Okay I have my ecu custom programmed for a 2.3L H23 VTEC. I'm thinking about getting an F20B (it's an H22a). And running my ecu until I get my other motor built back up. Here's the complications as I see it

2.3L - 2.0L = 11.5589 % drop in fuel

RC 370cc - 290cc = 21.6% drop in injector capacity

These are both DOHC VTEC engines, so can I make these direct assumptions? What I;m thinking is with the drop in injector size coupled with the drop in fuel needs I would need to increase the fuel pressure to increase fuel delivery by 10% or so at the end. Does this make sense? What is the formula for fuel pressure and it's effect on the amount of fuel supplied? I'm sure a 10% increase in FP does not = a 10% increase in fuel...but i could be wrong. Thanks in advance.

 

Is this what you are talking about...Selecting the Proper Injector

 

Yes it helps a bit. It does tell me that I would have to run at 70.8 psi of FP to flow 370cc/min. Now given my decrease in displacement can I assume a flow decrease need of 11.5589% to 327.23207cc/min?

THen by using the formula you provided, fuel pressure would need to be 55.39 psi?

Does this make sense or am I just fishing? I just need a starting point, then I can dyno tune it right.

 

anyone?

 

hey! thats my line!

anyways, satan_srv, you have taken a rather simplistic approach to changing the characteristics of your engine.

but that is ok, because it will work for you.

the engines will have similar BSFC of .45 to .50...

so you will be able to make fairly direct comparisons using HP estimates...

ie if you have 200hp engine, and run at 45 psi you need 290cc injectors...

it does not take account of displacement - only flywheel HP.

HTH,

t..

 

Great...based on engine characteristics I thought it would be somewhat similar. So if I ball park around 55 psi it should bea good place to start then, then tune on the dyno. Thanks!

 

yep, 50 to 60 is a good ballpark...

t..

 

Yea, I know I got it from you. Sorry, next time I will just refer them to you.

 

nah, sorry Jeff, just kidding!

it is great to see the wealth of knowledge is being shared so readily

honda-tech.com is the best resouce on the internet in the world for Honda dudes like us.

it is vital for me as i have literally no local support for my passion...

keep up the good work!

t..

 

Very interesting stuff guess. I'm just worried about 'pockets' of potential problems because of engine differences, but since they are both DOHC VTEC's I feel pretty confident about it. Even though the H23 VTEC was making 50 more crank hp...the advanced timing curves should be fun with my custom ecu...

 

Ok I'm back...I was just thinking...

What if I just transplant my ecu and RC 370cc injectors to the new engine? How rich will I be running?

It's an H23 VTEC Hybrid, going to an F20B DOHC VTEC. Is it going to be out that much? Or is it related to BSFC like above?

Under this setup I wouldn't have to mess with the fuel pressure, and I would at least know I am running rich until I tune...

 

Hey T,
I'm here for you buddy hehehe

 

yeah man, you & me -the only Honda's tearing up the track at Eastern Creek!

ill be back soon! going to put the block back in this weekned, back on hte track by 4th December...
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satan_srv, you will be running TOO rich with that setup, you will have to lower the fuel pressure too much and this will effect the spray pattern of the injectors...

it is hard to see how it was running well on the H23 with such large injectors (what fuel pressure were you running?)

maybe you should get your custom ECU re-programed to suit???

it is a fine balancing act, you really should aim to get it fairly right or you will have tuning problems and idle problems...

hth,

t..