DivineE

p.s. this thread is VERY interesting if you haven't seen it:

http://www.pistonheads.com/gassing/t...0litre%20turbo

fast951

It will make more sense to compare the cost of a complete engine rebuild 2.5L vs 3.0L (8V engines). The 3L adds the cost of the pistons, crank and block (either a 3L alusil block or a 2.5L sleeved to 3L specs). The difference between a 2.5L and a 3L bottom end alone is roughly $3-3.5K. Add to this the cost of a complete rebuild..

A 2.5L can run in stock form, while there is no such a thing as a stock 3L turbo (well there is the factory 968 Turbo). With either engine, to get more power you have to upgrade the turbo and the engine management, the cost difference between the two is not that great.

When rebuilding a engine, there are many options. Some are better than others, some less expensive than others.

Chris White

It all depends on how you look at it!
If you are going to build a ‘fancy’ 2.5 based engine (like a sleeved block with new pistons) then the extra cost to go to a 3.0 is just the cost of the crank and either a little block work for rod clearance or some aftermarket rods.
So when I am doing a MID sleeved engine the extra cost to go from 2.7 to 3.0 is usually under $1500…that’s not excessive.
But if you compare the cost of a 3.0 build vs a stock 2.5 then there is a lot of additional cost involved…

One piece of advice that I give out regularly is that if you want to build a trackable engine on a budget you are better of building a 2.5 based engine (like a 2.7 sleeved engine). If you came to me with a budget of say $10K I would rather put better parts into a 2.7 than go for more displacement and less ‘good’ parts. Sometimes its better to put the extra money into head work or turbo instead of displacement.

On the other hand….if we spec out a nice $10k build and then decide to add another $1.5k to make it a 3.0…well that starts to make sense too!

Bottom line – you have to consider the whole package when you are planning a build – not just individual details like which crank to use.

gt37vgt

I wish i had dry sleeved my 2.5 block out as there is no market here and it just sits there ..at least in the US you can sell the 2.5 stuff to offset the 3.0 bottom end parts and its this logic that makes me say again . some of the more expensive builds would have been better starting with a 2.7 or 3.0 car as less would be taken off as it is with a turbo ..

Chris White

There is some renewed interest in the 2.5 sleeved blocks over here due to the new PCA rules for GT class – is a displacement to weight type classification now. There is some life left in the 2.5 engines…!

333pg333

"That's the 2nd flattest afr line I've ever seen" - Maxwell Smart.

Chris White

its the actual AFR curve...but showing a '12' curve on a 650 axis dosen't give you much range..!

V2Rocket

is that an engine dyno or chassis dyno?

either way

333pg333

Yeah I figured the scale might have an effect on this optical illusion.

Chris White

Chassis dyno but calculated back to crank hp.

V2Rocket

whew!