Compresion ratio ?

[TrentNell]

secret?

Not my truck , dont want the thread to de-rail . I have held the cut piston in my hand that had rub marks on the bottom of the piston from the crank, it was just delipped , nothing off the top , so 16.9-1 ?

Edit: i know tuning could have played a role along with other things , but it goes to show that even built motor parts can buckle from too much cylinder pressure .

 

[SmokeShow]

Not my truck , dont want the thread to de-rail . I have held the cut piston in my hand that had rub marks on the bottom of the piston from the crank, it was just delipped , nothing off the top , so 16.9-1 ?

Edit: i know tuning could have played a role along with other things , but it goes to show that even built motor parts can buckle from too much cylinder pressure at the wrong time.

added a little to that. More people need to invest in the sweet setup fingers has for reading and logging cyl. pressure as part of their reg. tuning process IMO. That has GOT TO BE one of the best things to know when tuning. Talk about dialing in a tune!


C-ya

 

[Fingers]

The reason higher CP helps RPM performance is because of the scavenging. You clear out the chamber more completely and draw fresh air in better.

 

[Fingers]

From what I have seen so far. Decompressing drops chamber temp on a medium to max effort engine by ~1000* F. But the sample pool is small and could be skewed by other factors on the logged engines.

 

[PowerMax]

Reguardless a higher compression engine will make more power if you can hold it together.

Maybe, IF it holds together.

Cylinder pressure is cylinder pressure and when I build an engine it sure as hell isn't getting decompressed.

Your choice, of course.


Why do all of the gas guys go up in compression when they want to make power and all of the diesel guys seem to want to go down to make power? Something doesn't make sence. I am going with the gas guys.

Going down in compression only made sense when mechanical injection was around. They do have near the control that we have for when the fuel comes in. We also can get a larger shot in a smaller amount of time with bigger injectors putting the fuel in "EXACTLY" where we need it.

How EXACT is the tuning over 4K?? Let alone 5K-6K?

I didn't see anyone worrying. It was a discussion and to each their own. BTW I haven't seen much of your truck this year. What happened powermax?

Still in the stable waiting on a couple of machinest issues. Sure not laying awake at night worrying about c/r. I know high and LOW c/r Dmax's make power. I ran with and over alot of bigger turbo trucks in my day....with low compression.

 

[IdahoRob]

Not my truck , dont want the thread to de-rail . I have held the cut piston in my hand that had rub marks on the bottom of the piston from the crank, it was just delipped , nothing off the top , so 16.9-1 ?

Edit: i know tuning could have played a role along with other things , but it goes to show that even built motor parts can buckle from too much cylinder pressure .

Wasn't us. We are running over 100 pounds of boost without problems. Our C/R is lower than stock. I don't see that we are giving up much power.

I do know someone who has bent aftermarket rods more than once. What caused it is up for speculation.

 

[Brayden]

To quote Matt (Powermax) above...

In the LBZ ecm, the fueling is spot on all the way to 7000 rpm if you want. A little bird tells me the tables are getting rescaled in one of the next releases so you'll have control of the rev limiter instead of maxing the current tables out and hoping for the best.

Not that our motors can do that yet, but 5000 rpm was a stretch a few years ago and 6000 was a stretch this year and has been done.

IMO if you don't make 1000 hp in the 2.8 class, you didn't bring a big enough stick. Reason being.... Our 2.6 CR Dodge makes 850/1700... And the fact that Kentucky is a free for all as far as turbo rules go.. as long as the plug doesn't fit it's fair game.

Low compression isn't going to get you to 1000hp on a single charger. We've run S480's on cummins' and dmax's at stock and lower than stock compression and they're not going over 1000hp yet with plenty of fuel available.

Just my opinion..

 

[Brayden]

Wasn't us. We are running over 100 pounds of boost without problems. Our C/R is lower than stock. I don't see that we are giving up much power.

I do know someone who has bent aftermarket rods more than once. What caused it is up for speculation.

You're running over 100 psi though..

Sled motors aren't going to see that much boost on a single.

 

[McRat]

Wasn't us. We are running over 100 pounds of boost without problems. Our C/R is lower than stock. I don't see that we are giving up much power.

I do know someone who has bent aftermarket rods more than once. What caused it is up for speculation.

Which rods?

 

[IdahoRob]

I didn't realize this was a sled pulling thread

 

[IdahoRob]

Which rods?

PM sent, don't want to cause a @#$% storm.

 

[SmokeShow]

Please post the rod manufacturer. If someone chooses to get out of line, so be it - hopefully the mods would take care of it if need be. I don't think anyone will though. That's kind of an important consideration for those that might be shopping.

 

[McRat]

To quote Matt (Powermax) above...

In the LBZ ecm, the fueling is spot on all the way to 7000 rpm if you want. A little bird tells me the tables are getting rescaled in one of the next releases so you'll have control of the rev limiter instead of maxing the current tables out and hoping for the best.

Not that our motors can do that yet, but 5000 rpm was a stretch a few years ago and 6000 was a stretch this year and has been done.

IMO if you don't make 1000 hp in the 2.8 class, you didn't bring a big enough stick. Reason being.... Our 2.6 CR Dodge makes 850/1700... And the fact that Kentucky is a free for all as far as turbo rules go.. as long as the plug doesn't fit it's fair game.

Low compression isn't going to get you to 1000hp on a single charger. We've run S480's on cummins' and dmax's at stock and lower than stock compression and they're not going over 1000hp yet with plenty of fuel available.

Just my opinion..

Seems that Mega RPM is the Tornado Airswirler or Hydrogen Generator of 2009.

...

 

[duramaximizer]

I didn't realize this was a sled pulling thread

What else would you build an engine for?

 

[PowerMax]

Low compression isn't going to get you to 1000hp on a single charger. We've run S480's on cummins' and dmax's at stock and lower than stock compression and they're not going over 1000hp yet with plenty of fuel available.

Just my opinion..

Hmm? So I guess I can scrap my goal of 1500hp with a low compression setup. I'm pretty confident in saying when I peaked last season against some of the top unlimited turbo prostock trucks, I was at or over 1000hp....on seven cylinders:thumb:. To support that claim, preseason of that year I was at 900hp or so. With the fueling adjustments made every weekend up til that July, plus the trucks I was getting on top of, I will comfortably say I was at or over that hp number....on seven cylinders.


Sooo, again, IMO, a low compression engine will and is capable of well over 1000 hp on a single. My single at that time was small, IMO.

 

[Dazedandconfused]

Interesting read.

 

[Stingpuller]

single

I would have to see it on a dyno with a single. My truck is at or around 1000 with nos and I have everything that anyone else has. On 7 mine runs like crap! If you can make 900hp on seven I want you to fix mine. Its hard to tell on the dirt what kind of power you make. It's to much in the setup. Jeff

 

[PowerMax]

I would have to see it on a dyno with a single. My truck is at or around 1000 with nos and I have everything that anyone else has. On 7 mine runs like crap! If you can make 900hp on seven I want you to fix mine. Its hard to tell on the dirt what kind of power you make. It's to much in the setup. Jeff

Sorry, I don't have what everyone else has . I do alot of my thinking and building "outside of the box". Sometimes that hurts, but wow, sometimes it feels really, really good!

I agree, setup is alot when it comes to sledpulling, but it doesn't hurt to have the power to go along with it.

 

[Leadfoot]

I would have to see it on a dyno with a single. My truck is at or around 1000 with nos and I have everything that anyone else has. On 7 mine runs like crap! If you can make 900hp on seven I want you to fix mine. Its hard to tell on the dirt what kind of power you make. It's to much in the setup. Jeff

X2

I've seen a few trucks PULL better on 7 cylinders (dropped a valve) because they actually hooked better and did not overpower the track. A dyno of two trucks or drag strip would be a good indicator of HP, not how you did at a truck pull.

I've lost pulls with too much power and not enough traction. Truck pulls are not all about power.

 

[PowerMax]

:hail: :hail2: