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Tank outlet diameter increase


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Update:

A friend machined a ferrule for the tank outlet from an 1/2"UNF bolt with a sufficient long un-threaded shank. ID is 8.5 mm, minimum wall thickness 0,75 mm (like the original pipe).

Hose from tank to filter will be 10 mm ID, and hose from filter to pump will be 12 mm.

I have not decided yet on the filter, Bosch does not provide data like microns, flow rate, pressure drop etc, so will follow "bigger is (probably) better" method for filter selection .

 

To seal the ferrule in the tank, I plan to use Wellseal, according to the information on the packing it should be ok, but I'm not sure.

Has anyone used wellseal for threaded connections in fule (petrol) service?

 

Regards,

Waldi

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attachicon.gif ferrule.jpg

Update:

A friend machined a ferrule for the tank outlet from an 1/2"UNF bolt with a sufficient long un-threaded shank. ID is 8.5 mm, minimum wall thickness 0,75 mm (like the original pipe).

Hose from tank to filter will be 10 mm ID, and hose from filter to pump will be 12 mm.

I have not decided yet on the filter, Bosch does not provide data like microns, flow rate, pressure drop etc, so will follow "bigger is (probably) better" method for filter selection .

 

To seal the ferrule in the tank, I plan to use Wellseal, according to the information on the packing it should be ok, but I'm not sure.

Has anyone used wellseal for threaded connections in fule (petrol) service?

 

Regards,

Waldi

I use PTFE pipe thread tape for thread sealing never had a problem!

 

Bruce.

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Waldi,

Where is your Bosch pump in relation to the tank? Boschs are notoriously poor suckers, which makes any obstruction to supply worse, so it should be well below the tank floor. Maybe yours is already.

 

But the other problem with Pi is air entrainment, on sharp cornering and/or low tank level. My solution is more complex, a swirl pot with a lifter pump. Facets are good suckers, and I mounted the pot as high as possible to give about a foot (300mm) of hydrostatic head to encourage the Bosch.

 

A lot more work than just a wider outlet, but effective. If you need, you might consider a small Facet between tank and Bosch, to increase the inlet pressure.

EG https://www.merlinmotorsport.co.uk/p/facet-posi-flow-electric-fuel-pump-1-5-4-0-psi-60104-fac-60104 20 Imp. gallons/hour should be sufficient!

 

JOhn

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Hi Bruce,

Thanks, PTFE it will be.

 

John,

I plan to install the 996 pump in the bottom of the boot, next to the spare wheel, as low as possible.

I thought about air entering the fuel pipes to, this is a different issue than cavitation.

My original tank has an internal swirl pot, so I will see how that works out, probably ok as long as there is sufficient level in the tank?

The original CAV filter with a vent to tank was a good idea, I think to remove entrained air.

Im not planning any racing, so want to see how the setup with one pump and one (suction) filter works first.

 

Tomorrow is a big day, then I will install engine+gearbox in the car with my son and a friend:)

 

Regards,

Waldi

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Hi Bruce,

Thanks, PTFE it will be.

 

John,

I plan to install the 996 pump in the bottom of the boot, next to the spare wheel, as low as possible.

I thought about air entering the fuel pipes to, this is a different issue than cavitation.

My original tank has an internal swirl pot, so I will see how that works out, probably ok as long as there is sufficient level in the tank?

The original CAV filter with a vent to tank was a good idea, I think to remove entrained air.

Im not planning any racing, so want to see how the setup with one pump and one (suction) filter works first.

 

Tomorrow is a big day, then I will install engine+gearbox in the car with my son and a friend:)

 

Regards,

Waldi

I have a Bosch pump mounted on the passenger side wheel arch with a Carter booster pump and the original CAV filter mounted in the wheel well next to the spare. My tank has an internal swirl pot and pump return on the passenger side , well away from the pump suction. The CAV filter air bleed is plugged and manually vented on initial start up with no pumps running and tank head for pressure, it's then sealed. My pipeline from the Carter pump to the Bosch suction runs continually upward to avoid air pockets. Works well, even on hot days. If your Bosch is in the wheel well make sure that the connecting suction pipe grades upwards from it to a point that vents air- a small air pocket locked in a pipe causes an unexpectedly high pressure drop.

 

Good luck with your engine installation, my suggestion is to take it slowly and keep checking for any problems as you lower.

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Thanks Mike.

Your experience and design also indicate its not only cavitation but also air bubbles and your design is largely like John (above) has done.

Although 2 pumps in series seems like too much, it definitely increases inlet pressure (static head) to the Bosch pump, making it less susceptible for cavitation.

A proper vent solves the air bubbles.

I will start simple, no vent, one filter and one pump.

Thanks for the hint about pipe angle, will keep that in mind.

When not ok, I can easiky modify.

 

Greeting from a rainy Holland (we need a lot).

 

Waldi

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Hi Waldi,

 

I'd just make sure that there are no bends or loops in your suction line that can trap air bubbles. Vent air to the tank, the filter air release or away through the pump discharge.

 

I use the Carter primer pump because it has good suction performance, it allows me to install the Bosch pump higher up. As you know, a lot of owners use one Bosch pump mounted as low as possible. The Carter contributes almost nothing to final injector delivery pressure.

 

Still cold down in Melbourne, finishing off a few jobs on the TR before spring.

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Waldi.

 

I have the 996 mounted in the spare wheel well ( just off centreline to clear the spare tyre) and use the cav filter set up with the original tank outlet in a 70 car. No problems for many, many years.

 

Cheers

Dave

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Thanks Dave,

I do have an original CAV filter house, so thats an option too. Advantage is it has a vent on top of the housing.

Choises choises choises:)

Waldi

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HI Waldi hope your Engine install went well today.

 

I would recommend that you consider the two filter option with the Bosch pump for Max flow and protection.

Pre filter to protect pump with 50-100 micron filtration and to give max full flow from Tank which should eliminate cavitation. Post filter to protect MU and Injectors with filtration of 10 micron. Then hang the pump and filter in the wheel arch again to get Max fuel flow. I recently changed my pre filter to 55 micron from 10 micron as i suspected it was restricting fuel flow to the pump and I noticed a big improvement in pick up. Together with adding a fuel pump relay and bigger wire direct from the Positve terminal on the battery the car has been transformed.

 

The following make interesting reading regarding the filters

 

http://help.injectordynamics.com/support/solutions/articles/131145-fuel-system-filtration

 

http://aeromotiveinc.com/wp-content/uploads/2014/12/TB_101_InletFilter02.pdf

 

regards

 

Roger

 

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Hi Roger,

Thanks for sharing, this is a good read and food for thought.

I think our injectors and the MU are more forgiving than those in modern cars, which are fabricated to narrower tolerances.

Bosch sell some large filters, but no indication of filter size (microns).

Regards,

Waldi

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Hi Waldi

 

Your probably right about about the tolerances for the Mu and Injectors, but I think the important bit is to choose a pre filter that will not throttle the flow rate from the tank and the pump doesn't appear to need a filter that filters the fuel to say 10 micron. My arrangement bought not by me, but by Po through a well known supplier had two Bosch filters either side of the pump of around 10 microns. A bit overkill really. Not sure how big a filter your looking for, but my Bosch filter is part no 450 905 005. Hope it helps.

 

Roger

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Thanks Roger,

The 450.905.005 is also sold by Rimmers as a suction filter.

It is not the biggest Bosch filter (volume), but I dont know the microns (could not find those data).

Interestingly, you say it is 10 micron, where did you get that info from?

Thanks!

Waldi

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Ive been using these sytec disposables as pre filters for several years now.

 

Mounted vertically, fuel in at the top, they seem to provide good protection from cavitation and i can run my car down to the last 3-4 litres of fuel without issues.

 

Only downside is the 8mm tails which is too small in my opinion, but then again i dont have the large outlet nor do i have any performance problems !

 

Steve

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Steve,

That is the one Stuart recommended some time ago.

It is a relatively small filter, but if it works, it is apparently enough!

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All PI drivers should be aware that the electric fuel pump power

is transferred to heating the fuel.

As the PI has no provision to react on less energy content of warm

fuel the engine runs significantly leaner with warm fuel.

 

The terrible 996 pump draws more than 12 Amps compared to

less than 5 Amps of a well maintained original LUCAS pump.

I would strongly recommend to use a pump for a swap that

does not draw more than 7.5 Amps.

 

So for a short travel to the Cafe any solution will do the job

but for long day travel and/or hot weather conditions the system

must be improved, otherwise fuel temp in the tank will rise that

one does not want to touch the tank and its boiling inside,

 

Besides the outlet from the tank the focus must be on a real

coarse pre filter with about 300 microns, not a EFI fuel filter with

80 or less.

 

Just for the papers: My V8 with double the power of a TR6

still relys on the original tank outlet! I felt lazy to change that

as I did with the 6 cylinder because I do not have problems.

I have the smallest BOSCH pump in use because I only need 3 bars.

So I have less heating than original, the fuel cooler in the front

and a catchtank and absolutely no problems not even in Italy in summer.

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And make sure that the warm return fuel from the pump doesn't "short circuit" straight back into the suction line.

 

My return line is on the opposite side of the tank from the suction line. Any warm returned fuel has to work its way across the aluminum tank before it can reenter the pump. The tank surface temperature doesn't rise much above ambient during normal operation.

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Im in catch up mode on the forum after a holiday and have skimmed through this thread. Waldi and I are in the same industry with similar thinking for sure. I am a retired chemical engineer and have an understanding of pump cavitation resulting from increased fuel vapour pressure, low suction head, high resistance to flow leading to a reduced net positive suction head. I changed my standard Lucas installation probably 15 years ago to the Bosch type arrangement partly persuaded by one cavitation incident experienced and partly by Clive Manvers at Manvers Triumph! Apart from a failure of a union a few years ago (another story????) the pump has performed perfectly. I have a T piece fitted at the metering unit and can check and adjust the delivery pressure as necessary.

 

Heres the real point of the story. Returning from Le Mans 3 years ago, our convoy didnt stop at our normal petrol station on the final leg home to Calais. I was down to just under 1/4 tank on the gauge. The other cars a Healy 100, MGB, and a Focus all had bigger tanks. I was at the rear and didnt know where the next station would be. I was very worried and slowed up to 40-50 mph. This on a motorway too! I stopped on my own at a Aire and phoned the helpline to review my options. I even found a suitable stick and had about 4-5cm of fuel in the tank. The gauge was well under a 1/4 now. I think the next station was 40km away and decided to go for it and around 40mph. I made it and was able to put 38.5 litres in the tank. This was a high potential near miss.

 

The day was hot and I did not suffer with cavitation. The pump performed faultlessly. The following year I did replace the filter though. To add on these long runs in France at moderate speeds I always get 30-33 mpg. This year was no exception.

 

This is my experience, so needless to say Ill leave the pipe work well alone.

 

Regards Trevor.

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