amirpc

Hey while we're asking questions like this:

What does it take to get a 2.5L to a 2.8L?

Lorax

Either a 3.0l crank and aftermarket rods or an overbore with custom pistons.

amirpc

Know where I can read more about this? Search is broken and clarks doesn't have anything that I can find.

Lorax

What do you want to know?

RolexNJ

Tim, you are dead on the money with that one.


Well now, since you clarified your usage you have many options. You should do a search on someone called Special Tool and see what he did with a 2.5L. Actually, below is a link to when he made that 600+ RWHP, and he gives you his exact build as well. Good luck with the project.



https://rennlist.com/forums/944-turb...whp-951-a.html

amirpc

Really just looking as to whats involved in putting in a 3.0L crank...that increases the stroke right, so does that have anything else it needs besides the rods? I'm rebuilding my engine, I mean if its that simple I'd do it...but nothing is ever that simple!

Seems like thats a heck of a lot simpler than overboreing my cylinders, or am I mistaken here?

Lorax

The cost is about the same whether you go stroker/overbore. The piston pin height is different for the 3.0L as well.

Personally I would recommend going overbore because then you have the added benefit of strong steel cylinders. They are tougher and If you get some kind of damage to them, you can easily hone them.

amirpc

hmmm okay. Search is back on so I'm going to do a little research there. Thanks for the info though I now have enough to figure out the rest I think

tone3721

Sleeving our blocks is kinda controversial, in a way. Some say dont do it, some say do. For a DD, I personally wouldnt sleeve. Thats just my $.02 tho.

Lorax

People have been doing it successfully on all kinds of cars for decades, why wouldn't you?

You have more piston options, and they are very very strong.

tone3721

Thermodynamics.

Lorax

Care to be a bit more specific

If it's good enough for some of the toughest race motors, why isn't it good enough for a street car?

The two metals expand differently, but on the boost/power levels that a street car sees it's probably no big deal.

tone3721

You said it, the different metals expand, and contract at different rates. Some have told me it works, some say the alloy our block is made of doesnt take it so well. The cylinders walls in the 2.5 are also said to be "thin", and the block has a tendency to "twist". Most of the the engines prepared for track use, expect to be rebuilt often, as stated earlier in the thread. Street cars the opposite. If I ever find a good deal on a tub locally, and find some space to fit it, Ive been thinking about building a trackrat. If I did that id just bore one of my 2.5 blocks to hell and sleeve it. I expect to be constantly building a maxed race engine. Even easier to rebuild all the time with sleeves. Many piston options, and can change the sleeves out. Like I said its not something that everyone agrees on. I could see it being a possible issue with our Al alloys.

Lorax

It definitely works, and if It's done properly they are very tough. I had a dry sleeved 2.8 block for a while, unfortunately I never got to use it. I would gladly trust a properly sleeved block just as much as I would trust an alumisil bore.

tone3721

As you said yourself, its "probably no big deal" I tend to have problems with maybes, and probablies. Any degree of doubt is usually enough for me to go the safer route. I dont care for grey areas when it comes to my 951. Im also sure there are a few around who could build such a motor, and would last. Im not saying every time you sleeve it it will fail, just that theoretically it is possible. My philosophy is WWPD, what would porsche do?