Mitsubishi 4.5L DOHC V8 in a Mitsubishi Legnum AWD Manual turbo

Mitsubishi Legnum vr4 awd V8 conversion

Current car

I drive a 1998 Mitsubishi Legnum VR4, it’s been a really reliable car and I’ve slowly modified it to be a relatively powerful street car. Below you’ll see some photos of the car when I first bought it, it already had some impressive bolt on modifications and some rather (in my opinion) disgusting rims.

A Legnum is an AWD 2.5L V6 twin turbo (6A13tt) JDM Wagon. It weighs around 1550kgs. The running gear is similar to an Evo 6 so there’s some differential and gearbox options from Evo’s that transfer over.

It currently sits at 196kw atw on a dyno tune by Steve at Transformance Mechanical Engineering (TME) Springwood.

Current modifications include- no engine internal work.

Walbro 255 Fuel pump, 3 port solenoid, full hard pipe kit from Custom Pipeworx, HDI GT2 Intercooler, upgraded fuel rail loop, Meek front pipes, 3” exhaust, TME HD Clutch kit, TME braided clutch line, Golpher Alloy radiator, Upgraded coil on plug kit.

Evo 9 Brembo brake upgrade with braided lines and Evo 8 Master Cylinder, DBA slotted and Dimpled rotors and Project MU NS400 street pads, Evo 1-4 Rear Mechanical LSD with Weir Performance Clutch kit upgrade, M Factory Helical front LSD.

XYZ height and Dampener adjustable coilovers, Selby rear and front adjustable swaybars

Interior- Evo 7 Recaro seats on Bride rails, Prosport digital boost, water temp and oil temp gauges in a custom cluster. Evo 6 Momo steering wheel.

Exterior- Super VR4 Legnum rear wing, Dolphin Front bumper and a Vestatec front grille, HID Projector lights, 5zigen 17x 8.5” Pro Racer Gn+ Wheels with R17 235 45 Bridgestone Potenza RE003 Tyres. Ganador side mirrors.

The mitsubishi v8

Why this engine??

Now I’m well aware that throwing an Evo motor into one of these will give me more power and be a lot easier to fit and even find parts and upgrades for, but as far as daily drivability, it’s just not what I want.

I want something unique and different. So, I went searching- I found snippets of discussion on Evo, FTO, 3000gt, VR4, Magna and even Pajero forums regarding Mitsubishi’s only V8 ever made, known as the 8A80, almost all the threads are old, and most of the information is guesses and assumptions.

The 8A80 engine was released in 1999 in the Mitsubishi Proudia, A VIP style saloon also released as a Limousine known as The Dignity, it also sported a 3.0L V6 6G74 engine option. Due to financial challenges at Mitsubishi the car only sold approximately 2000 units in Japan over a 15-month period and then ceased production. The emperor of Japan’s son is known to get around in a Dignity.

The 8A80 is a 4.5L V8 GDI motor with DOHC it has forged rods and crank (possibly pistons) a compression ratio of 10.7:1. It is only 10kgs heavier than a 6G74, weighing in at 230kgs approximately, this is due to having an Alloy block and heads. The engine is a transverse engine with a bore of 86mm and a stroke of 96.8mm. it uses 2mm dry iron liners and five 4 bolt main bearings. This engine isn’t ideal for a few reasons- The GDI system makes tuning a lot more difficult, and has a long stroke and high compression which isn’t ideal for high rpm and boost, but there’s ways around this.

However! The engine was made by Mitsubishi in conjunction with Hyundai known as The Global Engine Manufacturing Alliance (GEMA). The car was sold in the Hyundai Equus VS450 in Korea with the V8 known as a G8AA 4.5D by Hyundai from 2000-2002. In 2002 due to difficulties with the quality of available fuel in Korea the engines heads were adjusted to accommodate a Multi-Point Injection (MPI) set up. This is the same fuel injection type as on the current V6 engine in my car (and most petrol turbo cars) and is a lot easier to tune. The engine code changed to a G8AB with the upgrade.

The measurements I can find regarding the engine compared to mine are as follows-

Engine

Length

Width

Height

6A13TT

560mm

800mm

650mm

G8AB

611mm

846mm

741mm

Looking at my engine bay and where things fit, I can see the engine fitting in place of the V6 with hopefully minimal modifications needed. Realistically any more measurements or queries I have regarding the engine will have to be answered upon inspection on arrival of the engine from Korea.

So I’m at the point I know what engine I want, now comes the tough part of sourcing it!

Sourcing an engine

If the engine I wanted to import was found in Japan I would have had multiple options for importing a front cut into the country using companies such as Import monster, ICHIban Imports or Just Jap Imports to name a few.

However, importing an engine from Korea isn’t as easy, Korean cars are left hand drive so the import market isn’t very big and due to the fuel quality and condition of a lot of the cars it isn’t worth it. I found a few companies who gave me some quotes which were reasonable, but only for the engine. Then I found one amazing individual called Jason from a small company called KC Trade Korea who, although having difficulties with translating messages was able to give me some solid and reasonable quotes for a front cut, shipping and full-service kits for the engine (which I’d like to install myself and ensure the engine is in good running order before it’s pushed). I plan to source common second-hand parts to be sent over with the front cut as well such as- alternator, starter motor, Ignition Failure System (IFS) etc, to ensure I have some spares to rebuild if anything went wrong with the parts on the motor. Jason has been happy to research parts, give me quotes and package all these in the half cut to save me on postage.

I am about to order the engine and it should be here by October.

Engine Fitment

The biggest challenges will include clearance on the firewall and radiator and clearance on the chassis rail for accessories belts and pulleys.

I have spent the last 3 years parting out or buying and selling VR4 Legnums and Galants. I’ve owned a total of ten of them usually selling all the parts and making a nice profit. Due to this, I have access to a spare gearbox and car shell to use for fitment and adaptation. The V8 will be fitted in the spare shell and any custom work completed. The plan was to then put it in my car, however, I’ve found a newer nicer car shell that I will now build the motor in and transfer good running gear into from my car.

The Alternator on the 6A13TT is located at the rear drivers’ side of the engine and is very close to the chassis rail. To anyone looking at measurement comparisons most have written off this engine as an option. Luckily, the V8 having a 90° V has opted to sit the alternator in the V instead of under the rear rocker cover. Making this not a problem for clearance. All the other accessory pulleys on the 6A13TT have around 100mm+ clearance on the chassis rail. I foresee the strut tower being pretty close to the Alternator. However, the V8 runs a single serpentine accessories belt, unlike the 6A13tt which runs two, this could possibly give me an extra 20mm to work with. The other option could be relocating the alternator with a custom bracket. The height of the engine may be a problem, however my current bonnet has given me a fair bit of extra clearance and spacing this out higher could be an option as well.

Engine mounts- Luckily the Legnum gearbox holds 3 of the 4 engine mounts and the 4th engine mount is in a very similar spot on the V8 to the standard V6’s drivers side mount. So one relatively easy custom mount and the V8 should sit in the same spot quite easily.

Other challenges may include- power steering lines, A/C lines and coolant lines, however these should be relatively easy to adapt to fit.

Gearbox Fitment

My plan is to keep the car as a manual AWD car.

I ordered the plate that goes between the engine and gearbox from the V8 to give me a good idea of the size of the engine and gearbox. As suspected the gearbox is completely different to any other Mitsubishi gearbox’s bellhousing, although runs a variation of the same Auto gearbox internals that an automatic Legnum comes with.

My plan is to use a spare Legnum gearbox I have, machine 10-20mm off the bolt surface and have a custom-made adaptor plate welded onto the bellhousing, due to the extra width and different location of the starter motor, further modifications may be required, or machine the bellhousing from the gearbox side on the V8’s gearbox and leave 20mm and then knock 20mm off the face of the legnum gearbox and weld in place. Seam weld inside and out, and possibly strengthen with some extra sections welded on the outside. Upgrade bolts if necessary to ensure strength to handle the power through the bellhousing.

The transfer case may be another challenge as far as fitting it behind the engine, however from the pictures I have, I’m hopeful the space is there for it to sit. If this ends up a big challenge I have the option to look at other Mitsubishi transfers/gearboxes. The rear exhaust manifold may be an issue, however I plan on modifying this anyway as it has a rather large catalytic converter built into it, which I plan on moving into the exhaust.

Engine management, tuning, turbo or N/a?

There is some popular aftermarket ECU systems that I’d be really interested in exploring as this will be a really unique build specifically Haltech ECU management systems has been recommended to me as a great option for running the engine.

The obvious choice moving forward is a big single turbo, after discussions with Ben Neal from ICHIban Imports (you may know of his V8 single Turbo Nissan Stagea Build), he suggested using a GTW3884R Garrett Turbo. This would involve custom made oil and coolant lines an aftermarket ECU, log manifolds, wastegate, exhaust, and a mounting point for the turbo. These are just a few of the things that would be required and possibly engine internals such as head studs or upgraded valve springs, cams etc.

The other option would be to initially copy the Cams in it for a later turbo build, regrind cams and port the heads and some nice extractors to give better flow and run a nice N/A build. This would save a lot of work on designing a lot of the turbo set up side of things as I could always look at this later down the track.

Personally, I’m excited to see what this engine is capable of in both an N/A and Turbo set up. So I’m feeling like this will be the way I’ll run it initially.

THANKS GO TO

Legnum Brother’s INC

Steve Hunt at Transformance Mechanical Engineering

Daniel Trotman at Custom Pipeworx

Jason at KC Trade Korea

Ben Neal at Ichiban Imports

Reference List

http://www.sae.org/automag/globalview_03-00/04.htm

http://www.mitsubishi-motors.com/en/corporate/pressrelease/corporate/detail771.html

http://www.mitsubishi-motors.com/en/corporate/pressrelease/products/detail522.html

The above post is from mid 2017.

I've since imported a front cut from Korea and pulled the motor, wiring etc out of it!

I've striped the motor down and am up to looking for internals for it.

I've also changed my plans for quite a few things on the motor and car.

However the main things have stayed- Turbo, Manual, AWD. has all stayed.

The accessories have changed- I'm planning on going LS1 Alt, A/C and starter motor just to keep things the same and I have an electric Astra power steering pump to take that off the belts.

The intake manifold is rotate-able! so the throttle body will be down in the front corner and piping can go straight through to the intercooler and to the turbo. so a nice short flow. but the main thing is it cleans up the other side for the turbo to sit happily!

attached is another photo of the motor in the legnum.

Definitely an ambitious build. Can you still get parts for it? Sounds like used is the only option?

hey man, that Mitsubishi is looking proper. id swap out that walbro for a Bosch 044. I've seen those like to heat up and drop flow. turbo that all the way... a large frame turbo on the v8 would save the gear box. instant torque would shred teeth on the gears. ever hear of VeMS? its a great standalone management, with tons of support.

cheers,

Brendon

Hey Raymond,

I actually got everything I need as far as Hyundai goes with a full timing belt kit, new water pump, new oil pump, all new gaskets.

they even had a brand new set of rocker covers for it for $70AUD each. I got all new valves for it from Hyundai as well as they were only $4.5 each AUD.

i just need to find some forged pistons and rods that’ll fit- although it’s looking more like custom ones for it.

Also working with ARP to make up a main stud and head stud kit.

I have all new everything else you could dream of from Hyundai. I’m been impressed with the quality of the stuff tbh.

Hey Brendon,

I was looking into a Bosch 044 actually! Glad I’m going down the right track! :)

I’m looking to build a gearbox, going triple synchro Evo 8 1st and 2nd, reweld the 3rd gear, billet diff tube. But I agree I should be careful with how much load I put on it.

I haven’t heard of VeMS I was thinking a Haltech tbh. What would be the advantages of VeMS?

cheers

Lindsay

Currently moving house and about to start a new job. So movement on the V8 is at a pause for now. Will resume once I have my shed all set up again.

Have had a chat to ECU Masters about their EMU black ECU as well and they’re very keen to help me out with a discounted ECU to run the set up.

Have some quotes for pistons and rods.

I might wait till I get a home loan in the next 12 months and go all out on stuff for the build with a slightly bigger home loan though. Otherwise I’ll be slowly chipping away instead of doing it all in one go. Would prefer to not have components sitting around for months or years at a time I think.

I did give the heads a clean up myself and was very impressed with how they cleaned up!

Cool project