crank work would cost in the vicinity of 800-1200AUD for the modes on the original crank, It would need to be done to any modern or lightweight motor in which you aim for that magic 1188cc figure. The saving will be made by modding the crank to take off the shelve motorbike fracture split forged rods and forged pistons with some of the valve recess peaks removed to lower compression which would be helped with cheap custom copper gasket. (I mean cheap as a Nismo unit is around 130-150aud anyway which is the cost of a custom 1.5-2.5 mm copper gasket.)

The crank modifications is where the savings can be made by adapting off the shelve parts but needs careful calculations.
I would seriously consider the 78mm bores for best rod stroke ratio.

The exhaust side wouldnt matter as a turbo only has a single 2 inch or 2.5 inch outlet pipe.

sikyne - I don't think that you would need to do the offset thing on the gsxr engine install. They do on the Legend because the car is only 4 feet wide. I bet that you could package the engine in the engine bay and maybe just have to run the driveshaft on a bit of an angle but probably install the engine pretty close to the center.

The crank mod might not be that expensive.
If it only has to be destroked 3 to 5mm you could just offset grind the crank and run a smaller rod journal. (no welding)
I dont know the deck height of those late nissan engines but you might be able to get away with using a bike rod. saving a heap of coin.

I`m destroking an A12 crank from 70mm to 64.5 mm and using GSXr1300 bearings in custom rods. This is as much as we could destroke without building up the crank with weld.
Im using a 76mm bore.

lightweight motor... toyota 1uz 4L V8... all alloy lol.

havent read the thread, just posting that..

Racinaround, You might be right, if you could move to engine to the left enough. this would help offset the drivers weight a bit aswell (RH drive in Aus).

The FJ1200 gearset in the 450kg`s Legend seem to be strong enough. I wonder if the GSXR gearset/case would be in a 700kg Datto?

Bike motors are friggin expensive, I like the idea of your motor sykine as you only use the head and the block remains cheap once you get it all going.
A transfer box could also be used to offset some of the motors available.

As for the Hr15 a 78mm stroke down to 62mm will need welding hence the price but the rest is cheap, especially the 78mm pistons can be bought for Honda and many other sources.
I can get a set of rods for around 200AUD which is a set of split fracture forged items from various bikes with damaged engines.
Tell me you wouldnt want these 78mm pistons from Wiseco to go on your buildup!
wiseco 78mm forgies

i have a mini that i am putting a b16a honda vtec into, but in england they use the gsxr 1300 motor and gearbox alot for racing. i have read that they have trouble with the gearbox and drive train as its only built for pulling 200kg.... not 700-800kg.i have actually seen a mini running 2 seperat R1 engines. one in front and 1 in back !!!!!!...... just my 2 cents.

The whole issue with bike motors having troubles pulling 600kg car's is rubbish. A two up hayabusa is going to easily weigh 400kg (bike alone weighs 250kg).

Then you have to realise in a car application they are geared down hugely compared the the motorbike. Hayabusa's are geared to do 160kmph in 1st or something stupid. In a car application you'd gear it to do 200 max.

Double the weight, half the final drive ratio = engine under same load.

D those pistons are PORN. Are the Off the shelf wiseco motorbike pistons?
How would the Bike pistons handle with boost?

Ok I did some number crunching.
Standard bore and stroke for a cr12 is 71mm bore 78 stroke.
If you could over bore it to 73mm and offset grind the crank to 71mm stroke, this would give you the magical 1188.65cc
I'd assume you'd have to build up the journals with weld to offset grind it that far.


OK just theorising now, let me no what you reckon.
I would assume that the motorbike pistons wouldn't like stupid boost levels, like say 20+psi probably required to make 300whp out of 1200cc so......

here is what i reckon
cr12 overbored to 73 destroked it to 71, run as long a rod as possible with motorbike style forged piston (maybe there is a factory bike piston/rod combo that could be used)
I'd look at running 10:1 with lower boost say 15 psi on race gas. (i would assume most of the turbo boys with 8.5:1 would be running 20+ psi)
This would hopefully give a motor with a nice rod/stroke ratio that could rev high enough to make the power with a big turbo and the higher compression could make up torque especailly off boost hopefully making the little motor more drivable off boost.
CR's also have CVTC which is a completely variable version of VTC so instead of changing at a set rpm like VTC it changes by up to 32 deg over the rev range. So with a decent ECU to control that you could also make up more torque down low and off boost as well.
I think the biggest problem to over come with a small motor would be off boost drivability because the bigger turbo motors would make huge low down torque in comparison.