The main thing with the crank is making sure it is perfectly balanced along with the pistons, rods, flywheel and clutch. If it's all balanced together then you'll have a smooth running engine which will put minimal stress on the crank. Obviously a point will come where the rpm is still too much, but I would expect this to be quite high and as Rich said, I would expect the rods and bolts to be a bigger consideration than the crank. With the piston going from roughly 80>0>80mph in less than half a second the stress on the rods and bolts would be immense.

With the lifters Rich has proved that they are reliable well over 8k rpm, but I would be a little concerned if it was a pure race engine, and basically spending it's entire life at 6-9k rpm, and I personally would fit mechanical lifters.

The other thing to consider is longevity. Sure the Maxi engines were revved to 11k rpm, but I suspect they would have had titanium valves and mega lightweight pistons to reduce the stresses. With mega lightweight stuff and high revs comes the need to rebuild the engines regularly. I spoke to Matt at Pug1off a bit back and he told me that the engine he has built that made just over 300bhp at around 9800rpm needed a rebuild every 500 miles. Not a problem if you're pockets are deep enough mind!

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Oulton Park in a BTCC 306 vid 1
Oulton Park in a BTCC 306 vid 2
Lap of the 'ring

I think 8.5k will be the limit on mine, I will find where my peak power/torque is when setting my limit.

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Dimma + Gt35 turbo =
Solid rear beam mounts £130
07889376885
Dan

i`m sticking to stock revs dude

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^ good point well presented mate

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I'd rather my power came in at 2000 and ended at 6500-7000.
That would be a perfect power band in my opinion,

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andrew315rawson@live.co.uk
Moonstone phase 7 gti6
My Project thread: http://www.306gti6.com/forum/showthread.php?id=119992&page=1

turbo ftw always

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I think a lot of the posts made in this thread have very good points, if you are talking about a full-time race engine.

I wouldn't be happy having hydraulic lifters in my engine if it was a pure race engine and spent ALL of it's time between 6-8.5k. However, seeing as it's very driveable and happy and every now and then gets its legs stretched to 8k I don't see it as a problem...

I think for each application it is different and before starting a build you need to consider what that engine is going to have to suffer in its life. A road going supercharger conversion like mine running over 450bhp is fine with standard lifters and crank, however if I raised the rev limit even more and put my engine in a pure racing enviroment I would reconsider which components to put in it.

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"Supercharged - 454.1bhp/317.5lb/ft"
Peugeot 306 GTi-6
2000 (X), Moonstone

Please explain this comment as it makes no sense whatsoever

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www.bridgecraftmotorsport.co.uk

Facebook

Really?

How did F1 cars manage it then in the late 80's with 1.5l V6 Turbos revving fairly high?

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"Supercharged - 454.1bhp/317.5lb/ft"
Peugeot 306 GTi-6
2000 (X), Moonstone

Most import STi impreza engines run just past 8k iirc.

A friend of mine has a V40 T4 running 450BHp @ 9.5k rpm

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Nothing to see here

Yes Ashok's blue one. Its a beast of a thing and very standard-looking.

So the valve has to move further, quicker matty?

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Nothing to see here

Got a freind making 1.200HP on a VW R36 engine by 27 PSI 5.500 revs

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/Henrik C