How much is a relatively well sorted normally aspirated 1380 worth?
Turbo Mini Forums

I have been considering selling my enigne to allow for the creation of a k head based 16v turbo item.

The dilemma I face is that the short motor has covered about 250 miles from new and features fully worked crank, powermax pistons and balanced rods. All the other parts featured on a previous engine of mine and have covered less then 5000 road miles from new, benross head, minispares high lift rockers weber, ultralight flywheel, 4 pin diff, megajolt ect. basically all the usual tricks to make a mini engine faster. The engine is making 100 bananas at the wheels.

Would it command £1500 do we think?

If I can't get anywhere near that figure I may throw out the idea of doing the 16v turbo for a few years till I have the required 5k to build such and engine. The other option of course is to sell the 5 port head, rockers and weber and plonk a ported out k1200rs head on, with set of sc's hot cams and deliver the fueling via a set of r1 bike carbs, that coupled with the megajolt should keep me happy until I can build a monster.

Edited by minimole23 on 3rd Apr, 2012.

100 brake at the wheels. CHEAP!

Own the day

The short motor alone was 1k!

Can't you just use the short block etc from the 1380, sell the head, cam, and other parts no longer needed. Im sure you'll make a fair amount of money back on them.

A K conversion shouldn't cost 5k.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Edited by minimole23 on 3rd Apr, 2012.

Ah what do you mean by compromise, are you thinking CR wise?

The EFI part was the most expensive part for mine, by the time I bought the ECU,loom, sensors, and injectors it was about £700-800. I found most of my old parts could be re used though. Are you still running a helical box at the moment?

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1/4mile in 13.2sec @ 111 terminal on 15psi

To get the compression down to even 10:1 I would need to use a 6cc head gasket and nibble some meat out the combustion chambers. The engine is not up to the planned 8.5k I would want to throw at it anyway due to the Cast pistons. I also want to go down the 1150cc short stroke turbo engine route too as that offers the best compromise between power, revs and economy of build.

I'm currently running a rebuilt standard box with minspares 4 pin diff. By the time you factor in straight cut drops, quaife diff, and 600 quid for gearset and bearings it gets expensive. I would also have to buy off the shelf fuel injection which of course gets very expensive.

Edited by minimole23 on 4th Apr, 2012.

Ive thrown over 8500rpm at power max pistons, worked rods and a worked crank.

20 thousand miles later the only thing to fail was one piston ring. everything is fine.

Surely the most economical route is to keep the 1380 bottom end - fit new larger cc pistons with a light hone. Sell the cylinder head and old pistons and fit new/secondhand head to suit??

Why do you need to sell everything? Are you trying to fit into a hill climbing class?

How can your bottom end get any better than a worked a+ crank and rods balanced? Unless you go forged?

If your not confident in the pistons you could sell them as well as the head and fit new ones?



Could you build a new short engine up to the spec you want for £1500 is the big question. Forged omegas are 450 odd?

Matt W

Would you take 1200 for your engine/ box? Have you got any photos of the build or receipts? Thanks Ben

The general consensus here is that I am under rating the engine I have. The short motor is a a Harris Motorport item so its certainly been put together properly. If I were to put the 16v head on it and pump 12psi into it then it should certainly deliver 160hp. I'll leave the rev limiter unaltered at 7700rpm who would be happy caning that round a circuit all day long?

I'm worried that at the end of the day the budget 73.5mm piston is being pushed massively out of its design criteria and failing big time taking the rest of the engine and importantly head with it. I do not want to start putting forged pistons in what is now a used block so I either use what I have or start again.

Edited by minimole23 on 4th Apr, 2012.

Right, here is the last thing I'm going to say on the subject.

We all know these k1100 heads can deal with plenty of boost on a relatively high compression ratio, so my question is simple. Do we think 10psi on a 10:1 compression ratio is too high? Matty seems to be running 25psi at 9:1 ish.

I will Dry deck the head and block and fit undercrown cooling jets. Then Deliver 10psi boost via a gt17 with decent intercooler.

Lets assume the engine will always be run on a v-power petrol.

Depends on ignition timing. You can run loads of boost, retard the timing to make it work and produce no (less) power.

Easily! If you think the standard metty engine ran 9.4:1 and 7psi of boost on a dizzy and carb. You'll have the advantage of mapped ignition, EFI, aluminium head with better chamber design, and an IC. I have mistakingly ran over 30psi before, but its quite comfortable at 25psi even on 95RON.

I'd say go for it! Isn't Johnk's SC setup is running 10:1 and 14psi.

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1/4mile in 13.2sec @ 111 terminal on 15psi

It all depends on cam timing and duration also how high a static CR you can get away with.

The higher the cam duration and closer to NA timing figures you can get away with running on a higher static CR with boost.

This engine would feature the LT cams.

Well I think thats the decision made.

Turbo this engine to around the 150hp level, and build up the short stroke bottom end at a later date.