G'day, I am in the process of building a little Hillclimb car and had the rather ambitious target of getting 1hp per kg for the final product.

After doing some measuring and research, I determined that I could squeeze a 6G7x Motor and Gearbox behind the rear seats of a Daihatsu Handivan.

I have purchased a donor Daihatsu that is pretty sound and weighs about 550kg.

I can probably remove close to 50kg through carpet and fold up rear seat removal, side and rear window replacement with lexan and replacing the front seats with lighter versions.

My question is whether I am better to go for a 3.0L 6G72 from a late 90's Magna, or use the bigger 3.5L engine.

Do all the 3.0L engines have the Forged Crank? Was there a certain date?

To get the power I was after (500ish hp) I would need to turbocharge the motor and there appears to be far more off the shelf parts (forged pistons etc) available for the 3.0L

I was going to rebuild the motor with a stock balanced bottom end, new Rods and Pistons and a MLS head gasket. I'd probably leave the cams stock, as mild NA cams are usually OK for turbo application.

Have people here turbocharged the 3.0 with any success?

Is the 3.0L the best option?

Also, I'm tossing up on choosing between finding a manual or an auto with the sports shift.

I have heard there is a certain running change in the transmission that made them more long lived, but I can't remember what it was. It was something small like a spring that often failed or similar.

Again, Is there a certain year to look out for?

Not sure if it will last long with the power, but the car is light which should reduce load up a bit and the auto may be a good choice for motorkhana's and the like, as finding reverse can be a bitch sometimes in a manual.

personally id say a turbocharged 6g72 3.0L dohc using pajero hardened crank, stock magna pistons an rods, thicker copper head gaskets and some dohc heads from either the mitsubishi 3000gt or im pretty sure the hyundai grandeur shares similar (but much cheaper) dohc heads. bam not too much torque for the weight but when you rev it she goes hard.

I assumed all the factory Pistons would be Cast? Cast are usually ok up until about 7-8psi, then you get the inevitable ring land issues.

I was going to throw in some forged Pistons from a 3000GT. You can get them quite cheap from the US and they drop the compression ratio without needing a thicker gasket.

I would probably stud the block at the same time.

How are Pajero cranks hardened compared to the Magna? Do you mean Forged?

Is the flow a lot better on the 3000gt heads?

I'd love some solid data before spending the money, because I'd rather stick to common parts.
In a Turbo application you can usually get away without the greatest in NA volumetric flow.

My other car is turbocharged and makes an easy 275whp out of 2L with only 2 valves per cylinder on LPG.

ive been told by a good source (a 3000gt owner and enthusiest) that he replaced 1 rod and piston on his 3000gt engine using a standard 2nd hand magna rod and piston.
and yes id say the pajero crank is forged.
and im unsure if the 3000gt heads flow better i havnt had a set in my hands yet but i do have some grandeur dohc heads and just going from photos theyre very similar.
and yeah depending on compression ratio most magna motors will take 6-7 psi without breaking immedietly