Ouboard Engine Setup

[Paul D]

Paul you don't want to be on wot for any extended time anyhow. 4 strokes are not designed to be driven at wot unless you want engine damage.

Kam,

 

I beg to differ with regard to engine damage. I have the owner manual ( from the USA of all places ) and there is not a single mention of any limit wrt. WOT operation ( apart from recommending for fuel economy to operate at less than full throttle. ).

 

The engine itself actually contains a rev limiter which if engaged you should allow the revs to settle and then once again apply full power. ( their words not mine ).

 

I am sure Honda would mention if continuous WOT operation causes engine damage - especially in the USA of all places

 

I suggest therefore that my engine doesn't have any WOT limit.

 

Besides, if it were 1 hour, I don't think I have cruised anywhere flat out continuously for an hour in any case.

 

Finally, I would suggest that greater engine damage / wear will be brought about by using a prop which continually places a high load on the engine - bit like driving around everywhere slowly in 5th gear with your foot on the floor .

 

 

 

[Newboy]

I'm no engine expert, but there isn't much difference between flooring the gas pedal whether it's in 1st, 2nd, 3rd, 4th or 5th, end of the day, you are thrashing the balls off it (in a matter of facts, it's less damaging in 5th as the max rev in top gear is usually lower than the rest).

 

Just think boy racers, who redline the engines all the time, would you buy any car off them?

 

 

[Paul D]

There is a difference.

 

A marine engine is designed to be operated at a particular RPM range at WOT.

 

Get the prop pitch too small and the engine will indeed wear due to too high RPM. Too small and excessive load will cause poor fuel consumption and strain = bearing wear.

 

A car engine being floored and red-lined is doing too many RPM's with too little load = wear and is equivalent to running a marine engine at WOT with a prop which has too small a pitch.

 

A car engine being driven around all the time in 5th at low RPM will cause wear in the bearings and is equivalent to running a marine engine at WOT with too highly pitched prop ( too low RPM and strain on engine ).

 

 

 

 

 

[jack]

I have always been an "economical car driver" always using the highest gear possable.I had a lot of trouble with a newish 6cyl.ford granada.After the garage had sorted things out {for the third time } I was known ever after by them as "the man who murders engines". So it seems someone has the correct thread somewhere.

[Afishionado]

Quote........ always using the highest gear possable

 

 

Ahhhhhhhg! Murderer!!!

 

And by golly it dates you. Back before the war the government came up with a road tax formula based on the bore and stroke of the engine (to limit big bore powerful engines). Now one could fairly ask what the heck has that got to do with 2005.

 

Well this taxation formula affected British engine design for the next 30 odd years.

 

Because of this in the 30's engines were developed with small bores and long strokes. Loads of low rev torque but no ability to rev much over 4200rpm. Therefore a culture of going for the highest gear as soon as possible developed as the norm for driving.

The legacy of these engines were to be seen in the appaling engines made by BMC/Leyland and Roots groups. Neither had the money to totaly design new modern big bore short stroke engines as Ford did with their Kent and Essex engines. These factors actualy lead to the demise of both BMC/Leyland and Roots they just had crap old engines.

 

An up to date big bore short stroke petrol engine needs to be doing at least 2000 rpm before it even starts it's power/economy 'best band'. And develop best efficiency at about 4000 to 4500rpm (which was just about the limit on the older pre war designed engines).

 

So use all the gears (I had an engine wrecking uncle, who swore first gear was only for steep hills towing caravans, and used to judder along at 30 in fourth.) and hold each gear until at least 3500 to 4000 RPM is there. If you are at a steady speed with only 2500 to 3000 rpm showing, change down to increase efficiency and economy.

 

Mad Mike

[jack]

Bloody hell mike,you could be my long-lost nephew !!.Seriously 'though I still usually drive round at 2500 revs or so,In both my Ford Ka ,and my Peugot 2500 turbo Campervan. On the van I can feel the Turbo come in at spot on 2000revs. I frequently manage to drop into 5th gear about town without " shunting " or anything.I cant do that with the van when towing the car,but I am usually in 5th on the open road,usually at under 3000revs,thats about 50 mph or so.;So are you telling me that I am not being"economical" but still murdering engines ?..Waiting for an answer with baited breath...jack

[Afishionado]

Bloody hell mike,you could be my long-lost nephew !!.Seriously 'though I still usually drive round at 2500 revs or so,In both my Ford Ka ,and my Peugot 2500 turbo Campervan. On the van I can feel the Turbo come in at spot on 2000revs. I frequently manage to drop into 5th gear about town without " shunting " or anything.I cant do that with the van when towing the car,but I am usually in 5th on the open road,usually at under 3000revs,thats about 50 mph or so.;So are you telling me that I am not being"economical" but still murdering engines ?..Waiting for an answer with baited breath...jack

Certainly on the Ka's 1.25 injection engine. It's most economical engine speed will be a lightly loaded 3250 to 4000 RPM. Top gear and 2500rpm will kill the little fast reving efficient engine. Also you will notice that you are depressing the gas pedal less for the same or better effect by using a higher rev band. Let the engine get up to its best rev range by using a LOWER gear in necessary.

 

 

Is the van diesel? Cos' they're a different case. As they actualy prefer to slog away in a high gear and a lower rev'. But then again if you look at how the car makers are designing high reving diesel engines for the passenger car market that is not always the case these days.

 

All in all as a general thing, modern engines are best lightly loaded at a higher rev than you use normaly and in a lower gear to give flexability of drive. Except of course on a motorway type road when every one will be in fith.

 

 

Mad Mike

[jack]

Thanks for all that info. Mike. The van is diesel, [although I did once fill it with petrol ! ].... [ it did'nt improve performance,and did awful damage to my wallet ] so I will carry on "murdering" that. I will however take your advice with the Ka. and let it rev more.I am doing a fair run -about this weekend in the car so it will be interesting to see if economy is affected by the different driving style....thanks again..jack