What’s bigger then a 128 and reliable

[MakoHD]

I want to go bigger then a 128! Does anyone know of a good set up bigger then a 128 that can have some real balls and be reliable?

[TXChop]

Leading edge 151?
Turbo 128?

[No Cents]

  George Bryce @ Star Racing has a M8 offering bigger than 128", and I believe Frank Drago has a big cube M8 engine offering too. I think Frank's is like 160" and George's is in the 140+ ci range.

  You state reliable...I don't know how reliable those big inch offers are...but they are out there. Just have your wallet out because it's not going to be cheap. Cases have to be bored...etc.

[HogMike]

S&S T 143
About 160HP

[turboprop]

S&S T 143
About 160HP

The OP is asking about an M8 not a twin cam.

Not sure why you would mention that in this thread. Are you saying S&S is now offering the 143 in an M8 vision?

[1workinman]

  George Bryce @ Star Racing has a M8 offering bigger than 128", and I believe Frank Drago has a big cube M8 engine offering too. I think Frank's is like 160" and George's is in the 140+ ci range.

  You state reliable...I don't know how reliable those big inch offers are...but they are out there. Just have your wallet out because it's not going to be cheap. Cases have to be bored...etc.

Ray I also have to wonder how big a bore can be had and still have good ring seal and not have cylinder wall problems . A while back I watched a video that George produced and I try to watch them after the weekly production and seems like one of them he mentioned skirts of a piston and how he had them made in order to reduce wear . George is a smart guy .  I noticed he has bag zilla for sale . I would like to have the motor but a reduced compression ratio .  I only guessing but he might be moving on to a m8 platform now .  The m8 has come a long way with heads that move a lot of air , the bottom end now can be had with Timken or dual Timken . Lots of cubic inches . Better cranks are offered . I pretty happy with my street bike but if I did not have it I might want one of those some time .

[HogMike]

S&S T 143
About 160HP

The OP is asking about an M8 not a twin cam.

Not sure why you would mention that in this thread. Are you saying S&S is now offering the 143 in an M8

vision?

Missed that part, wife said I need new glasses!

[yobtaf103]

Can go 130' without case split carillo pistons @4.280"
also Suburban HD has Mahle pistons/ 130 kits

[Don D]

Regarding reliability
The cases will only handle a certain size barrel spigot with adequate wall. Poking the pistons out the bottom and especially when the gauge point is exposed kills pistons, ring seal, and reliability. The barrels get bigger and longer then need bigger reliefs so skirt stability is sacrificed. Its a question of real estate available to get the job done. The better large motors are taller for a reason. How big do you want to go?

[rbabos]

Regarding reliability
The cases will only handle a certain size barrel spigot with adequate wall. Poking the pistons out the bottom and especially when the gauge point is exposed kills pistons, ring seal, and reliability. The barrels get bigger and longer then need bigger reliefs so skirt stability is sacrificed. Its a question of real estate available to get the job done. The better large motors are taller for a reason. How big do you want to go?

Excellent example of limitations when it comes to piston life. I'm amazed some of these builds last as long as they do with the pistons poking out of the cyl bottoms at BDC.
Ron

[Goopdienes]

without boring the cases you can go 130. as of right now 143 is the biggest with boring cases. i have read that 160 is in the works

[Nastytls]

without boring the cases you can go 130. as of right now 143 is the biggest with boring cases. i have read that 160 is in the works

151" is larger than 143"... by quite a bit.

[Hillside Motorcycle]

Revolution is about to release 139", and 143" cylinder kits.
On another note, the larger the bore, the closer the pistons at BDC, and the 22.5 degree rod/piston scallop cut on the intake side of the skirt can become so large, that piston stability can/will be be fubared.......unless raised deck cases are brought into the mix.

[Barrett]

Star has a 143" also. 

[Don D]

A 4.5 bore x 4" stroke at 10.5:1 with less than .500 lift and a 7000rpm redline

[Nastytls]

Does anyone actually difinitively know, at what point the bore is too much in these M8's to have stability at BDC? This picture on Drago's site shows a HUGE cutout at the bottom of the cylinder spigot. Not sure if that's for their 160"or 143" kit.

[Don D]

How can they without the stroke in the equation? And how tall you are willing to put up with in a stock chassis or modify it.

[Hillside Motorcycle]

Those LE 151"s have a 5 3/16" arm.....wonder what the piston speed is at say, 5000 rpms?

[Nastytls]

How can they without the stroke in the equation? And how tall you are willing to put up with in a stock chassis or modify it.

My question is related to an engine with largely stock dimensions. So, stock stroke, engine height etc... You said: "Poking the pistons out the bottom and especially when the gauge point is exposed kills pistons, ring seal, and reliability." And Hillside said: "piston scallop cut on the intake side of the skirt can become so large, that piston stability can/will be be fubared"  At what point does that happen? So, if you build a 130" or a 143" with the stock crank is there enough material in the spigot for proper stability? Or is 124"-128" the maximum, or 117"-120"? There must be a clear threshold somewhere. For people that don't build engines every day this would be valuable information to know.

I believe the OP's question is about a engine with stock dimensions as well.

[rigidthumper]

Those LE 151"s have a 5 3/16" arm.....wonder what the piston speed is at say, 5000 rpms?

4323 feet per second @ 5K, and 5620'/Sec @ 6500; better have great components and deep pockets.

( I'm certain this was rhetorical, as you've done those calculations a thousand times over the years )

[CVOThunder]

Leading edge 151?
Turbo 128?

I was just thinking why not turbo the 128 and call it a day? Then I reread the thread and you already mentioned it. I also like the Grudge box idea, not so much from regearing for take off but for the taller top end. Kinda defeats the intended purpose I reckon but man that sucker would be fast for a street machine. Jail time.

[Don D]

How can they without the stroke in the equation? And how tall you are willing to put up with in a stock chassis or modify it.

My question is related to an engine with largely stock dimensions. So, stock stroke, engine height etc... You said: "Poking the pistons out the bottom and especially when the gauge point is exposed kills pistons, ring seal, and reliability." And Hillside said: "piston scallop cut on the intake side of the skirt can become so large, that piston stability can/will be be fubared"  At what point does that happen? So, if you build a 130" or a 143" with the stock crank is there enough material in the spigot for proper stability? Or is 124"-128" the maximum, or 117"-120"? There must be a clear threshold somewhere. For people that don't build engines every day this would be valuable information to know.

I believe the OP's question is about a engine with stock dimensions as well.

I dont have the answer without drawing it up in cad. The reliability comes with shorter stroke and largest bore that can be utilized and still not cause huge cutouts at the base of the cylinders. Now the pistons remain supported, the piston mean speed reasonable, and barrels packaged in a stock block with stock dimensions except case bore. I don't believe anybody has approached this motor yet by destroking it.

[rbabos]

How can they without the stroke in the equation? And how tall you are willing to put up with in a stock chassis or modify it.

My question is related to an engine with largely stock dimensions. So, stock stroke, engine height etc... You said: "Poking the pistons out the bottom and especially when the gauge point is exposed kills pistons, ring seal, and reliability." And Hillside said: "piston scallop cut on the intake side of the skirt can become so large, that piston stability can/will be be fubared"  At what point does that happen? So, if you build a 130" or a 143" with the stock crank is there enough material in the spigot for proper stability? Or is 124"-128" the maximum, or 117"-120"? There must be a clear threshold somewhere. For people that don't build engines every day this would be valuable information to know.

I believe the OP's question is about a engine with stock dimensions as well.

I remember I assembled my 120 on the bench with half a case to check the clearance for piston clearance on the bore machining from the previous 113. Just about "Potty mouth" when I saw how far out of the spigot the bottom the pistons poked out, not to mention reduced support from piston notches. It really is amazing it works but it's a no brainer that a thrust load direction change at BDC with no support won't be doing much in long term piston life. Now, let's rev the bastard in that condition to extreme piston speeds at the same time and expect it to last.
Ron

[Hillside Motorcycle]

Those LE 151"s have a 5 3/16" arm.....wonder what the piston speed is at say, 5000 rpms?

4323 feet per second @ 5K, and 5620'/Sec @ 6500; better have great components and deep pockets.

( I'm certain this was rhetorical, as you've done those calculations a thousand times over the years )

[MakoHD]

Thank you all for your feed back, I made up my mind. I'm going with the kit from shaker product it's a 150ci taller cylinder (billet stock look alike) same amounts of fins. Billet crank shaft with CP rods, cp pistons. The compression is going to be in the 11s. I'll let you know how it goes.

[Nastytls]

Long stroke. Will be interesting to see how she does, power and longevity wise.

[scotman623]

I definitely will be looking forward to hear the outcome...

[MakoHD]

yes It's a longer stroke but it's also a talker cylinder.