38 replies to this topic

[sapper]

At some stage after my warranty runs out I'll be upgrading my stock MY08 2.5 I want to keep it naturally aspirated, but here's the catch. I want to see how close to 300bhp I can get... Ideas? (Money isn't a problem as this will be about 4 years down the track) Keep in mind that I know only very little about engines...

[Soop]

G'day matey. I really hate to burst your bubble but you simply wont ever get close to that target figure. They simply will not do it. You are far better off converting to a EZ30r if you wish to keep it Naturally aspirated. In standard form these 3.0ltr 6cylinder DOHC engines are making 150kw@w, or 180kw@fly wheel. This I believe is on par with the 2.0t GT. And if I remember correctly is the same power output the V3 STi made. To get an EJ25SOHC NA to make power will be very very hard. You'll sacrifice reliability in a big way, your fuel bill will go through the roof and the engine will have to idle at 4000rpm just so you don't stall as soon as you let the clutch out and you'll have a 500rpm power band. It just isn't feasible mate.

[alexGT]

ill save you some effort, sell the car now before it devalues anymore and just buy a 3.0r/rb.

[sapper]

G'day matey.
I really hate to burst your bubble but you simply wont ever get close to that target figure. They simply will not do it.
You are far better off converting to a EZ30r if you wish to keep it Naturally aspirated. In standard form these 3.0ltr 6cylinder DOHC engines are making 150kw@w, or 180kw@fly wheel. This I believe is on par with the 2.0t GT.
And if I remember correctly is the same power output the V3 STi made.

To get an EJ25SOHC NA to make power will be very very hard.
You'll sacrifice reliability in a big way, your fuel bill will go through the roof and the engine will have to idle at 4000rpm just so you don't stall as soon as you let the clutch out and you'll have a 500rpm power band.

It just isn't feasible mate.

Yeah I thought it might be that bad... talked to a lot of the guys at work (for some reason a lot of Aussie Army engineers love cars) they basically said my car would lose it's street-worthiness and just die on me all the time.

(EZ30r) Yeah Xon has been wearing me down on that front... he may eventually win I think.

ill save you some effort, sell the car now before it devalues anymore and just buy a 3.0r/rb.

Yeah um no... It will be cheaper to convert later on... besides, I'm a bit attached to my car...


Reference EZ30r conversion, does the engine require more bonnet space? And how difficult are we talking...
Also on that line, what sort of power could I get with an EZ30r if I did stick to naturally aspirated... could I eventually reach the 300bhp mark, (I don't understand the bhp:kw conversion). Or would I run into the same problems as the 2.5?

[Soop]

I can't speak on how difficult the conversion would be. But provided you get an engine with the loom and ECU, I can't see it being too difficult. I'm unsure how much power the standard EZ30r is capable of in standard form. Perhaps with some head work and a higher static compression ratio plus a re-tune, you may see 200kw@w. Eventually the engine will run into the same reliability/economy/legal issues as the 2.5, but so will any naturally aspirated engine. It is so purely because of the way a naturally aspirated engine operates. To give you an idea 240kw roughly equates to 300hp. Generally the more top end power a naturally aspirated engine makes the less bottom end torque they make. So having a hugely powerful engine may not be the best option. But having a good compromise between top end power and responsive torque is the key to having a quick street car. Perhaps contact Mav about his 3.0r Spec-B he may take you for a ride in it to give you an idea on how they function in a practical sense. Honestly, before worrying about an engine conversion, I'd be looking into the suspension and brakes. A lot can be gained by upgrading these components.

[sapper]

I can't speak on how difficult the conversion would be.
But provided you get an engine with the loom and ECU, I can't see it being too difficult.

I'm unsure how much power the standard EZ30r is capable of in standard form. Perhaps with some head work and a higher static compression ratio plus a re-tune, you may see 200kw@w.
Eventually the engine will run into the same reliability/economy/legal issues as the 2.5, but so will any naturally aspirated engine. It is so purely because of the way a naturally aspirated engine operates. To give you an idea 240kw roughly equates to 300hp. Generally the more top end power a naturally aspirated engine makes the less bottom end torque they make. So having a hugely powerful engine may not be the best option. But having a good compromise between top end power and responsive torque is the key to having a quick street car.
Perhaps contact Mav about his 3.0r Spec-B he may take you for a ride in it to give you an idea on how they function in a practical sense.

Honestly, before worrying about an engine conversion, I'd be looking into the suspension and brakes.
A lot can be gained by upgrading these components.

Cheers... I know about the problems with torque at lower revs... Yeah I would do brakes and suspension, but the thing is they're not that complicated, I'll probably end up being lazy and sending my car away to some mechanic with the new parts and engine block, dump money on him and go 'build'.
I just wanted to get an idea from the people who know and love Libs to clear some things up for me... thanks mate.

And you can guarantee I'll see Mav when I get back to Sydney (we grew up together)


Fact of the matter is I wanted to see how far my engine could get power before doing the aftermarket turbo thing... Although I still think I won't turbo... Can't stand em.

[Soop]

What can't you stand about turbo-chargers? I've found most people that say that have no idea what they're on about. Simple theory. There is no replacement for displacement when talking about powerful NA engines. If you want a big HP number than your going to need a big CC engine. If money is no object, look into sleeving and overboreing the Ez30 block, perhaps the conrods form the EZ36 (The rods allow for the extra stroke that increases the displacement by 600cc). You'll also need to looking into whether or not the engine is over or under square in standard form, I'd say under. But I don't know for sure. There are so many elements to it, it will take for ever to build a good reliable powerful NA motor. EZ30r + Big f*ck off turbo = Powerhouse.

[Richo]

Did this go anywhere ?

[Soop]

Yeah it did. The owner needs to have it tuned and its good to go AFAIK.

[alexGT]

Yeah um no... It will be cheaper to convert later on... besides, I'm a bit attached to my car...



and your basing this on????

there will be so much hassle in converting your own gen4 liberty into something else. why not just buy it like that in the first place. on top of that your resale is going to go up the shitter as its a completely pointless exercise when you can already buy a car thats ready to go!

i'd knuckle down and do some serious research before you go diving into this.

[Soop]

I agree with Alex. But in the end it makes little difference. I wouldn't worry to much about re-sale value. Its just a car and you'll never make money on it anyway. If you enjoy it that's all that matters.

[Blaeven]

perhaps the conrods form the EZ36 (The rods allow for the extra stroke that increases the displacement by 600cc).

*cough* bent conrods = **** *cough*

besides, i thought it was the fact that they attached offset from the centre that gave them extra stroke... so wouldn't he need ez36 pistons too...??

do they even make performance/higher compression pistons for the ez36...?

[Soop]

Your a f*ck whit Blaeven.

[sapper]

I just like Naturally aspirated engines. There is no why... I don't like Turbo's and Superchargers.

[Soop]

Okay. I'm not trying to sound like a prick here. But in your first post you said you " know only very little about engines... " and yet you have decided that you don't like any form of Forced induction. How can you come to such a decision with such limited knowledge? My suggestion is mate, that you do some research. Sit in on some conversations and find out how the whole concept works before coming to any conclusions as drastic as that. Again, I don't want to sound like an arse. But your current stance is somewhat naive mate.

[alexGT]

i've got a solution, buy a carrera/m5/lp640/430 etc etc. thats about the closest your going to get to 300hp+ because your NA 2.5 litre little subaru motor sure as hell wont do it without some forced induction!!!! leave it to the guys who've got it right as previously stated. /close thread.

[Soop]

Its hardly useless if Sapper learned something.

[93tzlegacy]

Your a f*ck whit Blaeven.

is this statement directed at the bent conrod theory? if so he is right........


now, if your deadset on converting your lib to h6 the best thing to do is buy a wrecker 3.0rb from auctions and swap it all over, then sell off everything you dont want from the wreck to partially subsidise your conversion.
failing that buy a late (read gen iv) h6 and swap that into yours. there is a guy in perth with very late model half cuts , but they aint cheap.