H22/F22 fuel rail ?

[Stoner51]

So it clearly says in the swap guide that the fuel rails are the same.
Are they?

I was gathering up all my parts to take to the recycle place and had the f22 and the h22. I picked them up and was just about to throw them in the bucket when I realized they are diff.

The H22 is bigger. So Today a brought home a syringe and measured the volume of the two rails.
F22=25cc
H22=35cc
I have a OBD2 97 h22 with the smaller injectors. I have also read where many people who did this swap with the obd2 injectors had complaints on power.

So I'm thinking about getting a custom line made for the JDM h22 rail.

I am curious to know peoples thoughts on this. I can post pics if needed.
Is it that maybe the OBD2 fuel rail is bigger and the obd1 is the same as the f22.

Just asking.

thanks

steve

[deevergote]

10 years of this site, and you are the first one to post about measuring the fuel rail!

Most people use the F22 rail to avoid a custom line. It works well enough... but that's interesting that the H22 rail is 10cc larger.
I believe USDM H22s have the fuel line on the same side as the USDM F22, so a USDM H22 fuel rail might be a cheaper/easier solution than a custom line (though I'm not positive on that... don't get a chance to tinker under the hood of Preludes much these days!)

Aftermarket rails are also probably larger. I'm kinda mad I traded my brand new AEM rail now!

[4GAccordH22]

Honda part number 16610-PT3-A00.

Fits all 1990-1993 Accord and all 1992-1994 Prelude

1995 and 1996 Preludes used 16610-P13-A00

1997-2001 Prelude used 16610-P5K-000

I have no idea what the difference are for the later versions...

[deevergote]

Is the PT3 rail the H22/H23/F22 rail across the board?

[Stoner51]

Yeah. I didn't think I needed to measure the volume the difference is big.

I am wondering if this has something to do with Honda switching to the lower cc injectors. I don't really know. But I plan to get a line made at the same place that made my PS line and see if I notice a diff. The car pulls good, but low end seems to be lacking some compared to the top end.

I have read numerous posts and everybody says the same thing. However the HP rating from year to year never changed just the parts.

It makes me think that some people could use this fuel rail as a cheaper alternative to an aftermarket rail. I don't know the volume of AEM's rail

I looked through posts and never saw it mentioned. I think its because most people use obd1 because its easier.



Steve

My motor has 96 stamped on the block, but I think it is a 97. Made in 96 Make sense. My 91 said 90.

[nusdogg]

Interesting.

My JDM H22A came with the correct fuel rail, so I didn't need to use a USDM one.

[deevergote]

That's odd... if it's JDM, it should have the fuel line on the opposite side. If it came with the line on the correct side, then it wasn't a JDM rail...

[Stoner51]

The H22 rail in the pic is upside down. The inlet is not on the same side.

[Stoner51]

OK. So I have been thinking about this for two days now. I have read several posts about OBD2 motors lacking power when using the OBD2 injectors. Everybody recommends using the obd1 injectors.
I am wondering if this lack of power is due to the fact that the fuel rail. That I assume most use is the accord fuel rail f22. Most prob never look at the size. I didn't just took off the H rail and put the F rail in.
The motors put out the same horespower through all 9 years 92-01. The only difference I can see is the 345 vs 290 injectors.

Now my common sense thinking. I don't know this is just me thinking and correct me If I am wrong.

But in order for a 290cc injector to put the same fuel in as a 345 it would need to pump more and have more avail to pump.
So is it possible that using this rail and the 290 injectors you could get the better performance like the 345. My thinking is with the F rail there is not enough fuel avail.

If you have used the 290 and an AEM rail and it still lacked then you've proven my theory wrong.

This may be totally stupid to think. But I thought I would ask.

Thanks

steve

[Jarrett]

It's definitely not stupid to think. But I don't think you're considering the the fact the pressure is still pressure. The fuel pressure regulator is going to ensure that the preset pressure is maintained in that line regardless.

If we agree that the factory fuel pump is rated at 120 lph then we can use some easy math to envision this better.

120 Lph = 120,000 mLph

120,000 mLph = 120,000 cc/h

120,000 cc/h = 2,000 cc/min

Divide that value by the number of injectors you're running (4) and you have a theoretical maximum supported flowrate of 500cc/min. This likely explains why many CB7 drivers have been able to upgrade to 450cc DSM injectors without modifying the pump itself. Now, with duty cycles and efficiencies coming into play I'd say 450cc is probably the absolute realistic limit.

So, if using the CB7 fuel pump, fuel rail and regulator (36-43 psi) is enough fluid capacity to flow 450cc/min then it's not starving anything for sure. Perhaps it's a matter of the spray pattern, though. The H22A actually runs about 3 psi lower than the F22A/H23A and if the higher pressure Accord regulator is used then the spray pattern will change. Not much, but maybe by enough. I seriously doubt this is the issue but it's worth a thought.

I'd say the more likely culprits are bad/dirty injectors and faults with the tune.

[Stoner51]

You know a lot more than I do. I know that I can fix this with a tune. I have a tunable ECU.

I was just wondering in general. It seems most peoples problems were at lower RPM where the fuel pressure was lower. My thinking is there will be less fuel avail and the rpm as the rpm increase the pressure goes up and more fuel is avai. OF course more fuel is used to.

It just made me think. It is almost a 50% larger fuel rail, and essentially everything else is the same.

Maybe your are correct and the difference in two is the tune on the P5m or whatever is the 97 ecu.