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Post by dickie on Jul 22, 2020 17:22:54 GMT
I am having fun finding a local engine machine shop prepared to offset grind the crank for me.
I suspect they do not want to risk reputations on such a mad scheme, I will keep sending out emails to other machine shops.
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jon
Chats A Lot
Posts: 270
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Post by jon on Jul 22, 2020 18:44:57 GMT
Not sure of the technicalities of it all (and how it would affect willingness to rev etc), but would it be 'simpler' to get the block sleeved down to drop you 41cc, keep standard rods / crank / stroke and use undersized pistons?
For the race engine builds I've seen in the US, the limiting factor tends to be oil pump / valvetrain etc which doesn't give you that much higher a limit compared to a mk2 engine..
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Post by dickie on Jul 22, 2020 20:06:54 GMT
Hi Jon,
The plan is to build a long road oversquare BP that will fit into the up to 1800cc class and be very revable.
My valve train will support 7400 sustained revs with 7800 momentary limit on single valve springs,
I will be going big valve and double springs and looking for 8500 Rpm sustained.
Sleeving the block would not be worth it for me.
I would be upgrading the oil pump, I already have an ATI harmonic damper installed.
Its only a play project Honest.
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Post by Zed. on Jul 22, 2020 21:04:20 GMT
Not sure of the technicalities of it all (and how it would affect willingness to rev etc) longer conrods would improve the 1.8 engine. (although most people are happy with them as they are) the 1.6 & 1.8 share the same conrods but the 1.8 has a longer stroke so this inreases piston acceleration / deceleration at top & bottom of stroke - have a read en.wikipedia.org/wiki/Stroke_ratiolonger stroke / smaller bore can have more torque but less rev-happy www.superstreetonline.com/how-to/engine/0506-ht-rod-stroke-ratioexplains the longer rod bit I'm doing a 'long-rod' & overbored 1.6 so dickie is jumping on the bandwagon but wanting to over complicate things with shorter stroke   Rich. |
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Post by dickie on Jul 22, 2020 21:23:42 GMT
I am just trying out a differant idea just for the hell of it.
As Rich has just explained its the reason the 1600 is a more rev happy engine than to 1800.
I am just joining the fun from the other end.
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jon
Chats A Lot
Posts: 270
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Post by jon on Jul 22, 2020 21:56:31 GMT
Questioning from a curiosity perspective, rather than anything else, but will a pretty small difference in stroke/bore actually be noticeable?
I know the fundamentals of 'squareness', but not the realities, and how it compares to sleeving / bandsawing 1/2" off the top of the block etc to reduce the capacity..
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Post by Zed. on Jul 23, 2020 8:02:03 GMT
I am just trying out a differant idea just for the hell of it. I am just joining the fun from the other end. he who dares....  Rich. |
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Post by dickie on Jul 29, 2020 20:29:05 GMT
Hi folks,
I am not having much luck finding a local machine shop willing to undertake an offset crank grind.
The amount of grinding would go through the hard surface of the crank so it would need to be nitrided after grinding then polished.
Its all possible with the right equipment.
I recon I could get a custom crankshaft made for the same price as a turbo install.
The engine rebuild cost is only in the parts and machining for me, I have been building engines since I was sixteen.
I have owned my other sports car for 28 years just to give you a clue.
I am collecting parts for an engine rebuild on that on as well, Nothing wrong with it current engine though.
Fully counterbalanced crank with new rods cost £2200 for that little baby.
(Crank good for 8000 RPM on an 85 year old side valve engine)
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Post by wannabe on Jul 29, 2020 21:41:59 GMT
IIRC it's Bassett Down workshop who do balancing of engine parts and other things - not sure if they might be of any use? bassetdownbalancing.comI think I have them in my bookmarks because of someone recommending them on nutz. |
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Post by dickie on Jul 30, 2020 15:24:02 GMT
Thanks Wannabe, They were my first email. They were not happy to do the machining for a self build.
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Post by wannabe on Jul 30, 2020 16:37:03 GMT
That's annoying.
Even if you pay cash and don't ask for an invoice so can't take it back if you build it and the engine breaks? lol
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Post by dickie on Aug 14, 2020 20:30:18 GMT
I have put out a quote request for a De Stroked Billet Crankshaft,this will enable stock big end shell size to be used.
I would need custom length rods to go with it and some funky pistons too.
Its all a silly idea at the moment but will be fun to see it through.
With modern machining it takes about five to six hours on a CNC machining centre to make a crankshaft from a plain billet once the machine is programmed.
I am hoping the crankshaft and rods will be less than £3000 all the other parts will be common with any decent forged engine build.
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Post by dadbif on Aug 14, 2020 22:22:19 GMT
Don’t know where you are located, but this company are excellent, the chap who founded it used to work at RR when I did, he bored my cross flow years ago and once built at twin engined Westfield. Well worth a phone call www.gbengineering.co.uk/ |
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Post by dickie on Aug 17, 2020 21:05:43 GMT
Hi Folks,
I now have a quote for a Custom Billet Crankshaft.
Its now become a serious temptation.
I will have to see if the crankcase will take larger big end journals before I go ahead with a final crank spec.
The block will have; boundary oil pump, ATI damper, 85mm pistons, custom rods, lightweight flywheel.
I will use a Mk 2.5 Block with the main bearing support plate.
I might use my existing head as it already has some development
I will have to go big valve with double springs though.
My current engine is supporting 169 BHP and power is still building at 7500 RPM.
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Post by dickie on Jan 28, 2021 21:04:09 GMT
I have been a Naughty Boy !!
I have just ordered a Boundary VVT oil pump. The first part of the mad short stroke build. I will be collecting a VVT engine from a local breaker when he has one out of a car. The VVT head will not be used, I am only after the short block and starter motor.
I will be stripping the crank out and sending if off to be copied into a short stroke version !!
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le sigh