Power Boost Port Pistons

[Old Tigger]

 I just picked up a fresh Kawi T-7 base and crank.  It came with 2 new boost port pistons, single ring.  What is the theory behind
 these pistons ??  Also, can I run them in stock cylinders ??  Or does the port timing need to be modified for them to gain any hp ??

[duane]

You will require port work to the cylinders to work w the boost port pistons.

[clem79]

The boost port pistons should work in a stock cylinder but wont add any power benefits(that I know of), you would need the boost port cylinders to benefit from them.

Is it an RX bottom end? What size are the pistons, 340 or 440?

[Old Tigger]

is it an RX bottom end? What size are the pistons, 340 or 440?

  It's a T-7 bottom with  440 pistons ..  could the stock intakes be ported to work ?? or is it a whole different type of cylinder ??

[clem79]

is it an RX bottom end? What size are the pistons, 340 or 440?

  It's a T-7 bottom with  440 pistons ..  could the stock intakes be ported to work ?? or is it a whole different type of cylinder ??

I cant answer this with 100% confidence.... but I'll spew some "stuff" and see what comes about...

The booster port cylinders had extra transfer ports that lined up with the boost port on the piston. I looked at a set of T1/250/2C mod cylinders a few years ago and they had two extra holes lined up with the holes in the pistons. Sure wish I had bought them, because now I have a set of T1/250/2C mod cylinders and pistons and neither of them have the boost port. But this is T1 stuff...

Is this an RX or RS T7 bottom end?

[duane]

Is this an RX or RS T7 bottom end?
Is there a difference?

[clem79]

Is this an RX or RS T7 bottom end?
Is there a difference?

Yes, the crankshafts have a couple of differences, rods, counterweights. Ignitions are different as well. Performance wise does it matter? Probably not.

[Old Tigger]

 I would imagine RS (as in what came in the '73 - '74 El Tigre) , these boost ports are oval and right under the ring of the piston,
 directly in front of the intake port. I'm wondering if you could get away with just raising the intake ??

[Link]

I would imagine RS (as in what came in the '73 - '74 El Tigre) , these boost ports are oval and right under the ring of the piston,
 directly in front of the intake port. I'm wondering if you could get away with just raising the intake ??

 How about knocking a lil off the piston skirt on the intake side?

Link

[wrenchman]

todd, give our ol buddy everett a call hell be able to explain it. dave

[Old Tigger]

     

todd, give our ol buddy everett a call hell be able to explain it. dave

                   That's where they came from !!!!  LOL  He told me to bring my top half over to him to check it out, I'm just trying
                   to get a basic idea for myself first, I always did my own port/polish work (nothing to extreme), but I've never toyed
                   with these pistons.

                   P.S.  How was your visit with the "Widow Maker"  ?? 

[zoom]

DON'T THINK RUNNING BOOST PORT PISTONS IN NON BOOST PORT CYLINDERS WOULD HURT A THING, BUT OF COURSE THERE WOULD BE NO REASON TO DO THAT.

[2slow]

What Twister said I think you will find that at BDC the boost port in the piston will not be covered and will be open on each side of the little "thingy"  (technical term) that hangs down in the intake port to keep the ring from catching on the port

[shewelt]

A boost port hole in a piston, even without the boost port can help...here's how.  Back in the pre-L/C days, when racing motocross, it was well known that the air-cooled engines ran great for the first 10 minutes.  After they got hot, performance dropped off significantly.  One of the reasons for this is the engine parts heat up, thus you no longer can get a good mix of cool air & fuel.  As the air heats, it expands, and less oxygen into a fixed space means less power.  It was found that adding a boost port (hole) to the intake side provided some cooling effects to the underside of the piston.  How it works is. a hole was drilled below the lower ring, and it's aim was to add cooling to the wrist-pin & underside of the piston dome.  This occurred from the exhaust pulling a vacuum when the piston is at BDC.  The movement of cooler intake mixture / charge cooled & lubricated at the same time.  Performance still drops off, but every little bit helped until they came up with L/C engines.  I'm sure any go-cart guys from way back also know of this trick.  Knowing the exact location to drill & the hole size is also a closely guarded secret.     

[wrenchman]

     

todd, give our ol buddy everett a call hell be able to explain it. dave

                   That's where they came from !!!!  LOL  He told me to bring my top half over to him to check it out, I'm just trying
                   to get a basic idea for myself first, I always did my own port/polish work (nothing to extreme), but I've never toyed
                   with these pistons.

                   P.S.  How was your visit with the "Widow Maker"  ?? 

todd, the visit was great, you can always learn little tid bits from the veterns, they still dont spill the beans, just have to read between the lines