Cast Pistons

[cummins6turbo]

I'm building an '89 T2-S60. I'm planning on running a min of 18# boost. Has anyone used the stock cast pistons for this, and if so, what's the most boost used without damage? I'm trying to avoid spending an extra $450+ on forged, if the cast will last. I'd appreciate any and all "responsible" responses. Thanks in advance!

[yogurtslinger]

With cast pistons the MAX pressure someone would run would be 18psi, and I think thats pushing it even with a good fuel setup. Save yourself the hassle and just save up for forged pistons, if you blow the cast ones you'd wished you had dished out the dough for forged ones in the first place..... my 2cents..

[glhsken]

For a 2.5L I would agree with that comment. Not for the 2.2's.

There are better calibrations available than the S60 now. I run 22psi on pump gas with cast pistons in a 8.5:1 compression motor. The set-up is an 88 block, cast crank, TII rods and stock cast mahles, 55 psi fuel pressure, full 3" exhaust, and 52lb/hr injectors.

The set-up dynoed at 276 hp and 323 ft lb despite the fact it needs some fine tuning (way rich and not enough timing up top). I'll be looking to go 25 psi on May 9 at the dyno.

[yogurtslinger]

Hhmmm..... Maybe I'll just use my 2.2 with cast slugs instead of the 2.5 I got, it would be WAY more cost effective than buying forged ones. 22psi?!?!!? No bull****???? EEEEKKKK!!! That seems like it would push your pistons to the limit..

[glhsken]

According to my "sources" lots more room to go. There is a 2.2L out there making over 400 with cast slugs. The key is doing it right (something I've forgotten at times )

BUT that is only for the 2.2's... 2.5's are WAY more fragile.

[turboshad]

I keep hearing that the 2.5s are more fragile or they can't take the same boost as the 2.2s. Why is this? Are the cylinder pressures that much different between a 2.2 at 8.5:1 and a 2.5 at 8:1? Some one please explain this to me. Thanks.

DJ

[glhsken]

If you have one of each piston, looking at them makes it chrystal clear. The top ring land on the 2.2 is MUCH beefier (read taller). More metal to "absorb" the shock of detonation without breaking the top of the ring land off.

Typical 2.5 piston damage I see, up to 1/4 of the top ring land is "missing" and does a # on the head.

at that boost, cast or forged your breaking a piston. I'm running this boost on my daily 150 mile a day driver (cast Mahle's), and I beat the crap out of it, As mentioned you need a very stable setup. if you have the money I would go forged! Just keep in mind forged pistons can be destoyed just as easy!

[NJMarc]

dbltrbl's shadow has a stack of 12 and 13 second time slips using cast pistons... 20-25+ PSI

[glhsken]

Quote:

Originally posted by pauvil at that boost, cast or forged your breaking a piston. I'm running this boost on my daily 150 mile a day driver (cast Mahle's), and I beat the crap out of it, As mentioned you need a very stable setup. if you have the money I would go forged! Just keep in mind forged pistons can be destoyed just as easy!

Not true.. Of course forged is best... But the 400hp car I mentioned IS a daily driver. You break pistons with either 1. the wrong set-up, or 2. something in your set-up fails.

[LancerShelby]

Well I'm gonna run 20psi on my stock rebuilt 89 T1 bottom end with 40%'s and 255 pump and we'll see how she goes.