My cars development

[AlexCim]

Just an update with my car for those interested. It's an LS7/6 speed vehicle.

My factory fuel system (change over switch) was clogged with fuel tank baffling, so engine has to come out for that job. Plus I really didn't like the design, so I put in a new system. In the mean time, also did some upgrades

- MSD intake manifold
- Custom ground big cam
- Redid whole fuel system (balance pipe (run as 1 tank), twin lift pumps, twin filters, two 044's in larger 3L surge tank, larger fuel rails)
- New valve springs, head studs, etc
- Heaps more heat shielding on the car, fuel tanks, etc (was boiling my fuel is lower than 3/4 tank....)
- New tune

Should see 700+hp easy, so GTR720 territory. Next upgrades will be suspension / driveline.

Photos below

[deadscoob]

I had the same problems with the tank material, but didn't have the factory fuel system like you, so guess I was lucky the engine didn't need to come out.

I have that intake on order, are you pleased with it? What else have you done to the engine to get 700+, heads too?

Your fuel setup is now very similar to mine, simple and effective

[AlexCim]

My switch over valve thing was clogged, so bad it stopped working for a while and I only have the right tank. It's a PITA to change cause its right up in front of the engine on the firewall. The factory sent me a new valve, but glad I didn't swap it over cause if I had to change the hoses over in the crazy box it would have been ridiculous. So I just decided to redo the whole system because anyway the surge tank from the factory was only 1L, and the O44 was very loud mounted to the firewall (plus, I needed a second one anyway). Anyway, everything is a lot more serviceable now too (ie filter locations, etc)

Havn't run the car yet. Waiting on my second lift pump and some fittings to arrive. Car will be running Tuesday, then tuned later in the week. Should be "finished" (for now) by next weekend.

Standard heads, valves, push rods and rocker arms (the beauty of an LS7), but just upgraded valve springs and head studs. It's quite an aggressive cam, basically a cam from a GT3 Z06 with a bit less lift and lobe separation. Pretty much, slightly less agressive than this car: https://www.facebook.com/lsowners/videos/vb.139898...

The person tuning my car is a very well renowned LS tuner here in Australia (he basically just flys around the country tuning LS motors) and he suggested the parts list and said it will make 700hp pretty easily with the manifold. I'll let you know next week what it makes, how it drives, etc. Standard motor made 345rwkw for reference.

[deadscoob]

Cheers, will be interested to see how you get on, only a mildish cam in mine (Katech torquer 110) so I'd expect perhaps 30-40hp less.

[Abbosevolution]

Looking good - I've never quite seen the point 2 separate tanks - mine are linked and just one fuel tank sender used - makes life simple

[Racingroj]

Thanks for the info Alex. As you probably know many are experiencing boiling fuel (cavitation). I'm going to change my fuel system but probably only 1 HP fuel pump as mine is a standard LS7, also linking the tanks with a bigger pipe and adding bigger swirl pot to contain the HP pump. Also have noise problems from the HP pump on the bulkhead.
Roj

[UltimaCH]

Anybody thinking of using some Jenvey products?
http://www.jenvey.co.uk/products2/throttle-body-ki...

|http://thumbsnap.com/JSlkeYRi[/url]

[AlexCim]

Yes, I never understood the two tank thing either. Unnecessary complexity. I pick up and return into each tank, with just one of the -6 lines to balance it. I don't expect much movement between tanks, it's more just for equalizing it.

My surge tank can work with either a single pump, or two. So if you buy it, you've always got that capacity for future to add another pump. https://www.aeroflowperformance.com/tanks/fuel-sur...

[Abbosevolution]

Make the link pipe as large as is practical - I found the fuel return from the swirl pot took the path of least resistance so one tank would fill quicker than the other - a large link pipe or equal length returns solves the problem.

[AlexCim]

That sounds reasonable, but the fittings welded into the bottom of the tank are no bigger than dash 6 anyway though? How would I make it larger?

[2001ultima]

A quote from another topic post....

Storer said:

This forum is ultra quiet at present. Am I the only one doing anything on their Ultima?

Nice to see some nice work being done. I like all the protective heat wrap, I'm a huge believer in that. Swirl pot looks good too.

[AlexCim]

Abbosevolution - Further about the fuel system (as I'm probably asleep when you're awake, so writing it now). Basically it goes tank, filter, lift pump, surge tank, 044, rail, surge tank, return (one into each tank). I guess it's a pretty standard two tank system with a pipe at the bottom.

My theory with -6 being big enough or not is that that each tank is emptying at the same rate (the lift pumps flow rate) and less fuel than what was sucked up is going to return (as it's being burnt), the bigger that difference is the more WOT it is. And so considering the idea of path of least resistance, both tanks will return to the top of the tank, which is air, so resistance is minimal anyway.

So even if the pumps are +/- in flow rate, and the return is +/- in flow rate (tank to tank), I am not asking the balance pipe to flow any more than the real difference between the two return rates. I know that a -12 is 4x the surface area of a -6, but I don't see as much as a difference of 25% in return rates?

Has anyone tried to use a -6 before with issues?

I'll find out Tuesday when the car is started for the first time, it will be most obvious on idle with completely full tanks.

[Storer]

I use twin balance pipes at the bottom of the tank on the standard fittings.

Fuel is pumped by an in tank pump fitted via the fuel guage tube.

The twin balance pipes easily cope with keeping the level in each tank similar. When filling the car I can almost do it from one side.


Paul

[Abbosevolution]

Alex - I had the same view regarding the returns but my swirlpot being on the drivers side means that one return is significantly longer than the other. The tank closest to the swirlpot filled significantly quicker because the weight of the fuel in the pipe and the force required to push it is less than the weight of the fuel in the longer return, hence the difference. The solution is to either make both returns the same length or improve the link pipe between the two tanks to make balencing quicker as Paul has done.

[Graham-P]

Strange this should come up as I'm just revamping my fuel system, like Paul I have a lifter pump in the passenger tank where the fuel sender use to sit, this feeds a new surge tank with a Walbro 450l pump in it. My tanks are linked by a -12 pipe also I've linked the -6 pipe, the old external pump feed. The overflow from the surge tank returns back to the passenger tank that I'm pumping from, the drivers tank is basically a big reservoir balancing the levels.

[Storer]

Graham-P said:

Strange this should come up as I'm just revamping my fuel system, like Paul I have a lifter pump in the passenger tank where the fuel sender use to sit, this feeds a new surge tank with a Walbro 450l pump in it. My tanks are linked by a -12 pipe also I've linked the -6 pipe, the old external pump feed. The overflow from the surge tank returns back to the passenger tank that I'm pumping from, the drivers tank is basically a big reservoir balancing the levels.

Neat tank Graham. what does it hold?

I see you are spying on the neighbours with a drone!!!!


Paul

[AlexCim]

Abbosevolution said:

Alex - I had the same view regarding the returns but my swirlpot being on the drivers side means that one return is significantly longer than the other. The tank closest to the swirlpot filled significantly quicker because the weight of the fuel in the pipe and the force required to push it is less than the weight of the fuel in the longer return, hence the difference. The solution is to either make both returns the same length or improve the link pipe between the two tanks to make balencing quicker as Paul has done.

Unfortunately for me, I only have a -6 fitting on my tank, so I'll start with that as a balance pipe and go from there. I think there is no point trying to put a step up fitting/bigger hose etc, as the fitting itself is the restriction.

The overflow on my surge tank goes into a Y piece, and upon your advice, I am going to run equal length (and similar bends) hoses to try my best to keep the rates of return as close as possible.

I used the old surge tank, 1L, and filled it with water and measured the rate of flow from the bottom fitting a) with no hose on the end, and b) with a hose on the end. a) emptied the 1L in 16 seconds, b) emptied the tank in 8 seconds. I presume the hose provides more laminar flow and hence drained faster.

So the approximate conclusion I draw is that a -6 balance pipe should be able to equalise side to side around 1L every 10 seconds if there is a 1L volume difference between tanks. I am happy to be corrected if someone sees fault in my theory?

My lift pumps are 420L/h, so 1.15L / 10 seconds, so even if there is a 50% different in return rate to each tank (I think that's unlikely), that's only half a litre per 10 seconds. So I conclude a -6 should be fine?

Just going to be annoying filling the car up at the servo I think as it will be balancing too slow to just fill one side.

[k wright]

I have essentially one fuel tank with two pumps. I linked the two together using a -12 line that is about 3/4 up the inside surface of the tank. The goal was to prevent the fuel from sloshing back and forth but still allow transfer during fueling. I still have the -6 line connection at the bottom of the tank. The two pumps join in a Y fitting after the fuel passes through a one way valve on each side.

[Graham-P]

Storer said:

Neat tank Graham. what does it hold?

I see you are spying on the neighbours with a drone!!!!


Paul

I was going to say petrol but that would've been childish ........Tank holds 3 litres, should be enough for my driving it's a quality piece of kit.

The only spying I do on my neighbours is when I go round and ask for my drone back as it landed (crashed) in their garden!!! Actually they're indoor ones........that only happen once......honest.

[UltimaCH]

Alex, where are you fitting your twin pump surge tank? On the bulkhead downside somewhere?