How smooth does your truck accelerate?

[sparks57]

I've been noticing a lot of things about my truck lately. Two things that strike me as interesting:



•My truck accelerates A LOT faster if I give it have 1/3 throttle for a second or so, then slam it.



•My truck is very quiet while accelerating (except for the turbo!) except at full throttle, when it feels like my engine is going to fly apart... but then agian, as DANIEL always points out, I'm a jumpy SOB when it comes to this.



So do guys notice the same thing? I think the 1/3 then full throttle comes from having this big turbo that needs a second to spool.



But at full throttle... my whole truck gets really noisy, like the whole drivetrain is gonna fly apart... and I think the Getrag might!



So any input?

 

[sparks57]

BTW: I can make 30psi pretty regularly out of this 35/40, what HP do you guys think I'm at? Keep in mind that I would be making more boost with the stock turbo... bigger turbos move more air at a lower psi.



I wish I could DYNO!!!

 

[CDegner]

Originally posted by CB_Parker

Keep in mind that I would be making more boost with the stock turbo... bigger turbos move more air at a lower psi.

How do you figure that? It is the moving more air that increases boost.



[QUTE]I wish I could DYNO!!! [/QUOTE]



You can. All ya gotta do is fork out the cash. If ya wanna play, ya gotta pay.



Carl

 

[sparks57]

I was told that bigger turbos move more air, but at a lower PSI from what I have been told.



More air does NOT equal higher PSI, just more air. The impeller is bigger so it moves more air... but it is not pushing it as hard.



This is what I have been told.



I know I can dyno, but dyno's are far away from here.



Thanks for the input!

 

[sparks57]

I could be wrong, but that was the impression I was under... I may have been miss-informed.



I'm looking into it right now.

 

[phillips5]

A bigger fan can move more air (volume) if there is a place for it to go. But restriction causes pressure big turbo or small turbo 10 psi is 10 psi and so on in the same pipe is the same volume. I took air balance class last october and learned a lot about this stuff.

 

[Greenleaf]

I'll throw "sumth'n" in... ... . You can have a small air compressor in the shop with, say, a 20 gal tank. Rated for 125psi. And X no. of CFM.



Now take a 140 gallon tank with the same psi, and a much higher CFM.



I have know idea what I'm talking about. However, I do know that I use two air compressors as mentioned above. The smaller compressor will power my air tools for 10 seconds. The larger unit,,,indefinatly.



"Sumth'n" to do with volume (CFM) not pressure.



Scott

 

[Case500D]

Chris,



My W-350 seems to accelerate better by going from 1/3 throttle to WOT than just mashing it (less smoke too). But at 1/3 throttle I am running between 5 and 10 lbs of boost. BTW, I can also tap 30 psi of boost. The main top end difference on power and boost is the custom ground fuel pin. I am also running a PDR HX-35/16. The engine does have a quieter operating range. For example it is quieter at 70mph than it is at 55 mph. Not sure why. As far as the engine flying apart, it is mainly the rusted out exhaust system rattling on mine that scares me. Afraid it might fall off and then I will have to spend $$$ on a 4" system. When I haul hay or equipment the truck gets a lot of WOT shifts just to keep it moving. With 287K on the clock, it hasn't blown yet.



Jeremy

 

[1stgen4evr]

"Sumth'n" to do with volume (CFM) not pressure.

Actually everything to do with volumn. Your air tools will do nicely on 100 psi if given adequate supply (volumn). I use a larger supply hose than some shops have. The Cummins is going to respond in much the same way except it can quickly swollow a whole lot more air. Higher pressure will push more air through the same size tube. If you can't maintain the pressure to the end of the piping/hose, the volumn delivered will fall off.



Don't let me give the impression that I know about turbo science or art as some of these guys practice it. Mine turbo is box stock and going to stay that way. I am mostly refering to shop air and the situation of a lot of shops where there is a very large compressor that is eating dollars with excess capacity to feed a fifty foot quarter inch line on a three quarter inch size air wrench.



On a one inch air wrench, I use a one inch line. Haven't found a lug yet that it won't take off.



I expect that some of you have experienced all this but some readers might not have.





1stgen4evr

James

 

[paccool]

Yes, if you use a larger line you will get more volume at the same pressure. But if the same size line is used, the volume will be the same at the same pressure. I think the restriction here is the turbo pipes and the inlet area into the engine.



35 psi will push more air into the engine than 30 psi. It sorta like those air tools, if you increase the pressure they will speed up a little. If you increase the feedline they wil have more power.



Stan

 

[sparks57]

Originally posted by Case500D

Chris,



My W-350 seems to accelerate better by going from 1/3 throttle to WOT than just mashing it (less smoke too). But at 1/3 throttle I am running between 5 and 10 lbs of boost. BTW, I can also tap 30 psi of boost. The main top end difference on power and boost is the custom ground fuel pin. I am also running a PDR HX-35/16. The engine does have a quieter operating range. For example it is quieter at 70mph than it is at 55 mph. Not sure why. As far as the engine flying apart, it is mainly the rusted out exhaust system rattling on mine that scares me. Afraid it might fall off and then I will have to spend $$$ on a 4" system. When I haul hay or equipment the truck gets a lot of WOT shifts just to keep it moving. With 287K on the clock, it hasn't blown yet.



Jeremy

Thanks Jeremy.

I've also got a custom fuel pin. I was kinda kidding about stuff flying apart... it's mostly this exhaust I have rattling around under there. My truck is also quieter at 70mph... not sure why. Maybe the RPM's smooths it out a little, 70 is 2krpm's on my truck.

 

[Excessive Force]

I don't know how it reacts to 1/3 throttle 'cause i love "mashing it" too much !! I do know one thing though, my nephew didn't like it very much when i beat his new 6. 0 FERD the other day... :-laf He's got an AUTO... HeHeHe

 

[sparks57]

But does anybody else's truck tend to get real loud and wild at WOT in high RPM's?

 

[hdm48]

I'm not sure,, All I hear is my wife yellin 'SLOWDOWN"!!

I must be getting old

 

[dpuckett]

Originally posted by CB_Parker

But does anybody else's truck tend to get real loud and wild at WOT in high RPM's?

Yes, mine is loud at all PRMs. And it gets wild if I hit it on gravel. But I have a few exhaust leaks, a reg cab, and straight pipe. I have noticed that mine has a bit of a dead spot if I just mash it, too. If i ease into it (more the way it was INTENDED to be done, I believe), it runs smoother, just as fast, and seems to make less noise and smoke. I normally start mine out with about 1/6th throttle, then ease into it as boost comes on; otherwise, it smokes like a chimney. I notice little difference between 2/3 throttle and full throttle until higher RPMs, like say at 60+ in 4th.



If one didnt like the dead spot I mentioned, one could loosen the AFC spring ( mine is pretty tight) all the way.



Part of it could be your old injectors- mine changed tone with the new ones.



Daniel

 

[sparks57]

I was expecting another crack about beer and sororities???



Oh well...



I can't wait to get the EDM's, they're supposed to be great for low end.



My engine get's loud when I'm already making a bunch of boost (over 20) and mash it... the thing shaked and the exhaust get really high pitched.

 

[dpuckett]

boost and drive

Chris-

right now, I think the limiting factor is your head No, not the one on your shoulders (ok, there seems to be a few isues there- we'll address them later), on your engine. True, the HX35/40 hybrid will flow more air, but it is with less drive pressure, so as not to spin the turbo into lunar orbit while meeting your airflow needs. If you have a stock HX35 and your hybrid 35/40 making 30psi each, the stock 35 is spinning faster, but they are both moving the same amount of air; the hybrid is just doing so at a slightly slower RPM, due to the bigger fan blades. The limiting factor here is the airflow in and out of your head (again, no pun intended ), since it is going through the same IC, tubing, head, etc. Now, you take the 2nd Gen cooler I will someday install after I win the lottery- it flows more air faster, or so I've been lead to believe. At x- psi, I'll be moving more air into the engine, due to differences in DENSITY, which another topic altogether.

Clear as mud now?

Thought so; someone more versed in this field can clear it up.



Daniel

 

[dpuckett]

Originally posted by CB_Parker

I was expecting another crack about beer and sororities???

Yeah, sounds like you may need to cut back on both of them at this point.



THat, or upgrade to grad students and hard liquor. :-laf

 

[sparks57]

I am getting my head ported here shortly, and o-ringed when I replace my head gasket. I'm also just waiting for the go-ahead to send in my exhaust manifold, intake horn, intake elbow, and turbo (just maybe touch ups on the turbo) to Dave Miller to have it all ported and matched.



Daniel, it is a time consuming job, but the first gen intercooler can be welded and ported to flow as much as you'll ever need.

 

[Stomp]

Mine runs about as smooth as a 2 year old yearling getting castrated/shots/ears cropped/and a ring in his nose. Naw its not that bad. It runs pretty smooth.



Stomp