Well here's my question. I'm aware of this cheap pump mod and how you'll gain that extra 500rpms but what does it do to your truck mechanically? Say if I put it on my 310 000km truck would it hurt it from all that milage? Would this mod cause a negative effect on it, like reduce engine life? Say if you kept it below that stock 2700 even once u had it installed, would it be the same as having the stock one in there? The reason I ask this is because I went to an autoparts store and was told that it would be too hard on a truck with so many miles, considering age and all. I read on here and I cant quite decide whether he's right or wrong. Help me out here.

Mike

 

Good question....I've often wondered the same thing....Anybody out there have any ideas?.....I would assume that since the Cummins is such a stout engine it shouldn't hurt?

 

If you keep it below 2700 then why do it in the first place? I think the object is to be able to wind it up a little higher when going through the gears without the govenor defueling. You will get more top end if you floor it in high gear but why would you want to do that for long?

I think the engine life will depend more on how you drive than anything else. If you keep it floored it won't last as long as if you just drive normally. The fact that you can wrap it tighter going through the gears doesn't mean you keep it there for long. I don't think it will have that much effect on engine longevity. IMHO.

Edwin

 

Hi well the the truck may be old but the engine is still young 310,000km is only 180,000miles i belive the average rebuild is 350,000miles or 560,000kms many are out there with 3/4 million miles untouched the parts guy must be used to psd's

 

well if you run it wide open all the time sure you will get increased wear but I never run my truck a full throttle except for a few time now and then. 500 rpm is not that much. what i have noticed is with the automatic its a lot better throttle responce my top speed is still 83 mph but I can hold it now on a grade. plus my foot is no longer smashed on the floor driving there its more like 1/3 down.my trucks got over 250K and for me I think it was the best mode i did .even if I would have never turn the fps it pulls through the gears now instead of feeling like its falling flat. if the motors had good PM done to it no reason it wont go 1/2 mill miles or more

 

bushy will tell u i was one of the first on this board to install the 3200 gov. spring . it is probably the best mod i have done to my truck. will NEVER go back.

 

The only situation where I can see the 3200 RPM spring shortening the engine's life would be if somebody with a 3 speed automatic used the extra 500 RPM to raise their cruise speed. I'd expect that to knock 10% off the life of the engine if it ran mostly on the highway- so you go 270k instead of 300k average life.

If you're just using it the keep the transmission from hanging or to help with the 2-3 shift on the Getrag, or downshifting to reduce EGT while towing I wouldn't expect it to reduce engine life by a noticeable amount.

It's not just a hot-rod mod, it really will help towing performance as well. You can drop out of overdrive at 65-70 and still have plenty of power instead of having the truck bog down to 55-60. RPM is your buddy when you're pulling a heavy load.

 

all these posts, and im still waiting for mine, my fuel pin from pdr is holding up my shipment of the spring . AHHH, drving me nuts.. jiMMy

 

This does not seem to be a problem with anyone who has installed the new spring, but I have had it happen to old gasoline engines:

Over time, the piston rings wear into the cylinder walls, and form a lip, or "ridge" at the top of the cylinder where they stop sliding at top dead center. The problem is that while the engine is running the connecting rod stretches and compresses as the piston goes up and down. It stretches more at higher rpms, because the piston speed is higher. If you suddenly start runing an engine that is "broken in" at a higher rpm than it was ever run before, the top ring will start smacking into that ridge. If the ridge is deep enough and "sharp" enough, it will break the ring or piston. In some cases I have seen scoring, even without anything breaking.

This doens't seem to be a problem with these engines -- I think because they experience such little cylinder wear that not much of a ridge forms -- but I figure it is something for each BOMBer to take into consideration.

 

I'm getting mine 4/30


Man, I can't wait

 

Hey! I am looking to do this mod as well as the fuel pin. Does anybody have any of the part #'s for these items? My 92 is screaming for a little more power!!!!!

 

just call PDR and tell them what you want, thats what i did.

jiMMy

 

I'm going to explain what your going to see with the 3200 spring and what your not going to see from my experience with an auto. High idle adjustment at full and 2 turns Full P screw only. Stock otherwise.

Your going to find that the RPM band is broader, the engine will be fueling and keeping boost at 2600-2700 instead of falling off. The truck is going to continue to shift near it's previous shift points.

Shift RPM is controlled by the governor in the transmission (near output shaft) and shift quickness and quailty by the kickdown lever.. If you lock out OD it will pull to 3200 at max boost in 3rd. I hit the OD at that point, but it was stilling fueling and not laying over.

Your not going to see 1st gear to 3200, 2nd gear to 3200, etc. It will pull strong to each shift point, but it will be in it's regular 2600-2800 range. You'll also notice a midrange half throttle difference. The truck will fuel better in these situations because the strength of the new spring is going to keep it from reaching that sycronized "spring/governer weight" balance as quick as the stong spring...that is my guess.

I would call it and extra 400 RPM, because with the stock spring I could achieve 2800 ..but as it approached that point it was already defueling

Looking at the size of the connecting rods in this thing and other internals, I'm not really worried about it. I worry more about EGT's, Water temps, etc. What are the new engines turning? 3500-3800?

Den

 

Thanks for the info all. I kept wundering about this modification and within a couple months I'll be thinking of gettin it done. I figured it wouldn't hurt anything because why would so many people use them eh?

Right now I've got a few other things to juggle but oh well. Gauges are a must have so once that's tackled the spring'll be the next on my hit list.

Thanks Again

 

Thats what I would be worried about, with this bore/stroke ratio-Bore x Stroke: 4.02 x 4.72 coupled with the weight of a piston and rod assy (God only knows what those things must weigh....BEEFY) you have a couple of things working against you, 1-piston speed with such a long stroke must be pretty darned high and 2-the inertia from said high piston speed,coupled with the heavy piston/rod assy must place alot of stress on the big end of the rod. Now i should preface ALL of this by saying I am comparing this to my experience with gas engines (this is my first diesel) soooo I`m sure the extra beef in the bottom end can handle it...just makes me a little nervouse. Thats not to say I`m NOT going to get one...it`s on my short list of future bomb`s , just thinking out loud. Oh ....might get a set of 60lb springs too....yeah!