Crankshaft

[Old SchoolParticipant @oldschool]

[Old SchoolParticipant @oldschool]

I am going to convert a comercial 2.5cc engine so that it is suitable for tether car racing. The main part of the conversion is to rotate the exhaust 180 degrees so it exhausts in the direction of the crank shaft.

To do this I need to make a new crankshaft, as I cannot grind it after hardening I am considering nitriding and a final lapping of the crankshaft to bring it to final size after nitriding.

The crankshat will be machined from EN24T which I belive can be nitrided. The crankshaft is a simple shape so I expect little or no distortsion. The manufacturers of the engine claim a figure of up to 45,000 rpm my current engine does just under 39,000rpm this would be a usefull increase in rpm.

Look forward to your comments

Oliver

[mike TParticipant @miket56243]

Oliver

Unfortunately, unable to help you at the moment. However, I will be very interested to hear of your experiences with nitriding your new crankshaft as I intend to follow your lead in a the near future. Therefore I would be pleased to learn, who are prepared to do the nitriding, the cost and any special preparation that is necessary such as dimentional considerations.

Good luck

Mike

[FMESParticipant @fmes]

Hi Oliver,

Can't quite visualise what you are trying to do, how would a new crankshaft alter the exhaust position?

[Old SchoolParticipant @oldschool]

The donor's engine is front induction and rear exhaust the engine when turned round will be front exhaust rear induction. Apart from the crankshaft I will also have to make a front housing and a zimmerman disc induction for the rear of the engine.

A lot of work but hopefully worth it. I will try and put a picture on.

Olly

[Steve WithnellParticipant @stevewithnell34426]

If you turn it round so the exhaust is forward and the induction is at the rear, won't that reduce performance? The exhaust gases are in a high pressure zone, and the inlet in a low pressure zone.

Just a few armchair comments. I've only built one IC engine and not at all high performance, so book learned rather than actually done it, but I am curious as to why turning the ports around improves performance.

Steve

[Ian S CParticipant @iansc]

Steve, it's in a car, so it's probably facing the other direction to what it would in a plane. Ian S C

[Sub MandrelParticipant @submandrel]

Hi Olly,

Surely you should be using an old Oliver engine?

I must admit, I have a secret admiration for tether cars. As a boy my dad brainwashed me that real racing cars had the driver sticking out the top and beautiful curved bodywork.

Neil

<edit> I see you're the UK record holder at over 200mph! Congratulations! Are there plans for something vaguely resembling the Buck 2A out there?

Edited By Stub Mandrel on 12/10/2013 11:20:29

[Old SchoolParticipant @oldschool]

Neil

Unfortunately they no longer make a competitive engine the best speed with a modern Oliver is about a 100mph my modern engine and car has done 161mph. Things have moved along since John Oliver designed his famous engine. The big change is the tuned pipe exhaust system which has given a massive increase in power.

Oliver

[EmgeeParticipant @emgee]

Hi Oliver

Do you need to harden the shaft because of an integral crankpin ?

Current Pylon racing 6.5cc engines have pressed in crankpins and run at 32k in air, using this method

may save you nitriding as the material choice is very tough.

Rgds, Emgee

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