|
|
Post by xr2300 on Jan 20, 2022 13:21:13 GMT -5
I'm looking at installing a Walbro High Pressure in-line pump in my 84 SVO. Will this change my base fuel pressure, like from 39 psi to ...?
When one is installing a HP pump, does a FPR also need to be installed to adjust the pressure after? OR will the stock FPR maintain the stock pressure?
Cheers.
|
|
|
|
Post by Stinger on Jan 20, 2022 13:45:22 GMT -5
It will only change base pressure if the stock regulator can't control the extra flow. This is a "sometimes" scenario. I don't know why but sometimes the stock regulator works fine with the Walbro, other times it requires an FPR upgrade like our Kirban that has a larger return side flow rate.
|
|
|
|
Post by xr2300 on Jan 20, 2022 14:02:56 GMT -5
Thank you. Although my regulator was recently replaced with a Standard Product piece, I'll anticipate it might change. I'll consider the Kirban.
|
|
|
|
Post by Stinger on Jan 20, 2022 14:11:25 GMT -5
If the stock one doesn't work, there isn't really any other regulator to consider other than the Kirban as the others are too large/heavy and crack the rail over time.
|
|
|
|
Post by xr2300 on Jan 20, 2022 14:28:36 GMT -5
Of course. And I also understand the Kirban needs an edge ground down to fit the early style Inline intake fuel rail...
|
|
|
|
Post by Stinger on Jan 20, 2022 14:39:31 GMT -5
I believe the early inline rails are odd in some way around the FPR (besides their oddball injector spacing/angle and mounting oddities).
|
|
|
|
Post by xr2300 on Jan 20, 2022 15:08:23 GMT -5
The early fuel rail has a raised edge on once side, so those larger regulators like the BBK or Aeromotive will not sit flush. The Kirban is small enough to almost fit. I guess to make it fit, one edge could be ground down with a file. photos.app.goo.gl/uqVNSCndiP2pCe2KA |
|
|
|
Post by Stinger on Jan 20, 2022 17:45:36 GMT -5
Gotcha, thanks for the pic. I don't remember modifying my Kirban almost years ago when I installed it on my SVO (when it had an inline intake) but obviously after that much time, me not remembering doesn't mean it didn't happen.
|
|
|
|
Post by xr2300 on Jan 21, 2022 20:43:47 GMT -5
We’ll for what it’s worth, the inline Walbro 255 HP pump I got from Stinger is in, and my Standard Product fuel pressure regulator is holding up. I’ve been driving around and the AFRs have not changed and my electric gauge still reads 36 psi at idle (with vacuum). All good.
|
|
|
|
Post by Stinger on Jan 21, 2022 21:27:58 GMT -5
That's significantly higher than stock (unless your engine is pulling very little vacuum) but if that's what it was before, I guess it's OK.
Stock should be around 39psi without vacuum and drop to low 30's with vacuum.
|
|
|
|
Post by xr2300 on Jan 22, 2022 12:17:11 GMT -5
Hmmmm, I'll look into this. My boost gauge reads 17 inches (inHg) at idle, which I think is good vaccum. The cam is a Esslinger 450 if that makes a difference.
I'm sure 36 psi is what Ive always been seeing. It might be the electronic fuel pressure gauge I have...Ive always been meaning to get a mechanical gauge on it....
I'll look into this.
|
|
|
|
Post by Stinger on Jan 22, 2022 12:41:20 GMT -5
Yeah, that's good vacuum, particularly for that cam. The "right" way to check fuel pressure is vacuum off. Whatever it reads vacuum on sort of "is what it is". I wouldn't waste much effort on it if it's running good.
|
|
|
|
Post by xr2300 on Jan 22, 2022 19:14:53 GMT -5
Ok, so I read my electric fuel pressure gauge with the vacuum line off, and it reads 46 psi. Wow. I've never seen that, and perhaps I was mistaken when I said 36 psi was normal. There seems to be a 10 psi increase with the new pump.
Now possibly why the car seems to still run ok....at bit of background:
Right now Im running a J3 chipped 8UA with some Mopar Super 60's. At 39 psi the injectors are supposed to flow 43 lbs/hr. The actual tune on the chip is for 45lbs injectors. When I first started tuning for the larger injectors, I started off with 43#, but the car didn't feel right. It showed slightly rich while cruising. I raised the injectors rate up and finished with a tune for 45lbs/hr injectors. The car ran better, the AFRs were good, so I just left it.
So, now with a base pressure of 46 psi, my injectors should flow 47lbs/hr. And maybe because my tune is for 45lbs/hr injectors, that is why the increase in pressure is not noticeable... I don't now.
If I change the injector rate on my tune for 47lbs/hr injectors, and the car runs right, can I just leave it and keep and eye on things? Or will my stock FPR eventually explode? lol....
|
|
|
|
Post by Stinger on Jan 22, 2022 23:38:16 GMT -5
I don't really think that scenario has much to do with why it's running fine. Without knowing what the pressure was before, it's hard to say why. Maybe it was already 46psi before? It should be but it's not impossible. I've never found stock ECU tuning to be all that consistent (meaning it doesn't always do what it should do based on changes made). The other factor is that AFR can vary quite a bit without it making a noticeable difference on how it runs.
The FPR won't explode. You can do whatever you want with the pressure. If you want to leave it there, do so (as long as it's consistent which isn't guaranteed when it's on the edge of pressure control already).
|
|
