Hi All,

I have a 1998 GC8 Classic, and am considering putting in a 2.5 litre scooby engine.
Just wondering if any one (on here) has done it, does it fit, what pros & cons, what power and/or torque would be reasonable.
My car at the moment has a EJ20 re-bored to 2.2L, with front mount intercooler, bigger turbo (GReedy), Haltech ECU, pushes out 220kW (295 HP) at the wheels.
However, I have no boost as the turbo may be buggered, and the crank does not sound healthy due to not so recent oil leak from the oil cooler.

What are peoples thoughts please.

 

are you thinking of a whole engine and ancillaries or just the block?

drive by wire is your first issue

 

Probably put in the whole engine.
Do the EJ20 heads fit ?

Drive By Wire ????

 

classics had a cable drive accelerator, 2.5's are out of later models and have electronic throttle control

 

ok, drive by wire is the first issue, although not insurmountable.
Any other issues with putting a complete 2.5 litre engine into the GC8.
The engine bay at the moment is a little cramped, but I guess a 2.5 L engine is not that much bigger ???
Would be interested to know what other issues I *could* face.

You mention the block only option.
Do the EJ20 heads fit onto the 2.5 L block.

Maybe another EJ20 engine would be the way to go.
But then again I could just replace the crank as it already has forged pistons. Probably the *cheaper* option.

 

You can search on american forums the topic of "hybrid engine". It seems to be popular mod there. Basically you put ej205 heads on ej255/257 block (thanks to that all wires and ecu can stay stock). AFAIK there are 2 ways to make such hybrid:
- you machine heads to fit to 2.5 shortblock (which seems to be better option, but I don't know if you find anyone who can make it for you locally);
- you buy hybrid pistons which are manufacturede especially dor this setup.

 

the 2.5 block with 2.0 litre heads isn't uncommon. I've had that set up for a number of years, following ringland failure in my 03 blobeye wagon I replaced the short motor with a forged 2.5 block. There can be a small amount of blending done to the 2.0litre cylinder heads but it isn't much.
The important bit is speccing the 2.5 short motor to your power goals, that needs to be right as it's well known for it's weaknesses.
Trev
the 2.0 and 2.5 use the same block but the latter is bore for bigger displacement and there lies the weakness, thinner cylinder walls

 

I've got the 2.5 block, but FORGED, (VERY important), and 2.0 '98 heads. Boost is limited to 1.5bar by my mapper as I didn't bother with thicker studs, but DID go for a better gasket.


I then had a HSTD05 20g, Harvey trick up-pipe, FMIC, 740 injectors and have around 400+/400+

 

That's a lot of useful info from everyone, thank you all.

I did not know the 2.5 block was the same size as the 2.0 L, so there's no point taking mine to 2.5L if the cylinder wall becomes weak.
Looks like I have a lot of research to do.

Car goes to tuners late next week, so I will better know the reason for no boost, and the state of the crank.
Seem like google will be my friend for a while, LOL.

 

Guys with 2.5 hybrid, are you running on 5speed or 6speed?
Also did you machine heads or buy hybrid pistons?

 

Six speed is pretty much an absolute. I was told the extra torque from the 2.5, esp at higher powers to, would strip second gear out of my five speed. You also need the rear diff and drive shafts. (Cue others to come on and tell you different, but the two guys that told me are VERY well regarded.)



Pistons: buy forged to fit. DO NOT have the crank ground, fit race bearings, and forged rods if your budget stretches.

 

Mmmmmm. I've got the six speed, but not the rear diffs, or drive shafts
(Still 2.2 Litre at this stage)

 

I will be re fitting my 2.5 with 2.0 heads later this year but I need to choose some forged pistons to suit, up rated gaskets and studs (not thicker, ARP). The engine has been run without up rated pistons for 60k miles, on luck. Time to fix that.