Is multiport injection worth the extra cost??

[cycleguy55]

Originally Posted by eschaider

Keith (I am guessing from your screen name),

The blind from birth conundrum and the Knight's Templar admonition are unvarnished but just the way it really is.

The number of EFI users who have used more than one fueling model (i.e. Alpha-N, Speed Density or MAF style) can typically be counted on one hand with a lot of fingers missing. The problem is quite similar to the blind from birth conundrum. Most users will be enamored with how well the engine starts compared to carb(s) and loose sight of the tuning for drivability or MBT (maximum brake torque) timing or sometimes even max power.

When you ask the "satisfied user" a simple question about the enrichment strategy they used for accelerator pump replication, you will get a blank stare. When you ask them if they used a time based model, a wall wetting AE model or an EAE model, a wall wetting x-tau model or why they used one over the other, you will get a blank stare once again!

So lets go to another consideration. Ask them if the injectors were flowed to the SAE J-1382 standard — blank stare time again. It’s a dirty little secret in the industry that not all fuel injectors of the same part number actually perform the same. Sooo, who flowed the injectors, what were the conditions they were flowers under, were they corrected values or raw data, did they get high and low slope values for the injectors, what is the actual flow rate of the injectors, and of course lets not forget their short pulse behavior.

Aside from the blank stares you will get comments like why does that matter (to me) and I am sure the manufacturer addressed that for me along with the "I never heard of that before," commentary telling you quickly how valuable that opinion is.

There is a short way home for you that involves keeping the carb and either learning how to tune it (more time consuming) or buying someone who does (more risky). Alternatively you could get the MS3Pro hardware I described in post #3 which addresses all of these issues and a boasts a lot more (not meaning to terrorize you) allowing you to do a spectacular tune. BTW The MS3Pro lets you choose Speed Density or MAF fueling models, blending Alpha-N where it is better suited than the other two.

Spend $199 and buy Greg Banish's Advanced EFI Tuning Series DVD's <= clickable. the DVDs have six hours of training, half on prepping the car and half on tuning fuel, timing, air flow and other maps in the ECU. Learn not only what it is about but how to do it right! More importantly learn it from the guy Ford, GM and Chrysler go to when they are in a jamb.

Go buy the MS3Pro ECU and associated gizmo's from DIY Auto tune. Do it yourself and know not only that it is done correctly but how to do it correctly.

BTW, nowhere in any of these posts have I commented on the fail safes the aftermarket ECU brings to the table to protect your engine or in the case of traction control you and your car, or in the case of power adders like nitrous, turbos or blowers the tools to do the job correctly — and I've just scratched the surface.

Tony and I are trying to help you avoid stepping on an engine fueling land mine hidden below ground level that is for all intents and purposes invisible. You are currently struggling with a carburetor that is mis-behaving. Tuning a carburetor has fewer tunable variables and is less complex than tuning an EFI system.

Tony's representation of a speed density system as an electronic carburetor is spot on. He did not represent it as inexpensive or anything other than an electronic carburetor. It gives you a digital adjustment capability for what effectively were accelerator pump(s), jets, power valves and air bleeds. It also gives you digital precision and adjustability. Most importantly it does not give you any way to measure the air mass being consumed by the engine which is foundational to the tuning process. Remember AFR is pounds of air divided by pounds of fuel.

Virtually all the speed density systems will provide some level of self learning (read tuning) capability adequate to minimally get the car drivable if not better. That's the condition you need to drive to the dyno shop and get the tune properly done. Once you have the car properly tuned it will perform admirably for the ambient air conditions at the time of tuning.

The further you get from those conditions the further out of whack your tune will become. Ambient air related changes will only affect a speed density system, they will not affect a MAF based system — it's really that simple. It doesn't mean speed density does not work, it does! However, when atmospheric conditions change so to will the quality of your tune. This is not be the case with a MAF based system.

You are essentially out on the fringes of the Cobra universe effectively by yourself. That means you will either need to learn how to manage the tune for your engine or you will need to travel and pay money to someone else, who you hope will be able to help you. This should sound like the pickle you are currently in and stymied by with your carburetor.

Whether you ultimately embrace a carb solution or an EFI solution you are going to need to send yourself to school and learn how to manage your engine's fuel delivery system. If you elect to do this with an EFI system I highly encourage you to use a MAF based system and spend the money to learn how to use it — you will be muuuuuch happier in the end.


Choose wisely ...



Ed

Ed, clearly you know your EFI stuff - I'll give you that.

Regardless, your dissertation on the various elements of an optimal EFI system remind me of the numerous conversations and meetings when I worked in IT services for many years. Hearing those with deep technical knowledge (a.k.a. geeks) is often enlightening to those so inclined, but the vast majority of people, whether IT users or Cobra owners / drivers, are interested only in what matters to them. Does it work? Is it reliable? Can I count on it to meet my needs?

While perhaps not 'optimum' or 'the ultimate solution', TBI meets the needs of a significant number of users, er, Cobra owners and drivers. They're oblivious as to whether there's a 'better solution' - and that's probably okay. IMO, TBI meets the KISS principle - Keep It Simple, Stupid. Another way of expressing it: How good is good enough? TBI is 'good enough' for most of us.

Like those tired of hearing IT geeks blathering on and on about the merits of the optimum or ultimate technical solutions, I'm not interesting in seeing any more of your MPFI dissertations.

Thanks.

Have a safe and Merry Christmas.

[patrickt]

Originally Posted by cycleguy55

Like those tired of hearing IT geeks blathering on and on about the merits of the optimum or ultimate technical solutions, I'm not interested in seeing any more of your MPFI dissertations.

...

Have a safe and Merry Christmas.

Alright! Nothing like a little Holiday cheeer.

[joyridin']

Originally Posted by cycleguy55

Ed, clearly you know your EFI stuff - I'll give you that.

Regardless, your dissertation on the various elements of an optimal EFI system remind me of the numerous conversations and meetings when I worked in IT services for many years. Hearing those with deep technical knowledge (a.k.a. geeks) is often enlightening to those so inclined, but the vast majority of people, whether IT users or Cobra owners / drivers, are interested only in what matters to them. Does it work? Is it reliable? Can I count on it to meet my needs?

While perhaps not 'optimum' or 'the ultimate solution', TBI meets the needs of a significant number of users, er, Cobra owners and drivers. They're oblivious as to whether there's a 'better solution' - and that's probably okay. IMO, TBI meets the KISS principle - Keep It Simple, Stupid. Another way of expressing it: How good is good enough? TBI is 'good enough' for most of us.

Like those tired of hearing IT geeks blathering on and on about the merits of the optimum or ultimate technical solutions, I'm not interesting in seeing any more of your MPFI dissertations.

Thanks.

Have a safe and Merry Christmas.

Well said. It gets old listening to people blather on about stuff that doesn't matter to 90% of the car population. It becomes ridiculous. Does it work? Yes. Does it work a LOT better than a carb? Yes. Does it work as good as MPFi (batch fire or true SPFI)? Yes. Ok. End of subject. Telling somebody to spend $5000 over $1500 becomes stupid when they don't even know how the vehicle is used.

[twobjshelbys]

Originally Posted by joyridin'

Well said. It gets old listening to people blather on about stuff that doesn't matter to 90% of the car population. It becomes ridiculous. Does it work? Yes. Does it work a LOT better than a carb? Yes. Does it work as good as MPFi (batch fire or true SPFI)? Yes. Ok. End of subject. Telling somebody to spend $5000 over $1500 becomes stupid when they don't even know how the vehicle is used.

On one hand you criticize the info of the tradeoffs of one EFI system vs the other based on price, yet you don't suggest that the OP simply spend $300 to get his carbs adjusted properly instead of ditching it for a 1500 EFI system that will result in the same operation (given his conditions)???

The question was on the various types of EFI systems. Objection your honor, asked and answered.

[joyridin']

Originally Posted by twobjshelbys

On one hand you criticize the info of the tradeoffs of one EFI system vs the other based on price, yet you don't suggest that the OP simply spend $300 to get his carbs adjusted properly instead of ditching it for a 1500 EFI system that will result in the same operation (given his conditions)???

The question was on the various types of EFI systems. Objection your honor, asked and answered.

Carbs are a waste of time and money unless you are using it for a specific racing purpose or for originality.

You adjust it today, and tomorrow you have to adjust it again if you want peak performance. It will in no way shape or form result in the same operational aspects.

Yes, it was on EFI systems based on price/performance. No mention of a carb was suggested, so there was no reason to waste time explaining.

[jhv48]

I don’t know about the rest of you, but I bought my cobra to take me back to driving as I remembered it in the sixties. Cars we’re cantankerous. They belched, farted, and we’re sometimes unreliable and that’s what I wanted my cobra to be.
If I wanted a car that drove like, and was as reliable as a Honda, I wouldn’t have bought a cobra.
Regarding my carbed engine, I set the tune on my carb three years ago when I set up the engine and haven’t had to touch it since then. It has no choke so after starting it can take a few minutes to warm up during the winter before driving off.
Summer starts are no problem. Never have a driving concern. Always performs like the loud, snorting, stinky powerhouse that I love.
Having a fuel injected engine may be more drivable than their carbed equivalents, but that’s not how I want my car to act. I have a 760Hp 2020 Shelby GT 500 and my cobra is much more fun to drive. Total involvement. My wife drives the GT 500 to work. She won’t even think about driving the cobra.
So, if you want originality, stick with the carb.