So ok, the bigger the overbored pistons you get, the thinner your cylinder walls become to accomodate them which is not good if you have alot of power. And from the research I have done, there are 5 sizes of pistons you can go with



Stock size

0.25mm Overbore

0.50mm Overbore

0.75mm Overbore

1.00mm Overbore



So, with that being said...what benefits are there to havin overbored pistons on an N/A engine? Anything Anything? Bueller Bueller?





Thanks guys!

 

moarrrr toruqe!!! it increases displacement

 

Overboring increases displacement, which should increase HP and torque nearly across the board. However, the head in stock form doesn't flow very well in N/A Applications. The V6 is better than the I4 when it comes to N/A mods, but both respond well to forced induction.



You can do it, but you'd probably only get about 15-25 WHP out of it max. The Stock head would be holding you back. (I'm assuming you've got the basic bolt on's of headers and exhaust work along with a an intake)



Throw in some bigger valves, bumpier cams(more lift and duration) and some porting/polishing and you could easily get 30-45WHP on top of your 14-20(on the V6, not the Beta I4). Then you'll need a piggy back to tune the engine with the new cams larger engine and increased displacement.



The problem is, that work is going to cost you 4-5 times what the overbore did. So you're looking at $2000-$4000 bucks for 40-60hp increase.



Spend $200(used)-$500(new) and get a Nitrous wet kit(say a 75 or 100 shot wet), same benefits, less cost, and doesn't affect your daily driveability.



Now, if you want to get into it to LEARN, Then go for it. But read as much as you can on engine building and tuning first. $200 spend on books (or free @ your local library) can save you literally THOUSANDS of dollars later (when you blow/break something expensive).

 

thats so real good advice^^ ive been planning on boring my cylinders .80 over essentially making my tib a 2.2l should be interesting im not sure if its been done before in the us

 

RPW out of Australia used to make stroker kits for the Beta engine. But they wanted a ton of cash for them so I don't think many if any were produced.



But a larger displacement motor with boost is always a nice way to go if you have the money to do it.

 

Keep in mind that, while overbore is a great idea, it is (like Random said) very costly for little gain. You need to calculate where you're getting the pistons and rings, both which will likely be a custom job. Now, for a ground-up build that's brilliant, but expect about 200-250/cyl for all the parts.



For instance:

In one of my project cars, the cost per cyl is about $175 per cyl for the 104mm piston.

The overbore custom piston from JE is 200-250 depending on coating or other options. And the block is sleeved so the job is relatively easy for a full blueprint.

The stock 3.0L crank is 3k and a custom crank from a reputable tool and dye joint is about the same.

In the end the cost of a custom bore/stroke is not much higher than that of the OEM variant.







In the beta one can grab a use short block for under $300. The cost to bore is WELL beyond even the cost of the block. The input will be far more than the end value, no matter what.

Boost or nawz and be happy with the results

 

And then, when you have a max-overbored engine and it comes time to rebuild . . . time to max-overbore another block, because installing new sleeves would be waaaaaay expensive on this engine

 

Whats the maximum overbore you have seen in beta engines?