K Series to Rev to 8,000RPM All day Long !!!

The Oily Bits S1 Specific Topics
81

Sounds pretty good guys - any chance of a peek at the figures - no probs if you don’t want to post them, totally understand

Long live the K

82

No Mate I haven’t touched that for ages. I guess could do though.

83

No Mate I haven’t touched that for ages. I guess could do though.

Here you go, I’ll help you out:

[color:“blue”]Next job was to remove some uneccessary weight, which we found in the sills [/color]

[image]http://www.mine-safety.mtu.edu/clipart/mobequip/gravel.jpg[/image]

84

Hi
Im new to this forum stuff but cant help interjecting. The issue with the 1.8K engine is it is inherantly poorly balanced and as simon says it does have a nasty resonant frequency. Due to the small crank pin/big end overlap there is a weak point between no 4 big end and no 5 main. The fact is that the moment of inertia of a large flywheel is a major factor in the failure of the crank as well as the resonant frequency. At certain points in the rev range the back of the flywheel at its periphery will move as much as 4-6 mm !!! hence you can understand why the cranks break and by the way i was the sucker measuring it while the engine was doin 7600 rpm WOT so i have seen it. Unfortunateley it is inherant in the design. Improvments can be made by the following methods. Heavy metal counterweighting as done by Steve @ Vibration Free and reducing the monent of inertia and peripheral weight of the flywheel. I would not recommend excessive lightening of a standard flywheel though the material really is cheap monkey metal. Reduced diameter lightweight flywheels can be obtained from Ark Racing but they are only for use with 7.25 Racing clutches and you need to use an offset starter to go with it also avaiable from Ark Racing. They are not cheap but do work well and reduce the flywheel weight down to just under 3Kg.

85

… the back of the flywheel at its periphery will move as much as 4-6 mm !!! hence you can understand why the cranks break and by the way i was the sucker measuring it while the engine was doin 7600 rpm WOT so i have seen it…

4-6 mm !!! Hellfire, I wouldn’t have wanted to be too close to that !

Bernard

86

That’s a fair bit! So that’s at the starter ring gear and the movement is axial (relative to crank axes)?

Was that at constant rpm or during accel-deccel cycles, loaded or unloaded?

Is that with the clutch plate and housing assembled or rig/dyno etc?

So many question - just interested to understand the environment and test conditions :wink:

Thanks for you comments.

Welcome to Exiges.

87

Just figured one of my questions out… ‘WOT’ meaning ‘Wide Open Throttle’

That would be loaded then to limit the rpm??

My query re the clutch being installed, or not, is to ascertain if the flywheel had any support representative of an in car installation?

Thanks!

88

That was on a supeflow dyno. with an alloy adaptor to the prop shaft. Engine was solid mounted to the bed. This situation would not be representative of the mounting system in a vehicle unless it was solid mounted.
I have tested many k series engines and the dyno is not a good place for them !!! For example when dyno running try to avoid sustained high rpm with a standard front pulley because it falls apart but … Its ok in the car albeit the alternator runs too fast if you are revving consistantly above 7000 rpm hence people put the smaller pulley on

89

Just to add to the discussion, I did a test day at Snetterton last week and a qualifyig session and half a race (gearbox issues) at the weekend and I was revving the car to 9,300RPM in every gear and was holding it there in 6th at the end of the straight and had no problems.

I had wanted to keep my supershort final drive in my gearbox, so went to test to see if I had ebough revs for it to make it to the end of the straight. To be fair I had a bit of a misfire on the test day which I fixed with new plugs. I was hitting the limiter in 6th when it was at 9,000RPM, so I simply upped it to Hard cut 9,400 and soft cut 9,300 and all was well.

People at Snett may have seen smoke from the back of my car, but I have a leaky oil temp sender, oil is actually leaking out the middle of the sender where the wire comes out and it was dripping onto the under tray and on right hand bends it was washing accross the under tray and onto the exhaust.

90

It certainly did sound like it was revving well coming out of the chicane. But not convinced about it lasting all day

Bernard

91

It will be at Oulton, but probably with a standard Exige gearbox, so wont be doing mental revs in 5th, unless I grow huge balls and steal some talent.

But yesterday at Snett, I wouldn’t have forseen any issues if the gearbox hadn’t let go.

Sean…

92

…unless I grow huge balls and steal some talent.

See you at Oulton, Brummie Boy

[image]http://img.photobucket.com/albums/v222/Exiges/VV.jpg[/image]

93

Should add thanks to Turboboy for getting back - not so easy to relate your experience with what happens dynamically in the chassis and with a clutch attached, but very interesting - sorry for the delay; been a bit busy

Sorry to hear of your gearbox wows Sean… keep it simple

94

Sorry to hear about the gearbox Sean.

Disappointing that the Quaife bits are still giving problems…