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Discussion Starter #1
Hi im thinking of upgrading the power of my 156 v6.Im aware that the best for the money is to opt for the 3.0 engine.However i would like to know from you who have done such convertions yourselfs.What is the max bhp/hp you can go with a 156 without needing surgeries and keep breaking things every 10miles?I want to keep my current setup which is koni fsd+eibach,My 2.5 gearbox+q2 diff.I still want to keep the same everyday drivability form as the 2.5 without running hotter etc etc.So in other words what is the best bang for buck?and what is needed all in detail to built a 3.7 engine?thanks
 

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I thought the 3.7 conversion was only available to 3.2 motors. Realistically I don't think you're going to be able to flow enough air through the 2.5, you're adding 1.2litres capacity to the motor, so going to need a vast amount more fuel air, cams, heads the lot.

you would be better off slapping in a 3.0V6, which are widely available. a 3.0 I believe will run on a 2.5 map so nothing more needed really, although of course to get best out of it you will want to remap it.
 

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3.0 converversion ....... loads of info on here ....tuning section as well........... reports of better economy.....that be better torque of 3.0 and yes to get best out of it remap as fuel/ ignition curves are different
 

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A straight swap to a s/h 3.0 v6 is the cheapest option.

As for modding, you can go to 3.3L with the 2.5v6 crank, 3.5L with the 3.0v6 crank and 3.7/3.8 with the 3.2v6 crank.
 

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Discussion Starter #6
Mine is a 1999 so no traction control.But is it better to go 3.7 or 3.8 than a 3.0 or a 3.2?or you need much more work?
 
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It's been VERY clearly posted by DavidC. You need the 3.2 V6 crank, which is nearly impossible to find in good condition, to be able to go to 3.75.
 

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3750cc is going to cost you about 7 grand or more on top of what buying & fitting a used 3.2 engine would cost you as you would need to buy a 3.2 engine to start with if you wanted a 3.7/3.8 (or a 3.0 block & 3.2 crank, but try finding just a good used crank, new ones are no longer available)

What work are you capable of doing on the car yourself? As this is what is going to determine what route you should possibly take with the car.

As yours is a '99 manual then you have the CF2 exhaust manifolds, in terms of the exhaust equal length front pipes give a good boost to torque at low rpms, and a decat will help give more power. You could get more air in via forced induction (turbo or supercharger) rather than going for a bigger engine. But I can understand the appeal of a bigger engine, as it keeps the same characteristics.

Here is my old 3 litre converted 156, with Q2 diff, GTA wheels, Ferrari 360 front brake calipers, Unicorse exhaust, equal length front pipes etc

156 3.0 V6 - YouTube
 

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Discussion Starter #9
i can put the engine in and out myself but for machining etc they have to be taken to an engineering shop.So in other words is it better to settle for a 3.0 or 3.2 instead of bigger as its not that much worth going further for just an other 70bhp at most?and if so what is the best bang for buck engine to have between a 3.0 and 3.2?,i was thinking about having my car fast as a stock mitsubishi evo in straight line.
 

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220bhp vs 250bhp. The extra 30bhp is partially because of the cams, partially the extra 200cc, yuo can fit GTA cams to the 3.0 which will get you somewhere between 230 and 240bhp :)
 
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i can put the engine in and out myself but for machining etc they have to be taken to an engineering shop.So in other words is it better to settle for a 3.0 or 3.2 instead of bigger as its not that much worth going further for just an other 70bhp at most?and if so what is the best bang for buck engine to have between a 3.0 and 3.2?,i was thinking about having my car fast as a stock mitsubishi evo in straight line.
There is no such thing as a stock Mitsubishi Evo ;) And even if there was, you'd need more than 250 HP to be as fast as it in a straight line, with FWD.
But if that is your goal, then why not buy the stock Mitsu Evo (assuming you can find one that is still stock) or a Subaru STI ?
 

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Discussion Starter #12
So the best of the best is the 3.0 engine?even better than the 3.2 for the money+parts availabilty?but what about low down torque as i heard that gta cams reduce torque on 3.0.So in other words the 3.0 or 3.2 are better than any 3.7 or 3.8 as for the extra money you spend you will gain minimal improvement?i dont think that a well set gta will be that much slower than an evo.
 

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Best bang for buck is a s/h 3.0
Massive improvement over the 2.5 (the 2.5 has a VERY poor torque curve below 5000rpm).
As I said earlier, you can go to 3.5L with the 3.0 crank, but it is a lot of work (you could probably buy an Evo for what it will cost!).

As for comparison with an Evo, as said above, very few if any "std" Evos around and even then you obviously won't have the traction from a standing start.
 

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A good 3.2 engine is worth at least a few 3.0 engines, purely down to rarity. Depending on mileage and condition you could pick up a 3.0 for £400-£800, but a 3.2 engine is gonna be 2 grand plus at most places that will sell you one, not many people have them.
 

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Discussion Starter #15
Ok then i have understood the matter,the 3.0 engine is more better than a 2.5 than how much a 3.2 is better than a 3.0,and for the money to buy a 3.2 you will get about 4 3.0 engines.but if i were to get a 3.2 engine at a bargain price would it be better than the 3.0?i know there's isnt much difference in terms of power but how about fitting as i think a 3.2 is more work than a 3.0.Mine is a cf2 one.
 

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Yeah, if you can find a 3.2 for cheap, then I'd definitely say snap it up, they are better than the 3.0.

If you bought a 3.0 CF2 engine it is a straight swap. But after 2001 the 3.0 became CF3, which means there is a few more things to swap over (p/s pump, fuel rails etc).

All 3.2 engines are CF3.
 

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Discussion Starter #17
Yes i understand the differences betweeen cf2 and cf3 engines.But how about engine managment will a cf2 2.5 ecu+managment work spot on(Fuel,timing etc) on a 3.2 engine like a 3.0 cf2 or its more work?
 
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2.5 CF2 to 3.0 CF2 they are a straight swap Your 2.5 ECU will work but needs re-mapping the 3.0 engine loom is required and used IIRC

No matter what you do to it, it will never beat an EVO off the line, but with 220bhp as standard you will blow the crap out of an "standard" evo or an STI mid and upper range (70mph onwards)That's if you can get anywhere near in the first place,but thats where they are the weakest and the V6 is the strongest:lol:

If it was my money get a CF2 3.0 and supercharge it, a hell of a lot cheaper than completly re-building up to 3.5 spec onwards and probably a hell of a lot more bang for your buck.
 

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Use 2.5 MAF, 2.5 ECU, 2.5 exhaust manifolds, lambda sensors etc

Use 3.0 fuel injectors, 3.0 chrome runners & base plates.

It will run fine without a remap but you can get more power out of it with a good remap. But there isn't many places that can map a CF2 ecu as it can't be done through the OBD.
 

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I've owned 3.0 and 3.2, as many have from here. my experience the extra money the 3.2s command are not worth the difference as an engine block. if you bought a GTA outright then the difference becomes night and day as its the complete package.

just buy a 3.0 lump and plop it in.
 
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