13mm pump, low power
- Thread starter Vincejax
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Ive had it on the test stand with the same exact injectors as are in the truck. The issue we ran into is the stand didnt have enough power to pump 600+cc's (pump maxed at 850) of fuel at 4-5000rpm. So flow calibration was done at 2000rpm and baseline governor setting and then I tightened springs more on the truck. Although tightening them showed slight improvement, it did not remedy the issue. My question is, what else within the pump could limit high rpm fueling? I have ran it with no afc and low end smoke was horrendous, but it was still starved for fuel above 2500rpm. Are there other adjustments that can be made to the governor to raise rpm besides tightening the springs?
Maybe, but I like playing detective first.
Destroked 450
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Does it still have the 175's slow fill pump cam, if the cam isn't letting the fuel in it doesn't matter what size p&b's you have.
I've read of guy's pushing 60-80 psi fuel pressure against a 160/175 pump just to keep good flowing 12mm p&b's filled.
I've read of guy's pushing 60-80 psi fuel pressure against a 160/175 pump just to keep good flowing 12mm p&b's filled.
This is what I think is the problem, the cam.
This doesn't explain why the truck is >500hp and has very low power above 2500rpm. Same cam in pump before with 12mm p+b and the truck would scream past 4k under load if I didn't shift fast enough. Now it won't even rev over 3700 or so. Also, the 13mm p+b also have larger spill ports, so require less fill time.
Destroked 450
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A 160 cam only allows fuel into the p&b's for a short period of time, I'm not a pump expert but I'm thinking it's around half the amount of time a 180/215 cam allows fuel in.
Look at it like this.
Take a 8 oz cup (12mm p&b) turn on you kitchen faucet for 5 seconds (160 cam), how much water do you have in the cup?
With the same 8 oz cup (12mm p&b) turn on the faucet for 10 seconds (180 cam), it probably over flowed the cup (12mm p&b where filled).
Now replace the 8 oz cup (12mm p&b) with a 12 oz glass (13mm p&b), turn on the faucet for 5 seconds (160 cam), you'll get the same amount of water in the glass (13mm p&b) as was in the 8 oz cup (12 mm p&b).
The problem is that 5 seconds (160 cam fill time ) wasn't enough time to fill the 12 oz glass (13mm p&b), since the glass isn't full what else is in it, AIR.
Everyone knows a diesel engine with air in the fuel system runs like poo.
A simple test will tell, crank up the fuel pressure another 25 psi, if the engine runs better the pump cam is the problem.
You can get more water from a faucet in the same amount of time at 75 psi than you can at 40 psi, this is why I've read several post of guys having to run 75-100 psi fuel pressure to make power with a 160 pump cam because it doesn't allow enough time to fill the p&b at lower fuel pressures.
As others have said, I've never heard of a 13mm pump with a 160 pump cam, I'd say lack of sufficient fill time is the reason.
Look at it like this.
Take a 8 oz cup (12mm p&b) turn on you kitchen faucet for 5 seconds (160 cam), how much water do you have in the cup?
With the same 8 oz cup (12mm p&b) turn on the faucet for 10 seconds (180 cam), it probably over flowed the cup (12mm p&b where filled).
Now replace the 8 oz cup (12mm p&b) with a 12 oz glass (13mm p&b), turn on the faucet for 5 seconds (160 cam), you'll get the same amount of water in the glass (13mm p&b) as was in the 8 oz cup (12 mm p&b).
The problem is that 5 seconds (160 cam fill time ) wasn't enough time to fill the 12 oz glass (13mm p&b), since the glass isn't full what else is in it, AIR.
Everyone knows a diesel engine with air in the fuel system runs like poo.
A simple test will tell, crank up the fuel pressure another 25 psi, if the engine runs better the pump cam is the problem.
You can get more water from a faucet in the same amount of time at 75 psi than you can at 40 psi, this is why I've read several post of guys having to run 75-100 psi fuel pressure to make power with a 160 pump cam because it doesn't allow enough time to fill the p&b at lower fuel pressures.
As others have said, I've never heard of a 13mm pump with a 160 pump cam, I'd say lack of sufficient fill time is the reason.
The depth and angle of the helix as well as the spill port size are much bigger factors for injection duration and fill time than cam profile. Even considering that the 13mm p+b has a deeper helix and larger spill port. Both would cause a gain in upper rpm power (even if ultimately limited by cam profile at some eventual point) Lets get off the cam subject because the pump cam profile is definitely not the reason for this issue. All signs point to a governor calibration issue. I have bumped up supply pressure to the injection pump already and power showed no improvement.
Also the difference between the 215 and 175 cam is not fill time, it is lift. The 215 cam has slightly more lift. But 12mm plungers have a shallower helix than 13mm plungers and don't take advantage of all the lift from the cam anyway.
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Destroked 450
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Well looks like your the pump expert.
I've read several post and even had a conversation with Seth Farrel about the differences in the fill times between pump cams, so at this point all I can say is good luck, hope you figure it out.
I've read several post and even had a conversation with Seth Farrel about the differences in the fill times between pump cams, so at this point all I can say is good luck, hope you figure it out.
You aren't making a case that you know what you are talking about when you use terms like "slow fill cam" and "good flowing 12mm p+b". Namedropping someone else that may be an expert doesn't increase the validity of your points either. I'm looking for technical data, not secondhand speculation based on internet rumor.
95cummins5.9
Old man ***** gossiper
Throttle stop screwed all the way in?
95cummins5.9
Old man ***** gossiper
You mess with the height of the Gov arm? Could bind I bet, get stuck under the plate etc. I'm sure you made sure the woodruff is on the shut off shaft too?
Destroked 450
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As I said earlier I'm not a pump expert and some times use the same internet jargon as others instead of 903 cam, quick rate, ect.
Guess I should have said good flowing 12mm pump instead of p&b, sorry it confused you.
Since I dropped a name I'll do it again.
Farrell Diesel Service is a sponsor on this forum and a name I hear more often than any other when it comes to injection pumps.
Since your only wanting technical data about your inj pump, it would probably be best obtained from a professional pump shop, I suggest you contact one.
95cummins5.9
Old man ***** gossiper
Seth is the only guy I'd ever have do another pump for me. I've tried a few other shops, Seth's run the best, I'm sure he would give you the 5 mins of his time to help you out too bud.
95cummins5.9
Old man ***** gossiper
I have a pump from Kevin on my 95. Granted it's only a 175 vs Seth's 215. I'll pick that 215 all day.
Well that's like comparing an apple to a beer, I'd prefer the 215 also.
YOUNG GUNS15
Im AWESOME!!!!
Remember, the pump turns half speed of engine rpm. 2000 pump rpm = 4000 engine rpm. So calibrating it at 6000rpm on the stand would be 12000rpm engine speed. Lol
Honestly whoever set it up MOST LIKELY didn’t set the governor up properly, AND, your going to fight the cam for awhile, 13mm pumps are super fun when setup correctly, if not, well you already know it’s a pain. Dealing with a slow fill cam is going to make upgrading to 13mm p&b’s less of a benefit.
I had a somewhat similar issue with a 215 pump (which was totally rebuilt into the 13mm pump I have now) where after swapping the original 160 out ran softer 2500-3500rpm. Couldn’t really pin it down where I was loosing power. Made a max effort of 740hp on nitrous and 620 on fuel. After being rebuilt turns out the shop I was using had left a screw out on the governor arm and had totally set the governor wrong for what I was trying to do. After the 13mm rebuild, and almost zero tuning time it produced 748hp fuel only and 878hp on nitrous. Granted it’s not a perfect back to back comparison since the Motor was rebuilt, but the pump seriously makes or breaks everything about how your truck performs. I temporarily swapped another 215 in place of my 13mm and it was obvious that they were not even in the same realm. (Home built 12mm pump vs a shop calibrated 13mm)
Hope you get it figured out.
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Honestly whoever set it up MOST LIKELY didn’t set the governor up properly, AND, your going to fight the cam for awhile, 13mm pumps are super fun when setup correctly, if not, well you already know it’s a pain. Dealing with a slow fill cam is going to make upgrading to 13mm p&b’s less of a benefit.
I had a somewhat similar issue with a 215 pump (which was totally rebuilt into the 13mm pump I have now) where after swapping the original 160 out ran softer 2500-3500rpm. Couldn’t really pin it down where I was loosing power. Made a max effort of 740hp on nitrous and 620 on fuel. After being rebuilt turns out the shop I was using had left a screw out on the governor arm and had totally set the governor wrong for what I was trying to do. After the 13mm rebuild, and almost zero tuning time it produced 748hp fuel only and 878hp on nitrous. Granted it’s not a perfect back to back comparison since the Motor was rebuilt, but the pump seriously makes or breaks everything about how your truck performs. I temporarily swapped another 215 in place of my 13mm and it was obvious that they were not even in the same realm. (Home built 12mm pump vs a shop calibrated 13mm)
Hope you get it figured out.
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When I said we ran the pump on the stand at 2000rpm I meant engine rpm, so pump speed actually 1000. I went to swap governor springs yesterday and noticed one side of the governor is damaged and the stud the springs go over is bent a bit. I am pulling the pump off and bringing it back to the pump shop to sort this out. This time we are going to gut a set of injectors and set the breakaway on the governor at 5000 engine rpm. With the reduced load the stand will be able to turn that speed no problem. Thanks again for the helpful suggestions. This is a fun hobby for me and I enjoy figuring out how it all works just as much as the racing. Thats why I didnt just send it off and have a pump guy work their "secret magic".