Hi I'm new to this board and want to know if any one could help me. I have a 225 slantsix and the man that is going to build my engine is looking to bore it out around between .150 and .200. My question is does anyone know what forged piston i could purchase without going to a custom piston?

The biggest bore I've seen anyone get to live is +.130", and that was drag race only. Any bigger than that and there isn't much cylinder wall left.

_________________
Official Cookie and Mater Tormentor.

Go .060 for the street or first race engine. Cox Bros. can cover all your piston and valve needs.

Will

My engine builder has been in the business of building engines for race cars for well over 40 years. His name is Eddie Flora. He says i can go about .150 over or sleeve it and go more up to .200 My dad is a machinist so sleeving it won't be the any problem but i would rather go around .150 over if i can find a forged piston that will work.

Yeah i forgot to add that i have had the block sonic tested.

The machinist who is doing my work just finished sleeving an Acura block. He installed "wet" sleeves. Basically he bored the whole darn cylinder out of the block and then machined what was left to accept a sleeve. Not sure what the original/final bores are, but I'm pretty sure he maxed this one out. That little 4 cyl dyno-ed at over 200 hp at 7500 RPM (w/o NOS). No telling about durability. He said this is one of the "hot tickets" for the street racing croud.

I had been mulling over the prospect of doing wet sleeves on a slant, but it looks/sounds just a wee bit off the chart for me.

Just something to thing about....

_________________
Gilly

1960 Dodge Pioneer
"Long Rod" /6, A833 Pistol grip Hurst
8 3/4" w/Suregrip and 3:91's
Still have more parts in boxes than on the car....

I'd rather not go the sleeving route either maybe the next motor i build if I have more money next time.

You need to be careful when boring-out most all of the original cylinder walls because the bore walls add a lot of support to the top deck. Without this support keeping a head gasket sealed becomes a problem.

If you do ever go the "six sleeves" route, the trick is to intentionally bore off centerline, towards the driver's side and leave some original cylinder structure behind, on the major thrust side of the block. Some "block rock" should also be used to add back some stability. All of this special machining is expensive.

I would look at going .100 oversize (3.500) or 89 mm (3.504), there are a lot of pistons to choose from at those sizes. Get a piston makers "diametric listing", these show all the piston applications grouped by bore size. You will find that the other limiting factor will be the piston pin size, not many pistons have the .900 wrist pin. (that's what makes the 198 con rod, 2.2 piston set-up so nice, same wrist pin size)
You may be "dollars ahead" if you just go out and buy a set of custom pistons.
DD

Thanks for the info Doc. My dad is going to do most of the machine work for free and the my engine builder is my dads buddy and he is going to build my engine for free except cost of parts. I'm no machinest but i think he talked about boring off the centerline. But to save money i might go with the .100 oversize.

I have another question i planning on making this car streetable and taking it to the strip on the weekends will overboring this much have anything to do with the streetability of the car?

As long as you do some sonic checking and have a good, thick block, you will be fine. Thickness on the cam shaft side is where you want it. The SL6 blocks are thinnest on the front to back walls, where each cylinder comes close to the neighboring one so be sure to pay attention to these sections.

About a 1 inch bottom fill of "rock" also helps and this will not hurt cooling on the street. Acid clean the block completely if you plan to use some "block rock".
DD

I belive the 100 over bore is the way to go the Cox bros just sent my engine builder a set of custom Venoila pistons that can be custom made for your app. I am putting together a 198 rods on the pistons and i know other racers that use this combo. When this engine is finished im pulling out my current engine and am going to build a 2.2 bored 1 mm over on 198 rods for a backup engine . One is a all race engine and one will be milder backup engine. Thanks Ron Parker





gone bagel bagging back in 11 seconds