SVO fuel issue.

[oomadoc]

I recently had my 1986 SVO on a dyno after I swapped the stock head out for a Bo port head www.bo-port.com/index.php?act=viewProd&productId=72. The cam is the bo port 2.1.  I have a K and N airfilter, stinger single 3 inch exhaust with downpipe. Am I going to have to upgrade my stock injectors? The guy who did the dyno tune told me not to run it over 6 psi of boost due to a lean condition. Does this sound right? If I need to upgrade my fuel system what parts do I need? Thanks in advance.

[Stinger]

Yes, those parts will exceed the limits of the stock fuel system. You'll need a Walbro 255 lph high pressure pump, larger injectors (sized according to your power goals), and a way to control those injectors since the stock ECU can't do it.

[oomadoc]

I just want 325 to the wheels. What size injectors would accomplish this? Would I need to upgrade my computer? I'm considering getting the PIMP system if the stock computer cannot handle the power goals.

[oomadoc]

The exhaust system I got from Stinger and the Bo port head really woke up the car. Its faster at 6 psi than it was when it was stock at 18 psi!

[Stinger]

These sorts of answers are explained in our FAQ page but I'll give you the basics.

All the stock parts max out around 280-300hp at the wheels (turbo, injectors, ecu) so to go beyond that, all of those items need to be upgraded in some way. Since you've already got a ported head and good exhaust, once you upgrade the parts listed above (and add an FMIC), it will cost the same amount to make 325hp or 400hp.

[oomadoc]

Do you guys sell the after market fuel pumps? I can't seem to find them. I am about to order the 60lb siemens high impedence injectors.

[oomadoc]

I meant 75 lb low impedence injectors.

[oomadoc]

Is it absolutely necessary to replace the computer? Right now all I can afford the injectors and the fuel pump. If it doesn't make 325rwhp Its not a big deal.

[Stinger]

You can't run larger injectors with the stock ECU. If you install the 60's or 75's with the stock ECU, you'll be injecting twice the fuel that's required under all conditions (idle, cruise, wide open throttle, etc.) which won't even run.

I would assume your fuel pump is probably what's holding you up currently (the weakest link). This can easily be tested with a fuel pressure gauge that you can view while driving. Go wide open and see if fuel pressure climbs with boost, or if it initially climbs but then drops off as RPM continues to climb. You need a Walbro 255 lph High Pressure pump from jdsperformance.com for an 87-93 Mustang 5.0.

Proper fuel flow from the pump, as well as raising the fuel pressure a bit with a Kirban adjustable regulator (for a 5.0) should allow you to run 12-14psi and make 275whp or so. You'll be pushing the parts pretty hard at this point and it would be highly advised that you get a wideband o2 meter to monitor the air/fuel ratio to make sure you don't go lean. You'll need the wideband for the PiMP anyway. That should give you time to save up for the PiMP and injectors.

[oomadoc]

Thanks. What do you recommend for a Wideband o2?

[filasfinest86]

Hey stinger not to go against what you said I know you know a lot more about efi than I but in the 90's they did experiments on a 2.3 turbo ford and they did use bigger injectors with no drivability issues the magic size they found was 42lb low impediance... The series was called tinny avenger if you wanna do a search for it they made 350hp with the svo roller cam I'm sure with all your Bo stuff you should make that easy..but yes 255lph should be at the top of your list... The fuel pumps are the same as the 5.0s just be carefull when pulling your sending unit out don't pull or pry to hard on the stems.. Got an authentic walbro on ebay for 75 bucks keep your eye out on there don't get the jap version I've heard all the internals are plastic.....

Hope this helps derek



Link to 42lbers: www.ebay.com/itm/Holley-522-421-Universal-Fuel-Injector-42-lbs-hr-Low-Impedance-1-Each-/130822226011?pt=Motors_Car_Truck_Parts_Accessories&hash=item1e759cc05b&vxp=mtr

[filasfinest86]

My vote is for AEM I've had innovative and I find them to be a pain in the @$$..... AEM plug it in and go it has a self calibration and can be had for 155 free-ship on eBay...

[Stinger]

The AEM units are good widebands and I agree, they are simple to use.

I'm well aware of the Tiny Avenger series of articles. While 42's "can" work if you're well versed at tuning 2.3T engines and have the tools to do so effectively (which isn't the case in this thread), and you're willing to sacrifice low rpm driveability and MPG for the sake of high rpm power. Technically you can turn stock 35lb injectors into 42's by raising the base fuel pressure (as I mentioned above) but you need a wideband to see how far you can raise the pressure without hurting driveability and MPG.

The 42's are also the same price as larger injectors (which he'll need anyway to match the parts he's already got) so what's the point in buying injectors twice?

[filasfinest86]

True he does have some pretty nice parts! They claimed with the 42s there was no change in drivability they also tried 52's and said you could notice it then.. I'm with you they prolly didn't even have a wideband back then to see how much fuel they were pumping out the tail pipes driving around... I love that article I think ive read it like 100 times... Love the part when they say" we finally found how to coax the power out of this little sucker" did they have widebands back then? I know they prolly had them on the dyno

[timmer35]

Nice thread, I got the 255 and kirban ajustable reg. I raised my pressure about 5 lbs over stock seemed to help, but what would you think would be the limit on raising that pressure with stock set up?