engine dynamics?

[MattL]

Hi All,

My engine went bang last week almost 100% sure it’s the bottom end. It runs but sounds like a bag of spanners. Me and my Mate took the engine out yesterday, I have decided to get forged pistons and conrods, I think the best bore size and comp ratio would be 84mm and 12.5:1.

Where do u think would be the best place to take it? Somewhere in the south would be best.

I got a quote from engine dynamics, they seem like a good company anyone had much experience with them? I think they use to be called bbpt.

Thanks very much

[16v_paddy]

Have a word with Dan here http://www.519automotive.co.uk/, he'll get you sorted properly

[robi1000]

84mm overbore is a little bit too much. It's right on the edge of what this block can take. If possible go with 83.00 or if damage is too severe 83.50mm. Also 12.5:1 CR pistons are a bit OTT without really wild cams with lots of overlap. With actual 12.5:1 CR and mild cams you will be losing potential power (if using pump gas), because of possible detonations mapping will be very conservative.

[robi1000]

grr no edit button...

You should use 11.2:1.

For example engineer from Catcams told me that 5502225 cams were calculated to work best with 11.2:1 pistons. If your cams are milder don't bother with 12:1, if wilder, then maybe.

[sideways danny]

84mm overbore is a little bit too much. It's right on the edge of what this block can take. If possible go with 83.00 or if damage is too severe 83.50mm. Also 12.5:1 CR pistons are a bit OTT without really wild cams with lots of overlap. With actual 12.5:1 CR and mild cams you will be losing potential power (if using pump gas), because of possible detonations mapping will be very conservative.

I've already recommended an 83mm bore and not going too high with the compression as he wants standard ecu for now, and running piper 270's

[Laine_16v]

Nout wrong with 84mm. No replacement for displacement!

[robi1000]

Ha ha, it's true that there's no replacement for displacement, but it's also true that when something goes wrong in the bores of such engine, there's no replacement either. Performance gain would be minimal and not worth it (IMHO). But at the end of the day, do what you want it's your engine.