T
I was wondering if anybody has figured out how to use DPM with the turbo setup on the rev. It would be nice to run like it use to stock. Any info would be helpful.
turbo DPM
- Thread starter turborev
- Start date
nope....everyone uses power jets....
T
yes i do run the power jets but would like to try to get the DPM running.
S
at the moment i dont know all the details but within a month i'll know what you have to do, buddie of mine is turboing his XP.
S
DPM will not work with a turbo. It requires vacuum to operate and the turbo Pressurizes the intake.
Summitguy is right. Vacuum is needed for DPM to work.
R
I wouldn't say it is impossible to get the DPM system to work with a turbo.
People are right in saying the DPM needs a vacuum to lower the pressure in the bowl and in turn lower the amount of fuel allowed to pass through the jet.
If you add boost this line will become pressurized and push more fuel through the jet, but when the boost is being built you need more fuel. This is just the basics of it. It would take a lot of recalibrating and in my opinion you would have to add a little something, or do some reprogramming to make the system work properly. Anyway as Stalefish said there are people working on it, and I hope they get it working.
Cheers
People are right in saying the DPM needs a vacuum to lower the pressure in the bowl and in turn lower the amount of fuel allowed to pass through the jet.
If you add boost this line will become pressurized and push more fuel through the jet, but when the boost is being built you need more fuel. This is just the basics of it. It would take a lot of recalibrating and in my opinion you would have to add a little something, or do some reprogramming to make the system work properly. Anyway as Stalefish said there are people working on it, and I hope they get it working.
Cheers
T
thanks for the info. If there is anything that a guy can do to help with the figuring out of it i would be willing to help.
0
DPM would be out the window with a turbo...
But, on the other hand, a person could just as easily design a different type of fuel enrichment setup. Like using solenoid controlled powerjets (which are already mfg'd, they are built into the carb on TMX style) and somehow programming the MPEM (with use of a map sensor) to operate these secondary powerjets for enrichment under boost.
Probably 100000000x easier said than done, its easily done with a seperate standalone PCM, i dont know if that would be possible with any factory MPEM...
But, on the other hand, a person could just as easily design a different type of fuel enrichment setup. Like using solenoid controlled powerjets (which are already mfg'd, they are built into the carb on TMX style) and somehow programming the MPEM (with use of a map sensor) to operate these secondary powerjets for enrichment under boost.
Probably 100000000x easier said than done, its easily done with a seperate standalone PCM, i dont know if that would be possible with any factory MPEM...
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H
So why can't you use a vacuum storage system? Very lite. They have used them in the auto industry for 25 years!
0
Thats going to take one hell of a vac reserve canister to lower the pressure in the float bowls when you have 10psi+ of boost at XXXcfm pressurizing it!
H
You're saying the float bowls are pressurized (eg) 10 psi ?
he ment under 10 psi off boost. vs 10 pounds of vaccum.
we are working very hard on this problem and will soon have a fix. By the time we a done you can take away fuel or add fuel on the bars or tank.
Watch close.
oh ya the bowls are pressurized.
Watch close.
oh ya the bowls are pressurized.
0
Yes, the bowls pressure up as the boost increases, that is why you have to raise fuel pressure with the boost or else the air will blow the fuel out of the bowl and back up the lines!
F
few questions for the wise dpm guys
this last year i bored my carbs from 40 to 42mm and have been very happy with overall performance gain on my engine setup, and would do it again
now for my insight
last year on the stock 40mm carbs, i was seeing around the 1250egts on average, with mid range spikes to 1350f
this year with the 42mm carbs i was told to raise pilots needles and mains to compensate for lower air velocity from larger bore lessing fuel threw jetting and leaning motor egts
so i went to 550 mains, 30 tho shims under needle clips, and 20 pilots... on the 42mm carbs....(prevous jetting was 460mains, 30 thou shims, and 17 pilots on stock 40mm carbs)
now for what i have found this year, is egts have been under 1000f for most part, and since then i have slowly jetted down to 470mains, 20 tho shims and still only seen egts around 1040f on long pulls
now after some more thought i have wondered if the dpm has been the culprit, adding more fuel with the larger bore carbs??
from what i have read, i thought the dpm works under vacume and increases or decreases float bowl pressure as what it reads from the barometric and ecm?? which in this case i would think reads a lower pressure from carb boring and leans fuel... but this is not happening... rather the opposite
now for my questions, how many jet sizes does a dpm compensate for, if i remember right i thought it was around 100 main jet sizes, and would you think a dpm would still work with the larger bore carbs?? or will it not fuction properly and lean out engine
i know as i am slowly dropping mains i am getting closer to projected egts, i just want to know how dpm will manage after
engine has been running sweet with lower egts but do feel i am losing a few hp from it(and plugs and piston wash also reflect richness)
we will be dynoing soon and bscf will be monitoured, but would like some info from guys that have maybe some insight on this issue
thanks for your help
this last year i bored my carbs from 40 to 42mm and have been very happy with overall performance gain on my engine setup, and would do it again
now for my insight
last year on the stock 40mm carbs, i was seeing around the 1250egts on average, with mid range spikes to 1350f
this year with the 42mm carbs i was told to raise pilots needles and mains to compensate for lower air velocity from larger bore lessing fuel threw jetting and leaning motor egts
so i went to 550 mains, 30 tho shims under needle clips, and 20 pilots... on the 42mm carbs....(prevous jetting was 460mains, 30 thou shims, and 17 pilots on stock 40mm carbs)
now for what i have found this year, is egts have been under 1000f for most part, and since then i have slowly jetted down to 470mains, 20 tho shims and still only seen egts around 1040f on long pulls
now after some more thought i have wondered if the dpm has been the culprit, adding more fuel with the larger bore carbs??
from what i have read, i thought the dpm works under vacume and increases or decreases float bowl pressure as what it reads from the barometric and ecm?? which in this case i would think reads a lower pressure from carb boring and leans fuel... but this is not happening... rather the opposite
now for my questions, how many jet sizes does a dpm compensate for, if i remember right i thought it was around 100 main jet sizes, and would you think a dpm would still work with the larger bore carbs?? or will it not fuction properly and lean out engine
i know as i am slowly dropping mains i am getting closer to projected egts, i just want to know how dpm will manage after
engine has been running sweet with lower egts but do feel i am losing a few hp from it(and plugs and piston wash also reflect richness)
we will be dynoing soon and bscf will be monitoured, but would like some info from guys that have maybe some insight on this issue
thanks for your help
S
Been able to do that for years... its call remote power jet adjusters.
F
The first thing that comes to my mind is (if I remember right) the DPM gets its vacuum source just behind the carbs, on the engine side. With a larger bore, you loose air velocity, which reduces the vacuum the DPM would normally see (I would suggest you double check to make sure you don't have any broken fittings or leaking hoses from your carbs to your DPM - this can easily happen when removing/reinstalling the carbs). So with a weaker vacuum signal, you will have more fuel.
I always liked the idea of the manual adjustability of the Holtzman variflow, and wondered why not use it on a turbo, or better, control it electronically according to boost, or just take over control of the DPM that is already there. But I never found the time or money to spend developing this - it would be cool to see it work for those running carbed turbos...
