What needs to be done to a NON VHPD short motor to allow 8,000 RPM to be used on a regular basis for the purpose of track use (Not sustained 8k down the straights just on the upchanges) This is not a money no object question but a post to ascertain weather it is possible to produce a cost effective solution. if any of the experienced posters could include costs that would be a big help. Starting point is a low mileage std K series short motor ???
Forged pistons (around �450), effective balancing (�250 for full engine set).
Dave
Dave did say effective balancing.
What about rods? - I am not convinced I would want my VVC rods at over say 7400 odd.
So �700 odd for rpistons, balancing
Rods - �450 - �700 depending on type and spec
Bearings, oil pump etc.
Assuming a self strip and engine removal + refit, total cost? (excluding head work)
So the pstons are more of a weak point than the rods. How does one eliminate the resonance frequencies?
I have over 40 engines out there revving regularly to 8000+ RPM on stock crank and rods with just forged pistons. Less than 10% have steel oil pumps.
I have yet to see a broken crank from any of those. The picture shows a classic break across the rear main usually brought about by unsympathetic use of the clutch and very sticky tyres. There is very little wind-up in the Elise transmission and the mass of the car is connected effectively to the flywheel, a sudden chenge in loading and differential speed between crank and transmission can bring about extremely high loadings across the rear main bearing, even a steel crank isnt completely immune to this kind of problem.
Life is full of horror stories, if you listen to all of them you wouldn’t eat drink, sleep, wake-up etc.etc.
IMO based on lots of practical experience, a set of single tang rods, forged pistons and a stock crank effectively balanced is good for 8000RPM.
If you want to add steel rods or steel pump innards then you can.
Dave
Thanks for clarifying.
Shangani - I’m not sure I see what you find it that post that needs to be deleted. Aren’t people allowed to disagree anymore?
Simon - Do you mean “change” the resonant frequency or move where the resonance occurs? How do you do that on a stock crank? I’m just interested.
David - I’m sure you’re right about “unsympathetic” clutch use aggravating the problem, especially on sticky tyres. My starting technique used to be to drop the clutch at 4000 - with the VHPD I’ve had to move up to 6500 to get any kind of momentum from a start. If that’s enough to snap standard drive shafts (does happen), I’m sure it’s enough to snap a crank under some conditions. And lightening the flywheel would only aggravate the situation further.
So what should we be balancing - rods and pistons too?
Cheers
Didnt say nuffink - wasnt even there that day!!!
Sorry had to edit my last post - I mis-spelt Shangani - my spelling was much more fun!!
Cheers Simon
Thanks for taking the time to explain. I am still a numpty with most of these things. Fixing people is a lot easier - you can’t redesign anything.
And Simon didn’t edit anything untoward out - I probably overreacted.
Cheers
Andrew
PS what did you call me Tone? I have seen every spelling permutation of my pseudonym (which is actually a place in Zimbabwe) - I sort of regret not having used my real name on all the forums from the outset.
Thanks, Simon - very clear.
Clearly I need to think more the about flywheel - suggestions?
(BTW I got your PM - you have my email now - ta)
Didnt say nuffink - wasnt even there that day!!!
Shagani? Wish it were so…
I mis-spelt it by accidentally missing one letter out - I’m not going to say which letter it was I mis hit on this keyboard without my solicitor and barrister giving their approval. (and I guess Ani would want to know too)
The wife’s family come from Ndola, Zambia
Simon, these special flywheel and clutch assemblies that you suggest are a vital ingrediant of a high reving K series - where do you get them from, and how much are they ?
Do they fit straight on or are mods needed, and what power are they good for ?
A lot of questions there …Thanks
… Vibration analysis at Rover identified just why, similar work recently done at Ricardo 2000 and for my book, all independantly.
simon
Maybe if Rover had got the counterweight right on the 1800’s in the first place then vibration wouldn’t be such a big issue would it ?
As Dave says, it looks like a classic “dumping the clutch” type of failure to me.
Bernard