39 replies to this topic

[JonBooth]

Hello,

Which oil do people generally use in their HIF44 dash pots? I have a draw through supercharged Mini and just looking at ways to possibly improve the pickup/throttle response. It's a 1993 Mini so therefore has the standard electronic distributor and it has SU oil in the dashpot at the minute put in last time it was on the rolling road.

Just wondering what other people use and how successful it is. Also would a Megajolt (or similar) ignition system drastically improve throttle response or is it likely to be more limited by the carb?

Cheers,

Jon.

[Mk1Ruby]

Manuals recommend 20w50 engine oil but give sae20 silicone based oil from a hobby shop a go they use it in remote control car dampers and it makes a noticeable difference

[mike.]

Is your megajolt fully mapped to suit the engine spec? Thats the idea of it and once mapped can drastically improve response and remove flat spots.

Dash pot oil wise I use 3 in 1 oil in mine and seems spot on.

[freshairmini]

When I got my mini tuned up on a RR (Slark Race engineering, they developed a super charger kit for the mini) the guy recommended for most tuned engines to use the same engine oil, so 20w50.

[JonBooth]

That's great. Thanks for the replies. I don't have a megajolt system but it may be a possibility in the future. I originally had 20W50 oil in the dashpot but at the rolling road he drained it and said it was too thick... I may have to give it a try...

[firefox]

There is a big debate on here about dashpot oil and i think we agreed on 3/1 , engine oil is to thick
ring burlen fuel systems who make the su carbs and they will tell you the same

[firefox]

There is a big debate on here about dashpot oil and i think we agreed on 3/1

Agreed by people who don't know what there talking about and burlen won't have recommended 3:1......
You want the piston to rise as slowly as possible, it's the only way to get full acceleration enrichment.............

I beg to differ i rang Burlen and please read this


3-IN-ONE_® Motor Oil


Keep your moving parts moving

3-IN-ONE Motor Oil created a special blend of high-grade oils that’s equivalent to SAE 20. The motor oil formulation is ideal for lubricating the moving parts of electrical motors.
And this off the Burlen site

The first is SU Damper Oil, which is a straight 20 grade and comes in a handy 125ml bottle. This oil is for use where the carburetter is fitted with a damper inside the piston and can be used on all SU, Zenith and CD carburetters.

SU Damper Oil (125ml), Part No: BDR125S
So now who dosen't know what they are talking about

if the oil is to thick it takes longer for the piston to rise and fall which can result in false economy

[firefox]

Well I don't know where that actually came from but it's just wrong..........I'd suggest you do a little reading up on how the SU works........

It came of the burlen su website, what do you think i did make it up, and i know how the su works, i think you need to do the reading , want to borrow some glasses

[6joshh6]

I use engine oil at the moment but it might be an idea to experiment yourself as most engines are slightly different so I imagine old carbs are probably a similar scenario.

[Ethel]

No disrespect to Burlen, but they can't possibly know what oil will work best in your carb on your engine. BL/Rover developed their cars to use the same oil in the carb as the engine, so it seems the logical place to start. Thinner oils lean out the mixture under acceleration, thicker ones do the opposite - if it's a turbo motor I'd err on making it richer until you've thoroughly measured what you're actually getting.

[firefox]

No disrespect to Burlen, but they can't possibly know what oil will work best in your carb on your engine. BL/Rover developed their cars to use the same oil in the carb as the engine, so it seems the logical place to start. Thinner oils lean out the mixture under acceleration, thicker ones do the opposite - if it's a turbo motor I'd err on making it richer until you've thoroughly measured what you're actually getting.

Oil has come on a long way since the su was developed if you take the viscsity of 20/50 you have 2, 20 cold and 50 warm
SAE 20 gives you a standard vicosity so it is the same warm and cold this is why they recomend it, vicosity is measured in a redwood meter
50ML of oil passing through a hole basicly so 20/50 the latter number warm is way past the sae20

I am not saying it,s the way to go, trial and error is best i think but i use sae20 cant see the point of having a rich and lean running engine

Edited by firefox, 04 August 2012 - 10:03 AM.

[firefox]

Oil has come on a long way since the su was developed if you take the viscsity of 20/50 you have 2, 20 cold and 50 warm
SAE 20 gives you a standard vicosity so it is the same warm and cold this is why they recomend it, vicosity is measured in a redwood meter
50ML of oil passing through a hole basicly so 20/50 the latter number warm is way past the sae20

I am not saying it,s the way to go, trial and error is best i think but i use sae20 cant see the point of having a rich and lean running engine

So you don't know how the SU works...............

what so what you are saying is the thick oil before it is warm enriches the mixture and as it warms up this eases and alows the carb to run leaner, but what about summer and winter running, and if the viscosity of the oil is to thin when it warms will this not cause piston flutter

Edited by firefox, 04 August 2012 - 01:42 PM.

[firefox]

I asked you to explain how you thought the SU worked, particularly the acceleration enrichment side and you came back with the above rubbish.............

No you never you said i didnt know how they work

[firefox]

Come on then explain how it works particularly the enrichment side........

Seems like a question to me............

Right smat ass i will ask u a question if the oil is to thick will the engine use more fuel

[Ethel]

Keep it civil please. The techie section is for sharing knowledge 'n helping fellow Mini enthusiasts. The topic will be closed if it's not doing that.