torque curve with 4gsk? Also premature wear with 110# springs

A

ashby

New member
Joined
Feb 7, 2010
Messages
44
So I was talking to a diesel mechanic today and he was saying that he didn't think that a 4gsk would be good for a daily driven and towing truck..

He was interested mainly in the fact that he was afraid the it would make the peak power and torque way to high in the RPM range to actually be usable without winding the truck out. So with a 4gsk where is the max hp and tq at in the power curve? Will it be to high to use the power for towing? Would A 3gsk be better for towing?

Question 2:

He also showed me some valves that had been run on a stock engine, and the valve faces where they seat into the head was so worn that it was razor sharp on the edges. He was also warning be about how if I put heavier springs in that it might wear the valves out really fast due to them closing so hard with the 110# springs.

What are you guys' input on this? Will these mods lower the longevity of the engine? I don't plan on running WOT all the time, I just want power where I can use it.
 
well if you have 3.54 gears, you don't have much need for 4k springs, if you have 4.10 gears 4k springs might be a good idea. also i think the what turbo you have and how much timing you have determine where your peak torque and hp will be.
 
4K governor springs fuel harder from just off idle till 3800 rpm +/- depending on setup.

The only down side to 4K springs is a more touchy throttle.


I agree that heavier valve springs will cause more wear than stock springs. The question is, do you care if your valves only last 500,000 miles instead 600,000 miles? Now if you spin big RPM 4000+ and have extra heavy valve springs, they will obviously wear much faster.

If you're worried about wear, add a bottle of STP oil treatment each time you change your oil. It has extra Zinc to help minimize valve train/camshaft wear.
 
For now I am going to be running stock turbo, and I have been told to run 18-20 degrees timing. The wear issue isn't as bad as I want a good tq curve.

The way he explained it was like this: the max power on the torque curve of a Cummins N14 (I think thats what he said it was) is around 1200 rpm, and that is max power and max torque. Since you don't need max power all the time, it starts falling flat about 1500ish.. That way when you get into a load situation, the RPMs fall, thus putting you back into max power again.

He was saying it is the same with this, and you don't want to be running max power all the time because you would loose fuel economy and also put more strain on the engine while cruising because it's wide open all the time.

Just trying to decide whats the best way to go..

I am definitely going to put in a Hamilton big stick, since the stock cam is coming out anyways.
 
I have 3K kit in my '98 auto and it pulls strong to 3500 and will hit the peg at 4000. I say go with the 3K kit.
 
ashby said:
For now I am going to be running stock turbo, and I have been told to run 18-20 degrees timing. The wear issue isn't as bad as I want a good tq curve.

The way he explained it was like this: the max power on the torque curve of a Cummins N14 (I think thats what he said it was) is around 1200 rpm, and that is max power and max torque. Since you don't need max power all the time, it starts falling flat about 1500ish.. That way when you get into a load situation, the RPMs fall, thus putting you back into max power again.

He was saying it is the same with this, and you don't want to be running max power all the time because you would loose fuel economy and also put more strain on the engine while cruising because it's wide open all the time.

Just trying to decide whats the best way to go..

I am definitely going to put in a Hamilton big stick, since the stock cam is coming out anyways.
Click to expand...


Running at a steady speed on a level highway will consume the same amount of fuel regardless of which GSK you have in. Based on what you just said, I would take everything your buddy says with a very large grain of salt.
 
Interesting.
I take everybody's info with a grain of salt and then ultimately decide what to do for myself.

I agree with this, but he is also way older than me and has probably 30+ years of experience diesel mechanic. Not defending what he said, just saying, hes not just saying stuff to say it.
 
Big Blue24 said:
4K governor springs fuel harder from just off idle till 3800 rpm +/- depending on setup.

The only down side to 4K springs is a more touchy throttle.


I agree that heavier valve springs will cause more wear than stock springs. The question is, do you care if your valves only last 500,000 miles instead 600,000 miles? Now if you spin big RPM 4000+ and have extra heavy valve springs, they will obviously wear much faster.

If you're worried about wear, add a bottle of STP oil treatment each time you change your oil. It has extra Zinc to help minimize valve train/camshaft wear.
Click to expand...

The face of the valve sees no oil whatsoever. The stp or an oil additive is a great idea for less wear on oiled parts like the tappets, camshaft, or rocker fulcrums but will have no affect on the valves. As far as valve wear, that was a stock engine with stock springs, which in my opinion will greatly increase wear on valve seats and valves in a performance application. Stock springs allow the valve to close harder than with heavier valve springs the reason being that if a valve "floats" certain parts of the valvetrain loose contact with the valve when the rocker, pushrod and tappet are closing. THis lets the valve freefall to a closed position and bounce off of the seat greatly accelerating wear. If you have enough seat pressure and the valves never float then the cam closing ramp rate multiplied by rpm(1/2 the speed of crankshaft rpm) dictates the speed at which the valve meets the seat. Keep in mind that the original bullydog springs were around 180# at the seat and had no valve face problems.

On the 4k kit. I have always liked them in tow rigs if you have a conservative plate. They allow you to run rpm up enough so that when you shift into the next gear you are right in the meat and taters of the torque curve and you don't lug your 5th gear nut off. If you have a lot of fuel at the higher rpm with larger plates it will get damn toasty. In short I disagree with everything he said. Please forgive me if I come off arrogant, I just want you to make informed logical decisions. As for the 181/210, I hear they work well, again just an opinion.

Zach
 
sounds like you have a good diesel mechanic that just may not know the aftermarket performance aspects of these engines....
 
A local cummins dealer ship told me the same thing. your wearing the pump down with those 4ks your doing this, that, blah blah blah wrong! and went through everything i was doing wrong and told me my truck would fall apart in the next 10k miles....

10k later my truck runs even better than before.
 
ashby said:
Interesting.
I take everybody's info with a grain of salt and then ultimately decide what to do for myself.

I agree with this, but he is also way older than me and has probably 30+ years of experience diesel mechanic. Not defending what he said, just saying, hes not just saying stuff to say it.
Click to expand...

sorry, but he is just saying stuff just to say it...

a 4k kit doesn't change your torque and power curves... it effects the governor section of the pump and allows the pump to continue fueling to a higher RPM. that's it.
 
Forrest Nearing said:
sorry, but he is just saying stuff just to say it...

a 4k kit doesn't change your torque and power curves... it effects the governor section of the pump and allows the pump to continue fueling to a higher RPM. that's it.
Click to expand...

Well said.

I'm actually debating a 4k for towing, because of the additional fuel down low.
 
What Zach said. Valves chaotically bouncing off the seat due to lack of valve train control will destroy things 9 times as fast (throwing a number out) as ones running more spring pressure to control conditions present in aftermarket modified cummins apps turning 3500+ and seeing 50+ psi.
 
I'm hoping my 4k kit moves my power band up slightly. This 2400rpm crap sucks.
 
BgBlDodge said:
I'm hoping my 4k kit moves my power band up slightly. This 2400rpm crap sucks.
Click to expand...

its not gonna move the power band up, its gonna extend it, so your not limited to 2400rpm. If you were still on the stock turbo and switched to an a5k that would move your power band up to around 2100 or so vs. having lots of low rpm tq and hp with the stock turbo.
 
Yeah, he's got a 66/71, not real well matched for the RPM his GSK is forcing him to live withLOL
 
The heavy springs will were the valves quicker, but that is better that runnig stock springs with any governor spring kit.
 
As stated before, a 4k kit will not move your power curve up, it will only extend it. A cam, turbo, timing will MOVE your power curve where the gsk only controls how long and how hard the pump will fuel the engine. Break it down logically to what the gsk is doing and you can answer your own questions sometimes. If you are not removing fuel at lower rpms (below 2300 or so), the power curve would not go down correct?

I tow and drive a 4k kit all day and love it with a 3.54. Had a friend upgrade a 3k to 4k within a few months and said he would never go back (manual tranny). It all depends on how you want your truck.
 
Move up, extened, whatever, I'd just like more than 600rpms to play with. LOL
 
You must log in or register to reply here.
Back
Top