Fuel injection options

[Simon]

I've just bought a 408 stroker engine with 490 bhp (480 ft lbs torque) running an 850 double pumper (taken out to 920 cfm!)
I'd like to change it to fuel injection but know NOTHING about it. What are my options?
Thanks
Simon

[Neal]

Option 1: Stack TB Injection
Very Cool Parts, TWM, DC&O, Roaring Forties.
Plenty of options for an ECU - Motec, FAST, Redline, Electromotive

Be prepared to dyno tune to get optimum performance. Definite WOW factor.

Option 2: Throttle Body Injection
http://www.mass-floefi.com/

Uses Ford ECU for simplified setup. Custom mapping is available through various dyno shops.

Definitely talk to someone with a setup before you commit. Tuning can be a bugger.

[Paul Thompson 'Hooligan']

Hi Simon

Neal's spot on but over here you will probably find it easier to get an aftermarket ECU mapped than one of the Ford EFI units as we have very little Ford V8 aftermarket tuning of standard vehicles over here.

You can always do it in stages (depending on budget), fitting an ECU + fuel rails/injectors to your existing setup and retaining the carb as a throttle body initially.

Then, later, funds permitting, add perhaps an individual throttle body arrangement such as those made by Jenvey or Kinsler to name but two.

Finally, don't forget to look at the fuel supply too, you'll need different pump, swirl-pot etc etc

Have fun though - Injection is the best (and yes I am biased!) [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[Kalun D]

You might try a search but EFI info gets sort of dated because of the constant upgrades. Especially when it comes to ECU's.

Look at spending 5K to 10K though for anything with 8 Tbodies, or 20K for top of the line, cheap it is not.

There's a recently published book (2004) that covers EFI quite well, and shows all the brands of programmable ECU's.

BOOK LINK

Once you decide what level to go with then you may want pick something that has a rep close by in case you need hands-on help.

I chose the Accel Gen 7 just because the rep is local and has a chassis dyno. Some other systems were a little less expensive but the local support wasn't as good.

Beware of the hidden costs. Motec USA is famous for this. Try to anticipate everything you need up front as it can be quite expensive later to add on. Specifically question, "what are ALL the add-on options and how much do they cost?"

Accel did this to me, they have two levels of hardware keys that they don't tell you about. It comes with a standard key but if you want all the software features you have to buy an upgrade. It wouldn't be so bad if they told you this up front.

[Peter D]

Simon, the guys above have pretty-much covered it - all I can add is some approx costs :

- DC&O manifold for 8-stack = AU$900
- DC&O 8 x t/b's = AU$880
- Linkages to suit = AU$150
- Custom inner fuel rails = AU$300
- Autronic ECU = AU$1,600
- 8 x Holden Commodore S/C V6 injectors = AU$800
- Basic Commodore wiring harness = AU$250
- Sensors (2 x O2, air/water temp, tps, etc), say AU$400
- 2 x Igniters + 4 x dual coil-packs = AU$600
- Modify dizzy for triggers = AU$300
- Wiring work by experts (ie, not me !) = AU$750
- Basic Tuning by Autronic expert = $300
- 2 x 1/2 days on the dyno (incl Autronic expert) = AU$1500

That's all I can think of for now - a total of nearly AU$9,000 for a relatively inexpensive setup !!

Kalun's points are really important :

- Proximity of an expert on the ECU (my reason for choosing Autronic).

- Look very carefully into the hidden software lock issue (my second reason for picking Autronic - they have none).

There seem to be maybe 3 reasons for going with EFI :

- Registration : here in Oz, there is no way on the planet that you can get a carburettered engine to pass the emmissions tests - you just have to go EFI.

- Looks : An 8-stack just simply looks cool (& can easily be mistaken for a quad Webber setup by non-experts)

- Reliability : Once set up correctly, they almost never require re-tuning (most ECU's even account for changes in atmospheric pressure). I can just reach into the car & twist the key - it starts every time, hot or cold, & runs totally evenly right throughout the rev range.

BUT, if you already have a registered car, it just comes down to looks & reliability - is the change worth AU$9,000 upwards ?

Hope this helps a bit.

Kind Regards,

Peter D.

[dwe8922]

Is there anyone w/ a gt40 that is using the edelbrock pro flo, or the very cool parts maf EFI systems? At about $2500, they seem like a great alternative to the much more expensive weber like efi systems, yet it seems people either go carbuerated or the weber type.

How do they apply to the gt40s in terms of needing hi and low press. fuel pumps, swirl pots, etc.? They come with a single fuel pump, so I wonder how they would accomodate 2 tank fuel pumps, and the additional pump. Maybe a better question to ask is why do gt40s require swirl pots and a high and low press. pump system? I understand needing a reservoir for tank switching to avoid interruption, but I always thought fuel tank baffling solved fuel starvation issues. I also don't understand the need for high/low press. pumps.

[Peter D]

Hi Dave,

Attached is a pic of my fuel system diagram. The LP pump is basically a "lift pump" to keep the swirl-pot full - these tend to be more tolerant of pulling air for a while than the HP pumps. (And you will probably pull air, regardless of baffles in the tanks, if you park facing downhill for a couple of hours with fairly empty tanks).

Most GT40's simply need the swirl-pot as "holding tank" - simply because of the long fuel tanks which usually have the pick-ups at the back.

Hope this helps a bit.

Kind Regards,

Peter D.

[Tim Kay]

Following Peter's schematic above, I'm not quite clear on what appears to be a return line from the Swirl Pot thru the change over valve and back to the main tanks.

Is it necessary to return fuel to the main tank?

Would a swirl pot float switch that turned off the LP pump eliminate the need for return lines to the main tanks?

Would a LP fuel pump be susceptible to failure if starting a stopping constantly?

[Bill Bayard]

Tim,

That's a return line for excess fuel (EFI). HP pumps push more fuel than the EFI uses(pressure regulated). From the changeover valve, the excess fuel is distributed to which ever tank is currently being drawn from(no possibility of overfilling the wrong tank).


Bill

[Paul Thompson 'Hooligan']

Hi Tim
Interesting idea re the float switch and only topping up the swirlpot as required - I like the idea but suspect that running the same fuel repeatedly through the fuel rails will to an extent turn the swirl pot into a radiator, which will gradually take heat from the engine back to the pot, thus heating all the fuel you are drawing from - not ideal.

The swirl pot is important though, without it, unless you have very tall tanks (bit like Dave's R42), you won't maintain an even (air free) delivery of fuel to the engine - which in turn will make it a bitch to tune, will run lean and lose power every time air runs through the fuel rails..

[Gary Gibbs]

I believe you can get away with two pumps and no swirlpot if you have trap door pickups in each cell like in this thread:
Buzz Clarke Fuel Cell Mods.

[Tim Kay]

[ QUOTE ]
.....running the same fuel repeatedly through the fuel rails will to an extent turn the swirl pot into a radiator.....

[/ QUOTE ]
Good point Paul

Are the return lines from the swirl pot to the main tanks gravity feed?

The design I am considering would be just like Peter's. Since my left hand driver side fuel tank is shorten due to the position of my battery box I think I will reduce the passenger side fuel tank the same and use that rear area for my swirl pot. But gravity feed from swirl pot to main tank may not work, especially to the opposite side tank.

Thanks Gary and Buzz, more design suggestion would be helpful [img]/ubbthreads/images/graemlins/tongue.gif[/img]

[Paul Thompson 'Hooligan']

Hi Tim

The 'non-injected' (excess) fuel returning from the fuel rail back into the swirl pot, together with that being added by the lifter pump, will create an overflow condition and it is this which will flow back to the main tank(s).

The lifter pump needs to be able to flow enough fuel at max rpm/full throttle to keep the engine fed, so when the motor is idling or at part throttle, ALL the excess capacity of this pump will be fed back by the overflow return from the swirl pot to the tank(s), together with any air that might have been picked up by the LP pump during cornering/braking etc. Consequently, the fuel will be flowing at quite a speed during idling and part throttle so there will be no problem with it flowing across to either tank.

One thing, always make sure your return lines/fittings are capable of flowing the max capacity of your HP pump without causing a restriction to the flow, if they do restrict and cause a back pressure, the fuel pressure regulator will have a hard time holding the desired fuel pressure.

Returning to Dave Parker's R42 - this has no swirl pot, feeds from one tank and returns the other with a 2" dia balance between the two - but his tanks are tall and short, see pic below where I have indicated the location/shape.

[Peter D]

Tim, I suspect that the swirl pot will be under slight pressure all the time, courtesy of the LP pump - so any overflow of fuel or air should be forced from the top exit of the swirl pot back into the tanks, regardless of where you mount the swirl pot. Buzz Clarks setup seems to bear this out - his are just mounted inside the tanks, but I would bet that the same situation would apply to the return lines / venting ports at the top of his internal pots.

Paul's point about the heat transfer provided by continually cycling fuel is a good one. I only really noticed it the other day, but I had the engine well & truely up to temp with the clip closed, then opened the clip & put my fingers on the fuel rails - they were stone-cold, whilst everything else around was way too hot to touch !

Colder fuel = denser fuel & no vapour locks. I understand that some drag racers use ice-filled "cooler boxes" to run their fuel thru for this reason.

Kind Regards,

Peter D.

[Ian Anderson]

Sorry if this is obvious but I am trying to set up my system *Rover EFI)

On the schematic above the return from the fuel rail goes into the swirl pot. 3 questions
1)If the swirl pot is slightly pressurised would the return feed not also be pressurised to force the return fuel into the swirl pot and thus put additional back pressure on the rail relief valve and hence invrease pressure on the injectors?
2) If the "hot" fuel is returned to the swirl pot are you not possibly continually heating the fuel?
3) Would it not be preferable to T the return from the rail into the excess return from the swirl pot this should be at 0 pressure and flow direct to the fuel tank from which the fuel is being drawn.

I am also looking for a source of the valves - potentially from Jaguar EFi V12 which uses 2 tanks etc.- on a search I read about Pollack Valves - sound great but I couldn't find a source.

Two last questions
How big a capacity do you need in the swirl tank?
What volume LP pump do you suggest?- Or do you suggest 2 one for each tank?

Sorry a simple question raised a load more in my head!

In a way I want to kep it dead simple to get through SVA - the less on the car the less they can potentially fail it on but at the same time I will yield to experience

Thanks
Ian

[Peter D]

Hi Ian,

I am a complete amateur when it comes to EFI, but I felt comfortable going with the setup in the diagram after pouring over it for some time - just based on logic.

With regard to your questions :

1) At the end of the day, we have 2 fuel circuits operating out of common swirl pot. The HP circuit pump just works away at pressurising the injector rails, and fuel that is not used by the injectors is returned to the swirl pot via the regulator - ie, return pressure is much that same as in the swirl pot. My understanding of the regulator is that the HP side stays as set, as long as the downstream (LP) side pressure is lower.

The LP circuit pump simply keeps circulating fuel from the tank to the swirl pot & back to the tank (just keeping the swirl pot full). Any excess pressure in the swirl pot would just ensure the flow of fuel back to the tank. My setup has vapour breathers from the tops of each tank back to a carbon cannister, so pressure in the tanks should be pretty much atmospheric (ie, virtually open).

2) The HP pump keeps circulating fuel around the rails & via the swirl pot (potential for heating up the fuel), BUT, the LP pump is also circulating fuel from the tanks to the swirl pot & back. This last bit is the secret for keeping the fuel cold - the tanks effectively act as huge radiators. As I mentioned, I can put my fingers on the fuel rails after the car has fully warmed up, & they are stone-cold.

3) I think that the fact that the LP circuit is continually refreshing the swirl pot with cold fuel from the tanks solves this problem.

Re the valves - I'll check out what mine is & let you know. From memory, it is a marine job that is basically a double-pole / single throw switch/valve.

I am not sure that the capacity of the swirl tank is critical, but I'll also measure that as well.

Re the Lp pump capacity - all that really matters is that it can deliver enough fuel to match consumption by the engine. Therefore, any decent LP carb-type pump should be able to do the job.

Kind Regards,

Peter D.

[dave harris]

Hi Ian,

the multi-port valve was discussed in another thread - One that a lot of us are using - it's made by Polak (sp?). do a search on Polak, Polack etc and you should find it (I can't find my paperwork right now).

If you can't find the part number with a search PM me and I'll look it up.

cheers

[Ian Anderson]

Peter D and Dave

Many thanks for the feedback - it makes more sense now and I'll be ordering the bits

Thanks
Ian