Friction Free

[phoenix]

We rebuilt the bottom end of a Lancia twincam engine and reduced the torque needed to turn it from 17 ft/lb to 8.5 ft/lb - thats 13bhp at 8200 rpm - so I think it's worth it! Very cheap HP anyway, whatever way you look at it.

Reducing the torque required to operate the valve gear - by not having triple springs if double springs are good enough for example - will also end up at the wheels.

The same is true for friction in the wheel bearings and drag from pads - I don't know how much can be gained and it will vary from car to car, but every little helps. Greases become more liquid as temperatures rise. They don't get as liquid as oil, which is why grease stays in the hub bearings. I am sure oil could be made to work, but you would need oil seals to keep the oil in, and oil seals create their own drag. Only experimentation will give the answer - and then durability testing, which may see you in the Armco with a seized wheel if you get it wrong!

Low viscocity engine oil in the gearbox of FF1600 was a common trick in the old days as this reduced drag, but I would be reluctant on a clubmans racing budget to do that with my gearbox as engine oils are not designed to tolerate the kinds of loads generated on gear teeth, so the gears would essentially run 'dry'. I am sure that gearbox bearings would be fine with just engine oil.

All the above is my humble but informed opinion, of course

[maddogf3]

Originally Posted by Tim Draffan

Any idea what make of loil they use on the wheel bearings and how often they re-lube them, how long do the bearings last?

Hi Tim
They all seem to be ganging up on me!!!! telling me not to be so serious
When has motor racing not been serious. We might do it for fun but its still serious I still think what the pros are doing is dead interesting specialy for paddock bull**** .
Its very hard to be specific when you are given information like the above ,but the car is stripped after every outing and cleaned including bearings and gearbox is stripped for the next ratio change got the impession light oil was being used .how long do they last ? they dont care.
If you rear the thread about Renault rear suspension Ian_W has explained in great detail how modern thinking is going on suspension and the like ," Believe me He Knows" Makes a change to get asked a question . Should see the info I got to set the Stack up ,the one on the Mono shock I'm not spilling the beans on that though.
regards Martin

[Dave Brand]

Originally Posted by phoenix

engine oils are not designed to tolerate the kinds of loads generated on gear teeth, so the gears would essentially run 'dry'.

Engine oils can be used to lubricate gearboxes - millions of Minis, etc., & most modern motorcycles, use it! However, they have lubrication systems designed to use engine oil. It is also necessary to use an oil designed for the purpose; modern oils designed for car engines use can create problems in bikes - most motorcycle-specific oils only meet the, now-obsolete for car oils, API SG spec.

[Tim Draffan]

Any thoughts on what to use in MK9 Hewland in FF1600, EP80/90 is recomended but I
I am sure thiner oil is possible?

[Richy_Rich]

And then, is there any benefit in adding 'friction eliminating magic potions' to your gearbox? And if there is, why don't Castrol just blend it in to start with?

[jonners]

13bhp free at 8200rpm - you must be joking...

...the point I was making is that the torque required to make the crank turn is an entirely different matter to the energy required to keep it turning

optimising everything is always the best policy but there's always confusion on this point

drag is an issue but it doesn't equate with the torque required to start something moving from rest

[phoenix]

Originally Posted by jonners

13bhp free at 8200rpm - you must be joking...

I'm not joking

[graham bahr]

half that figure i'd go with but it does seem a lot, did you get this figure from back to back power testing without any other tuning or reconditioning work?

[phoenix]

Originally Posted by jonners

the torque required to make the crank turn is an entirely different matter to the energy required to keep it turning

That's true - but I was referring to the CONTINUOUS torque required to turn over an engine; that does not reduce - in fact it may well increase with speed.

[phoenix]

Originally Posted by graham bahr

half that figure i'd go with but it does seem a lot, did you get this figure from back to back power testing without any other tuning or reconditioning work?

Back to back - this was just a bottom end overhaul - no change in any performance giving parts, no machining, nothing whatsoever. Just a routine change of bearings and careful re-assembly. Even humidty and temperature were within 2% of the previous dyno session - and yes it was on the same rollers.

If you do the maths, it also checks out....

[graham bahr]

ok accepted, but i'd say then that the earlier inital torque figure if it was a continual rather than a starting one was too high

[jonners]

hmm - might just have to take your word for it but am still very sceptical - don't mean to give offense

am no engineer and am not even particularly mathematically minded but how do the maths check out? On the nose or give or take a bit?? Surely general losses have an effect on the gain?

thinking about it 17lbs ft to turn the crank was an awful lot - makes me wonder whether this is a rogue result since there was clearly something wrong in the first place...

any other views?? am interetsed in this because free torque/hp is always welcome...

[graham bahr]

it always was fairly universal to grind performance cranks on or just below the bottom size limit to make them nice and loose
i've also read about swapping yank V8 cranks and blocks around, thus using a big main journal crank ground down in a small main journal block to save friction.

anyone seriously into x/flows or BDA's will know that cranks and rods can be bought for them with narrower big end journals to save friction.

when bmw introduced there ETA ecomony 2.7 straight six, they ran the cam in only 4 cam bearings rather than 7 as in the rest of that engines range to cut down on friction. this made me wonder about shortening tha jack shaft in a twin cam or BDA to do away with the rear bearing.

back in the 60's bill blydstien used to lower the oil pressure in his 2.3 slant 4's to save parasitic losses from the oil pump.

[Richy_Rich]

There's something in that, I think. In the Triumph engines there are two different journal sizes (we call them large bearing and small bearing cranks, clever eh?).

Anyway, you can never get as much power out of the large bearing cranks, the current thinking (which probably is the same as it was in the 60s) is that due to the larger areas involved with the large bearing cranks the surface speeds are higher and therefore friction losses are greater. It's probably no coincidence that the large bearing cranks also have a reputation for knackering bearings.

[phoenix]

Originally Posted by graham bahr

ok accepted, but i'd say then that the earlier inital torque figure if it was a continual rather than a starting one was too high

Yes, the initial rate was a little too high - but the net gain was still as I said. The engine had previously been built by a HUGELY repected - and published - engine builder, but even he got it wrong. So such potential gains should always be considered. I also mentioned valve springs. The previous engine builder had used triples. We found doubles were absolutely fine for our cam. Not prepared to disclose details, but the improvement in torque and bhp from this change, was also significant.

[phoenix]

Originally Posted by Richy_Rich

There's something in that, I think. In the Triumph engines there are two different journal sizes (we call them large bearing and small bearing cranks, clever eh?).

Anyway, you can never get as much power out of the large bearing cranks, the current thinking (which probably is the same as it was in the 60s) is that due to the larger areas involved with the large bearing cranks the surface speeds are higher and therefore friction losses are greater. It's probably no coincidence that the large bearing cranks also have a reputation for knackering bearings.

Spot on. Larger bearing surfaces will have higher frictional losses. There are other threads in which tyre width/diameter/contact patches are discussed and it is clear that a larger contact patch has greater grip - i.e. more friction.

[Richy_Rich]

Yep and guess which one I use

[dtype38]

Does that mean my 7 main bearing crank with 1"+ wide journals might be a bit draggy then?

[graham bahr]

yes, however before we get too carried away we should remember rpm, all these savings were talking about only really start to add up at very high revs, pheonix might of found 13brake @ 8,200 but i bet at 6,000 the gain is only half that, and probably only a quarter at 4,000rpm, i think your find frictional losses are like aerodynamic drag, they go up at the square of speed.

[Al Weyman]

The fitting of a low friction full roller cam with roller rockers and followers is reconed to be worth 40bhp in a small block over a a similiar spec flat tappet cam, in fact this is one of the reasons Chevrolet wento over to roller followers to improve fuel economy on the 5.7 small block, this then allowed them to mate it with a manual gearbox on the 4th gen Camaros where as the 3rd gen 5.7 only was available with a computer controlled (read too quick upshifting) auto box so they could meet CAFE fuel economy figures.

[graham bahr]

knife edged crankshafts and scraper plates help save a little power although once again only at high revs.

[ian.stewart]

So, if I machined my bearings to clearance. 0.25 of an inch from both sides and left the middle at running clearance, my engine would last more than 5 mins?? intresting idea, but I dont think I want to risk it,
But on a similar thread, has anyone looked at the journal size on a F1 engine, best described as rediculous, , but as they are only designed to run about a max of 5 hours, I dont suppose it matters too much, also given a chance have a look at the rings, or what there is of them, again, designed for min drag and a limited life.
Has anyone ever wondered where all these Hi spec low friction light weight alloys and composites have materialised from in the last few years, My theory is; since the end of the cold war the aero and weapons industry has been a little strapped for trade and are looking for any outlet to sell their Hi Tec materials, and F1 teams will pay the earth just for that sort of advantage over the other teams.
Ian
Just an afterthought, as roller rockers may liberate another 40 g-geees has anyone got any for a rover v8 laying about, just a thought.

[dtype38]

Originally Posted by ian.stewart

But on a similar thread, has anyone looked at the journal size on a F1 engine, best described as rediculous, , but as they are only designed to run about a max of 5 hours, I dont suppose it matters too much....

I haven't seen one, but I guess from that they're quite small. That isn't necessarily a problem though. The ability of the oil film in the bearing to support the load is proportional (can't remember if its a power of not) to the speed the crank is rotating, so at 17-18000rpm a narrow bearing can support more load than a much wider bearing at half those revs. Also, the life expectancy of the bearing if probably much more down to the condition of the oil than the size of the bearing. If the bearing is even slightly too small for the max load, surface to surface contact will occur, however momentarily, then its goodbye engine

[blue nose]

Originally Posted by maddogf3

After Ratio change in hewland box ,gears lubed with an oil can only no additional oil added ( they use some purple Stuff thats fully synthetic and expensive ) cant remember what make it is ,does anyone know ??

Royal Purple.

[Chucky]

Originally Posted by phoenix

I'm not joking

I don't think you're joking either.

There's a lot of other tricks. Turning oil pressure down to 25psi for qualifying. Running juuuussst enough valve spring to just keep it under valve float (and replacing them every 200km rebuild). All worth little bits.