The Technical Questions Thread

[clutch-monkey]

what criteria do manufacturers use when selecting what oil filter their engine will use? volume of oil etc?

[Matra et Alpine]

Volume of oil is only a secondary factor - ie more oil circulated regularly will last longer and absorb more impurities than less oil.

What matters is ...

oil viscosity
operating temperatures
oil pressure
oil flow rate
pressure drop through the filter
minimum contamination capture size
replacement/cleaning period
oil type
contaminant types

In reality, most of the above are a "given" for a modern engine so really only flow rate, pressure and pressure drop.

[Ferrer]

Do different suspension types (say multilink v torsion beam) actually affect overall grip?

[Matra et Alpine]

Yes, because of the way they alter the tyre contact patch with weight transfer, body roll, braking dive and acceleration lift.
More to do with the geometry of the setups eg nultilink has more freedom of design movement than say macpherson strut.
Were you thnking of anything specific ?

[Ferrer]

Well I was thinking of the C-segment hatches, where there are two clear options mostly, multilink (Golf/Focus) and torsion beam rear suspensiom (french and italian cars mostly).

I've found torsion beam cars to be somewhat more understeery but more planted and multilink cars more prone to lift off oversteer but more nervous as well, I was wondering if there was a difference in actual grip (and therefore speed) or it was only handling characteristics.

[RacingManiac]

One of the thread I ran into at VWvortex was talking about the suspension setup for the multilink/semi-trailing arm setup of the Golf/Focus. Golf's setup is actually a derivative of how Ford's control-blade is setup. I think they trade off some of the ultimate grip for better compliance of the independent rear suspension. They actually go slightly positive camber on limit on the outside rear tire. Which is not good for grip...

[zique]

Hey guys,just a question thats got me wondering.Do tyres with a bigger sidewall offer more flex with hard cornering?

Reason I ask is because I've downgraded to higher profile (175/65R13) tyres and wonder if those tyres would flex more during hard cornering than say a lower profile (195/50R15) tyre because of the larger sidewall.

[Matra et Alpine]

Check the "load index" markings on the tyre.
It is all down to the sidewall strength and MOST will get stronger with lower profile.
A higher load index is indicative of a higher sidewall strength.

Also, in general higher wall tyres flex more just because of the shape and different manufacturers differ even on the same sizes.
But if it is very noticable then check the load index - the last two numbers in the tyre specification before the speed letter. See Car Bibles : The Wheel and Tyre Bible Page 1 of 4.

[Magnum9987]

Has anyone ever heard anything of industry development of 6 stroke engines? I've seen and heard of prototypes over the last 15-20 years, but I was wondering if anyone had heard anything.

[NSXType-R]

Has anyone ever heard anything of industry development of 6 stroke engines? I've seen and heard of prototypes over the last 15-20 years, but I was wondering if anyone had heard anything.

Whoa.

What would you do with the extra two steps?

[culver]

I've heard of two 6 stroke motors.
Six-stroke engine - Wikipedia, the free encyclopedia
I think some have emissions issues but a number of designs have been discussed. I don't know if any have seen commercial use. I like this one in principle
The Six-Stroke Engine Damn Interesting

[pimento]

The main issue with commercialising Crower's and others that consume water will be educating the masses that they need to fill up with water as well as fuel. Then of course there's the fact that most will probably not bother with distilled water, unless it can be mass produced cheaply enough to warrant not just using the garden hose. I could see a lot of failed warranty claims in the future of any commercially available six cycle engine on those grounds.

[Horba]

Engine Design- Is this possible
I m not an engineer by profeession but I jsu love the staff. I am designing an engine and would like an informed opinion on my design.

The engine Iam designing is a 4.0L engine which has two engine blocks with 4 cylinders each. The blocks are mounted on one head in a flat configuration and the crank shafts are connected to a fly wheel behind the head. Each of the blocks cylinders will be opposite the other blocks cylinder and the valve systems will be inbetween them. The engines head has a compression chamber into which air from the two cylinders on either side is compressed

Each cylinder will be fed by two inlet valves and one outlet valve which means in fact that each double cylinder will have six valves all mounted on the head inbetween the cylinders.

I have drawwings of the engine and they seems to make sense to me but I would like to know. How efiiet would this engine be, it looks compact but I am worried about the two crank shafts that would make it all heavy.

[Matra et Alpine]

It's not as efficient as a custom V8 block.
Look for the Matra Bagheera U8 where the French built a prototype of a "ferrari beater" using two simca engines in exactly the configuration you are thinking of.
It had the performance to match the Ferrari, sadly it would have cost a LOT more than a Ferrari .... for a "simca"

[Magnum9987]

Couldn't water be filtered in much the same way fuel is? 2 or 3 stage carbon filters are very effective at getting contaminants out. Of course they need periodical replacement, but air, fuel and oil filters do as well.