Throttle Body Injection, how much hp?

I'm considering FAST, Holley, FiTech, etc... for a 900+hp pump gas hemi. Has anyone done this successfully and if so, which product did you use?

The engine is an aluminum 604 Hemi with just under 0.700 roller cam. I want to run Pro Street N/A Drag Week 2018 and/or Drag Weekend. The increased drive-ability of FI is tempting, but I haven't seen many (any) higher HP combos with the plug 'n play throttle body injection systems.

This will be a single throttle body setup.

Thanks!

Fuel injection might be more precise and accurate than a carburetor, but an engine peaks power with a proper a/f ratio. Injection will not give you more hp than a good carb.

I have done several 1000+ HP using throttle body injection ... but (there's always a but) this only works on systems that do NOT have a minimum vacuum requirement and are tuneable with a laptop. The hands-off totally self-tuning systems cannot learn at idle on high HP engines. Also most TBI systems do not have large enough injectors. FAST offers a TBI throttle body with (8) injectors that will support 1000 HP. It has (8) 74 lb/hr injectors. That throttle body paired with their Sportsman XFI ECU can do the job. Although it is self-learning you must tune the idle, cold start, and accelerator enrichment fuel.

Although this works I always ask myself why not just go the final step to port injection. I'd rather not have a wet manifold for cold start driveability.

Systems like this that I have tuned run great, are easy to drive, and are tunable from inside the car, but you will not gain HP.

I routinely make fun of people with fuel injection. Most cars dont idle or do anything better than my Thumpercarb did. A proper return style fuel system goes a long way when your in bumper to bumper traffic for hours on end

I'm the middle of a 572 C.I. pump gas street hemi build that will probably end up with two dry 4150 1000 CFM throttle bodies with direct port EFI injection. I'm hoping for 850 HP and more torque than HP with 10.5 to 1 compression ratio

As said, EFI won't make more hp. Hp is a function of proper timing and proper fuel ratio.

But those who make fun of EFI users don't understand the technology or advantages of computer controlled electronics.

Timing advance is limited to the curve of the weights in the distributor. EFI allows for infinitely adjustable timing curves to dial in efficiency and power at any throttle setting, any RPM.

Likewise on fuel delivery. Regardless of RPM or throttle, you can tweak your fuel delivery, to include completely shutting off the injectors at high vacuum, high RPM, 0% throttle. In other words, closed throttle coasting in gear; which can help increase fuel economy ever so slightly.

Carbs are cheap, easy to use, and effective, but EFI is superior in tuneability and efficiency.

What is selling you on wanting to go throttle body?

Don't let the self tuning marketing steer you.

Go with a carb or port EFI. The tuning is not difficult, its easier than fine tuning a carburetor that is for sure.

The bonus of going to fuel injection is that with the right system you get a fuel controller, an ignition controller, and a Datalogger all in one package.

I started with no EFI expierience and I have a few thousand miles on my EFI setup now and I would never go back.

Just like you can find people with crappy carb tunes you can find people with bad EFI tunes as well.

In most cases maybe not but if there is a distribution problem the right EFI system(and its not the most expensive) can adjust timing and fuel per cylinder.

All valid points. But after a half century of use, most guys today cannot/will not tune much more than the main circuit on their carbs. The real appeal of EFI for most guys is that IT'S SUPPOSED TO TUNE IT'S SELF. The reality is that sometimes it does and sometimes it doesn't.

But let's be honest, getting the real advantages of port EFI with optimum timing curves is really beyond most guy's abilities. And probably beyond their desire to even try. Which explains the attraction of plug and play.

The EFI that most muscle car guys buy is not much more than an electric carb whose benefits could be enjoyed with a carb that is properly tuned by a good carb tuner. And for a fraction of the money.

Besides, the EFI system you buy today will be obsolete in a year and you may not be able to get key service parts in a few years.

So while computer controlled fuel and ignition systems have the potential to be infinitely superior, it can only reach that potential in the hands of an experienced, competent tuner. Which, in the real world, rarely happens. Sorta like a carburetor.

While I don't necessarily agree, I can hear what you're saying about the ability of many to tune, but I think the reason most don't is because they simply don't want to learn. Much like a carb, there's nothing magic about EFI. Having the correct tools and a working knowledge of internal combustion engines can yield results for anyone who wants to take the time to do it correctly.

I'd also be interested in hearing what EFI systems have become obsolete and/or unable to service? Exactly what service parts are you talking about?

All carburetors are at least partially self-adjusting to engine demand.
No FI system is.

How do you figure that?? Most fuel injection systems determine fuel needs based on throttle position,vacuum(aka engine load), O2 sensor readings, and some even measure fuel pressure..

Seems baiting, but I'll bite. How "no FI system is." could you elaborate?

No FI system is self adjusting to engine demand?

Humph... news to me. I wonder why my EFI has air temperature sensors, air pressure sensors, and O2 sensors for no reason at all, since it doesn't automatically adjust to atmospheric conditions and engine demands?



Another example of someone who doesn't understand EFI, and therefor proclaims the superiority of carbs.

I'm not against carbs. They are cheaper than EFI, they can be tuned without a computer, they are effective. When tuned to deliver proper air fuel ratios, they make equal power. They can make for a much neater engine bay by not requiring wires, sensors, fuel lines, injectors/ports, etc.

But I sure am glad my daily drivers are computer controlled EFI systems.

This is working for me as well my efi did....or better.

I'm leaning towards the "devil I know."

I researched the throttle body injection systems several months back out of pure curiosity and noticed all were 4150 flange. My new engine came with the MP/Barton single plane with the 4150 flange. I questioned the builder and they said that they use that intake with a tapered 4500 adapter to increase velocity. I thought that this might be a good time to really consider one of the new TB systems as I now have an intake that would bolt up without using a spacer.

I'm a few weeks away from crossing that bridge. Just hoping to see a few examples of big cube high hp cars using a TB Plug and Play kit.

Thanks!

If you buy a TBI EFI system, and it self tunes, then you might as well just run a carb. To maximize the potential of EFI, you need sequential multi-port EFI, and to have a custom tune written either by yourself or a paid expert. Generic self learning won't take into account your combustion chamber shape, compression ratios, quench values, cam timing, etc in the timing tables. It may do a good job at hitting 12.5:1 at WOT and 14.7:1 at part throttle cruise, but that's like tuning your engine and never touching the distributor.

Not to mention the advantages to a dry manifold over a wet one, and a TBI is still a wet manifold.

There are many dry 4500 throttle bodys out there
I'm going to use dual 4150 1000 CFM dry throttle on the 572 C.I. pump gas hemi I'm building for a local customer so it will fit on the stock type Stage V EFI intake kit they offer with the 4150 bolt pattern Hopefully I'll be find a Shaker base plate to fit those throttle boys on that intake
I will use dual 4500 throttle bodys on one of my motor with a tunnel ram intake with EFI also, hopefully soon

Yes there are dry tb EFI systems, but the op is asking about throttle body injection. Not mpfi

https://www.youtube.com/watch?v=f76168Y6H9M

Something to remember, Steve Morris is a Holley dealer. From what I have heard about the throttle body stuff I would be questioning why he wasn't using his sensors to gather per cylinder data, you can see plugs for 8 02s and EGT sensors in his headers. Just my thoughts

They built you a 900+ hp pump gas 604" hemi and used a 4150 flange MP/Barton manifold???

I sent you a PM.

I haven't found any real world examples yet. I'll probably post on a couple other boards and then dust off my 4500 stuff.

The closest I've come was a 3yr old video of Freidburger's '70 Bee. He swapped from a Dominator to the FAST 2.0 (1200 hp advertised at ~ 1000cfm). It's a HRM video of the swap, but no track time. That car is pretty slow anyway and probably not a good comparison.

Freiburger's car is also only 484" and has a mild cam. Nowhere near the motor you or I have.