Another "Is Fuel Injection a Worthwhile Upgrade?" Question
Nobody will read this and care, but I'll respond with what I know. Both FI and Carbs work. I think most don't understand how a carb works, no matter how long they have run them.
I'm still learning as well. But for clarification, let me use these two examples....
- I put a 750 double pumper on a super six intake (using adaptor) on a stock bottom end 225 slant six using the original head as well. No header. It ran great and performed awesome.
- I, right now, have 1200 cfm's on a stock short block 318 with 318 heads. It performs fantastic.
I said that to say this: Carbs operate by being pressurized and if set up right, will feed the engine exactly what it needs according to the pressure. The slant pulling air only pressurized the carb enough to get the fuel/air it needed. The 750 DP Holley wasn't faster than the 2bbl, but it wasn't slower either. Same can be said about the 1200 cfm's on my 318, with no headers and 318 heads w/318 valves. Most look for "bolt and go" carbs. They may run good. However, that's not optimal carburetion.
I agree. Interestingly enough in 1984 I was tuning my car (tunnel ram) a friends car (48 Austin with a flip up body and a TR) and another car with a single 4.
The friend with the Austin had a guy stuff some Hilborn injectors up his butt. I didn’t know jack about MFI, but since I was getting paid I had to learn and quick. So I called one of my dads life long friends who was a hydraulics engineer, among other things.
His first words were it will lose power with the injectors. That went against what everyone else said. Once the engine was ready to go on the dyno he came by to look at it. He said the tunnel ram will beat it by 50 HP and the injection was on alcohol and the carbs were gas.
He added two bypasses to the one I already had and off we go to the dyno. We brought the TR with us, thinking it wasn’t needed.
On the dyno, the injected engine would only do 485 HP and it did that at about 6000 RPM. That’s all it would turn. And that was with all 3 bypasses hooked up.
For day 2 we put the TR back on. First pull on the TR with my base tune up went 540 HP at 7200 and it carried that to 7500 so we could shift at 8000 like it was supposed to be.
Screwing around for a while we pulled 568 HP at 7200 with an engine that at best maybe would have done 500 on the injectors.
So that I would KNOw what was wrong I called the guy who told me what would happen and asked him how he knew and everyone else was wrong.
He said the stacks were way too small to feed 377 inches to start. And, with stack injection you can’t get a single stack big enough to feed much anything over 300 inches. On top of that, the injectors are highly sensitive to reversion (which was true because every time there was a dip in the torque curve we could see fuel standing off above the stacks) and between the reversion issues and lack of air it just won’t make power.
But the biggest thing he said was very amazing. He said when you get everything correct for the injection you will have “carburation”. In other words, he said perfect injection IS carburation.
Of course, I was already sold on MFI because I was switching to alcohol (another giant waste of time, money and effort) so I bought two flying toilets and a Holley Pro Dominator and walked away from carbs. For years I tuned only injected stuff, unless it was on the dyno. If a customer with a carb wasn’t happy after the engine came off the dyno he was on his own.
I don’t remember exactly when it was, but it had to be 2001ish and I was on the dyno with 4 bypases, and idle check valve with a 22 pound spring (just to get the idle in shape and as a comparison, most guys run 3-5 pound idle checks) because the nozzles were now so far up the runner it wouldn’t idle will less fuel pressure at idle. I had the first check (the main bypass) set at 68 pounds and every check after that came on 8 pounds later.
After beating on my crap all day I ended up with enough power to get what I wanted, but when I got home and really looked at the numbers and did the math, I realized I could make the same exact power on two carbs and gas and not have all the bullshit of the injection.
The moral of the story is perfect injection IS carburation.
Certainly MFI isn’t EFI, but the principles are the same. The very first EFI I helped on had issues with getting enough injectors with enough duty cycle to feed the engine. That engine was not NA so it’s a bit different and in 2000 or 2001 the injectors weren’t all that good. The fix for that was using MFI over the EFI. The EFI was for low speed stuff and staging and the MFI pretty much ran the engine when it came off the 2 step. Eventually that guy got rid of the EFI. I don’t know what he is doing today, but he may be using full EFI. Or he may be retired. I should call him.
So I said all that to this...there is no PERFECT solution to any of this. I don’t care what it is. So just blabbing that EFI is everything is as nonsensical as claiming a carb is perfect in every scenario.
Sadly, the EFI worshippers will continue to equivocate and put words in other people’s mouths and will continue to denigrate anyone who doesn’t think EFI does everything and flushes their toilets.
