Another question about pop-off pressure

SHughes

SHughes

Too much is never enough!
Joined
Jan 7, 2008
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When converting your VP to a P7100 there is a difference in required pop-off pressure in the injectors. The P7100 system operates at a lower pressure than the VP system. The P7100 has to build more pressure to open injectors that are set for a VP.

When you run injectors set for VP pressures with a P7100, you are going to effectively lower the injection timing. I've been told this may be as much as 8 or 9 degrees. I would also assume that the injector will close earlier as well.

So not only do you have effectively lower injection timing, you will also have an over all shorter injection event. Injection will start later and end sooner. By as much as 16-18 degrees, possibly more or less depending on the pop-off pressures set by the injector manufacurer. Correct?

How does this affect power/smoke/drivability for those of us who have yet to have the injectors reset for lower pop-off pressures??
 
Usually, retarded timing along with short duration = low power and poor throttle response.
 
Thats a good thread now this post was about the best I read

I bought a set of DDP comp 250's this summer, I sent them in to get the pop-off's set for a p-pump conversion. I put them in and noticed the truck started a little harder and noticed it seemed like small drops of fuel coming out of the stacks. I towed a small boat and it completely covered the boat. I sent them back in and had them reset to VP spec's and the truck was fine, starts great and no drops of fuel out of the stacks. Not sure if there was something else wrong or not.

When u run a big set of holes a stock bar either 12/24 does not work the best for most modded applications.. I'v changed my pop alot from low to nose bleed . Now I dunno what Don does different inside I ask Jon and not much is changed unless u want to try some lift stuff

If u got the money best bet is to send yr pump ,lines and injectors and have it all setup on a stand
 
Has anyone checked with a timing light to see how much static timing changed with just a pop pressure change? I can't imagine it was a whole lot...
 
GOT-Torque said:
Has anyone checked with a timing light to see how much static timing changed with just a pop pressure change? I can't imagine it was a whole lot...
Click to expand...


I think some one really should try to.
 
I have talked to the local injection shop they told me I can pay them to set them or just play with my timming. All the change will do is effect timming. I dont know where Im at right now but Im at 20 on the pump and with ddps 175s set for vp and 024s its way up there. Ill put a light on it after work tom. Ill be playing with alot of injectors,dvs and timming so ill note all the changes.
 
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