[quote=“PhillipM”]Trust me, at the length of time you will spend at full throttle the first time you slog uphill through thick mud, it will result in the engine bay, seal tip, seal springs, chamber, plug, oil and water temperatures climbing so far, that pre-mix is a very good idea, even with the OMP at full chat, as a lot of the liquid lubricants will flash off before the chamber even gets around to full compression, and leave only the high-pressure metal compounds behind.
Then the side seal springs die.[/quote]
As far as serious off roading goes, diesel is the way to go. More favorable tourque characteristics, and generally built stronger to handle the increased compression.
Also generally heavier and less power for a given size, so you have to build a bigger, heavier chassis. And you need a larger gearbox to cope with the torque, and a bigger clutch and heavier flywheel…
Plus you’ve got a red hot turbocharger to worry about when you go wading.
Good for playing about with, but I can’t remember the last time a diesel won the awdc, bccc, rallyes tt, etc…
[quote=“PhillipM”]Also generally heavier and less power for a given size, so you have to build a bigger, heavier chassis. And you need a larger gearbox to cope with the torque, and a bigger clutch and heavier flywheel…
Plus you’ve got a red hot turbocharger to worry about when you go wading.
Good for playing about with, but I can’t remember the last time a diesel won the awdc, bccc, rallyes tt, etc…[/quote]
High-speed dashing across rough terrain one can do with any car with decent ground clearance and suspension travel. The times I’ve been out in the backwood crawling over logs, rocks, trough ruts and up steep inclines, I wouldn’t have wanted to be without diesel tourque to save my life, and I know for a fact that if the truck I was driving (Mitsubishi L200/Triton/Warrior.) had sported the optional V6 petrol rather than the I4 TD it did, it would have struggled a heck of a lot more. Clutch would be on fire halfway trough.
In general, cars aren’t designed around an engine. In a car with both petrol and diesel options the chassis will remain pretty much the same, and any changes to overall vehicle mass will be minimal, easily offset by the extra low down tourque. The placement of the turbo on a TD engine will in most cases not be the limiting factor when it comes to wading. The engine intake will.
I’m with Fenris on this one. There’s a reason most military vehicles are diesel. They have no trouble wading through water well above the turbo. And as far as victories go, one need look no further that Audi/VW. From Le Mans to Dakar, the TDI proves that diesel is fast, reliable, and a great match for racing.
LeMans and Dakar both had to swing the rules massively in favour of the diesel to make them competitive, otherwise VW/Audi were going to pull out as their money making arm is economic diesels for road cars. Money speaking at it’s finest.
Give them fair rules and they wouldn’t see which way the petrols went - in fact, the few series still running open engine regulations between the two are the ones I named, and petrol wins, hell, even the trails guys crawling along at a few mph are switching to petrol as it means a lighter rig with lower CoG…
The reason most military vehicles are diesel is nothing to do with torque, it’s fuel economy and the ability to run on a wide range of fuels from vegetable oil to kerosene - fuel supply isn’t always perfect in a war…
Fenris has a point - for his model of car - if the car had the same size petrol turbo model available, you’d find it also had much more torque.
The problem is it would also have much more power and would probably end up with higher gearing, hence the clutch slip problem at crawling speeds, but that’s a gearbox issue rather than an engine one
