Alfa Pages

[Brit01]

Just purchased a used but good 16v oil pump for my 8v engine.

They have bigger gears so better flow. Hopefully I'll be able to use thinner oil and maintain OP.
Thinner oil - better lubrication and cooling plus better fuel economy.

We'll see.

I know for now I get low OP at hot idle and I'm using 10w60!

Just have to wait a few weeks for it to arrive (and hide it from the misses!!)

Cheers
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Brit01]

It's arrived!
comparison of gears.

BUT just had a thought, are the 3 mounting bolts a different length?
Don't want a nasty surprise when I come to swap the pumps.



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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Bobkelso]

I read about that swap of the pump (it is 33mm gears tall versus 30 mm?)
also in older models tuned, I think it could be done without modifications,
but don't know about the bolts, if you go on Eper it seams
you got two type of bolts:
a) the ones that keep closed the pump
b) the ones that keep the pump at the motor

one type of them (the bigger ones) are equal for 30mm or 33mm gears,
the other type (the thinner ones) are differentiated, 55mm or 60mm bolts

from the graphics I cannot understand what type are the ones
that keep the pump to the motor
but with the pump you have probably you can see this,
if they are the bigger ones (equal in the two version off the pump)
you should not have bad surprises

Actually I'm confused about what car used the upgraded pump version,
I also was convinced 16v got a different version,
but from the gear codes it seams the upgraded pump is on every model from '90
and one single model in 89-90 (probably the early 1.7 i.e),
so the swap on your motor makes a lot of sense
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Alfa 33

[Brit01]

[Brit01]

Well bit of a disappointment.

Pump in and new 15w50 oil in.

Pressure was very good except for idle again! I was uusing 10w60 before though. This was unavailable so I used the motul 300v 15/50.
Still just 10psi.
Maybe that's all I am going to get.

Approx values when hot at 100c.
40psi @ 2200rpm
50psi @ 3200rpm
60ps max @ 4000+rpm

But maybe I'm getting better flow which is vital. How do we measure flow???
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Brit01]

This thing gives loads of pressure when revved.
Have to watch it with cold oil for the first ten minutes of driving at least.
Hits the bypass limit of 88 with ease when cold-warm.

But below 1000 rpm still drops to 10psi
1200 rpm I get 30 psi!!!!

Maybe gauge is inaccurate.
It is a mechanical gauge though.
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Bobkelso]

Hi Brit,
if you get flow increased, you get pressure increased,
probably is not linear, may be at some rpm small
increase in pressure is a consistent increase in flow
(with same oil type) and at other rpm is the inverse,
I should re-study some fluid dynamics..

Every case, at every rpm I think new pump is generating
about +10% of flow for geometrical reasons (gears and oil
chamber with same geometry but +10% higher),
so is better than before but you will not get huge
differences, only a positive small tuning of pressure values,
that is already a good thing to stay more in the safe side of values.
If I understood well, with the smaller oil pump you get same
10psi at idle but using thicker w60 oil? If so, you got that small
but still visible gain also at idle

10psi=0,7 bar seams acceptable, safety limit is 0,5 bar?
Probably you can stay with w50 oil without go to W60
if you will get similar values also in summer.

May be to get with same oil better pressure values specifically at idle it helps
not only a few mileage motor, but also a very few mileage or brand new oil pump,
with no play at all at the upper and lower face of the gears,
may be some very little plays in the pump can lower the
geometrical ideal flow and limit the pressure value but only at idle,
and became of no influence already at 1200-1500 rpm,
a not linear effect (probably at higher rpm, a good used oil pump
and a brand new one perform almost equally, both at the ideal
geometrical value of flow, for the viscosity of the oil that
in practice cancel the importance of plays).

Or you are right and the gauge is a little not linear at the start of the scale

[Brit01]

Good points there
Yes I went from a 60 to 50 oil

If the cheap gauge is inaccurate at a low pressure I may even like to try the 300v 10w40.
Very good oil and will run cooler.
Any recommendations on a better quality gauge mechanical?

With the 15w50 300v I find the pressure too high when cold even after five minutes of driving it peaks at 80 psi at 3000+.
When cold starting it will hit 90 at low revs! No more than that as the bypass opens.
I would feel more comfortable if it was thinner at cold start ups.

Worth a try.
Either the 300v 10w40 or x-cess 5w40
These have a lower viscosity at 40c


Also the old pump had some vertical play on the shaft indicating the gear was not tight in the casing.
The new used one was dead tight. No play vertical or lateral.
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Bobkelso]

uhm..don't know about W40 oil,
maybe W50 is the best oil to be always safe with boxer 1.7,
W60 is overkill, good for racing, instead W40 is a little weak,
considering your summer temperatures, some mileage of the motor,
and that 1.7 big ends/ crank ends are more under pressure than in 1.3 and 1.5.
(if I remember, in 1.7 shells are thinner to get space for bigger ends,
but probably this more surface is still less favorable respect 1.3-1.5).

If you want to try a 5/10-W40 oil (and Alfa prescribed W40 also on 1.7)
think about to choice one with a quite high value of viscosity at high temperature
if possible, so a W40 that it is near the W50 specification limit,
and to change it before 10000km, before it becomes a W35 or less
(maybe it will be enough to control the pressure values to know
when oil is starting to loose his original viscosity, as you have a gauge
in the car, or use a premium oil, full synt, to keep it more time,
but I don't know, I change the oil at 10000km also using a (economic)
full synt that maybe could resist 20000 km, to avoid that hard black
powders from combustion accumulate in the oil,
it seams the simplest way to reduce to minimum motor wear)

What about to have your perfect oil with a 5-W50 (or a 10-50W)?
(as you have rebuild heads with new valve steam rubber seals, probably you can use
also a modern gradation 5-Wxx oil without problem of oil leaks from them)
Respect the 15-W50, it should be considerably thinner at cold start ups,
and probably also a bit thinner during normal use (is I have understood
the graphs corresponding to the "nominal" specification X -W XX of oils).

[Brit01]

The only 5w50 o know here is mobil and amalie.
I think the 40wt 300v is a much better oil and it has a very good hths.
Not sure about m1.

Could be the mobil or a mixture of the 300v 5w40 and 15w50.

I can see some experimenting coming up.
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)

[Bobkelso]

probably having an oil pressure gauge in the car
you can try safety every gradation (or mix) starting from a good W40..

uhm..Mobile 5-w50 should be better than the average quality of oils from Mobil:

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_5W-50.aspx
- viscosity 40°=108 (a little more than a 5-W40 oil)
- viscosity 100°=17,5 (for W40 oil you have usually 14-14,5)
- HTHS 150°=4.4, very protective, as many W50 oil
(usually HTHS over 3,6, as a good W40, is considered already enough
at least until the oil is quite new), 4.4 is quite an overkilled value for street
use but it is a good thing if you think that modern oil for catalytic cars
don't have no more the quantity of ZDDP anti-wear addictive of previous oils
(ZDDP you know was useful for example for flat tappets, I learned it in this forum)

but honestly I'm not sure about this oil cost/quality ratio against other oils.

When you will have to change oil, it will be will be interesting
comparing pressure values, quite an exact experiment,
thanks Brit for posting these detailed data.

[Brit01]

Thanks Bob.

The 300v 10w40 has a hths of 4.2 so it's a very thick 40 and will not shear.
It also is lighter at 40c . 90 or so.

So yes probably mix the 300v oils to see how light I can go.
50-45-40

I have also seen oil analysis on the 300v 40wt oils and they have a good level of zddp 1300 or more. Probably why they are classed as racing oils as they could damage cats
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S2 33 1988 1.7 QV
Dellorto DRLA40 (32mm venturi)