Turbo head convertion
Turbo Mini Forums

got me a turbo head, its leaded. is it ok to have it converted as per normal heads or are there any special doo's or dont's? Also, by sticking it on my 1293, wha sort of comp ratio would that give me?

It should be fine to convert...

CR wise, you need to measure your chamber volume and then use

www.afracing.com/cr.xls

Alex

AlexF

what method do u use? the plastic over the bore and fill with fluid method?

/edit - just looking through some pics and it would seem i have hepolite 21251 +.20 pistons fitted not powermax's. the 21251's have a dish of 8.4cc and a comp ratio of 8.8:1 on a std head, so a 1293 with 8.4 of dish, an 8.8:1 CR on a turbo head (not sure yet what final CR that would give) would be a good start for a turbo setup?

Sorry to harp on about it but i'd just rather get it mostly right 1st time!

Edited by Mike on 29th Nov, 2004.

you need to consider lots of factors as well as piston and head volume... but you sound like your on target.

8:1 is about ideal

then again std was 9.4:1 but with low boost.

Its all about what you want vs what you can get!

alex

AlexF

true, i'm after something thats reliable and drivable not a 180bhp monster. infact i'll be well happy wilth 100-110 tbh

std engine... morspeed stage 3 head.... 8psi

120 bhp :)

Alex

AlexF

k'nell

std is 94... so thats only 26 more.... with a much better head and a turbo thats not unreasonable!

alex

AlexF

so what ARE the bloody differences between a std 940 and a turbo 940? can i 'convert' my lovely fresh 940 into a turbo compatible one?

coolant passages in the head itself and the exh valves are sodium filled.

you can use any head u like so long as the valves are good quality, but if you want to run more boost you need to drop the CR by grinding out the head (or changing the pistons!)

alex

AlexF

y the reason for asking is i have a head thats only just been reconned with new guides, converted to unleaded and 11 stud, and would like to use that. The valves however are the std ones, so if i change those to a better quality i can run std boost give or take a few psi. Not after huge boost.

Valves might be ok...

but the CR could be a problem... but you can get the chamber ground out for about 50 quid...

More boost on std cr isnt a good thing.

alex

AlexF