Can I toss my 2pence worth into this discussion
1) My Triumph 2500 (sedan) racer, now with 192bhp @ rear wheels is still
running stock (std bore) triumph/hepolite pistons. The latest hepolite
pistons have drilled holes in behind the oil rings rather than slots,
and this stops the piston crown flying off as they used to when Kastner,
Vizard etal wrote about stock pistons. I've lost the crown on road car
pistons after high mileage. Forged ones undoubtedly better, but quality
cast ones are OK
2) My racer is running 10.75:1 compression on pump unleaded petrol,
about 92 octane. I acheived this solely by head shaving (+ adjusting
rockers etc).
I'm about to add water injection and an oil spray under the piston and
increase compression further. If someone wants to alter the pistons go
for it, but an overall dome is not the answer. A better piston will
alter the squish and push the charge towards the plug, ie the "dome"
needs to be biassed. Radical combustion chamber mods try to achieve this
by welding up the chamber and re-milling it.
3) head numbers. I'll find my database and post it later this week. it
covers all non US cars (ie proper 2500's with injection!!)
Terry O'Beirne
2500 racer
TR5
38 Dolly
34 Gloria racer
2500S
2.5PI Estate
etc etc
***** English Spare Parts *****
You neeed ESP!
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