Shoptalkforums.com

No problem Max, I thought it was standard to run it off manifold pressure anyway to be honest. Having said that i'm looking to go turbo after I've sorted the injection so would need FPR boost referenced anyway.

Does anyone know whether there is a reason to not take the FPR reading from the box I'm going to use to smooth the MAP signal for the ECU? Would it affect the ECU reading at all? Just trying to keep the plumbing simple.

Cheers

Alec

Yes you want a smooth map signal to your pressure regulator reference (same for map sensor).

I am running my systems with the FPR referenced to atmosphere not manifold pressure now. I was trying to figure out a fuel pressure oscillation issue. I figured if my map was jumping around then the map referenced regulator would also jump. It turns out my fuel pressure oscillates whether referenced to map or barometric. This isn't ideal since all the effort put into mapping the ECU is assuming stable and repeatable fuel pressures at each point.

I can feel a surge/pulse in my big CB pressure regulator. The pressure also pulsated with a new Bosch regulator though. I'm just tuning around it and living with it right now. I have my pressure set to 3 bar flowing at idle.

I see a lot of OE applications with some type of fuel pressure damper on the injector rail or on the pre-regulator side of the plumbing. Some put them right on the fuel pump outlet in the tank too. Seems like the fuel filter itself would do some dampening, maybe there's more to those OE dampers than just a chamber of volume?

Thread jack

Pulsation: I was thinking of putting one of the large (~ 1/2 quart?) Vanagon steel fuel filters before the regulator. It may help the pulsing. I only have a T2 bus square pre filter right now. I wouldn't mind trying a pulsation damper either. Later Jetta fuel rails have them built in. They look like a mini regulator.

A CIS fuel damper might be a much better plan.
About ~10 million of them in junkyards.
I cannot recall ever seeing a failed one personally.

The CIS-basic ones have a lower 3~3.5 BAR operating range, the -M units are closer to 5 BAR.
(They all have quite a bit of volume and spring travel, even the CIS-M ones are probably "working" at 3 BAR, but are quite a bit smaller than the early units)

Which Bosch reg are you having issues with?

I have the CB big Malpassi adjustable regulator. I also tested a Vanagon regulator. Same +/- 2 psi. The pressure comes up nice and smooth when powered up, then when it gets to the regulator setting the pump gets noisy and the pressure starts hopping. It did this with a Vanagon pump and with the noisy CIS mercedes pump I have now. I'm not using a pre pump with the CIS pump which is probably not good.

i've heard of people running the regulator by the fuel tank to try and solve this, apparently the length of pipe to the rails can reduce the pulsing? I was thinking of mounting mine in the spare wheel well and running about 4 bar pressure to allow for the drop to the fuel rails.

Steve Arndt wrote:I have the CB big Malpassi adjustable regulator. I also tested a Vanagon regulator. Same +/- 2 psi. The pressure comes up nice and smooth when powered up, then when it gets to the regulator setting the pump gets noisy and the pressure starts hopping. It did this with a Vanagon pump and with the noisy CIS mercedes pump I have now. I'm not using a pre pump with the CIS pump which is probably not good.

The roller cell pumps REALLY need a feed pump/slightly pressureized feeder sump.
I don't think any OEM ran one without it, except possibly as an in-tank setup.

I'm currently using an 044 with a VW Fox sump setup, and a modified D-Jet regulator (in the OEM location) that rattled around in my toolbox for 20 years.(drilled the adjustment screw for vacuum reference like the ones you can get from Summit etc) Works quite well

started machinging the itb to manifold adapters today. Also decided not to weld them together, rather i'm going to sit the itbs into the adapters and hold them down using a clamp across the plate joining the two barrels down to holes tapped into the adapter plate and grub screws on the sides. This was due to concerns about the itbs warping and also means the itbs can be swaped out if i have problems.

cheers

Alec

built the adapter plates, going to use a metal "glue" and high temp gasket to ensure they're air tight and clamp the tbis to the adapters as well. I'll only glue when i'm sure they're fitted fine. Also decided to use ali box section to make the turbo hats, thought i may as well build them and fit them now even though the turbo wont be on for another 6 months or more. I'll just attach filters instead. Pictures will be up when i've made the turbo hats, could be a couple of weeks.

Also I'm having problems with some of the hose nipples on the tbis getting in the way of the manifold studs. The only way round it i can see is to have the injectors facing away from the engine. I've heard this is bad and so was thinking of using space saver manifolds to redirect the injectors towards the valves. Is this worth doing? or is there another way around the bolts?

Cheers

Alec

Pictures... Can't make comments about or even drool over what we can't see

At high RPM the upstream injector placement is likely a win.
At idle/low-mid rpm not so much.

thats what i thought, sadly this is a street car so most of the time will be idle or mid but i guess thats problems for the future when its actually running!

My main point is would it be a problem having the injectors facing the edge of the manifold away from the engine?

Will get some pictures when my laptop decides to work properly haha

heres the pictures then;

first shows the tbi mounted onto manifold using the plate, i have not fitted gaskets yet so would be a little higher up, but only a few mm.


second shows a top view and the strap I'm using to hold the tb onto the plate.


third shows the bores looking up, you can see where they do not fully line up, this is due to the tb having a slightly oval bore and a recess where the injector fires. Was wondering about filing the bore out so it smoothly transitions onto the manifold, any reasons why i shouldn't?


thats it for now, next is the turbo hats

cheers
Alec

Countersink/flush mount the plate to manifold bolts.

The step is no issue and may help fuel atomizaton and help prevent reversion.

good idea Piledriver, so i could bore the holes for the studs to 20mm for 5mm of the plates thickness, should give enough room to get a spanner in there and stop the nuts contacting the tbs.

Will get on it.