TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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Looking to install my intake man. next weekend. While im doing the swap id like to upgrade my fuel pressure regulator. However im having a hard time finding a good aftermarket AFPR for the install. What AFPR are you guys running and where will i have to go to get one? Thanks
I am currently working with a machinist to get him to cut a bunch of block off plates and some Viton gaskets to seal it. He has a flow-jet and made a CAD drawing based on Jet's adjustable regulator cover.
I will let you guys know IF and WHEN they get done. You can always use a regulator cover that has no "slot" on the side and then cutout the center of your regulator diaphragm and use the rubber/gasket material to seal it.
Well, it's not a direct bolt on. you will have to remove your fuel pressure regulator diaphragm, spring and stock regulator cover and put a block off plate in replace of it.
The 13301 will mount anywhere you want it and you will have to replumb your fuel lines as well. It's relatively easy to do, but can be a little time consuming.
If your 305TBI setup is still going to be relatively stock why are you wanting to change out your regulator?
a stock 305 even with all the ultimate TBI mods doesn't need any more fuel pressure than 13psi and certainly doesn't need an adjustable regulator.
If you were going to add the 13301 you would also need to add a nice higher flowing fuel pump as well otherwise the 13301 isn't necessary.
Just trying to save you a lot of time and money on a mod that will not change things for you unless you add a cam and nice set of heads.
Brian from Harris Performance and I both agree that is it not necessary to install an adjustable fuel pressure regulator cover on any TBI setup. With the right pump and the right spring that MATCHES a given horsepower there is no need to have the ability to adjust the fuel pressure. Seriously, let's look at why....
What I am saying is if you know what the horsepower is going to be then you should know what flow rate your injectors must flow at in order to support the horsepower. This will then tell you how much fuel pressure you're going to need and thus, finding the right spring to make the psi the correct amount.
Example is my 350TBI Firebird. 375HP needs to be supported with 65lb injectors running at 30psi or 90lb injectors running at about 19psi.
This assumes you have a nice strong high volume pump and the ability to tune your chip and nice wideband O2 sensor, etc.
Hope this doesn't muddy the waters any. I just see too many guys with an adjustable regulator cover messing with the fuel pressure hoping it will help performance lol.
I had a number of guys say the same thing to me 3 years ago and it saved me a ton of time and money.
With my LT1 and LS1 i always went excessive with my intake fuel and exhaust because i was setting everything up for the cam and heads i would need to have supported.
Ive have carried over the same practice with my 305. Ill have the intake off so i did the ulitmate TBI mods, bought the edelbrock intake, and had them both port matched. Now im at the point where ill be buying a 350 fuel injector pod and wanted to compliment it all with a AFPR. My other plans include a good set of heads and a cam shaft that will be respectable for the 305. Before that i wanted to make sure i had all the air and fuel upgraded so i could just do the heads and cam swap and only need to worry about the tune. My course of modifications may be different then most but i have to do everything in stages so thats what im doing by beefing everything up before the final purchase of the heads/cam.
I can find good fuel pumps but for some reason im unable to find a easy to install AFPR. The only two ive see is the Aeromotive 13301 and the modification to the stock FPR. I like the Aeromotive a little better because of the range of adjusability and the CNC machined finish. Just being honest here, ill pay more for a more modified professional look.
There is not one adjustable regulator cover out there that is easily adjustable while it's on the vehicle. I have CFM-Techs, Jet's, Xtremefi's and several others and I have modified my own on a number of occasions.
Since you're going to all that work with your setup it will be a piece of cake to modify your fuel lines and go with AN fittings and braided line and the 13301.
The great thing about the 13301 isthe nice constant, strong, steady fuel pressure that doesn't pulse. GM's regulator diaphragm is a very "ancient" idea and remedial at best. The pressure with the GM diaphragm is not steady and constant.
Talk to Brian from Harris Performance/tbichips.com. I am running his 255pph fuel pump (~43.5psi) and it was around $100 including shipping.
If you need Earl's part numbers for the AN fittings I have posted detailed photos and part numbers on here somewhere, lol.
I am going to have my machinist make the block off plates and I will let you know when they are done.
The Aeromotive 13301 also provides for a vacuum port. So when the fuel pressure is cranked up over 18 psi the regulator can be used as a VRFPR. This allows for the fuel pressure to vary as the manifold pressure varies.
Which provides for better driveability and easier tuning. Need to use a ECM setup that allows for this. It won't work correctly with a stock ECM.
The Aeromotive 13301 also provides for a vacuum port. So when the fuel pressure is cranked up over 18 psi the regulator can be used as a VRFPR. This allows for the fuel pressure to vary as the manifold pressure varies.
Which provides for better driveability and easier tuning. Need to use a ECM setup that allows for this. It won't work correctly with a stock ECM.
RBob.
from aeromotive 13301 instructions:
10. The Vacuum / Boost reference port is provided for fuel pressure compensation at a 1:1 rate, this is primarily used in blow-thru centrifugal supercharged applications or factory EFI vacuum referenced regulators. In most cases this port is left open to reference atmospheric pressure.
Hmmm - how much fuel pressure change can we expect for performance TBI application (20+ psi)??? 0 to 5 psi?? Which spring?? Experimentation time.
Theoretically there can be a 14.7 psi maximum change in fuel pressure (lower then the set point). For some real-life examples, say barometric is 100 Kpa (right above sea-level) for ease of math.
At this 100 KPa baro the fuel pressure is set to 20 psi.
At cruise the manifold pressure is 60 Kpa, for 40 KPa of vacuum (100 - 60). Converted to psi: psi = kPa x 0.14503, 5.8 = 40 x 0.14503 for a drop in fuel pressure of 5.8 psi.
20 psi - 5.8 psi = 14.2 psi.
Probably asking, so? What does this have to do with driveability? At the lower fuel pressure the injector PW will be longer. This provides for better fuel distribution along with better control over the volume of fuel injected.
Then as you put the pedal down the manifold pressure increases along with the fuel pressure. This provides the required pressure and fuel delivery under load.
But as you have mention to me RBob, it is not a necessity and as one of my friends have wisely pointed out, adds another variable to tune. I was going to go the route of a aero vapr, but didn't. So far, I have my LT-4 hotcam idling at 850 rpm very smoothly. Once I get it entirely tuned in, and I have some $ to wipe my rear with I may upgrade.
I don't know where to get a wide variey of springs, so I had an afpr from top down and used that. It is a pain to adjust on the intake, but I just jumpered the FP relay and adjusted it while unbolted to the manifold. Like dude says above, once it is dial in at the psi you want, you are not going to adjust it again.
I tried this with my TBI in an attempt to squeeze past an E-check. It actually worked along with a little extra timing (barely). My setup is really beat up and mismatched (3rd Gen 305 originally carbed switched to TBI and 7747 currently residing in a Jeep). So it's kinda 3rd gen.
I used a Malory 4307M that claims fuel injection compatibility and has a range of 3-12 psi (will bury the gauge past 15). All fittings were machined from the 8-AN to barb type including the TBI fittings ( I couldn't find compatible fittings).
It's great knowing what fuel pressure you are running at and being able to set it to what ever you'd like. My future plans are to tune with a EBL upgraded 7747 ordered this week. I would say fuel pressure is fine to 'rough' tune, but offers nothing for fine tuning.
just in case somebody is wondering which fittings you would need to plumb that aeromotive 13301 up, here is a list i compiled a while back:
TBI Inlet (Feed)
16mmx1.5 to -6 AN fitting Earl's 991955
TBI Outlet (Return)
14mmx1.5 to -6 AN fitting Earl's 991954
Fuel Return Line 5/16"
-6 AN Male to 5/16" Tubing Adapter Earl's 165056
3/8" NPT (as on the Aeromotive 13301)
3/8 NPT Male to -6 AN Female Earl's 916166
you can find most of these on summit from what i remember.
alternatively you can also use the push-on style fittings and hoses.
oh and here's another link that might come in handy for someone: http://www.fullsizechevy.com/forums/...-tbi-pics.html
from aeromotive 13301 instructions:
