Project57idi
New Member
Bravo Will!! Well put!
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New pre-cup idea?
- Thread starter THEFERMANATOR
- Start date
ak diesel driver
6.5 driver
I guess my point was I don't think anyone can expect to change precups and instantly be getting 300 rwhp. Dual IPs aren't in the average 6.5ers budget/skills
Mike K3500
Member
It's already been proven that IDI's in general don't need 2 injection pumps to make 300 or even 400 hp ......
A heavily modded DB4 should do the trick.
A heavily modded DB4 should do the trick.
ak diesel driver
6.5 driver
so when you gonna dyno yours so we know for sure??
Chevypoor
Active Member
I feel like modern technology would benefit the 6.5 since most of the design work dates to the seventies and early eighties. The new Corvette in 84 was a 9.5sec to 60 with 1/4 miles times in the low seventeen. Now your moms Camry runs 0-60 into the 6secs and the quarter in the 14s. I do know this though my old 6.5 gets as good or better mileage than my brother in laws 2012 dmax. His stock truck gets 11-12mpg pulling about 4500lbs and he regularly drops into the low teens in straight city driving empty. Little d would get 13-14mpg pulling a similar trailer and empty it got 18-18.5 city or highway. He does do slightly better than me on the highway as he gets around 20mpg. Obviously he has more power than the ol 6.5. Would be interesting to see what kinda extra power and efficiency we could see from new tech into our old iron.
schiker
Well-Known Member
I would say they need to be about the same size or factored size with angle change so that the restriction of the orifices is somewhat equivalent. First thought is very little would come out of side holes until the fuel rate was higher ???? Might even pull in or blow back some into the holes if the big hole shot out a mass of fuel and air ?????? BUT then again I couldn't bet on it. I know enough to be dangerous that's about it.
Sounds like the precup on these engines are almost like a separate combustion chamber more so than a pre-combustion chamber??? They probably can tailor the timing much better than our IP's and tune for fuel rate, temperature/boost, and RPM better. I am still thinking the small holes are almost like a peak pressure dampener not to blow out the head gasket or bend a rod.
What are the typical failure of these engines when they push the envelope?
ak diesel driver
6.5 driver
I checked the Olds cup,the divider is inside,kinda forgot how it looked . I guess the injector is supposed to spray on it . I'm actually quiet satisfied with my power limiting na cups
got any pics of the olds cup?
JayTheCPA
Well-Known Member
IIRC an article when the stage 2 jet engines were developed and it basically stated that jet and diesel engine development were somewhat related: in order to get the flame fronts correct it took something like 90% science and 10% black magic.
Not looking to derail, just wanting to do a bit of compare and contrast with existing 6.5 products. Question: (aside from stronger components) how is Peninsular reliably getting 3XX hp out of the engines? Or put another way, while on the quest to find a better pre-cup that works with the 6.5, can we leverage the science and black magic of somebody else?
Thats what ferm is doing with the MBs.
6.5 crowd needs to develop something now. I don't think anything like has been done on a 6.5 yet??
6.5 crowd needs to develop something now. I don't think anything like has been done on a 6.5 yet??
- Staff
- #51
It was brought up that the limiting factor for the 6.5 was fuel, until you can get enough fuel any furthur devlopments aren't needed. And then you have the current bottom end limitations. I was reading some the other night on COMPD about KEEMU who is doing the OM605(5 cylinder 4 valve per cylinder 2.5L engine), and he made just a shade over 450HP before his bottom end let loose(stock internals). He was on a quest to break 500HP come hell or high water though. So he reworked his precups, had his injectors extrude honed, and added 2 layers to his MLS head gaskets to lower the ocmpression a bit. He went back and redynod with the same amount of fuel and ended up breaking 546HP out of it. So gains can be made in efficiency without sacrificing your engine.
I know for me this is just ideas, but I like to share my ideas and maybe somebody out there will try it out and bring it to fruition.
I know for me this is just ideas, but I like to share my ideas and maybe somebody out there will try it out and bring it to fruition.
JayTheCPA
Well-Known Member
Leroy, Ferm: Yes, I got that part . . . Using MB as an example, changes to the precups (only) gets more efficient / effective power generation and we are looking to use that information for possibly getting more out of the 6.5.
Just want to explore other known good 6.5 configurations as a reference point.
Question is, does anybody know how Peninsular reliably gets its 6.5 engines into the 300+ hp range? Same (presumably diamond) precups, more air / fuel? Different precups? Or . . .??? I did notice that the marine setup looks like it uses a 18:1 CR and the Hummer spec'd motors call for external components (headers, ECM update, intercooler, and 'larger' turbo), so am sure that is part of it; but is that *all* of it?
Just want to explore other known good 6.5 configurations as a reference point.
Question is, does anybody know how Peninsular reliably gets its 6.5 engines into the 300+ hp range? Same (presumably diamond) precups, more air / fuel? Different precups? Or . . .??? I did notice that the marine setup looks like it uses a 18:1 CR and the Hummer spec'd motors call for external components (headers, ECM update, intercooler, and 'larger' turbo), so am sure that is part of it; but is that *all* of it?
tanman_2006
Just a farm kid...
Iirc, Penn is talking crank hp. 300 crank is mid 200 or a bit lower to the wheels.
Source Unknown
- Staff
- #55
300 at the crank should be around 240-250 at the wheels. My LB7 is 300 at the crank, and they say it should dyno right around 235-245 at the wheels(I have more parasitic loss due to the ALLISON). I'm sure PEN is using 18:1 compression ratio, current diamond pre-cups(or bigger like SLim has), and just using brute boost and fuel to do it. Hence why there engines in marine use at 300HP+ have a reputation for a short lifespan.
great white
Well-Known Member
Sounds roughly right if your Allison makes for higher losses.
I rolled 271 with the 4L80e.
I WAGed it at around 300 HP crank.
Mostly because I highly doubt I was over 300Hp crank.
That was pretty much a no compromises "tune" (ie: more advance than I like). We were all pretty surprised when it turned that. So surprised we ran it another 3 times to be sure.
My daily calibration rolled in the 235-250 HP range and is much more "liveable" day to day.....
RacinNdrummin
Member
Interesting thread, but I have a few things to throw in for you guys to ponder.
I am actually of the opinion that the Pre-cups themselves don't make too much of a difference from one another, that the throat area is only as important as your ratio of Chamber volume to displacement. As long as your running 6.xx or 7.xx Liters of displacement, you should be running X.XX cc's of Pre-chamber volume, and the corresponding Throat area for that setup. These are the constants in a particular setup, but that doesn't mean they are a restriction. We are playing with gases here, and flow, obviously, but I think too many get caught up in the flow aspect and don't look at the pressures seen, and how they affect flow of the setup itself. You are taking a gas and compressing it through an orifice, yes, but the difference is that the gas density is constantly changing on both sides of the orifice, and denser the gas moving through the throat, the more volume you are moving through the throat, because the flow itself is a constant, just like the displacement/chamber volume. The only variable is the amount of fuel to air, and how that impacts the pre-combustion, and therefore main combustion. Fortunately, we have turbos and can affect that variable significantly.
Now all that being said, the tuning variable we have is injection duration. Duration is constantly changing based off the cam ring in the pump, and how much fuel is being metered into the pumping chamber... As silly as it sounds, that constantly changing event is still a constant that can be tuned off of. Adjusting pop pressure changes duration by increasing the total injection pressure. If you have the same amount of volume, but its injected at a higher pressure, you have a shorter duration. Now if you take fuel volume, and inject it faster into the hot precup, you get a higher peak prechamber pressure, and with a higher peak pre-chamber pressure, you get a faster, more dense, Air/Fuel mix transfer from precup to cylinder, and therefore more release of energy on the piston and less out the exhaust. If you size and tune everything correctly, there is no restriction in our style of indirect injection, just a smooth burn (in comparision to a mechanical DI engine).
I have no doubt that the MB style prechamber is a more efficient design, but only slightly, its not the result of the larger power numbers they see, that's strictly do to Airflow and RPM as well as the BoreXstroke of those engines.
I am actually of the opinion that the Pre-cups themselves don't make too much of a difference from one another, that the throat area is only as important as your ratio of Chamber volume to displacement. As long as your running 6.xx or 7.xx Liters of displacement, you should be running X.XX cc's of Pre-chamber volume, and the corresponding Throat area for that setup. These are the constants in a particular setup, but that doesn't mean they are a restriction. We are playing with gases here, and flow, obviously, but I think too many get caught up in the flow aspect and don't look at the pressures seen, and how they affect flow of the setup itself. You are taking a gas and compressing it through an orifice, yes, but the difference is that the gas density is constantly changing on both sides of the orifice, and denser the gas moving through the throat, the more volume you are moving through the throat, because the flow itself is a constant, just like the displacement/chamber volume. The only variable is the amount of fuel to air, and how that impacts the pre-combustion, and therefore main combustion. Fortunately, we have turbos and can affect that variable significantly.
Now all that being said, the tuning variable we have is injection duration. Duration is constantly changing based off the cam ring in the pump, and how much fuel is being metered into the pumping chamber... As silly as it sounds, that constantly changing event is still a constant that can be tuned off of. Adjusting pop pressure changes duration by increasing the total injection pressure. If you have the same amount of volume, but its injected at a higher pressure, you have a shorter duration. Now if you take fuel volume, and inject it faster into the hot precup, you get a higher peak prechamber pressure, and with a higher peak pre-chamber pressure, you get a faster, more dense, Air/Fuel mix transfer from precup to cylinder, and therefore more release of energy on the piston and less out the exhaust. If you size and tune everything correctly, there is no restriction in our style of indirect injection, just a smooth burn (in comparision to a mechanical DI engine).
I have no doubt that the MB style prechamber is a more efficient design, but only slightly, its not the result of the larger power numbers they see, that's strictly do to Airflow and RPM as well as the BoreXstroke of those engines.
turbovanman
I has boost, :O)
^^^^^^^^ Ok so why do guys change out the small n/a precups for the larger turbo precups and pick up power?
tanman_2006
Just a farm kid...
One thing to consider is 7.3/6.9 idi guys only rev to 3,500, they are also more worried about torque. Small na cups are good for low rpm torque but choke in high rpm that we run our 6.5's. IMO its more of an rpm range match than any thing, I'm not expert and don't know the big words though.
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