100+ cc DB2...???
#46
05-02-2012, 03:46 PM
, from the ******* perspective it sounds promising.
#47
05-02-2012, 09:02 PM
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ah, this is sounding so promising.
at the rate you are going now i might need to buy you a beer once you are done, for opening up the potential of these pumps lol
what size is down though the injector? it look about .085"
if it is there is no reason for any of the hole on the hp side to be any bigger is there? (unless it is to modify timing)
at the rate you are going now i might need to buy you a beer once you are done, for opening up the potential of these pumps lol
what size is down though the injector? it look about .085"
if it is there is no reason for any of the hole on the hp side to be any bigger is there? (unless it is to modify timing)
#48
05-03-2012, 08:03 PM
I saw that post some time back, and it is definately an interesting read, if not for entertainment value at least.
Increasing the fuel pumping capability is the easy part, its the little stuff like port opening duration, and cross section that make for a pump that can deliver the fuel effectively. I think a lot of what he had going, while being well intentioned, was haphazard at best.
He seems to be under the impression that the metering valve is a big restriction in the supply side (Hence the external metering valve bypass), and while under certain circumstances (IE: blueprinting, porting, etc...Well get to that later), I could see it being a restriction, but not in any way is it a restriction in stock form, the galleries to and out of the metering valve, as well as the valve itself are bigger than other aspects of the supply side of the hydraulic head.
So far the biggest restriction (In real terms, obviously pressure has a different effect on things) I can see in all of the pump, is the distribution ports on the head itself. They measure out at .088". This is coming from the bore that the rotor rotates in, and the holes that the fuel is delivered through there, are are .114"... Thats a big difference on the supply side of things. The rotor itself necks down before that though, before it is distributed to the cylinders, the ports on the rotor themselves, are .090"x.100" (Because they are drilled at an angle). Upstream from there, the next restriction is the delivery valve, which (I need to check again) is 2 holes at .073" each, which isnt the smallest cross section wise. After that is the orifice into the pumping chamber, and that is the biggest opening on the line. Thats the pressure side of the pump...
I havent measured the supply side of things yet, so ill update that front when I get there.
As far as the blueprinting mentioned above, this is what i have found. First of all, this pump was meant for one thing, and thats to pump fuel into a diesel engine in the narrowest of RPM ranges (Maybe not as narrow as a P-pump, or other non-advancing pump) and delivering the fuel to an engine that isnt in high demand for it. The ports in the hydraulic head are simply drilled holes without any sort of smoothing of action, nor timing allowance in the function of their fuel delivery. There is a lot of work that can be done to help this out...
First of all being an 8 cylinder pump, the cylinders are divided in 45* increments, and those are divided in half between the filling and pumping action. That means that the plungers have 22.5* of rotor movement to fill the pumping chamber, and 22.5* to pump the chamber into the heads of the engine. One issue I have found so far is that the rotor bore (Larger orifice) gallery diameter of .114" is only 14* of the rotor rotation, that leaves 8.5* of improvement to be had, or Opening the holes up to .160" (To solve the duration problem, and open the cross section for more fuel) If one part of the equation is opened up, Than the rest should be as well, So I am going for a gallery diameter of .160" all the way through the pumping side of the pump. This should smooth the pump action out significantly, at least on the pressure end.
Like I said, I still have to work out the supply end, and Im sure there is a bunch of stuff I have missed here tonight, but its late, and im tired, and Im going to bed...
So more when I feel like it... Lol.
Increasing the fuel pumping capability is the easy part, its the little stuff like port opening duration, and cross section that make for a pump that can deliver the fuel effectively. I think a lot of what he had going, while being well intentioned, was haphazard at best.
He seems to be under the impression that the metering valve is a big restriction in the supply side (Hence the external metering valve bypass), and while under certain circumstances (IE: blueprinting, porting, etc...Well get to that later), I could see it being a restriction, but not in any way is it a restriction in stock form, the galleries to and out of the metering valve, as well as the valve itself are bigger than other aspects of the supply side of the hydraulic head.
So far the biggest restriction (In real terms, obviously pressure has a different effect on things) I can see in all of the pump, is the distribution ports on the head itself. They measure out at .088". This is coming from the bore that the rotor rotates in, and the holes that the fuel is delivered through there, are are .114"... Thats a big difference on the supply side of things. The rotor itself necks down before that though, before it is distributed to the cylinders, the ports on the rotor themselves, are .090"x.100" (Because they are drilled at an angle). Upstream from there, the next restriction is the delivery valve, which (I need to check again) is 2 holes at .073" each, which isnt the smallest cross section wise. After that is the orifice into the pumping chamber, and that is the biggest opening on the line. Thats the pressure side of the pump...
I havent measured the supply side of things yet, so ill update that front when I get there.
As far as the blueprinting mentioned above, this is what i have found. First of all, this pump was meant for one thing, and thats to pump fuel into a diesel engine in the narrowest of RPM ranges (Maybe not as narrow as a P-pump, or other non-advancing pump) and delivering the fuel to an engine that isnt in high demand for it. The ports in the hydraulic head are simply drilled holes without any sort of smoothing of action, nor timing allowance in the function of their fuel delivery. There is a lot of work that can be done to help this out...
First of all being an 8 cylinder pump, the cylinders are divided in 45* increments, and those are divided in half between the filling and pumping action. That means that the plungers have 22.5* of rotor movement to fill the pumping chamber, and 22.5* to pump the chamber into the heads of the engine. One issue I have found so far is that the rotor bore (Larger orifice) gallery diameter of .114" is only 14* of the rotor rotation, that leaves 8.5* of improvement to be had, or Opening the holes up to .160" (To solve the duration problem, and open the cross section for more fuel) If one part of the equation is opened up, Than the rest should be as well, So I am going for a gallery diameter of .160" all the way through the pumping side of the pump. This should smooth the pump action out significantly, at least on the pressure end.
Like I said, I still have to work out the supply end, and Im sure there is a bunch of stuff I have missed here tonight, but its late, and im tired, and Im going to bed...
So more when I feel like it... Lol.
Just kidding. This is insane the amount of knowledge you can get from this site. Eff OBN.
I'm gonna start taking notes of what Racin says just so I can sound like a mechanical genius myself.
#49
05-03-2012, 08:18 PM
Ok, so I need to backtrack a little bit, I went over all my math, and I found some big mistakes which changes everything I said the other night, and put things more inline with what I have known about this pump in the past.
For my mistake, I was just figuring port duration of the largest port and not "port-over-port" duration, which is substantially more than I thought on the stock setup. What this means is that the stock port timing is maxxed out (As it should have been for a good design). Now the drawback to that, is simple and for the most part, fatal as far as this pump is concerned. All 8 cylinders share the same pumping chamber and gallery on both the supply and pumping side of the pump, and are only separated by the timing of the already maxxed out port cross-section. That means that there is nothing you can do by "drilling" (like I had previously thought), and beyond that, the rotor and barrel can only either be EDM'ed, or slotted on a mill (very slight chance), to open up the cross section axially for more flow. Now that this is something I have confimed, it also limits the pump capability substantially, because to make up for duration, you have to have a very fast precise higher pressure injection moment delivered by the cam ring, as well as a very fast precise higher pressure filling moment provided by the transfer pump. The cam ring issue is easily solved, because the roller contact is limited with less leaf spring adjustment, by increasing the plunger diameter as far as possible, or by running more plungers (DB4). Thats that on the supply side, not much to it. However the filling side is a little bit more tricky, because we have the advance mechanism in the mix. Now I think we can get around this by putting a stiffer spring in the advance mechanism, and cranking the transfer pump pressure, or its also a possiblity that we can just deleted the hydraulic advance all together, and use a trim screw (The crude way of doing it). We can also drill more fill holes in the rotor (DB2 has 2, DB4 has 4, You could have 8 if you wanted). The Housing is also a big weak link too, because of the harmonics associated with having to pump so much fuel so fast.
The main point that I wanted to make after figuring all of this out on my own, is that most of this stuff I have heard second hand via Ken from DPS, and its falling right in line with what I have found myself. So, I want to say again, that I am no cheerleader for Ken, I dont get any special deals, the only thing that I have bought from him directly is a set of injectors, but he KNOWS what he is talking about when it comes to these pumps. There is a reason he feels that the DB4 is the most reliable option for these pumps, and thats because of the amount of fuel they put out over a certain degree of timing. However, I am of the opinion that a large plunger DB2 can do the same thing, provided the rotor is adequately modifed to be on par with the DB4 one.
So all in all... I think the overall output of the DB pumps (8 cylinder at least, I bet better things could be done with 4 and 6 cylinder pumps, and the reason the 4 and 6 VE pumps do so much better, an 8cyl VE would have the same limitations as the DB) is going to be less than what I thought, but I still think that there is the potential to have a DB4 rated DB2 and as reliable, its just a matter of getting the thing smooth, and I think that can be done with cam ring timing.
Hopefully Im right this time...
For my mistake, I was just figuring port duration of the largest port and not "port-over-port" duration, which is substantially more than I thought on the stock setup. What this means is that the stock port timing is maxxed out (As it should have been for a good design). Now the drawback to that, is simple and for the most part, fatal as far as this pump is concerned. All 8 cylinders share the same pumping chamber and gallery on both the supply and pumping side of the pump, and are only separated by the timing of the already maxxed out port cross-section. That means that there is nothing you can do by "drilling" (like I had previously thought), and beyond that, the rotor and barrel can only either be EDM'ed, or slotted on a mill (very slight chance), to open up the cross section axially for more flow. Now that this is something I have confimed, it also limits the pump capability substantially, because to make up for duration, you have to have a very fast precise higher pressure injection moment delivered by the cam ring, as well as a very fast precise higher pressure filling moment provided by the transfer pump. The cam ring issue is easily solved, because the roller contact is limited with less leaf spring adjustment, by increasing the plunger diameter as far as possible, or by running more plungers (DB4). Thats that on the supply side, not much to it. However the filling side is a little bit more tricky, because we have the advance mechanism in the mix. Now I think we can get around this by putting a stiffer spring in the advance mechanism, and cranking the transfer pump pressure, or its also a possiblity that we can just deleted the hydraulic advance all together, and use a trim screw (The crude way of doing it). We can also drill more fill holes in the rotor (DB2 has 2, DB4 has 4, You could have 8 if you wanted). The Housing is also a big weak link too, because of the harmonics associated with having to pump so much fuel so fast.
The main point that I wanted to make after figuring all of this out on my own, is that most of this stuff I have heard second hand via Ken from DPS, and its falling right in line with what I have found myself. So, I want to say again, that I am no cheerleader for Ken, I dont get any special deals, the only thing that I have bought from him directly is a set of injectors, but he KNOWS what he is talking about when it comes to these pumps. There is a reason he feels that the DB4 is the most reliable option for these pumps, and thats because of the amount of fuel they put out over a certain degree of timing. However, I am of the opinion that a large plunger DB2 can do the same thing, provided the rotor is adequately modifed to be on par with the DB4 one.
So all in all... I think the overall output of the DB pumps (8 cylinder at least, I bet better things could be done with 4 and 6 cylinder pumps, and the reason the 4 and 6 VE pumps do so much better, an 8cyl VE would have the same limitations as the DB) is going to be less than what I thought, but I still think that there is the potential to have a DB4 rated DB2 and as reliable, its just a matter of getting the thing smooth, and I think that can be done with cam ring timing.
Hopefully Im right this time...
#50
05-03-2012, 08:54 PM
#51
05-03-2012, 09:03 PM
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i would tune it for higher rpm/ more advance seeing as that is when you really need the high fuel flow.
edm, i want to learn about that
it would be nice to get in there when it is running to sample pressure/vaccume at points of interest.
what kind of pressure should the transfer pump put out? it's a rotary vane pump isn't it?
what if you could tap in right before the pump and just run a high pressure pump before in place of it, using the transfer pump as the advance only?
i have a bad habit of making things way to difficult.
what if you were to make a gallery before the barrel?(assuming that is also where the fuel enters the hp pump)
i almost think a small air pocket would help it by adding a spring effect to the fuel after the transfer pump so that it can build pressure and in that little bit, shoot more into the hp piston.
edm, i want to learn about that
it would be nice to get in there when it is running to sample pressure/vaccume at points of interest.
what kind of pressure should the transfer pump put out? it's a rotary vane pump isn't it?
what if you could tap in right before the pump and just run a high pressure pump before in place of it, using the transfer pump as the advance only?
i have a bad habit of making things way to difficult.
what if you were to make a gallery before the barrel?(assuming that is also where the fuel enters the hp pump)
i almost think a small air pocket would help it by adding a spring effect to the fuel after the transfer pump so that it can build pressure and in that little bit, shoot more into the hp piston.
#52
05-03-2012, 11:49 PM
***: Yes
And PM sent...
i would tune it for higher rpm/ more advance seeing as that is when you really need the high fuel flow.
Thats where im going with the whole locking the cam ring thing, that way the duration remains constant... The biggest misconception about these pumps is the Advance, the only thing that advances is the cam ring, and that doesnt do much for anything distribution wise. I think it could be made up with the right static timing, and the right camshaft.
edm, i want to learn about that
Its a "machining" process that uses a superheated wire to cut material out of the way, its very precise, and can machine things mechanical machines cant.
it would be nice to get in there when it is running to sample pressure/vaccume at points of interest.
Thats what a pump bench does, but luckily simple pump benches arent rocket science, and thats the plan either way, whether I build one myself or not.
what kind of pressure should the transfer pump put out? it's a rotary vane pump isn't it?
Stock- 40-90psi... But I have heard that it can handle pressures up to 150psi without grenading...
what if you could tap in right before the pump and just run a high pressure pump before in place of it, using the transfer pump as the advance only?
i have a bad habit of making things way to difficult.
I have kicked it around, and while it may work, there isnt a better way of pumping than the transfer pump... It would be easier to figure out another way to dynamically time it... But even then, what for?? P-pumps dont advance, if your after mileage, you probably arent gonna want a pump like this anyway...
what if you were to make a gallery before the barrel?(assuming that is also where the fuel enters the hp pump)
i almost think a small air pocket would help it by adding a spring effect to the fuel after the transfer pump so that it can build pressure and in that little bit, shoot more into the hp piston.
I regular old spring would achieve the same thing, just have to size it right.
Thats where im going with the whole locking the cam ring thing, that way the duration remains constant... The biggest misconception about these pumps is the Advance, the only thing that advances is the cam ring, and that doesnt do much for anything distribution wise. I think it could be made up with the right static timing, and the right camshaft.
edm, i want to learn about that
Its a "machining" process that uses a superheated wire to cut material out of the way, its very precise, and can machine things mechanical machines cant.
it would be nice to get in there when it is running to sample pressure/vaccume at points of interest.
Thats what a pump bench does, but luckily simple pump benches arent rocket science, and thats the plan either way, whether I build one myself or not.
what kind of pressure should the transfer pump put out? it's a rotary vane pump isn't it?
Stock- 40-90psi... But I have heard that it can handle pressures up to 150psi without grenading...
what if you could tap in right before the pump and just run a high pressure pump before in place of it, using the transfer pump as the advance only?
i have a bad habit of making things way to difficult.
I have kicked it around, and while it may work, there isnt a better way of pumping than the transfer pump... It would be easier to figure out another way to dynamically time it... But even then, what for?? P-pumps dont advance, if your after mileage, you probably arent gonna want a pump like this anyway...
what if you were to make a gallery before the barrel?(assuming that is also where the fuel enters the hp pump)
i almost think a small air pocket would help it by adding a spring effect to the fuel after the transfer pump so that it can build pressure and in that little bit, shoot more into the hp piston.
I regular old spring would achieve the same thing, just have to size it right.
#53
05-04-2012, 12:41 AM
So with no advance mechanism, wouldnt that mean that you would either have to run retarded on the top end, or really advanced on the low end? I mean i understand it can be done, but i know also running full timing is hard on the engine at low rpms. We ran our challenger locked out, but it was 4k-6200 in 1/4 mile bursts. When my MSD crapped out in my small block and i was running locked out at 24* you about couldnt start the thing, and had pretty bed detonation under 2500, then pulled like a scalded ape till around 4k and it would start falling off. Basically, not at all street friendly. Which brings me to my next point. What do the Cummins guys typically run for timing with no advance? Im going to guess 18-20* but im probably wrong. Also answers my question about why the CTD guys are always talking about timing and changing it all the time. Maybe not ideal but could just run conservative timing on the street and bump it up for.. more spirited endevours.
#54
05-04-2012, 03:14 PM
That one 6.2 turbo guy I mentioned earlier ran his Db2 build with a locked cam ring also. I really do think that is a good starting point also cus he said it made a lot of difference. As far as him running 50-60psi with his turbo, remember boost is a measurement of restriction and I think those Chevy 6.2/6.5 diesels don't take in air very well just like the 6.9/7.3 cus of their stock cams. That could be one reason he was reading 50-60psi. Also who knows he might have another bottleneck in his system elsewhere too. I have not seen what his turbo setup looks like...
#55
05-04-2012, 05:00 PM
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well what i mean by tap in and measure the pressure is to go before and after every valve and restriction to pinpoint the restriction with out having to guess (although it doesn't really give you flow)
and by the air pocket i meant more of a dampener on the fuel fill process so the fill pressure doesn't drop off in that sudden intake stroke. wasn't sure if you caught that how i meant it or not.
i would say put an actuator on the entire pump, but that would wear out the lines pretty fast i am sure.
i am kinda surprised that the cam and barrel aren't one peace. i would think that would have saved money and made it better.
do you plan on doing all of these changes at one time? might make it hard to trouble shoot if it doesn't feed the truck right. (then again you would have the bench)
i know what edm is :P i just want to get into it, aka do it a little bit.
what is the point of dumping a bunch of fuel in if you can't use it correctly?
and by the air pocket i meant more of a dampener on the fuel fill process so the fill pressure doesn't drop off in that sudden intake stroke. wasn't sure if you caught that how i meant it or not.
i would say put an actuator on the entire pump, but that would wear out the lines pretty fast i am sure.
i am kinda surprised that the cam and barrel aren't one peace. i would think that would have saved money and made it better.
do you plan on doing all of these changes at one time? might make it hard to trouble shoot if it doesn't feed the truck right. (then again you would have the bench)
i know what edm is :P i just want to get into it, aka do it a little bit.
what is the point of dumping a bunch of fuel in if you can't use it correctly?
#57
05-04-2012, 07:55 PM
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#58
05-04-2012, 07:57 PM
So with no advance mechanism, wouldnt that mean that you would either have to run retarded on the top end, or really advanced on the low end? I mean i understand it can be done, but i know also running full timing is hard on the engine at low rpms. We ran our challenger locked out, but it was 4k-6200 in 1/4 mile bursts. When my MSD crapped out in my small block and i was running locked out at 24* you about couldnt start the thing, and had pretty bed detonation under 2500, then pulled like a scalded ape till around 4k and it would start falling off. Basically, not at all street friendly. Which brings me to my next point. What do the Cummins guys typically run for timing with no advance? Im going to guess 18-20* but im probably wrong. Also answers my question about why the CTD guys are always talking about timing and changing it all the time. Maybe not ideal but could just run conservative timing on the street and bump it up for.. more spirited endevours.
That one 6.2 turbo guy I mentioned earlier ran his Db2 build with a locked cam ring also. I really do think that is a good starting point also cus he said it made a lot of difference. As far as him running 50-60psi with his turbo, remember boost is a measurement of restriction and I think those Chevy 6.2/6.5 diesels don't take in air very well just like the 6.9/7.3 cus of their stock cams. That could be one reason he was reading 50-60psi. Also who knows he might have another bottleneck in his system elsewhere too. I have not seen what his turbo setup looks like...
well what i mean by tap in and measure the pressure is to go before and after every valve and restriction to pinpoint the restriction with out having to guess (although it doesn't really give you flow)
and by the air pocket i meant more of a dampener on the fuel fill process so the fill pressure doesn't drop off in that sudden intake stroke. wasn't sure if you caught that how i meant it or not.
i would say put an actuator on the entire pump, but that would wear out the lines pretty fast i am sure.
i am kinda surprised that the cam and barrel aren't one peace. i would think that would have saved money and made it better.
do you plan on doing all of these changes at one time? might make it hard to trouble shoot if it doesn't feed the truck right. (then again you would have the bench)
i know what edm is :P i just want to get into it, aka do it a little bit.
what is the point of dumping a bunch of fuel in if you can't use it correctly?
and by the air pocket i meant more of a dampener on the fuel fill process so the fill pressure doesn't drop off in that sudden intake stroke. wasn't sure if you caught that how i meant it or not.
i would say put an actuator on the entire pump, but that would wear out the lines pretty fast i am sure.
i am kinda surprised that the cam and barrel aren't one peace. i would think that would have saved money and made it better.
do you plan on doing all of these changes at one time? might make it hard to trouble shoot if it doesn't feed the truck right. (then again you would have the bench)
i know what edm is :P i just want to get into it, aka do it a little bit.
what is the point of dumping a bunch of fuel in if you can't use it correctly?
We'll get there, I just wanna see what I can do with one of these first... Hell Id probably try out a CAT pump before a P-pump...Much cheaper and easier to find.
#59
05-04-2012, 09:22 PM
Locking out the cam ring is a worse case scenario, provided the cam pin cant take the fuel, luckily the degrees of cam advance are less than the duration of the port timing, so I dont think the cam ring is detrimental to flow. Again, if the hydraulic advance can be made to work under extreme transfer pressures, than there isnt going to be an issue there.
Who knows why he broke those cam pins though, could have been other issues with his setup... Who knows how rag-tag that guys pre-pump fuel setup was... We will only know when we get something not so "steam-punk" together and run it. As far as boost pressure being a function of restriction, yes, that is true, but only when you have a set amount of flow. Turbo boost isnt dependent on crank revolutions to move air, its dependent on flow through the engine regardless of displacement or RPM. Whether you have a high flowing engine, or a low flowing engine of the same displacement, a turbo is still going to get you your boost where you want it. Yes you will make more power with the higher flowing engine at the same boost, just because there is more air being packed into the engine, but boost pressures could be the same, thats why compressor maps are so important. As for his pressures, I am willing to bet his boost gauge was a little off, but Im sure he was probably in the 40psi range... Did he even have an intercooler? I cant remember if he did or didnt. I just dont see a chevy 6.2/5 handling 60psi of boost, I dont care what magic gaskets you were running...
Ill leave the Air pocket/actuator stuff up to that chevy guy, I have a few other ideas to increase fuel flow that would make such things obsolete. As far as tapping into various areas of the pump, its not really necessary, fluid will be restricted at the point of least cross-section, provided that the pressure remains constant... Being that there isnt multiple pumping points before each cross-sectional change, that sort of stands on its own. Basically, right now, with the stock dimensions of the pump, we are limited to a gallery size of .088" on the supply side, fortunately at 11k psi, you can move some fuel through an .088" orifice. The supply side is a little trickier, because you are limited to the push of the transfer pump pressure... Luckily you can have more than one port on the rotor to fill the chamber, the factory put in 2 (Due to the smaller port duration on the fill side) the DB4 has 4 ports, and you could have an many as 8, essentially doubling the chamber filling capacity/Flow at the same pressure, as a DB4) Once you max these out though, your flat done, thats all the fuel you get. As far as the "Cam and Barrell" not being one piece, I think your referring to the Head and the Barrell, the cam is totally separate. The Head and Rotor barrell are two pieces pressed together.They had to do this because it would have been impossible to machine the ports effectively had the head been in one piece. The beauty of this, is that a larger diameter barrell can be pressed into place, and a larger diameter rotor can be used, keeping the duration the same, but opening the port cross section and allowing bigger holes to be drilled without overlapping the ports. The big drawback here would be friction though, the surface speed would be substantially more. As far as the changes go, I plan to do what I can to the stock stuff all at once, this will be the prototype, and there isnt enough stuff to go wrong for me to worry about figuring out something not right, compared to what i was originally thinking, the amount of mods is WAY less. And if this works out, I might have to get a fancy turbo like NMB2 ordered for his setup...
We'll get there, I just wanna see what I can do with one of these first... Hell Id probably try out a CAT pump before a P-pump...Much cheaper and easier to find.
Who knows why he broke those cam pins though, could have been other issues with his setup... Who knows how rag-tag that guys pre-pump fuel setup was... We will only know when we get something not so "steam-punk" together and run it. As far as boost pressure being a function of restriction, yes, that is true, but only when you have a set amount of flow. Turbo boost isnt dependent on crank revolutions to move air, its dependent on flow through the engine regardless of displacement or RPM. Whether you have a high flowing engine, or a low flowing engine of the same displacement, a turbo is still going to get you your boost where you want it. Yes you will make more power with the higher flowing engine at the same boost, just because there is more air being packed into the engine, but boost pressures could be the same, thats why compressor maps are so important. As for his pressures, I am willing to bet his boost gauge was a little off, but Im sure he was probably in the 40psi range... Did he even have an intercooler? I cant remember if he did or didnt. I just dont see a chevy 6.2/5 handling 60psi of boost, I dont care what magic gaskets you were running...
Ill leave the Air pocket/actuator stuff up to that chevy guy, I have a few other ideas to increase fuel flow that would make such things obsolete. As far as tapping into various areas of the pump, its not really necessary, fluid will be restricted at the point of least cross-section, provided that the pressure remains constant... Being that there isnt multiple pumping points before each cross-sectional change, that sort of stands on its own. Basically, right now, with the stock dimensions of the pump, we are limited to a gallery size of .088" on the supply side, fortunately at 11k psi, you can move some fuel through an .088" orifice. The supply side is a little trickier, because you are limited to the push of the transfer pump pressure... Luckily you can have more than one port on the rotor to fill the chamber, the factory put in 2 (Due to the smaller port duration on the fill side) the DB4 has 4 ports, and you could have an many as 8, essentially doubling the chamber filling capacity/Flow at the same pressure, as a DB4) Once you max these out though, your flat done, thats all the fuel you get. As far as the "Cam and Barrell" not being one piece, I think your referring to the Head and the Barrell, the cam is totally separate. The Head and Rotor barrell are two pieces pressed together.They had to do this because it would have been impossible to machine the ports effectively had the head been in one piece. The beauty of this, is that a larger diameter barrell can be pressed into place, and a larger diameter rotor can be used, keeping the duration the same, but opening the port cross section and allowing bigger holes to be drilled without overlapping the ports. The big drawback here would be friction though, the surface speed would be substantially more. As far as the changes go, I plan to do what I can to the stock stuff all at once, this will be the prototype, and there isnt enough stuff to go wrong for me to worry about figuring out something not right, compared to what i was originally thinking, the amount of mods is WAY less. And if this works out, I might have to get a fancy turbo like NMB2 ordered for his setup...
We'll get there, I just wanna see what I can do with one of these first... Hell Id probably try out a CAT pump before a P-pump...Much cheaper and easier to find.
#60
05-04-2012, 09:25 PM
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well i think i would have had the cam and the outer part of the distribution ports on one part. that way the porting wold always be correct for the cam advance.
just kinda put and intermediate layer in there so that it can advance farther and still line up well effectively making the entire pump turn compared to the input shaft.
hard to explain...
the leaf springs in these don't really act like a spring as must and a flexible retainer do they?
this pump meters the fuel by allowing or stopping the fuel flow to the hp pump right?
so with your foot off the throttle the hp pistons do not extend and just kinda float to the next lobe?
and with your foot deep in the floor board fuel flow into the pistons and pushes the shoe into the leaf spring?
so if you had an air pocket like i was talking, it wouldn't want to idle down because after you let off the throttle the fuel would continue to flow due to the air pressure.
(the air pocket was for a pressurized reservoir) you could still use that, but it would have to be before the valve, i am however still not sure how that would affect the advance.
sorry kinda thinking out loud
just kinda put and intermediate layer in there so that it can advance farther and still line up well effectively making the entire pump turn compared to the input shaft.
hard to explain...
the leaf springs in these don't really act like a spring as must and a flexible retainer do they?
this pump meters the fuel by allowing or stopping the fuel flow to the hp pump right?
so with your foot off the throttle the hp pistons do not extend and just kinda float to the next lobe?
and with your foot deep in the floor board fuel flow into the pistons and pushes the shoe into the leaf spring?
so if you had an air pocket like i was talking, it wouldn't want to idle down because after you let off the throttle the fuel would continue to flow due to the air pressure.
(the air pocket was for a pressurized reservoir) you could still use that, but it would have to be before the valve, i am however still not sure how that would affect the advance.
sorry kinda thinking out loud