Pistons/Rod bolts?

[Rickys'S]

I am going to be getting my cylinder head reworked soon adding bigger valves in the process

I have seen in go-mini that minispeed has added accralite pistons and arp rodbolts to their demo cars engine, it also mentions that they have had a few engines blow up whilst testing my question is; have they added these components to stop the engine from blowing as they see this as a week point, i do not know of any other tuner in the UK that has done this or believes it to be a problem.

I was thinking that seeing as my head is coming off i could add in new/stronger pistons and drop the sump adding new rod bolts, is this possible with engine in car i.e will the con rod and piston assembly come up through the block to change the piston & rings?

I have also seen a picture of a mcs piston on north American motoring where the guy states that the pistons are off poor quality and do not help gas flow!

Just looking for views/opinions and maybe some one who has done it!!

[obehave]

The pistons could be better. I think that now that high HP is readily available we should start seeing long term results.

My 2p. Don't do it. If you're going to beef up and engine do the whole job right. Don't just do bits and pieces internally. I've never seen that give excellent results.
If you want to do it right, get a junk yard block an build the snot out of it.


BTW. I've used ARP fasteners in the psat. Very good stuff.

[Rickys'S]

Quote: Originally Posted by obehave

The pistons could be better. I think that now that high HP is readily available we should start seeing long term results.

My 2p. Don't do it. If you're going to beef up and engine do the whole job right. Don't just do bits and pieces internally. I've never seen that give excellent results.
If you want to do it right, get a junk yard block an build the snot out of it.


BTW. I've used ARP fasteners in the psat. Very good stuff.

Cheers for your thoughts Obehave you have a point i just cant seem to work out why minispeed did it and left their rods & crank in, they said it has boosted capacity to 1700cc,have they then got a stroked crank and modifyed the pin location for the new pistons, otherwise cant see it without a re-bore and cant really see that either (waterjacket)!

[obehave]

Quote: Originally Posted by Rickys'S

Cheers for your thoughts Obehave you have a point i just cant seem to work out why minispeed did it and left their rods & crank in, they said it has boosted capacity to 1700cc,have they then got a stroked crank and modifyed the pin location for the new pistons, otherwise cant see it without a re-bore and cant really see that either (waterjacket)!

If you're doing R&D and have the time/money then experimenting with one offs is educational. If they aren't offering that set of mods as a kit then they don't have faith in it being either practical or a money maker. time will tell on that.
That's a lot different than what you might want to do with your
daily driver.

[minimc]

I’ll second Obe’s comments re: the in performing only a partial rebuild.

Were I in your position I'd consider larger injectors and a piggy-back type fueling/timing solution like the Apexi or Unichip – each of which allow the adjustment of fueling & timing. These mods + some dyno time with a competent MINI tuner will net you additional power, improved fuel efficiency & will an added margin of safety (for your engine).

To give you some perspective on durability of the OEM parts:
There are tuners and private citizens in America who have been pushing the limits of the OEM pistons, rods, and head by turbo-charging and supercharging the engine simultaneously ‘Twin-charging’. The torque is immense (compared to stock) and so far the internals have held up. Peak torque is in excess of 250 ft-lbs., & wheel horsepower is in the range of 265 (close to 300bhp). I believe the mileage on one of these ‘Twin-charged’ cars is approaching or may have exceeded 45,000 miles.

[jlm]

from what I have seen,:
1. no-one exceeding 265-280 wheel hp with twin charging has been reported using stock pistons;
2. no-one has reported having to change out the rods and rod bolts (yet), though 430 wheel hp has been achieved (hubie) (no he wasn't using stock pistons)
3. you can trash the stock pistons with boost pressures exceeding 24psi as the crown collapses into the ring land at the periphery from too much combustion pressure (not heat)
4. At least one aftermarket piston has had its dome collapse due to excessive combustion pressure (C/R and boost) and a too thin crown.

[minimc]

[Revolution Mini Works]

Quote: Originally Posted by jlm

from what I have seen,:
1. no-one exceeding 265-280 wheel hp with twin charging has been reported using stock pistons;
2. no-one has reported having to change out the rods and rod bolts (yet), though 430 wheel hp has been achieved (hubie) (no he wasn't using stock pistons)
3. you can trash the stock pistons with boost pressures exceeding 24psi as the crown collapses into the ring land at the periphery from too much combustion pressure (not heat)
4. At least one aftermarket piston has had its dome collapse due to excessive combustion pressure (C/R and boost) and a too thin crown.

you are quite correct.... jedi master
I have a set of the latter