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09-20-2018, 07:12 PM #31
Check this out. Sounds like a nice product.
Wondering how it would be plumbed if using a balance hose off each rail?
Last edited by painlessauto; 09-21-2018 at 02:28 PM.
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09-21-2018, 02:15 AM #32
Your diligence and stick-to-it-tivity genuinely impresses me, Matt.
The presence of the unwanted pressure pulses in EFI fuel rails has been known of for many years. On n/a systems you will frequently find fuel rail pressure dampers designed to mitigate the phenomena. Below is a print for a typical unit set to the fairly common 3 Bar (43.5 psi) fuel pressure range for n/a applications. This design is a use once and replace type unit. Removal damages the damper locking mechanism;
The way the damper works is one side of a flexible diaphragm is exposed to line pressure and the other side is exposed (on an n/a engine) to ambient or atmospheric pressure. As the pressure pulses present themselves in the non pliable fuel rail the flexible membrane in the fuel rai pressure damper moves both inward and outward to absorb the pressure pulses effectively damping them to produce a fairly but not perfectly uniform fuel pressure at the injector inlet ports. The devices work fairly impressively on n/a engines. This is a Toyota unit for use on one of their n/a EFI engines;
The challenge comes when you attempt to use them on supercharged engines. The differential pressure across the injector that a boost referenced regulator attempts to maintain can drive absolute rail pressures to 60 or 70 psi under some conditions. When that occurs you need a 5 Bar or 6 Bar damper. The 3 Bar damper will rupture its diaphragm and because it is vented to atmosphere, it will flood the top of the engine with raw fuel. The follow on fire, as you might suspect, is impressive and can easily consume the vehicle.
The two big deals about the damper you found are;
First it is boost referenced. Boost referencing for the damper is as essential as boost referencing for the FPR for exactly the same reason — you want the FPD to track manifold boost so it's differential pressure management can rise and fall in lock step with manifold boost just like the FPR. An additional side benefit of the Radium design is if the diaphragm does burst the fuel will go up the manifold pressure reference line to the intake and make the engine run rich instead of burning your car to the ground.
Second it is available in two pressure ranges 40 to 70 psi and 40 to 120 psi. The 40 to 70 psi unit ought to be adequate for most of our engines but the 40 to 120 psi unit offers a very nice additional safety buffer that is well above the fuel rail pressure you are likely to see in any operating environment.
I think I would buy the 40 to 120 psi unit for peace of mind. It appears the assembly can be serviced by disassembling it and periodically replacing the diaphragm. I would ask them about recommend service life for a diaphragm and change it at reasonable intervals to protect against desication and embrittlement of the diaphragm that could lead to a rupture.
In case you have not already noticed I am quite impressed with their product and even more impressed with your diligence in digging it up! Killer sleuthing there, Matt.
p.s. With the balance tube at the end of the rails you will only need a single damper. I would split the balance tube in the middle, put a "T" fitting in and mount the damper there with its boost reference line going to the closest port on the intake manifold you can find. Balance tube proximity to the manifold along with length and diameter influence how accurately it can shadow manifold pressure changes — same exact story as the boost reference line on the FPR.
Last edited by eschaider; 09-21-2018 at 02:22 AM. Reason: Fix broken pic links
09-21-2018, 02:26 PM #33
Radium said that the pulsing valve can be plumbed into a tee between rails on the balance hose without issue. It can also be placed before the y fitting on the inlet side of the rails. Sounds like anywhere after the regulator on the feed side will work OK.
It was suggested to inspect/replace the diaphragm annually.
They offer inline kits for $120
09-21-2018, 03:04 PM #34
Way cool piece, Matt. I was selecting the middle of the balance tube to try to place it equi-distant from either rail. The non compressible nature of fluids would argue anywhere in the post regulator plumbing would be OK. My selection of the crossover midpoint had to due with the delay in wave propagation from origin to the damper. In the bigger picture it probably makes little difference and you could place it just about anywhere you want and still realize its dampening benefits as long as you are downstream from the FPR. As long as you use a balance tube you'll only need one damper.
Last edited by eschaider; 09-21-2018 at 08:46 PM. Reason: Spelling & Grammar
09-21-2018, 10:08 PM #35
I smoked my intake and exhaust today. Didn't find any intake leaks. (Not surprised)
I found a 1.5mm portion on an o2 bung I missed with the welder. Also found a pinhole on the other bung for bank 2. I have three bungs on that bank that are very close together. One for upstream, wideband, and dyno use.
Bank 1 had no leaks
No cracks in the headers
Exhaust manifold gaskets checked ok
Both vbands at the headers are air tight (upstream of o2's)
I have two vbands further back that do not have gaskets. They are 4ft away from the bank 2 o2's and 29" back from the bank 1 o2's. I plan on making gaskets for these as well soon.
Welding and relocating o2's tomorrow. I hope I see a change...
Last edited by painlessauto; 09-21-2018 at 11:26 PM.
09-22-2018, 12:20 AM #36
I doubt the two rear most V-band joints are the culprits, Matt. I suspect the FPD will do more to normalize the AFRs. BTW I read deeper into the Radium product and would probably use the -R version rather than the -XR unless you are running a high (>50psi) base fuel system pressure.
Yesterday, 08:22 AM #37
What are your thoughts on my AFR variance being caused by cam timing?
My previous compression test yielded these results. Engine was cold, sat overnight, and blower was off. 800 miles on the current build, total seal rings.
4 = 162 ...... 8 = 162
3 = 155 ...... 7 = 155
2 = 155 ...... 6 = 160
1 = 162 ...... 5 = 158
I am wondering if something changed. Chains slightly stretched or maybe my cloyes hex adjust gears moved a bit?
I replumbed my exhaust off the headers yesterday. Moved the o2's a few inches back and put them higher in the tubes. Both sides are identical and I am seeing the same results.
Figured I would bounce it off you before I go pulling my engine. Personally, I don't feel cam timing is an issue. This AFR difference between banks may just be nature of the beast.
Last edited by painlessauto; Yesterday at 10:47 PM.
Today, 10:30 AM #38
I don't feel the cam timing is the issue, Matt. It is improbable you will get the compression figures closer than you have them right now especially when the engine is cold. The numbers are virtually identical bank to banking if the engine were warmer they would be virtually identical. When compression is as close as that, then cam phasing bank to bank is spot on.
The important AFR numbers are when the engine is in closed loop and those are virtually identical. Your open loop performance is by and large mostly for warm up. Once the engine is warmed up, it goes to closed loop and your closed loop numbers look identical. I think you are chasing a distinction without a difference. The small bank to bank open loop difference is not going to matter a whit in the operation and driving manners the engine has.
I would let it go and enjoy your ride.
Today, 10:48 AM #39
Open loop is also wot operation. I have ultimately decided that I'm chasing a ghost. I appreciate all you insight to this matter. Wot will be tuned off the leaner bank.
I read the deadhead fuel system thread. I am in the process of increasing my FPR boost reference line diameter. I will also be installing the fuel pulse damper over the winter. If I see any results for either I will post results here.
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