Is fuel flow the only difference between turbo and NA pumps? - PeachParts Mercedes-Benz Forum

Proctor750 · #1 12-10-2012, 05:04 PM

I have 2.5 Non turbo om602 with pump 0400075976. pump housing is ruined and I am wanting to replace it with a turbo pump 0400075944. Is the Non turbo a derated engine? In other words with the turbo being the only added power potential between the two pumps, is the fuel flow the only real difference? If so it can be put on a bench and be adjusted to work for non turbo.
The timing is different on the pumps, the -944 (turbo) pump is 17 degrees, and is more power with 92KW vs my -976 (Non turbo) 66KW.

Anyone know if it's only difference for that power change is the fuel flow?

vstech · #2 12-10-2012, 08:40 PM

there is also an ALDA fuel compensator for keeping fuel low until the turbo pressure builds.
if you attach the turbo pump, and keep the alda open to atmosphere, you may be ok on fuel for your motor.

Proctor750 · #3 12-11-2012, 08:35 AM

Seems simple enough. So you think the 66kw vs 92kw power difference between these pumps is fuel flow?

vstech · #4 12-11-2012, 09:26 AM

I'm sure that there are timing/injection pulse mapping differences as well, but alda adjustment, and adjusting the timing should make the car drivable if it's all you have.
the correct pump is of course going to be the best, as the turbo pump is designed for positive air pressure, not negative, but it'll be close. you might want to plumb the intake manifold and attach a barb fitting and hook the alda directly to the intake so it actually senses the amount of air your car is ingesting.

Proctor750 · #5 12-11-2012, 11:05 AM

Lets say I went open atmosphere, would there be a noticeable difference in how the car runs? It was smooth no smoke and 38 mpg highway with oe pump. What would happen to these things. .

vstech · #6 12-11-2012, 11:07 AM

no idea.
let us know how it turns out connected and disconnected...

Proctor750 · #7 12-11-2012, 11:43 AM

Haha oh well. I only asked as I have found a few non turbo pumps for 2.5 124s over in europe for sale. Wasnt sure if it was worth the trouble since I have a working turbo pump available to me.

vstech · #8 12-11-2012, 11:51 AM

I'd never go the other way, but if I needed an IP, and I had one turbo, I'd stick it on and see how it drove.
pay attention to smoke... black can easily burn the motor up.

Proctor750 · #9 12-11-2012, 12:10 PM

Not to mention I have a manual trans so there's some odd vacuum pieces I won't need that it has.
Why would you never buy one from Europe? Shipping cost? Unknowns?

Proctor750 · #10 12-11-2012, 12:38 PM

Also: couldnt I just swap my aneroid over?

Diesel911 · #11 12-11-2012, 03:30 PM

Quote:

Originally Posted by Proctor750

Lets say I went open atmosphere, would there be a noticeable difference in how the car runs? It was smooth no smoke and 38 mpg highway with oe pump. What would happen to these things. .

I think a person in a Fuel Injection Shop could answer that because they could look up the internal parts and see what is the same or different.

It is possible that the Turbo Pump is almost the same but it is also possible that there is a lot of internal differences.

The Plungers on the Elements could be cut differently and there could be different Springs and Weights inside of the Governor; and it might be the Governors are not the same.

My expectation would be that if you did the swap it would run but not as the original did.

Proctor750 · #12 12-11-2012, 03:58 PM

Quote:

Originally Posted by Diesel911

I think a person in a Fuel Injection Shop could answer that because they could look up the internal parts and see what is the same or different.

It is possible that the Turbo Pump is almost the same but it is also possible that there is a lot of internal differences.

The Plungers on the Elements could be cut differently and there could be different Springs and Weights inside of the Governor; and it might be the Governors are not the same.

My expectation would be that if you did the swap it would run but not as the original did.

Would you do the swap if you were I? Or buy a non turbo pump from Europe?

Ie.

Mercedes Diesel Injection Pump 0400075938 6020705501 A6020705501 | eBay

Diesel911 · #13 12-11-2012, 07:16 PM

Quote:

Originally Posted by Proctor750

Would you do the swap if you were I? Or buy a non turbo pump from Europe?

Ie.

Mercedes Diesel Injection Pump 0400075938 6020705501 A6020705501 | eBay

With the shipping that is about $747 US. Paypal takes a cut of the Money exchange rate.

I don't really have an answer. I think you need to do somemore reasearch at some Fuel Injection Shops and ask some questions.

Tell them what you want and ask the if it is possilble to recalibrate the Turbo Pump as it is.
You don't actually have to do the work there just ask and see what they say.

You never said what is damaged on the Fuel Injection Pump. The front Section is the Fuel Injection Pump itself and the rear section is the Governor.