40 bhp per tonne ?

[MARK_5064385]

Hi folks does anybody know if it is true that a tow car should

have at least 40 bhp per tonne of car and caravan.i have got a

chrysler voyager which has 131 bhp and feels under powered

when pulling our abbey gts vogue 416.The voyagers weight is

1705kg and the caravans mtplm is 1429 kg.

 

[rayc]

Mark, I don't know if BHP per tonne is the whole story , I'm sure that gearing etc comes into play. I have a CRV with kerbweight 1520kg and 1350 kg van with 150bhp at 4,00rpm. All I can say is that it tows preety good but not as well as the Mondeo 2ltr estate I had previously which was 130bhp or so at 3000rpm. I think it towed better because it gave max bhp at lower revs and the gearing was better.

I tried once towing with a Sierra 1600 eco engine, with a much lighter van, and it was a real chore.

I expect somebody with the same car will respond so you will get another view on it. Good luck. Ray

 

[Lutz]

It's really a bit futile to make a specific recommendation regarding minimum bhp/tonne because, as Ray says, there's more to it like gearing and torque. Some outfits, especially diesels, will move along quite happily with the rest of the traffic with only, say, 30bhp/tonne so long as one is prepared to use plenty of gears. By the way, the figure that you are referring to is based on the total train weight, i.e. not just the kerbweight of the car plus MTPLM of the caravan.

 

[Icemaker]

MARK, ive never had a voyager since for some crazy reason chrysler stuck a stupid max tow weight of 1600 kgs on it otherwise i would have had one. i can only imagine you have a problem with the engine as i tow a coachman laser 590/4 with a ford galaxy diesel the van weighs 1690 kgs and the car is 1720 kgs so its very close a 100% match, the engine on this car is 130 bhp and it tows an absolute dream no problems with power at all.

 

[ARTHUR_5118341]

I have a Ford Galaxy Deisel which up to now has been excellent pulling my Sprite caravan for about seven years. Now although the car is fine when not towing I now cannot do much over thiry mph. when pulling the caravan. I have had the Galaxy and the caravan checked but can find nothing wrong with either. Has anyone had a similar problem - if so what was wrong.

 

[DavidW1]

Mark,

Just put the figures through the calculator for my Bighorn and the current van and it's 29 BHP/tonne - and yet I would never describe it as sluggish.

I think the best formula for a towcar is high kerbweight, high torque at low RPM and a realistic final drive ratio.

I suspect that in the choosing of that crucial ratio Chrysler have opted for economy rather than "stump pulling" so your engine is just off the torque curve in the higher gears. Fine for cruising at high speed but a compromise when loaded at under 60 mph

 

[MikeP]

I have a Ford Galaxy Deisel which up to now has been excellent pulling my Sprite caravan for about seven years. Now although the car is fine when not towing I now cannot do much over thiry mph. when pulling the caravan. I have had the Galaxy and the caravan checked but can find nothing wrong with either. Has anyone had a similar problem - if so what was wrong.

Borrow another caravan and see if the problem remains. If so, think about turbo/intercooler, exhaust gas recirculation valve or something to do with the engine management.

 

[Icemaker]

Arthur, most modern cars have a facility thats drops the engine in to "limp home mode" if the electronics develope a fault, my new alhambra did a few months ago when the altitude sensor and maff sensor both went out of calibration. my car would only do 30 mph max and would not rev above 1500 rpm. you may have a fault that is at the moment only a problem when the engine is under a heavy load when you are towing, only way to find out unfortunately is to have the car tested on a diagnostic computer.