thought perhaps the pressure loss of going through a remote oil filter and extra lines would warrant the increase in size...
_________________
1977 Westfalia Weekender Berlin "The Kitebus" aka " Colonel Mustard"

Previous romances:
1972 Ghia cabriolet (full body-off restoration -- stolen after five years of ownership)
2004 Passat 1.8T (manual)

http://21stcenturyhobo.com

turbo_bob · Posted: Fri May 20, 2005 11:05 pm Post subject:

26 is a good size oil pump. Save the 30 for twin external oil coolers, turbo oil feed, oil squirters in the case.

[email protected] · Posted: Sat May 21, 2005 12:44 pm Post subject:

The increase in size is going to 26 from the stock 21 or 24mm.

John
Aircooled.Net Inc.

gatorjos · Posted: Sat May 21, 2005 2:27 pm Post subject:

In that case my stock motor had an upgraded oil pump....

aha, it is all clear to me now Cool

Thanks for all your help. I think I still should replace my oil pump after 80k miles.
_________________
1977 Westfalia Weekender Berlin "The Kitebus" aka " Colonel Mustard"

Previous romances:
1972 Ghia cabriolet (full body-off restoration -- stolen after five years of ownership)
2004 Passat 1.8T (manual)

http://21stcenturyhobo.com

Bruce · Posted: Sat May 21, 2005 9:44 pm Post subject:

Eaallred · Posted: Sun May 22, 2005 9:31 am Post subject:

26mm pumps are all I use. Like John said, run too much pressure, and you'll end up bypassing more oil past the cooler and pressure relief.

I also don't run thick oils. My daily drivers get 5w30 oils year round, and my race motor gets fairly thin oils too. I tried 15w40 last oil change on it, and wasn't happy with the excessive oil pressure. I'm thinking of trying some 5w40 synthetic next time.
_________________
Eric Allred

You have to remember something: Everybody pities the weak; Jealousy you have to earn.

PHAT4 · Samba Member Joined: March 12, 2005 Posts: 237

turbo_bob · Posted: Sun May 22, 2005 2:20 pm Post subject:

BattleShipBus · Samba Member Joined: February 10, 2005 Posts: 172

Bruce · Posted: Sun May 22, 2005 3:07 pm Post subject:

turbo_bob · Posted: Sun May 22, 2005 3:23 pm Post subject:

Thanks Bruce for the info, I looked in the Bently book but it did not list the size.


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