Fuel Rails

[Aussie Mike]

Hi All,

The LS1 normally runs a single fuel line from the tank to the motor. The pressure regulator is in the tank and there is no return feed from the motor.

I want to run an extrnal swirl pot and an extra fuel pump. I also want to run an extrnal adjustable fuel pressure reg and generally beef up the whole fuel system. Part of this was to run a full retrn fuel system like conventional EFI systems.

So here's a pic of my home made fuel fails. You can buy the aluminium fuel rail extrusion by the meter. I've machined it to suit the injectors on th LS1 and threaded the ends for the speedflow AN8 fittings. Phil kindly donated the elbow fittings for the cross over and I put them on a new bit of braided hose.

The regulator mounted on the firewall is a SERD unit from Japan and they are popular with the big HP Turbo combinations so should be plenty big enough to support my motor.

All I've got left to do on the rails is make up some brackets to support them off the manifold.



Cheers

[justbetter]

mmmm, more polished shiny thingo bits, more room on them for advertising....

Still long enough for Better Bathrooms & Kitchens 03 9370 xxxx, even room for the phone number, gee thanks Mike

[Bathrone]

Hi Mike,

Your choice of fuel pressure regulator is a solid one. Personally I have used the SX performance fuel pressure regulator but both yours and mine I have seen consistently hold the base fuel pressure, even at high flow rates. What is the bad choice is the malpassi (malcrappy) I have personally seen and also had others report of shifting base pressure with the malcrappy and I know of one turbo rotary engine that blew on the dyno when it ran lean under WOT because the malcrappy wrecked the fuel flow.

Personally I would have run a twin feed parallel fuel rail system to better combat pulsation and to ensure the injectors are fed a solid diet of fuel and pressure. This is just my opinion and personal preference - from an engineering point of view there is devices you can install to control this in a single feed system so if its a problem we can talk about that later on.

Im not a great fan of external swirl pots but nonetheless my Mazda has one, using a low pressure lift pump and then a high pressure pump. I believe that custom fuel tanks are needed anyway because in high output applications your going to need large pickups, large feed and return lines etcetc. An internal swirl pot also means you can whack in a big intank pump.....One of the things that craps me about my Mazda is the phreakin bee hive that drives me mad that is my bosch motorsport "044" external pump. Ive still got problems with restrictive pickup, feed and return lines in the stock tank anyway.....

When it comes to pumps, 99% of the pumps on the market flow stuff all at higher pressures. This isnt so much a problem with NA engines as it is with force fed ones but nonetheless theres still alot of pressure loss in the lines anyway. Be sure your fuel system will flow the numbers at the pressures youll be running.

Im a big beliver in only one high pressure pump because the last thing you want is 2 or more pumps, where 1 fails and you dont notice during cruise but at wot you run the motor lean and pop it before realising whats gone wrong. Walbro and Supra in tank pumps flow up to around 5 litres a minute, but external ones like the bosch 044 and the SX performance can in some circumstances flow more.

With your surge tank, I highly recommend having the return feed back to the tank and not the surge tank. This is because otherwise it will be a closed loop and youll heat the fuel up.....This will lower the detonation threshold of your engine tune, the pumps will be noiser and other general problems with it.

I consider closed loop style fuel coolers to be a horror band aid solution to the problem of heating fuel between the swirl tank and the pressure reg closed loop.

Dash 8 is a good size but I prefer the double lip type of AN fittings onto the hosing not the single nipple type.

cheers

[Aussie Mike]

You wouldn't be able to see them under your engine covers Garrett.

It's all a bit of a w@nk really as we've seen the stock fuel rails can support more than enough flow for whatever HP you want to make. I guess I did it partly to make the plumbing a little neater and easier and partly for a bit of extra flash in the engine bay.

Cheers

[Aussie Mike]

I've got an in tank Walbro low pressure lift pump from a VL Turbo installed in the VN tank. In the 2L swirl pot there are 2 Gyrator style fuel pumps from the Gen 3 Commodore in tank setup. Just one of these easily supports 300RWKW in modified Commodores.

I looked at using a pair of Walbro 255 pumps but these Commodore ones came up at the right price (Thanks Boxhead)

I'll be running the return back to the swirl pot and a seperate return from the swirl pot back to the main tank.

What's the twin feed parallel setup? Is that where you run the high pressure from the pump to each rail in parallel and the other end of each rail runs back to the reg?

Cheers

[Aussie Mike]

I'm not planning on going forced induction with this car. I'll re use the whole fuel system including the fuel rails with an 8 throttle body system I'm looking at building.

The car with the right cam and tune should make 300+ KW at the treads with this setup and that will be plenty for me.

Cheers

[Bathrone]

Mike, yes that basically it. From the steel fuel rail, a Y distribution block then feeds each fuel rail and both go back to the regulator.

If you get pulsation problems there is devices for that in single feed setups.

My fuel flow at cruise and idle was around 4.5l per minute back to the surge tank and hence that was the cause of heating the fuel.

300kws at the wheels is about my target too. Whats interesting is my commodore freinds, an LS1 motor, roller cam modification around .588" lift, 228 @ .050" duration, some head work, roller rockers, better valve springs etcetc some nice easy power with the stock block and internals.

[Aussie Mike]

The cam I'm looking at running is a bit of an animal: INT 237 EX 242 @50 INT .603" EX .609" 113 LSA

Reports from the US have this cam making around 415HP at the treads on a stock manifold heads and bottom end. The 8 throttle body will smooth out the idle and make it a lot more drivable and hopefully unleash a few more neddies.



Cheers

[Bathrone]

Shywt! Thats a big cam.

Will the stock LS1 turn 7000rpm ok?

Being a lighter car than a commodore the cobra could probably get away with more duration.

What did the supplier say about valvetrain life with that cam?

It would have a sweet idle tone for sure

[Aussie Mike]

They reckon a set of good duals like Patriot Gold springs should last about 30,000KM.

if you want to hear one of these idle right click and save this link: Camaro Idle (dial up warning 9Meg file)

Cheers

[Aussie Mike]

The bottom end is good for the revs and the factory PM rods are plenty strong. However I think I'll be setting the rev limiter a bit more conservatively though, probably 6700RPM or so.

Cheers

[Bathrone]

Nice vid Mike.

Well I guess since the LS6 has a 6600rpm revlimit its seems solid. But the LS6 has a different block and I understand the oil control in the ls6 is different because of it.

I'd be interested in seeing what your doing with the rest of the valvetrain to handle the cam - does it need anything else other than the aftermarket springs? e.g. lifters, retainers, seats, pushords etcetc

[Aussie Mike]

There's no real difference in the LS1 and LS6 blocks apart from some thicker webbing in a few spots. The oil control all comes down to the different design of breather the LS6 uses in the valley cover. The LS1 and LS6 valley covers are interchangeable so that's an easy fix.

On top of the springs there's a set of titanium retainers and hardened pushrods. The springs come with their own spring seats seat as well. The stock hydraulic roller lifters are fine as are the stock rockers. the stock rockers are a steel roller fulcrum rocker anyway so there's not much to be gained in going to aftermarket rollers.

Cheers

[Bathrone]

Impressive Mike.

I itend to take a similar path if I convince myself of the Cobra's fit for my needs. I was researching your chosen cam and I found this out which might be relevant to yourself:

If you whack in some ported heads with bigger valves, clearance to the pistons will be a problem on this cam. Apparently the airflow research heads are the only ones that wont require cutting the pistons.

http://airflowresearch.com/articles/article48/A-P1.htm

Have you seen my email/pm?

[Bathrone]

One of things that has tickled my interest on this is especially the budget Im preparing.

If I get a similar motor, some AFR heads, cam, heavy duty valvetrain, custom exhaust (which Id need anyway), spend alot of time on the ecu tune Ive got alot of power thats come affordably. Maybe the injectors and other things would need an upgrade (havent done the calculations yet) but overall this seems pretty cost effective.

[Aussie Mike]

Yes, got your PM and a reply is pending.

I don't know if I'd bother with the AFR heads when there's so many good porting guys here in Australia. Initially I'll run the stock heads as they have some impressive flow numbers from the factory.

I'll probably get some heads done by Nathan Higgins down here in Melbourne. He's a well renown V8 Supercar cylinder head guy and has done a lot of development on the LS1 heads..

Clearance will probably only be an issue if I go for bigger valves or get too much material planed off the heads.

The stock injectors seem to run out of puff at around 500HP. I'm told you can go to 36 pound Ford Motor Sport injectors or 42 pound Bosch/Delphi items.

I'm looking at a new ECU development from Dicks Electronics. It's a factory Delphi ECU but it's been modified to incorporate an Ethernet port and real time programming software. It also does data logging at around 80 FPS. the advantage of this setup over LS1 Edit is that you can tune the thing with a laptop on the passengers seat. With LS1 Edit yo have to make changes to the code and then flash them into the ECU using a programming harness. You then check and see what difference your changes have made and tweek the maps again. It's all a bit hit and miss unless you're very experienced in tuning these things.

Cheers

[Bathrone]

Thanks for the tip on Dicks Electronics, great stuff Mike youve really done your homework. Looks as though I'll be selling my Autronic then.

Anyone want to buy a race spec Autronic SM2 with a new wiring loom and all sensors I also have a R500 CDI box for sale, brand new

[750hp]

Bathrone - how much?

Mike - I bet a lot of LS1 Cobra owners in the future will benefit from all of your research and homework. Great stuff !

[Bathrone]

Craig cos I respect you man Id do you a special price.

The story with it : My Mazda is off its tits and I needed a better ecu to get a finer level of granularity to control the ***** Well, and I have a Microtech plugged into her so its cant be good

Its a race spec version, not the retail SM2 version. It has additional hardware, a full other pcb inside the case. We think this is for extra data logging but calls to my Autronic dealer were met with silence and a perception if I were Larry Perkins they spill the beans but otherwise........

It has a rotary chip in it, so if you wanted to use it in your piston motor youd need to change the chip. Not a big hassle.

Ive got a brand new wiring loom I bought for it, plus a brand new manual.

Its got air temp and water sensors too......

As well I have a brand new, never used Autronic CDI box R500 these babies will fire even high boost water injection setups there is just no flame suppresion when a R500 is at hand. Crazy cracy milljoules of energy to the plug.

What the Autronic does that the Motecs dont, is the injector control. I have four 160lb/hr injectors...mate thats 1690cc per injector and I had these bastards idling at 800rpm I kid you not. Try that with a Motec.

Anyway Craig just want to say Gday to you and as you know, Ive always admired your Cobra. Cheers

[750hp]

I'll send you an email later in the week. Have a think about what sort of money you'd sell it for (I like special prices ! ) and I'll talk to Autronic to see what's involved in making it work for me.

Thanks,
Craig