What makes this so interesting is that it will be a direct comparo between carb and TBI, by someone that knows what they are doing with carb AND TBI tuning, vs someone who gave up on TBI and switched to carb.

Most comparos are by someone who gave up on TBI without optimizing it and then stuck a carb on and said "Wow, TBI sucks!". Anyone can do that.

 

So what's your guess on ET and trap speed with the TBI, and which TB you using Pablo?

 

I have the holley 2" bore TBI unit that I modified to use a GM injector pod spaced probably about 1/3 of an inch up. The throttle shaft will be ground down as soon as i get off my lazybutt. Same goes for radiusing the inlets. Im using the stock injectors at 20 psi. If i can squeeze it in ill be using an open spacer too.

I just got my wb datalogger set up and it is real badass. Ill be able to show everyone my WOT air fuel ratio for every .1 sec of the quarter mile for both setups. I should soon be able to also show my EGT when the software for it comes out. Should be pretty precise.

As for predictions. The only thing im fairly certain of is that my short times will go down with TBI. Id like to see my mph remain the same or get better but I dont think there is enough airflow for that. Whether or not the little tricks im pulling on the tbi unit do it or not is the key.

 

Try to bore it out more on the top and then polish and throttle body spacer anything helps and maybe a cold air intake instead of taking in the hot manifold air.

 

with this new airflow data that has come to light (that the 2" tbi flows 670 at 1.5 or so) I think i should easily match the carb mph wise if not exceed it. We shall see.

 

Hmmm. I contacted Holley myself and they said all of their tbi's, including the 670 tbi, is rated at 3 hg.

 

Well there is some pretty good flow bench data posted on several threads now about what it flows and what the stock one flows, in addition to that there is some literature published in one of the fuel injection books discussing the flow ratings and they specifically state that they are flowed at 1.5. Maybe the guy on the phone was misinformed?

 

Maybe the guy was misinformed as pablo suggested? I was always under the impression that 2bbls were rated at 3" hg, and the 4bbl tbis were rated at 1.5" hg. It's kinda a bad deal if the 4bbl tbis were rated at 3" hg.

 

Another thing that has always kinda boggled my mind was:
How is it that both the old and new style (in reference to injectors and injector pods) Holley 670s are rated at the same flow rate?
Given that they both were supposedly flow tested with the injector pod and fuel flow.....
The old style injetor pod is really bulky and each pod is larger in diameter as opposed to the newer ones with the delphi injectors. I am by no means an expert at all, but given the way the unit comes stock from holley, i.e. no injector pod spacer, I would imagine the newer unit would flow more air. Even if it's only something like 10-15 cfm, it's still a difference, yet both are rated the same......