Hi There - Just getting in to the kit car scene. Can anyone advise on engine types.

It seems as though Fireblade, Blackbird, Hayabusa, Yamaha YZF-R1 & Kawasaki ZZR1100 are the standars to use - has anyone had any experience with a Triumph Trophy 1200 engine?

Appreciate anyone experience.

James

Triton used the Daytona engine in the Challenger, see chaos999 on here he now uses the car on the road.

The reason they are standards is pretty much due to their ease of installation and reliability when installed. Quite nearly in that order too... as newer bikes/engines come on the scene things move on. I've personally not heard of the engine you mention in a BEC but maybe there is a reason for that. I'm looking at the low power: 107hp, and the low torque: 77Nm. A 900cc Fireblade generates more than both those figures, which when your pulling over 3 times the weight you're going to need.

I would suggest looing for a bike with wide gear ratios - a sports tourer rather than a racer. A ZZR1200 perhaps. BECs are very revvy in 6th anyway. A close ratio box would just be manic.

Also look for torque rather than power. A ZX12R has less power than a ZX10R but more torque and makes a far more suitable donor.

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Originally posted by smart51
A ZX12R has less power than a ZX10R but more torque and makes a far more suitable donor.

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quote:

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Originally posted by smart51
I would suggest looing for a bike with wide gear ratios - a sports tourer rather than a racer. A ZZR1200 perhaps. BECs are very revvy in 6th anyway. A close ratio box would just be manic.

Also look for torque rather than power. A ZX12R has less power than a ZX10R but more torque and makes a far more suitable donor.

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Cheers, thanks for the information.

With a ZX12 geared to give 64MPH in 1st at the red line, you get 147 in 6th and 5300 RPM at 70 in 6th.

With a ZX10 geared to give 64 MPH in 1st, you get 123 in 6th and 7300 RPM at 70 in 6th.

My sentiment is do you REALLY want that many revs when cruising? You DO? OK, put the ZX12 into 4th - Bingo!

ZX12 = 134Nm, ZX10 = 115. The 12 will give better acceleration in 1st due to the higher torque and you won't go deaf / insane at motorway speeds.

180BHP for the ZX12 is with ram air. not sure that applies to a car. does it? the ZX10 revs a lot higher than the ZX12 and so makes up it's power that way.

To get 147mph top end with a ZX12 you'll need a very high diff and/or large tyres, a friend of mine had a ZX12 in a Stuart Taylor and that was overall geared quite similarly to most other BECs, ie around 130mph top end, with ISTR a 3.38 diff and 205/50 - 15 tyres.
You'll never get to 147mph with 170 odd bhp tho so there's not much point in gearing that high unless you do a 50 mile commute on the M4 every day

to gear up a ZX12 as stated above, you need a 3.14 diff and 195/55R15 tyres.

I'm not suggesting you do this, I was just illustrating the difference between a wide ratio and a close ratio box. maybe you'd prefer this illustration

ZX12. 3.92 diff. 195/50R15 tyres. 64 MPH in 2nd at the red line. 114 in 6th. 70 at 6900 in 6th

ZX10. 3.92 diff. 195/50R15 tyres. 66 MPH in 2nd at the red line. 104 in 6th. 70 at 8700 in 6th

or perhaps this one

ZX12. 3.62 diff. 195/50R15 tyres. 53 MPH in 1st at the red line. 123 in 6th. 70 at 6300 in 6th

ZX10. 3.62 diff. 195/50R15 tyres. 57 MPH in 1st at the red line. 112 in 6th. 70 at 8100 in 6th

in any case, the point is the same, for the same diff ratio, tyre size, overall 1st gear ratio, the close ratio box will be very revvy in 6th. For the same 6th gear ratio, 1st gear will be much taller in the close ratio box (read slower acceleration but higher 1st - 2nd gear change point).

A wide ratio box gives more flexibility and better cruising. If you are making a track day only car then you may not care but if you want to use it on the road then it might be worth considering.

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Originally posted by ChrisGamlin
To get 147mph top end with a ZX12 you'll need a very high diff and/or large tyres, a friend of mine had a ZX12 in a Stuart Taylor and that was overall geared quite similarly to most other BECs, ie around 130mph top end, with ISTR a 3.38 diff and 205/50 - 15 tyres.

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In answer to the original question, Hyabusa without a doubt, but it will set you back £3000, which is the problem!

In autograss racing where bike engines are a mainstay category, Busa and Blackbird (both usually modified to enlarge capacity) seem to do very well.

quote:

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Originally posted by smart51
to gear up a ZX12 as stated above, you need a 3.14 diff and 195/55R15 tyres.

I'm not suggesting you do this, I was just illustrating the difference between a wide ratio and a close ratio box. maybe you'd prefer this illustration..........
...

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quote:

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Originally posted by smart51
I would suggest looing for a bike with wide gear ratios - a sports tourer rather than a racer. A ZZR1200 perhaps. BECs are very revvy in 6th anyway. A close ratio box would just be manic.

Also look for torque rather than power. A ZX12R has less power than a ZX10R but more torque and makes a far more suitable donor.

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70 MPH at 6000 RPM in 6th is not at all car like (not like my car) and is manic enough. 8000 RPM is a whole other level of manicness.

You lose none of the high rev acceleration with a wide ratio box either. With 1st and 2nd gear the same as a close ratio box you get the same 0 - more than legal acceleration but with taller 5th and 6th gears, getting to where you want to go is not as much mental.

If the ZX12 is not sports tourer enough then look at a ZZR1200.

The other advantage with a wide ratio box is that if you set 6th gear to give a reasonable top speed then 1st won't be overly tall. A shorter 1st gear (and were talking 0 - 45 MPH here rather than 0 - 70) will give you even more acceleration.

You should try cruising at 100mph down to Le Mans in a blade BEC with a 3.89 in the back, after that, 8k at 70 is like being chauffered in the back of a Roller

(The diff decision was forced on me BTW, my 3.54 knackered its diff bearing the night before departure).

At the end of the day though unless you use a real cruiser of an engine which won't perform, or you gear your car for about 160mph, you're never going to get away from the approximate 10mph/1000rpm gearing of the average BEC. Most suitably powerful engines rev to 11-12k rpm, and to maximise acceleration and give a decent top end you'll want it to top out at around 120-130mph. Having a top gear that tops out at around 150-160 just to give a nice cruising rpm seems a bit of handicap to me as you're effectively limiting the car to 4/5 useful gears to obtain maximum performance, and only use 6th as an over-drive for pootling around on the motorway which lets face it, these cars are never going to be good at, regardless of the gearing.