Mazda g6 engine info

OK, so I'm about to embark on playing around with a 2.6l g6 engine. But here's the thing, info on these engines is not exactly easy to come by. Accurate Info is even harder to find.

Basically I'm trying to sort the wheat from the chaff here so I can get a better understanding of the engine and its capabilities.

I'm looking at boosing the engine, and want to make sure that I'm giving it a decent chance at a fair service life. If I can't do that then I may need to go back to the drawing board. But given that the b2600i this engine currently lives in owes me about $300, im pretty keen to try and follow the path less traveled.

I'm looking for as much actual factual information on this engine as I can get my hands on.

Given their limited use, I get the feeling I'm going to struggle to find out much.

Here's some of the basics

Displacement, cc 2605

Engine model G6

Max.power (Net), kw(PS)/rpm 120 ps (88.26 kw) / 4500 rpm Max.torque(Net), Nm(kgm)/rpm 20.6 kgm (202.02 Nm) / 3500 rpm

Power density 14.67

Engine type 4 cylinder OHC12 valve water cooled

Turbocharger No

Fuel type Unleaded regular gasoline

Compression ratio 8.4

Bore, mm 92

Stroke, mm 98

Couple of quick myths to bust.

Myth 1: g6 is just a Mitsubishi 4g52/54 with a 12 valve head.

Fact: no, about the only thing the g6 shares in common with the mitsu engine is its capacity and use of balance shafts. The 4g54 has a smaller bore, same stroke but different head gasket design and deck profile.

Myth 2: g6 engines are directly related to the Mazda f engines.

Fact: the g6 shares very little with these engines other than the number of cylinders and the manufacturer. Of course they're going to have similarities to other engines made by the same manufacturer. But part interchangeability is basically non existent. The head is longer and wider than the f family of engines, the manifolds don't line up. The g6 uses timing chains vs the f series using belts.

Myth 3: g6 engines are total junk.

Fact: ? Yet to be confirmed or busted. Low factory compression ratio coupled with an engine management system that is prone to failure may have a lot to do with the hate for this engine. Ecu's are a Mitsubishi item which has a couple of capacitors that are prone to failure. When this happens, they leak a corrosive liquid onto the ECU circut board which often results in a gradual failure. Misfiring and poor fuel economy can both be early onset symptoms of failure

Myth 4: the factory Mazda heads were of poor casting quality and are prone to cracking.

Fact: ??? Whilst these engines have got a bad name for head failure, im left wondering how much is from poor head casting and how much is due to poor maintenance. Allegedly there are after market heads available with extra material in trouble areas, but am yet to see any conformation of this and who supplies them.

OK, myths aside, let's talk balance shafts. It's very common for mitsi guys to delete balance shafts. Whilst ive struggled to find evidence of balance shaft failure due to pounding on the engine, I have found plenty of stories of failure due to belts breaking (is this maintenance related? Or just a design that can't hold up when pressed to its limits). Is balance shaft removal worth while, or should well enough be left alone? It'll be a daily driven engine so I'm leaning towards leaving what skilled engineers deemed important in place.

Boost!? given the really poor factory CR and beefy internals, a moderate amount of boost shouldn't trouble these engines to much? And should help fix some of its short comings (namely being a bit of a slug and thirsty). Provided the head is up to task, is there anything wrong with this line of thinking. Aftermarket management is a given.

Definitely forging new ground- I'll give you that. I will support your concluding statement by adding that this is a good vintage for Mazda engines and boost. The B and F engines of the same era take boost well and have higher compression. The B has much smaller rods- the F is likely similar, or smaller than the G. I ran 15psi for nearly 5k miles on my FE-dohc and it is about to be recommissioned for more fun. As with any diy boost project tread gradually and carefully.

In reply to FE3tMX5:

Thanks mate. Though I'm not the first to tread this path, there are others out there, they're just not easy to find and getting info is harder still.

I've seen a few of the g6 engines with massive miles on them, so it gives me some confidence that they aren't totally appalling and that perhaps alot of the trash talk about them stems from poor maintenance. Being a truck engine and knowing how beat on and neglected trucks can be only adds credence to that train of thought.

Given some of the similarities to the 2600 astron(4g54), in hoping some of the DSM guys have a bit of insight as to what works and what doesn't when it comes to large capacity 4 cyls. Also wouldn't mind finding a Mazda tech from the 90s who worked with these first hand.

Just think of it as a stroker F2T. I don't see any reason why it wouldn't be reliable at 300whp. The rods are huge just like the F motors. Pistons don't show any signs of being weaker than F2T. Head is just as crappy as the F2T.

I'd throw an HX35 at it, ask questions later.

In reply to Swank Force One:

Hx35 is your answer to everything hahaha. And im all for it if you want to help me find one and get it to Australia. Unfortunately they aren't as common here.

I have heard about a few g6-t setups running pretty reliably in the 300-400hp range, but trying to find the info into how it was achieved, driveability, reliability etc has been border line impossible.

There was a guy in Australia with a g6-t running about 460hp but he'd done quite a bit of work, oringed head, custom pistons and rods etc. But again, the info is sketchy at best.

I figure the more I can learn up front, the less chance I have of screwing it up and putting my daily off the road for any prolonged period of time

How much are you really looking for? This motor should have the same limits an f2t should have. Chuck some arp head studs at it and start slow.

In reply to Swank Force One:

I don't really have a set goal power wise. I want to make it drivable and reliable. 250-350 should be a cake walk, but can I do it consistently and reliably is my issue.

It's a truck, massive power will just be stupid to try and control, as will boost that comes on like a sledge hammer. I still want to be able to chuck a load of whatever in the back, I still want to be able to tow a trailer... Basically I still want it to be able to be used for its intended purpose, just with more power and fun factor.