6.0-928S

Impressive calculations Louie! What's the pressure of the S4 pump/system versus the 85/86 pump/system?
Hammer

Louie928

The '85/'86 pressure regulator is about 2.5 bar or 37 psi while the S4 and later regulator is 3.8 bar or about 56 psi.

The fuel pumps do have slightly different Bosch part numbers. The delivery spec for the '85/'86 is 1350 cc per 30 sec while the S4 and up is 1250 cc per 30 sec. I can't recall if that delivery is under pressure or free flowing.

I use the 044 pump which is supposed to have high output, but takes more current. I wired it through an additional relay mounted in the spare wheel well. I took power from the rear power connections and activated the relay with the normal fuel pump circuit. The standard fuel pump relay and wires are barely adequate for the stock pump. I didn't want the voltage drop and other trouble from the stock circuit with using the higher current pump.

I use 36 lb injectors, but have my pressure set for 60 psi. My ECU shows a max of about 78% injector duty cycle.

ZEUS+

Very impressive. Maybe this link can be helpful with injector selection.

http://www.injector.com/injectorsele...e239c17f204cbf

6.0-928S

I see. Now you've got me nervous. I thought I'd be ok feeding 6 litres with the 30 pounders. Of course I could always unload them (they're still NIB) & go for some larger. I didn't plan on going this far with the mods, it just happened.....honest it did!
Thanks, Hammer

Louie928

You could probably get by with the 30s and up the fuel pressure. If you could return them and get 36# or 42#, then do that. A lot of the boosted folks run 42#. The 42# seem more available on eBay (cheaper) so that may be a route. Depending on your cams, you are going to have a real ground pounder and it takes fuel. I just noticed, is your engine 6.0L or 6.5L? Even if a 6.0L, I'd still get larger than 30s if you could.

6.0-928S

Thanks Louie, I value your opinion.
Cams,
Int. duration 260, Lift .410
Exhaust, 254, Lift .400
6.0 Litre

ARCFLEMING

Other than E-bay who would have these larger injectors (one of the 928 suppliers) and what part # or brand discription would I use?

Brian
6.5 liter

90 S-4

http://www.fiveomotorsport.com/

mark kibort

Thanks! good info on the injectors source. Ive heard the 24lbers could be fine for a 400rwhp 6.5 liter? at 70psi, it looks like it will work. The other factor is if I really have 70lbs at WOT at 6000rpm. i have never run the fuel pressure gauge on the dyno, just idling and reving in the driveway. I cant get the darn thing to not drip fuel (not the right seal). Its not a bad leak, but its a leak and that isnt right.

what do you all think about just taking .5mm of the base circle of the stock 86 cams??? i heard the lifters can adjust to this. I certainly wouldnt want banging lifter noise!!

mk

Louie928

Do you know at what lift those duration numbers are? What is the duration at 1mm lift, or else 0.050" lift?

Louie928

Summit has quite a few. Price is ok.
http://store.summitracing.com/egnsea...15&Nao=0#rstop

6.0-928S

At 1mm.

Hammer

Louie928

Thanks. That is one long duration cam set. Significantly more than I have. It will be interesting to see how that works with the auto tranny. Will you increase the tq conv stall speed?

6.0-928S

Probably, but first I want to try it with the stock one first. I'm prepared to go to the higher stall if I have to.

Hammer

Louie928

I bet it will sound wild. Hope I can hear it run someday.