Built Motor Discussion

T

TNRGreene

Kicked to the Curb
Sep 2, 2006
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Bradenton, Florida
I'm starting to get hard info. I know Guy would be the best on the heads & valve train, I just want opinions on this. What can I expect of RPMs? I think Pat has gone 5000. How much higher can you go & what supporting mods would be needed? Can the valve train take 6000, 7000, 8000? What about fueling,,,3-CP3's?
Discuss
 
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TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
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I am no expert but i think fuel is keeping it below 5000 . havent heard of anyone floating a valve from reving it to high with the right valve springs . what is Banks reving to ?
 
TrentNell

TrentNell

Finally underway !!!!!
Jul 7, 2008
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TNRGreene said:
Is anybody else turning them that hard? I haven't heard
Click to expand...

I kjnow a few guys that have ran them up to 4600 but didnt keep it up there due to loosing ET from it .and it took a 3.2 charger to make power up there but it did .
 
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JOHNBOY

JOHNBOY

< Rocking the Big Single!
Aug 30, 2006
2,159
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Saegertown, Pa
I just spun 5300 on a 6th gear rolling burnout!:happy2:

She is running good. The only issues that have had with the valvetrain have been caused by valves sticking in the guides. With my low compression and big injectors it just does not make enough heat at idle to burn all the fuel like it should. The fuel smolders at idle and leaves a hard black coating on the valvestems and guides. This coating is called fuel coke. It is a lot like cerosote build up in a chimney. The first time it stuck valves I broke the rocker shaft bolts and rocker shaft. I miss understood why the breakage occured. I put it back together with all new stuff. Custom rocker shaft studs, DPR billet bridges, and all of Guys springs and Ti retainers. It broke on me again. But this time it broke the ends off every exhaust rocker bridge. This is when I noticed the fuel coking. Some of my valves where stuck so bad I had to drive them out.:mad: I talked to lots of people and no one seemed for sure why this happened. Then I talked to Brent at GMS and Distributor (builder of bad ass tractors) the both said the samethings. I need more clearence in the guides. I had stock clearences of .002 to .0022. I now have .004. They said to remove the valve seals to help get more oil flow down the stems. I also chamfered the tops of the guides to help funnel oil in. Also they said I needed to get more heat at idle to help burn the coating off. I raised my idle rpm up to give the fuel less time to stick on and lowered my idle timing. It was idling with EGTs of 200* it now idles with egts of 400*. I am will not let it idle for long periods of time.
 
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T

TNRGreene

Kicked to the Curb
Sep 2, 2006
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Bradenton, Florida
trentnell said:
so i take your wanting to go after the big boys :eek: i know there are only a few classes that allow twins or more :D , not shure on the classes back east . sounds like you got a wicked project in mind ! i likey :D
Click to expand...

No you said they lost ET @ 4600 and I said chargers also ;)
I not shooting that high, just asking how high the limit is. I don't want to test anymore
 
Fingers

Fingers

Village Idiot
Vendor/Sponsor
Apr 1, 2008
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White Oak, PA
Provided you get fuel and air....

I have not heard of a hardware related failure because of high RPMs. But I don't hear everything either. Without the right cam and such, you will drop out of the power band at some point.

The mechanically supercharged/ Turbo combo engines seem to do better breathing up there. I personally am leaning that way. (have the charger sitting under the bench.) Little doubt that the engine will want lots of air.

Outside of the valve train, spinning faster is actually easier on the internals than grunt power. At what point it becomes a problem is a huge question that I don't know the answer to but I do know it is North of where people are now. At least the ones that are talking. :)
 
duratothemax

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
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Wyoming
keep in mind that the max rated input speed for the allison is 5000rpm, that is a big heavy trans to be spinning fast...if you are running an allison that is.

ben
 
bullfrogjohnson

bullfrogjohnson

Big Girl!
Nov 20, 2006
4,167
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Locust, NC
You are definately gonna need some valvetrain to handle the rpms and after what Johnboy has gone thorugh sounds like you will need some higher compression if you want to be able to drive anywhere but the trailer and at the track.

I stil plan on one day building an unlimited single dmax running big rpm but from everyone I have talked to and read about the fuel will be the limiting factor as the cp3's start to float and loose effieciency above 5k rpms


This is the highest rpms I have ever heard out if a dmax. I cant express how bad that truck makes me :drool:

http://www.youtube.com/watch?v=RNlw16ORpAQ

also another

http://www.youtube.com/watch?v=-34JtXUk9o0&feature=related
 
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