i read lots of posts regarding compression and lowering compression, often the information is conflicting. i want to know the resons for lowering compression. if i was to have an engine rebuilt to handle 380 bhp with a t34/63 and siemens 55lb injectors, BD14 inlet and standard ex cam would i need to lower my compression, some say its for mapping the ignition and its easier with lowered compression. some say its fine and some say lower t, why is this? i dont profess to be fully conversant with engine building, but i just would like to know

many thanks

 

Pretty sure you need work done to the pistons to use a BD14. You'd need either valve cutouts or skimmed standard pistons to lower their height. My car ran skimmed low comp pistons for years with a BD14 no problem. When i rebuilt it last year i got valve cuts done just to be sure

I'm running the exact spec you are plannig to as well (just needs a live map to finish!)

 

Hi Paul, I understand the valve cut out but why do some tuners prefer standard compression and some want to lower it?

 

I think its down to every one having the own ways and opinions. Although i havent heard many people wanting to lower compresion for that power.
I have just had a similar spec built except a gt30 and the tuner wanted to up the comp.