How much power do different ancillaries drain?
Discussion
up-the-dubs said:
Can't help on this issue but any chance of a seperate topic somewhere about the build with a few pics? Sounds mad and bizarrly interesting!
I'd be happy to start a topic somewhere, but the build is rather slow at the moment so it would get updated pretty rarely... I will start it when I have one of the engines running, and hopefully the whole thing will be finished (or at least road legal) before June.
GreenV8S said:
I'd have thought the difference would only be of the order of a few BHP so negligeable compared to all the other differences you're likely to have.
That was my line of thought too... What other differences can you think about? Both engines are exactly the same and will be rebuilt in the same way.
Alex@POD said:
GreenV8S said:
I'd have thought the difference would only be of the order of a few BHP so negligeable compared to all the other differences you're likely to have.
That was my line of thought too... What other differences can you think about? Both engines are exactly the same and will be rebuilt in the same way.
Well I don't know what sort of layout you're planning, but you may have different induction or exhaust layouts, the engines may be in different environments in terms of ventilation and cold air feeds. I guess you'll be splitting the drive front/rear so even if you start with perfect weight distribution it won't stay that way when you have weight transfer and aerodynamics, the tyres will behave differently and may not even be the same size, you'll have suspension geometry differences front/rear and so on. Even if everything else is identical, there are bound to be some differences between the engines and unless they've been blue printed this difference could be quite large, perhaps even as much as 10%. So I guess it comes down to, how imporant is it that the engine outputs are identical to within better than a few bhp, and how closely can you control all the other factors? If its really critical I'd expect you to link the engines mechanically or electronically anyway.
Alex@POD said:
I am running a twin engine set-up in my van, with one engine fitted with power steering, the other the air-con. Can I expect any difference in power that will be a problem, knowing that the engines are coupled to auto gearboxes?
Thanks for any tips...
Thanks for any tips...
O.K. so you can steer, and you're being kept cool. So you want to know why you're not going anywhere..... Right?
GreenV8S said:
Alex@POD said:
GreenV8S said:
I'd have thought the difference would only be of the order of a few BHP so negligeable compared to all the other differences you're likely to have.
That was my line of thought too... What other differences can you think about? Both engines are exactly the same and will be rebuilt in the same way.
Well I don't know what sort of layout you're planning, but you may have different induction or exhaust layouts, the engines may be in different environments in terms of ventilation and cold air feeds. I guess you'll be splitting the drive front/rear so even if you start with perfect weight distribution it won't stay that way when you have weight transfer and aerodynamics, the tyres will behave differently and may not even be the same size, you'll have suspension geometry differences front/rear and so on. Even if everything else is identical, there are bound to be some differences between the engines and unless they've been blue printed this difference could be quite large, perhaps even as much as 10%. So I guess it comes down to, how imporant is it that the engine outputs are identical to within better than a few bhp, and how closely can you control all the other factors? If its really critical I'd expect you to link the engines mechanically or electronically anyway.
Dammit, I was sitting there all smug with my ideas, and you ruin everything with all those very good points. I'll need to have the exhausts silencers very close to the back wheels, because of the fuel/LPG tank placed ahead of them. Induction layouts should be pretty similar, as I will have air intakes right by the back engine. As far as the suspension is concerned, I'll have a slightly wider track at the rear due to clearance issues, but other than this, the set-up is exactly the same.
I'd think the engines better be closely matched so that one doesn't out-rev the other all the time. They both use programmable electronic injection, and I was going to run them with two completely separate looms. Would it be possible or even wise to run them with only one ECU, to ensure they are matched, or is it better to keep it separate and leave the ECUs to it?
Are you just planning one engine driving the front axle and one driving the rear? Is it a road car or something with particularly unusual handling/performance requirements? If it's a road car then (a) I suspect you may find it's illegal to have two engines that are not mechanically inter-connected, and (b) they'll sort themselves out with the 'stronger' engine just working slightly harder than the other.
GreenV8S said:
Are you just planning one engine driving the front axle and one driving the rear? Is it a road car or something with particularly unusual handling/performance requirements? If it's a road car then (a) I suspect you may find it's illegal to have two engines that are not mechanically inter-connected, and (b) they'll sort themselves out with the 'stronger' engine just working slightly harder than the other.
It is a road vehicle, that will be used mainly for advertising purposes. I will use freewheel hubs to be able to drive it on the road with just one engine running (officially
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