Timing an engine

Grueller

All the threads about timing belts, chains and failures of them got me thinking.
I drive an 06 Isuzu Dmax. It is certainly an "agricultural" driving experience. However the engine is timed by gears and is a lifetime maintenance free solution.
Is there any good reason why this can't be done in more engines? Does it make an engine noisier or less refined which would make little difference in a pick up but a big difference in a car?
Are there many any other engines that have this solution out there?

tabby aspreme

Timing belts are lighter , have less resistance, so better fuel economy, less noise, gears are ok for a single cam, lower revving engine

Hotblack Desiato

tabby aspreme wrote: »

Timing belts are lighter , have less resistance, so better fuel economy, less noise, gears are ok for a single cam, lower revving engine

Honda VFR750 bike engine was DOHC (actually quad cam - a V4 with two DOHC heads) and far from low revving

The reasons they went back to chains were production cost and noise.

Also the head can't be skimmed unless thicker head gaskets are available to compensate.

Henry Ford III

Timing chains aren't bullet proof either.

Grueller

Henry Ford III wrote: »

Timing chains aren't bullet proof either.

Gears are fairly bulletproof though

A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

Timing chains even when in fairly poor applications do generally give plenty of warning signs.

If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof

dr.fuzzenstein

Henry Ford III wrote: »

Timing chains aren't bullet proof either.

They would be, but then some engineer says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"

mickdw

dr.fuzzenstein wrote: »

Henry Ford III wrote: »

Timing chains aren't bullet proof either.

They would be, but then some engineer says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"

Not only cost. Engine efficiency drives a lot of the decisions. If they can use light weight materials with reasonable lifespan, they will cause it will help the push towards lower emissions. They don't seem to give a damn once components are good enough to get them over the warranty period.

Grueller

Augeo wrote: »

A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

Timing chains even when in fairly poor applications do generally give plenty of warning signs.

If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof

Good response. Am I incorrect in thinking geared setups would be superior to chains or belts?

tabby aspreme

dr.fuzzenstein wrote: »

They would be, but then some accountant says "well, we can save €0.05 per engine if we make them just a tiny little bit thinner and lighter"

Fixed that for you

CJhaughey

Augeo wrote: »

A decent valvetrain design and a 90k mile timing belt interval shouldn't be problematic.

Timing chains even when in fairly poor applications do generally give plenty of warning signs.

If timing gear sets were more common you can be sure a manufacturer or two would make a mess of it somehow resulting in plenty bad press.

The added cost to gear the timing in a quadcam, 24v, v6 engine would be eyewatering.

You might reckon a gear timed engine is bulletproof but there's moving parts aplenty & contact so there's inherent wear.... conceptually it's not at all bulletproof

The Honda engine in the VFR is no different, Quad cam V4, only two extra pots per bank.
They rev a lot higher as well and had no difficulty with longevity.
It comes down to noise as well, timing gear engines tend to make more mechanical noise than belts or chains which engineers/manufacturers are trying to reduce as well.
I think its cost driven though.

kona

Chains gears and belts are a waste of time. Camless engines are the way to go but i dont think they will make it to mainstream with the impending obsolescence of the I.C.E

Grueller

Grueller wrote: »

Good response. Am I incorrect in thinking geared setups would be superior to chains or belts?

Superior in what way?
A belt & pump change on a 4cyl is €300/500 ......I don't see the need for a geared setup