Long Rams 3.0
#2635365
03/21/19 09:06 PM
03/21/19 09:06 PM
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jcc
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One more thing, what purpose does the balance Tube actually serve? Is it for idle quality, to help "balance" the carbs someway for some purpose, it a "softener" for intake pulses to help the carb, does air flow much in the tube, can it be replaced by a #12AN hose, etc? My thinking, for an EFI sequential port injection Long ram, it ain't needed. Well?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Long Rams 3.0
[Re: 360view]
#2635446
03/22/19 07:31 AM
03/22/19 07:31 AM
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Posts: 14,889 up yours
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The iron V10 truck engine manifold has 25 inch runners with EFI. The “plenum” volume of this manifold is far larger than the Long Ram. This probably works far better than the balance tube.
Not in a long horn cross ram application it won't. I have a vague recollection of a rule of thumb that says plenum volume need to equal no less than one cylinder's displacement on a multi cylinder engine. But that's probably out of date.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Long Rams 3.0
[Re: 360view]
#2635458
03/22/19 08:05 AM
03/22/19 08:05 AM
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Joined: Jan 2006
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360view
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Re: Long Rams 3.0
[Re: 360view]
#2635471
03/22/19 08:58 AM
03/22/19 08:58 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
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Plenum volume on an EFI application is not super critical like it is in a carb application because you're not worried about providing the right vacuum signal to the carb. You can go bigger on the plenum on an efi build and not hurt anything.
The balance tube on the cross ram would be to help balance out vacuum signal to the carbs. Imagine at part throttle in a low/medium vacuum situation, the vacuum signal off 4 alternating cylinders instead of 8 will be more uneven. Distributor vacuum advance and pcv wouldn't oppose a more stable vacuum signal either! If the carbs weren't properly sync'd, I guess the balance tubes could help bandaid this as well.
If you're using a speed density EFI system, the balance tube would help provide a more stable MAP signal to the computer in much the same manner. You could downsize the tube size in an EFI application, however I would probably just leave it.
As for the intake runner length, rumor has it chrysler used a formula of 84000/runner length in inches = peak rpm of power boost. There's various calculators out there that use the speed of sound vs runner length to calculate harmonics, peak rpm ranges, etc. The ones I've tried do put the chrysler figure in the same ballpark.
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Re: Long Rams 3.0
[Re: DaytonaTurbo]
#2635479
03/22/19 09:27 AM
03/22/19 09:27 AM
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Posts: 22,696 Bitopia
jcc
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If you can't dazzle em with diamonds..
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Thank you for the serious replies. My consensus at this point is: 1. increasing the size of my separated LR plenums would have little downside, unfortunately there is no easy solution for that because of space and headers. 2. OEM LR plenums are rather anemic sized, Since I am going to EFI throttle bodies, I have room to add a 1-1.5" open spacer, or at least experiment with that potential solution. 3. Hadn't considered the ignition vacuum signal issue , I might be able to just plumb the signal line to both of the small OEM plenums for a summation signal?. Not sure how much smoothing takes place in the vacuum sensor or software to reduce pulsing.. 4. I'm inclined to remove the remove/eliminate the OEM crossover, doesn't seem yet as a bad move, but does have some risk/uncertainty in the outcome.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Long Rams 3.0
[Re: jcc]
#2635481
03/22/19 09:33 AM
03/22/19 09:33 AM
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Posts: 14,889 up yours
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Really digging deep into the cobwebs here, but I also recall that without a balance tube a V8 will tend to run like 2 four cylinders rather than one V8. But I'll be danged if I remember where I saw that. Probably some patent application.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: Long Rams 3.0
[Re: 360view]
#2635490
03/22/19 09:54 AM
03/22/19 09:54 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
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I would just keep the balance tube. The connections are already cast into the intake and the middle of the tube would make a nice place to tie in your MAP sensor. Plus it looks good! Interesting read, however it seems he cherry picks his data. Other builds I have seen on the internet have had guys trim down the ends of their intake runners to smooth out airflow going into the runners. I suspect that's the effect that his plenum reducing plates are having. If so, that's a better solution than shortening the runners to radius in the air flow easier.
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Re: Long Rams 3.0
[Re: DaytonaTurbo]
#2635530
03/22/19 11:17 AM
03/22/19 11:17 AM
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Joined: Jan 2003
Posts: 5,138 East Aurora (Buffalo) NY
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I would also keep the balance tube. In our V8s, the cranks are all cross plane cranks. That is, the throws for the rods are each 90 degrees out. Versus a flat plane crank where throws are 180 degrees apart. What this does is add uneven firing to the cylinders. But does make for a smoother running engine. This uneven firing will "communicate" the air pulses back into the manifold. It really shouldn't matter too much with long tube but it is possible that the balance tube will help dampen the uneven pulses some. Just my
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Re: Long Rams 3.0
[Re: DaytonaTurbo]
#2635537
03/22/19 11:29 AM
03/22/19 11:29 AM
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Posts: 8,162 USA
360view
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I would like a scientific explanation as to why the 1992-1995 version of the Magnum V8 intake manifold had a center divider cast in place that reached down within 1/2 inch of the bottom. Was it there to block reversion pulses? Was it there to more evenly distribute EGR? A year after EGR was eliminated in 1996, the 1997+ plus intake castings had the divider greatly reduced so that there was 4 inches of open area above the bottom. In 1998 a new camshaft was introduced and peak HP at 4000 rpm went up by 15 I wish in 1998 that Chrysler had taken the science of V10 intake manifold and createda V8 version with 25 inch runners that would have peak torque as low as 1200 rpm resonate at both 1700 rpm and 3300 rpm. Magnesium and no troublesome plenum plate or gasket. Sample quote A Helmholtz resonator intake manifold was tuned to boost torque at 1700 and 3300 rpm. Long primary runners curved over the right cylinder bank to clear the hood. Resonance in the 25-inch primary runners enhanced low speed torque, with peak torque as low as 1200 rpm. Two plenum chambers supplied air to five runners each. Plenum chamber volume was tuned to resonate at 3300 rpm, broadening the torque curve. Passages across the longitudinal center of the manifold fed air from the throttle body to the plenum chambers. End quote https://www.allpar.com/mopar/V10.htmlhttps://www.allpar.com/mopar/performance/manifolds.html
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Re: Long Rams 3.0
[Re: 360view]
#2635593
03/22/19 02:10 PM
03/22/19 02:10 PM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
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I would like a scientific explanation as to why the 1992-1995 version of the Magnum V8 intake manifold had a center divider cast in place that reached down within 1/2 inch of the bottom. I wonder if it was there to help radius the air into the runners? Might have also served as enough of a restriction for flow through both bores of the TB that eliminating the divider was a wash in terms of power production.
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Re: Long Rams 3.0
[Re: DaytonaTurbo]
#2635691
03/22/19 08:29 PM
03/22/19 08:29 PM
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Joined: Dec 2003
Posts: 4,951 northwest USA
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Seriously though. How may engines have you seen that don’t draw all intake air from the same plenum? Hilborn mechanical injection with 8 stacks is one. How about those 1970’s British Cars, what did they have? 1950’s 6 carb setups had balance tubes.
I have a Long Ram car and have driven it 22K miles. You can purposely mis adjust the carb openings and it still runs And drives. Of course it runs way better with the carbs synced. I can’t see it working worth a darn without the balance tube. Chrysler called it a “balance tube” for a good reason.
Last edited by NANKET; 03/22/19 08:54 PM.
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Re: Long Rams 3.0
[Re: NANKET]
#2635712
03/22/19 09:21 PM
03/22/19 09:21 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
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If you can't dazzle em with diamonds..
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I can't dispute your findings, but the contention to me is, does using EFI and losing the carbs make the "balance tube" superfluous? As much as i want to cut it out, I'm likely to leave it initially, then bypass it ,and then make a determination, more work, but a lot less risky if i choose wrong. Was hoping to find some sound reasoning first.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Long Rams 3.0
[Re: jcc]
#2635805
03/23/19 08:46 AM
03/23/19 08:46 AM
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Joined: Feb 2003
Posts: 21,318 Manitoba, Canada
DaytonaTurbo
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Was hoping to find some sound reasoning first.
FWIW, if you're using a speed density EFI system, it's recommended to have all the cylinders tied together one way or another. The guys who are doing speed density EFI systems with Hilborn or other type individual throttle bodies generally still tie all the cylinders together, even with something small like a 1/2" hose in order to get a decent MAP reading. I guess if you were using an EFI system that used a mass air flow sensor instead of a map sensor you could get away without it.
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Re: Long Rams 3.0
[Re: DaytonaTurbo]
#2635823
03/23/19 09:20 AM
03/23/19 09:20 AM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
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Was hoping to find some sound reasoning first.
FWIW, if you're using a speed density EFI system, it's recommended to have all the cylinders tied together one way or another. The guys who are doing speed density EFI systems with Hilborn or other type individual throttle bodies generally still tie all the cylinders together, even with something small like a 1/2" hose in order to get a decent MAP reading. I guess if you were using an EFI system that used a mass air flow sensor instead of a map sensor you could get away without it. Well, using a MAF would tie them to a common point as well, the MAF sensor does need to measure all the air flow.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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