7 replies to this topic

[hcmini1989]

hi there i recently bought a 1293 mini turbo havnt been to collect it yet was just wondering about the bulkhead mods ive seen the bulkhead box on ebay think its about £20 problem is do i have to move the heater or is there enough clearence and does any one know what bhp to expect fro my engine it is a 1293 with avonbar pistons and a phase 2 cam its running a standard turbo and has had the combustian chambers de beaked by 28cc would this take it up to a 1330 im nt sure can anybody help me

[Checkmate]

yep you will have to move the heater... im not sure about the bhp though

[Sam Walters]

nope its still a 1293. the dish in the pistons and the combustion chamber size have nothing to do with the capacity of the engine, they just dictate the static compression ratio.

avonbar do three shapes and forms of thier pistons 6 14 and 18

your static compression ratio with 6cc dished pistons and that head would be 9.04:1
your static compression ratio with 14cc dished pistons and that head would be 7.71:1
your static compression ratio with 18cc dished pistons and that head would be 7.19

also i havent mentioned that your block could have been skimmed, however if you still have the engine plate on there its safe to say that it wont have been. leaveing you with the compression ratios as stated above, also thats provideing you use the standard gaskets ect.

if your on a standard turbo without a bleed valve or actulator you will be limited to 7psi, so i would place your power at around the 100 mark at the fly, thats assumeing the quality of the rest of the components are that of the pistons.

i wouldent recomend turning up the boost because you dont know whats in the engine crank, bolts ect. but also you dont know whats in the gear box and well, basicly a mini gearbox will only survive to 100 pound per foot of torque.

oh and as for the bulk head box. steveobennet has come up with a solotion:

Edited by flyingears2002, 17 February 2008 - 07:22 PM.

[steveobennet]

that pic is old! yea you can move it forward like that but my huge feet clipped it, so i just shifted it to the passanger side.



still fixed the same way though, with 2 long bolts on L brackets

[MarkGTT]

Hi, i wouldn't run any more than 7 psi without an intercooler and an uprated clutch, anything over 10 - 12 psi and you will have to look at changing the box and drops.

Sound like the head and piston combo could be good, but would need to know the dish size of the piston to know the engines true power potential (assuming all other components are up for the job)

[keccles]

nope its still a 1293. the dish in the pistons and the combustion chamber size have nothing to do with the capacity of the engine, they just dictate the static compression ratio.

I thought the dish in the pistons would have and effect on the capacity of the engine as the total cubic displacement of each piston within one stroke would be more.?? Bigger piston dish = more displacement and lower compression enabling more boost (within reason).

I also thought it would be the same for cylinder head modifications where the cubic capacity of each cylinder is changed. For example

Skimming = Increasing Compression + Reducing Cubic Capacity
and
Grinding of the area around the valves = Reducing Compression + Increasing Cubic Capacity


Keith

heres a photo of an interesting modified mini turbo manifold i found on ebay  a_series_head_modified2.JPG   23.89K   27 downloads

[Turbo Phil]

It's the bore and the stroke of the engine which dictates the capacity. The volume above the piston has nothing to do with this.
I don't like that chamber at all, maybe as a last resort to get the compression low enough on a big bore Turbo. But it's a poor design as far as swirl goes.

[Ethel]

An engine's capacity reflects how much air it can draw in, the cylinder head and piston dish volumes are the same at TDC & BDC so don't count, only the piston stroke and bore diameter make a difference.