Baseline settings for triple OERs

[Patcon]

Not only that but I can set up a fuel table to fuel at different levels across a myriad of throttle positions and refine that fueling based on O2 feedback. Fire right up when cold and idle perfectly without any choke.

Anecdotally, I would think if carbs were superior then somebody, anybody would still be installing them on new cars...

Now, don't get me wrong, I like carbs. I have SU's and may run some triple webers, but if I get an opportunity to got ITB's, I will and not look back

[Captain Obvious]

My non-expert thoughts on the matter? Most of the fuel injection systems have a long-ish intake tract and some sort of air flow meter along the way towards the air cleaner. Both of those restrict the air flow. Might not be much restriction, but it's more restriction than a short stub of a carb throat running wide open.

For example... When they went to the fuel injection in the 280Z, each cylinder got a whole lot less throttle plate cross sectional area to the air cleaner than they did when they were running carbs. In addition, the fuel injection system has that AFM flapper thingie which adds some restriction.

So while it's absolutely POSSIBLE to design and install a FI system that provides no additional intake restriction over a typical set of carbs, I think it's cheaper for the manufacturer to use something that shares components like throttle body and air flow meters. 

I don't think the manufacturers went to fuel injection because of performance. I think it was because of driveability, fuel economy, and emissions.

So I'm no expert in the field, but my take is that for most stock automobiles these days, if you're willing to forgo wide temperature range drivability, fuel economy, and emissions... I think you can get better straight up raw performance from a carb or a bunch of carbs.

Maybe a set of ITB's and a huge MAF that doesn't provide only negligible restriction could be the same as carbs?

[Patcon]

My understanding of ITB's is there is only a butterfly at each bore the same way a DCOE would be. There is a map sensor and a throttle position sensor. Using those inputs as well as rpm a fuel map determines fueling. No MAF used.

I agree that fuel injection was developed for better economy and broad range drive-ability. I also believe that all out power is better produced with fuel injection. Atomisation is much better at 40-50 psi than 3-4 psi. It would be interesting to see some dyno work using the same engine from carb to FI

Somebody like Eiji probably already has this info as he sells the Jenvey ITB's

[heyitsrama]

 

[jonbill]

I've heard that carbs can get better atomisation than injection. certainly the airflow through the venturi isn't the same as on ITBs. perhaps helps to vapourise the fuel. 

anyway, ultimately if they both deliver the same amount of air and fuel as each other, then they will produce similar power, all other things being equal. 

[madkaw]

Speed density systems eliminate the need for MAF. 
Carbs require taking into account the TAL factor where ported EFI does not need to deal with this . 
Less parts to go wrong with EFI . Temp compensation is automatic . 
 

I would break the motor in with the simplest method possible - SU’s 

[AK260]

The good news is my friend has decided to use his SUs for all the reasons mentioned until the initial running in period is complete. Thanks all for the advice and an interesting discussion - so far ;)

[Patcon]

Great video! I forgot I'd seen that before

Picked up 2.5% with ignition upgrade

5.7% with EFI

At the end of the video in their summary,  they say that the numbers don't tell the whole story. Mid range power is better. Drivability is better. Sounds better and fuel economy should be better.

That all sounds nice

 

[Patcon]

1 minute ago, AK260 said:

The good news is my friend has decided to use his SUs for all the reasons mentioned until the initial running in period is complete. Thanks all for the advice and an interesting discussion - so far 😉

What kind of rpm do you need to hold?

[AK260]

Well I’ve just been sent the builder’s pamphlet / notes on their recommended running in procedure and it’s quite the opposite of what I had been told before (or misunderstood). Frankly I’m horrified as it goes against every grain of what I’ve been taught, BUT he builds engines so he knows what is best for his engines.

The procedure is to fire up and let it idle for 20-30 mins, then baby it along at constant revs for 200-300 miles.

I’ve always been told that you need to get the rings to expand under acceleration and seat under deceleration but NEVER to be left idling or steady state as it’s just polishing the bores.

I know I didn’t want to get into this but there, I’ve done it myself! :p

[jonbill]

good recipe for more rebuild work. 

[Patcon]

Im ok with the babying part to some degree, but I agree on accelerating and decelerating to set the rings. The idle part wouldn't be my choice.

What kind of warranty is he offering?

Motors are motors. His shouldn't need a special procedure compared to someone elses.

@Diseazd

What is yours or Eijis preffered break in method?