Ultima Fuel Delivery System Flaw?

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UltimaCH said:

Any way of removing the brillo pad type swarf from the tanks? Could it be possible to put some baffles in the tanks to reduce surge?

Not sure about removing the Brillo pad material. May be possible but sure would be a pain in the neck to get out. Not sure really how effective it is anyway given the amount of it in the tank. A friend of mine just removed both of his tanks in the GTR and used then as shells for FIA Kevlar burst proof bladders. Not a bad idea if you consider racing the car on any track for piece of mind.

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crossram said:

I have noticed a pattern on this forum over the past six months, owners post about flaws their cars may have and the factory then posts back that they are all incorrect. As a new owner building my car I am not sure where the truth lies.

Congrats on the purchase of a new kit. I hope you are as excited as I was to be be building a GTR. Here is my personal opinion about Ultima and I am sorry if I offend anyone. The first major issue for me was what we refer to as the coloring book of build manual. It has not been updated in many years and as things evolve and change with the car it should be amended to reflect. I offered to make a new manual for the factory if I were to build another GTR just for this reason. I have built 2 now and know them inside and out very well. I have also developed templates on my cnc machine to assist in construction greatly saving time. A few major things I would like to see the factory consider as revisions are:

1) Solid brake lines through the side pod from front to back with flexible terminations that are short. Braided is great for ease of installation however this will fail long before a solid line will rupture. You will notice a bubble in the plastic before it fails, if this is hidden in the side pod and it goes unnoticed you may mash on the brakes and find they are no longer there!

2) Solid line for the clutch as well with short flexible terminations, same as above

3) Fuel system delivery system is way to complicated contrary to the factory's comments. There is absolutely no reason not to link the tanks as so many of us now have. The issues I personally have had with the fuel delivery system should have sparked the factory's interest right away. I have yet to get a clear answer.

4) The baffle material used in the tanks is in my opinion is a joke. I feel as the tanks were being manufactured they could have integrated internal real baffles and it would lead to a much better product. No chance of swarf making its way to the Pollak valve.

5) Fuel filters before the LP pump would be a great addition!

6) A note in the manual or make it standard practice to supply heat shield for the fuel tanks and bulkhead/ rear canopy.

7) Integrating a fuel pressure gauge in the cockpit as I have done to monitor fuel pressure. A very easy way to monitor your fuel filters health.

8) Supply mandrel bent aluminum tubing for the cooling system eliminating all of the silicone with the exception of the connections at the engine.

9) Non factory but worth thinking about.. Make up a plug that houses all engine wires from the ECU to be able to disconnect it right at the engine bay. This way you can simply unhook the plug and pull the engine in short order with out having to remove the entire harness from the engine.

Again sorry if I have offended anyone with my opinions on this matter. I understand it is hard to accept somebody's ideas some time as they are not your own however if it is for the greater good then why the hell not? I feel the brake lines would be a top item and will be retrofitting them in my car shortly. FYI I used all the factory supplied parts and tanks to effectively link mine. I had to order new line and fittings that's it.

These are just a few of my gripes and item I would change if I were to build another GTR.

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The Italian said:

skidiiii
Thank You!
that was a very good summary, and yes brake lines are very important to everyone. My brake lines were trashed from the kit (F5) and replaced w/ stainless(our kits come with pre-bent steel tube, not braid)
Nice to hear a great response like yours. Braid takes minutes while bending takes tools, mistakes and lots of time. Is there not a "split system" in the Ultima ? one fails you still have back up ??front/back

Thanks for the kind remarks. Yes the Ultima has a split system, only the left front could technically be all braid as it is very close to the master. I personally wouldn't want to loose front or back if one were racing on a track, could spell disaster!

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deadscoob said:

Edit - didn't take long, thread about them here:

http://www.pistonheads.com/gassing/topic.asp?h=17&...

Ref skiddiis post, agree with all of it, especially the pressure gauge.

I'd still recommend having dry break connectors on the filters still, as mentioned before, it makes cleaning them a 5 min job.

Yes expensive but well worth the money spent. No need to drain the tanks or system if you put them on either side of the filter highly recommend as well. Thanks for the tip deadscoob!

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Storer said:

Well, after boiling my fuel (60 deg C) sitting for an hour in a traffic queue at the St Saturnin car show on the Friday before Le Mans, I have now modified it to hopefully prevent a repeat.

I have moved the regulator from the bulkhead above the engine (probably the hottest part of the engine bay) down to the p/s side pod next to the swirl pot. I have changed the pipe routing too.
Now it is:
H/p pump to fine filter, then a 'T' .
One side of 'T' goes straight to the fuel rail.
The other side goes to the regulator. From the regulator it returns to the swirl pot.
The fuel rail now has the valve back in it so that the fuel does not 'flow' over the engine.

Still got some wiring to extend to allow my fuel pressure and temperature sensor to function but she seems to run fine.

Paul

Paul,
You may also consider if you are running EFI and not naturally aspirated this set up with the fuel regulator and rails. My set up utilized a stock GM fuel rail with an -6 fitting welded onto the inlet. With the new set up this restrictive single inlet rail has been removed and the new rails allow for fuel to enter both much larger rails at the same time. My set up has the HP pump off the bottom of the swirl pot into the 100mc filter then right into the fuel rails via Y. The excess fuel exits the rails left and right and feeds either side of the Aeromotive fuel regulator (part #131098). You will notice in the instructions for the reg in figure 1-2 stated optimum performance for V8 engines. The return from the reg is fed back to the swirl pot nest to bottom fitting or #3 from top. Again by moving the pot to the AC side of the side pod as far away from the exhaust as possible is the key. I sat in dead stopped traffic yesterday for over an hour with the ac running and the car did not stall once nor did the water temp go over 100'C. Hope this may help your situation as well.

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Storer said:

Thanks for the reply Roe

The set up you describe would not change the areas that I think I have that are causing my issues.
I am sure my issue is caused by the fuel passing over the hot engine and the regulator being at the top of the rear bulkhead.
The amount of fuel in the rail probably needs to be as little as possible to run the engine at WOT so it spends as little time absorbing heat as possible. The regulator does heat the fuel a little as it releases the pressure, but as the fuel that is bled off is not passing over the engine before it returns to the swirl pot, it should see the swirl pot temperature much lower than before.

The down side is the plumbers nightmare that now resides in my l/h side pod.

I may build a new swirl pot with many of the components integrated to remove a lot of the pipework if I have no issues for the rest of summer.


Paul

Hey Paul,
What symptoms did you have when the fuel boiled? Just curious what happened and how long you ended up waiting for it to cool down. Got me thinking as well.... never a good thing;) What about this for a thought. The factory has the fuel reg centered on the bulkhead in very close proximity to the "Ram air induction" scoop. What if one were to integrate a small slot on the underside of the enclosure (I have the forced induction panel installed) allowing for a small amount of cool air to pass over that area. You could easily add a deflector to direct the air when moving. When stationary this should allow excess heat a more direct path out as well. I am currently adding function vents to the 944 track car and this just dawned on me. It would not be any visible change to the exterior and I cant imagine it would affect aero considering the factory considers this an option and not included. Thoughts anyone??

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Should I wrap the swirl pot since it has been moved away from the exhaust and into the open area behind the RH pod? I understand wrapping it if you keep it as the factory installation manual a few inches from the exhaust, however moving it outward to a cooler environment thoughts would be not to insulate it but dissipate heat. Respectfully as heat rises and the fuel filter is on the bottom of the bulkhead and away from the headers(in my set up) wrapping it would make a minimal impact. (IMOP) However the regulator may be the culprit as it is near the top of the canopy where all the heat is trapped. Its funny if you look at serious GTR track cars they all have holes riddled in the canopy to allow the heat to dissipate. Not sure what else can be done to allow the heat to escape. Would be cool in dead stopped traffic to hit a button that would allow the canopy to open 3-4 inches and let the heat out;)

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Paul,
Great write up and explanation of how fuel reacts to pressure. When designing my system I read very thoroughly over all the components instructions and Paul is 100% correct. I have both of my pumps mounted slightly below the lowest fitting on the tanks near the center of the bulkhead RH side allowing for a natural gravity feed system to the LP pump. This is the only location that is the lowest point and as far away from the headers as possible. It is best as Paul said to feed the swirl pot via the LP pump and use the HP to circulate the fuel to the rails first then reg last. My return to the tanks via a T with 1.5mm orifices allows for the fuel to evenly trickle back to the top of the tanks and ensures a constant pressure in the swirl pot. Again I reused all the supplied factory pumps, reg, filters. Simply got rid of the antiquated pollak valve, bought a fist full of fittings and some new hose. I have run almost 500 miles on mine now since the conversion with out a hitch even in 90 degree weather in stop and go traffic for over an hour. I like the idea of adding chimneys to the headers however with the rear canopy being GRP I am not sure how a concentrated source of heat would react with it. Dan's yellow GTR rear canopy already changes to a darker yellow when the engine is hot and the entire bulkhead and canopy are heat shielded.