The x80 injectors tend to flow like x50 injectors. 850s are juuust big enough for a 35R at 43 psi base pressure, fuel SG of .724 (race gas) and target AFR of 12.5:1. With changes made for pump gas (.76/11:1) they are not big enough. The 255 LP will do ~60 lbs/min on the same race gas assumptions at 30 psi with 43 psi base, and I proved this the hard way, with a blown motor 64 lbs/min equaled 13.5:1 AFR at 29 psi (for what it's worth the math worked out to within a couple tenths of a lb/min). The HP is good for 70 lbs/min given the same values at 30 psi with 43 psi base, and though I didn't try a 255HP, I trust this to be accurate based on my experience with the LP.

One concern I would have is maxing out the turbo at the stated goal of 32 psi. Not sure if an intake manifold is in the plans (good for ~3 lbs/min at the same boost), but the 64 lbs at 29 psi I referenced above gives some indication of what to expect from a 65 lb turbo at 32 psi on a 2.3. Not that maxing it out is necessarily a bad thing, we all do it on the stock turbo eventually, but it's something worth mentioning in my opinion.

 

I think single should be more than enough. I am running GT35R at 32-33psi with single walbro and 1000cc injectors.

 

850cc is no problem for running a 2.0L 35R on 93 oct at 11:1 AFR and 22-23 psi. I'm doing it now with no issues at the 455-460whp (DJ) level, and I doubt anyone is going to get significantly more than that on pump fuel. Now, if one is using an AEM EMS an 850cc will be too small, but that isn't the fault of the injector, and is another issue entirely . . .


AFAIK, the default 255lph pump sold by every vendor associated with this forum is the HP model. That may have not been so in the past, but that's what you get now (fortunately). The LP model shouldn't be considered for turbo apps.


Actually, the limitations of a single 255lph pump have been demonstrated here. IIRC, the rail pressure tends to drop around the 550whp (DJ) level. One can resort to a larger injector and increase the injector duty in an attempt to compensate, but I consider that to be a 'band-aid' fix.

 

I'm not surprised, your airflow level is quite low at that boost level on a 2 liter. About 45 lbs/min based on my experience. It's kind of beside the point IMO, since it makes sense to size the fuel system to at least the maximum flow the turbo is capable of, in case boost gets away from you. 65 lbs/min in this case, which is significantly more than 45 lbs/min. At least that's how I do things now after some of the experiences I've had. But then again running DSMlink I also assume people can run anything up to 1000s and have it run like stock. If poeple are running AFCs and other piggy backs then it may make some sense to keep the injector as small as you can if there is no injector compensation done in the ECU to avoid excessively high timing.



That's what I've been hearing, and it's certainly good news. With the DSMs there was always the choice between the two. And the last person I trust is a vendor, so I like to be sure. Hopefully they are all HPs, but I provide the info on both pumps for those interested.


I have seen similar results repeated over and over again for the last 6 years or so. But I have a fundamental problem with quoting the size of fuel system parts in whp or track times. One person may get significantly more out of a pump for example than another may be able depending on tuning, setup, and other variables. Same goes for track times. A lightweight purpose built race car will get more trap/et out of a particular fuel system part than a full weight street car, since it will take less HP to get there. Looking at it in terms of strictly airflow, AFR, and specific gravity, you really can't go wrong. As I said above, the math works out to within tenths of a lb/min.

I'm certainly not trying to argue any of these points, just stress my own point of view. I seem to look at things from a different point of view than everyone on this forum. Maybe it's just the DSMer in me or perhaps it's because I still run DSMlink because flying blind is not an option for me. And I don't mind, it's half of the fun.

 

It floats when it reaches 35 psi!! at 32 psi its fine... The boost pressure is pushing it open... AM running HKS 280's... Someone mind telling me how to post my graph up?

 

I use a piggyback device (Xede), but this particular setup also includes a reflash of the ECU to reprogram injector scaling. This is advantageous for the reason you mentioned.



Fortunately, one can easily check the part number (stamped on the pump) if in doubt.



And what one gets out of a particular pump may change (for the worse) over time. My personal opinion is an ounce of prevention is worth a pound of cure, which is why I recommend upgrading the fuel system when the limits of the single in-tank pump are approached. IMO, there's just too much at stake at these power levels, and the acceptable margin of error is small and relatively unforgiving.


Your point of view is obviously an intelligent one, and therefore is much appreciated!