High Compression Pistons

[opjohnny]

raising the compression will make it harder to start. I am with you more off boost power is a ok and you can always plug in the truck.

 

[Forrest Nearing]

raising the compression will make it harder to start. I am with you more off boost power is a ok and you can always plug in the truck.

don't you mean easier to start?

 

[KLockliear]

don't you mean easier to start?

Easier to start... might be harder on the starter though.

 

[Vaughn MacKenzie]

With good batteries I suspect the starter will turn it over just fine. . . should light off easier in cold weather and/or high elevation.

 

[betterthanstock]

If you go thru the expense of custom pistons, it might be worth getting them ceramic coated on top. Better MPG and higher resistance to melting.

 

[DPellegrin]

rbattelle,

You stated some interesting numbers about cylinder pressures in your tread #6. I am curious how you derived these numbers. They seem to violate the laws of physics, namely Boyles law.

Regards

 

[Bugracing]

I think I gave you this answer on post #25.

Hello KLockliear - you are correct about me having posted the same answer back on post #25. My apologies if you are annoyed that I am repeating myself. But if you read post #1 you will find this:

"I am looking to increase the compression ratio of my '05 5. 9 liter from the soft 17. 2:1 to around 21 to 22:1.

Does anyone know of a piston manufacturer, who makes pistons for our 5. 9 liter Cummins that will achieve the higher compression?"



So please forgive me if I am annoyed that my initial question has only been answered by one person.



I am delighted that this topic has brought out so many opinions, but is becoming very obvious how little TRUE engineering knowledge is found here.

Any weakling can say "no-it can't be done". It’s the safe answer the deaper concepts are not fully understood.

Yet the same group of geniuses has no qualms bolting on a hole bunch of questionably engineered aftermarket crap and shoving 60+ psi of boost into an otherwise stock engine and then wonders why the head gasket shoots out the side, crank bearings fails, pistons melt, the engine over heats and the transmission has a catastrophic failure. Not to mention that they then come here and complain #@$%! about poor quality parts... .

True engineering will ensure that everything lives, but that has a price which few are willing to pay.

But enough philosophy for now.



Getting back right to the point now:

Does anyone here know of a possible supplier of high compression pistons for our 5. 9 liter Cummins?



It is ok if you do not know of one, just please do us all the favor of keeping your opinion about starter longevity, temperature probes and other off-topic thoughts to yourself.

 

[lmills]

OK, to keep it simple and answer the post at hand, NO. There are a few manufacturers that are producing ISB series pistons for after market use, but they are forged, not cast and they do not appear to hold up as well in this application. They are also usually either lower compression or factory compression specs.

Now, I'm not trying to be ignorant, but if you are in the racing scene, why not contact one of the manufacturers directly and have some built for you? I would think any manufacturer could handle it for the right price. The problem is you will be the guinea pig, so to say.

The pistons that we have do not share the same build characteristics that the gassers do. We have no other combustion chamber other than the bowl that is built into the piston. The CR pistons already have a piston protrusion of approximately . 005-. 010": and can be as great as . 020". So who ever builds them has to modify the bowl itself to decrease the chamber size. Which in turn will affect the injection timing of the fuel and the spray pattern needs to be accounted for to make sure the fuel enters the bowl at the correct time and correct angle.

 

[cerberusiam]

I am delighted that this topic has brought out so many opinions, but is becoming very obvious how little TRUE engineering knowledge is found here.

Any weakling can say "no-it can't be done". It’s the safe answer the deaper concepts are not fully understood.



True engineering will ensure that everything lives, but that has a price which few are willing to pay.

Before you start blowing off about engineering knowledge you had better spend sometime brushing up on diesels, Cummins in particular, and gain some of that deeper knowledge. In about 3 sentences you have proven you know little or nothing about the subject, insulted about the largest proven knowledge base on Cummins power that exists in ANY forum, and pretty much sealed the opinion you are one of THOSE.



You got the answer to your question in the first 7 or 8 responses in addition to the reasons why you are on dead end road. Pretty good answers for the minimal info you posted.



Just in case you didn't know, the names on that first page of responses read like the Who's Who in diesel performance with a combined knowledge and experience you won't find anywhere else. NOT a good way to gain any deeper knowledge.

 

[MCummings]

To achieve a higher compression ratio why not just shave the block down? Give the piston a chance to get closer to the head. Or, Maybe I'ma noob?



I shaved my pistons down (. 010), and put a thicker headgasket (. 020) in mine to drop the C/R. Runs Great from 1,500RPM to redline, but is kinda tame below that.



Merrick

 

[KHaines]

I think if you read post #15 it gives you a company name. What did they tell you?

 

[KHaines]

Call them up & ask them if they will make you some.



Introducing Mahle's Steel Monotherm Diesel Race Piston - Why Go Sixty? - Why Go 60?



Maybe they would be able to make some.



Maybe this isn't a good enough answer for you topic, but I like the fact that there are now 4 pages. If it wasn't for the rabbit trails this would have been dead before it got started.

 

[rbattelle]

rbattelle,

You stated some interesting numbers about cylinder pressures in your tread #6. I am curious how you derived these numbers. They seem to violate the laws of physics, namely Boyles law.

Regards

Well, I guess I wasn't thinking straight. Compression ratio does not equal pressure ratio, of course.



Sorry about that. I'll go back and edit the post.



Ryan

 

[KLockliear]

OK, if you want someone that will make a piston, call ROSS pistons. They made ours.

 

[opjohnny]

I guess we need to start our own post about the side effects of raising compression. When I posted that I was thinking it would make more work for the starter. Bug has his list and its time for him to call manufacturers.

 

[Forrest Nearing]

I guess we need to start our own post about the side effects of raising compression. When I posted that I was thinking it would make more work for the starter. Bug has his list and its time for him to call manufacturers.

it would be a little more work for the starter, but these things will turn over a stone cold engine at 20 below... that oil is THICK at those temps!!!



I wouldn't consider accelerated starter wear a real issue

 

[CodySanders]

to answer the original post question i got my custom made pistions from arias. they are only going through schied diesel out of indiana. i eventually took mine out because i tow and a forged piston does not expand like the block does and caused a lot of unwanted blow by. hope this helps and if you want the number to schieds pm me.