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Fuel cell installation


sf4018
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28 minutes ago, Croc said:

How many gallons is that new tank?  Does the bag completely fill the metal housing when full?

It’s 15 gallons, completely fills the housing.

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A couple of more shots: Top silver cylinder  is a small feeder pump that sends fuel to the surge tank. The bottom shot of the larger cylinder is tge surge tank itself, which has a large pump inside, and a check valve out side, the 2nd shot of a black cylinder is a 100 micron fuel filter that compliments the factory filter. The fuel regulator is in the engine bay.
 

And contrary to my earlier report, I don’t have a swirl tank, the surge tank solved the fuel starvation issue.


All of which is to explain why I never attempt mechanical repairs myself  (and should avoid offering mechanical descriptions of my Caterham:)).

 

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About to fly off on vacation got this message from Caterham…

“Looks like we have some crossed wires here with regards to your car as originally (a long time ago) when we spoke, I assumed your track car was a race car and the tank therefore would not be an issue. However as you can see from one of our engineers below, turning a car from road using “fuel on demand” is the first problem, map would be another as the 420 race cars have different cams etc as well.

 

Other than undertaking what would be a re-mapping process and much more I really can’t see a way around getting this to work.

 

I can see no other way than returning the tank and parts for a full credit and running either a replacement standard tank or some after market version (if you can find one in the US).

 

Apologies for the confusion and mis-understanding”

 

The fuel line to engine is already cut so it’s gonna take some major disassembly to put everything back the way it was. What a gigantic disaster, I’m gonna lose this whole year :(

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The only part of this latest  update that I understand is: “gonna lose a whole year”. 


I don’t understand why using a fire resistant fuel tank is such a massive technological step or why it requires re-engineering so much. I don’t doubt it, just don’t get it.

 

Also, given what a massive upgrade it apparently is, I don’t get why Caterham didn’t double check this with you first: they knew it could be a huge issue, you had no idea.

 

Hopefully someone here will have a suggestion to speed things  up?

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2 hours ago, sf4018 said:

 

 

I can see no other way than returning the tank and parts for a full credit and running either a replacement standard tank or some after market version (if you can find one in the US).

 

 

 

What a monumental cock up!  I feel the pain in this one.  Bit late to return now.  

 

Do you pitch in for an unlocked MBE ECU or another brand of ECU and put your own tune on it thereby fixing the fueling spec issue in a locked proprietary ECU?

 

 

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Might be worth a call to SBD.  They sell unlocked MBEs and they may have a 420R map available that works with a constant fuel pressure setup.  

 

-John

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I’m gonna check back with them next week when I get back to see what they come up with. They did suggest an alternate bag tank with internal pump that might work, but I gave them the rest of the week to see what paths can be taken. Gut feeling is if their race 420Rs have some different components like cams and other stuff on the top that would suggest the standard stuff isn’t quite sturdy enough for what I’m using it for perhaps, so I may push for that. The engines gonna have to come out anyways.

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The cam is not any better in the race 420Rs. Its slightly more aggressive but I have a standard 420R in the UK and I hang on the back of or ahead of the race 420Rs just fine at various UK circuits, so I assume any power increment is minimal.  I would not assume what you have is not sturdy enough.  I suspect what Caterham are choking up against is the locked ECU tune which is not compatible with the fueling programming in the existing ECU.  But that can be fixed with a bespoke ECU tune which they would never recommend as it takes you outside their proprietary ecosystem.  

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Traveling back to reality….

 

Options are:

1. Keep new bag tank/external pump/constant fuel pressure setup but use an unlocked ECU (not supported by Caterham) and figure out programming.

2. Caterham proposed retuning gear sent for a refund and shipping this new bag tank pictured below that has the same internal pump setup as the original tank I pulled out. The advantage of this is the electrical is plug and play and no ECU swap. Tank is much smaller though.

 

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I am a programmer in a past life so don’t have a problem with programming (I supplied some of the info to purple meanie fella about the CANbus stuff) but don’t know anything about ECU itself right now.


Opinions?

 

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Call SBD to discuss the unlocked ECU.  They carry a few unlocked MBE models and state they can supply starter maps as well as modified maps.  Given you have a known and common configuration, they may have a map ready to go or very easy to modify.  Worth a phone call to find out.

 

https://www.sbdmotorsport.co.uk/

 

-John  

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SBD recommended this ECU
https://www.sbdmotorsport.co.uk/MBE9A4-mbe9a4-ecu--fuel-injection-up-to-4-cylinders.html

they said they provide the starter map but I would have to tune myself. No idea how easy or hard that is to do. Not sure if the hardwired IO is standard or needs reverse engineering as far as pinouts. 
On the positive side it will mean greater control in the future if it works out.

Are there too many unknowns or should I press forward with the ECU for those in the know about ECU config?

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I had Steve at SBD do a remote Dyno tune for me that worked out well.  I went to a shop with a dyno and a good WIFI connection and he was able to monitor the Dyno pulls and make instantaneous adjustments to the 3D map.
That may be an option for you.  Tom.  

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An MBE 9A4 should be what you have in your Caterham now.  The only difference to your existing ECU is that it is an 'unlocked' ECU where you can customize your engine map.  It should be plug and play with the existing engine harness although SBD should confirm on the pin out.   You would then need to tune it yourself which you could do via the approach Tom (and others) have taken with the remote tune. What Tom did not say is he had the special cable for engine to laptop connection (only sold by SBD), had a wideband set up for monitoring during the tune since SBD could not monitor that, and Easimap software loaded up and ready to run.

 

Or you can find a local dyno tuner, provide them the ECU to laptop cable/software (Easimap) that would allow them to map it for you.  

 

Last option is buy an ECU (cue @JohnCh re Emerald) and modify the engine harness to connect it but then you can map it locally with complete flexibility.  

 

Or you can rip out the current tank, replace it with their proposed one and avoid touching the ECU.  

 

All painful choices sadly.  

 

If you ever think you will upgrade your engine in the future then I would go the new ECU approach with something that can be readily dyno'ed here as it will be easiest in the long run.  

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Actually I wouldn't advocate for Emerald in this case.  The easiest approach is the unlocked MBE which should be very close to plug and play and give added flexibility for future mods or diagnostics (data logging is great for this.)

 

Given the number of Caterhams SBD works with, I'd hope they know if they assign the configurable pins differently than Caterham.  That should be an easy change in the software.  Did they say if the starter map is specific to a 420R engine or is it a generic map?

 

-John

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Short update while waiting for the ECU. I thankfully figured out how to remove the old fuel line without removing the drivetrain…I removed the tunnel cover, then drilled out the rivets that fixed the top cover at the rear between the seats. The fuel line is just zip tied to the frame, so I just cut them off and pulled the line out. Pretty easy after all.

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It’s still unclear whether to just run some new flexible 7.9mm tube where the old one ran or install the copper pipe that Caterham sent. I’ll figure that out tomorrow.

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Some issues with the copper pipe that Caterham sent…

1. The rear exit looks fine except the connector goes back down which is odd…

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…it’s not the end of the world but will mean some hassle finding the right elbow/banjo connector to bring it back up and keep it away from everything else going on down below. Seems awkward.

2. Using this pipe means 4 connection points instead of 2.

3. Even though it’s installed in a pretty well protected area it would seem rational to want to put a protective cover over it. The old line was a crappy hard plastic tube with a shroud.

 

I’m leaning towards using stainless braided flexible 7.9mm tube that will run directly from the tank t connector to the engine rail. Easy install and only 2 connection points. The tube is rated to 250F so should take the heat, and the braid should protect the tube from stuff hitting it. I checked the cover of the old fuel line and other than dust it’s in immaculate condition so I don’t believe there’s a particular risk damage from stuff flying around from the road.

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The new ECU is in, started the plumbing, starting at the engine and going back.

5/16” fuel line quick connect connector, 6AN hose clamp, 7.9mm stainless braided high temp fuel hose…

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Although the internet said to use hose clamps not cable ties for fuel lines I used the latter like the original installation, seems fine to use for the tunnel…

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For the exit point from the tunnel above the LSD I didn’t feel comfortable snaking around the hose like the old one because it’s quite a bit larger diameter and didn’t want to risk pinching it, so I cut a notch in the wood above the LSD to use as an exit point. It’s cut to the right a little to make room for the fire extinguisher on the left…

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