MFI or carbs? Options

[ClayPerrine]

MFI has altitude adjustment...

Just sayin.
Pete

Yea, MFI has altitude adjustment... and a FANTASTIC sound. But it runs quite rich most of the time, and you get terrible gas mileage. You are lucky to get 16 MPG out of it. And a cold start with MFI is a bitch. If you use the built in cold start system, you risk a fire in the stacks if the engine backfires, and that happens a lot when cold. And it will be 20 minutes of warmup before you can go anywhere. Early in the morning, it will be rather annoying to anyone else trying to sleep in hearing your car warmup.

Honestly, I LOVE MFI! It runs great at full throttle and sounds fantastic. I would put it on a race motor in a heartbeat. But from experience, I would rather live with EFI for a daily driver, and that is what we are talking about here.

[Eric_Shea]

For the Jenvey carbs, is that price per, or for a pair? Ouch, that is pricey and I may have to upgrade my original estimate on price, a lot. Add a controller and all the other bits and bobs you need, it becomes very expensive. I do understand the allure of EFI though, especially after a face full of petrol.

The Jenvy throttle bodies are designed to look like carbs. Most throttle bodies are way cheaper, but they don't look like carbs.

PMO throttle bodies are blatantly throttle bodies and do nothing to hide it. They are probably better throttle bodies than the Jenvey ones. What you are paying for with the Jenvey ones is the stealth factor.

We sell both the PMO and the Jenvey. Both are of the same quality. Jenvey is top notch.

Also the Jenvey will fit common IDF/IDA air cleaners, run standard IDF/IDA linkage, fit IDF/IDA manifolds, has PICO fuel injectors included, had TPS (throttle position sensor) included, has fuel rails included. We went down this road with Borla as an example... once you got all of the other parts, the price shot up there and, custom air filter bases had to be fabricated.

Price adjusted yesterday to meet current exchange rate. (IMG:style_emoticons/default/wink.gif)

ALSOOOO... here's a lower cost set if you already have the manifolds and linkage:

https://pmbperformance.com/products/jenvey-...-ida3-42mm-pair

[JmuRiz]

(IMG:style_emoticons/default/idea.gif)

[horizontally-opposed]

Also the Jenvey will fit common IDF/IDA air cleaners, run standard IDF/IDA linkage, fit IDF/IDA manifolds, has PICO fuel injectors included, had TPS (throttle position sensor) included, has fuel rails included. We went down this road with Borla as an example... once you got all of the other parts, the price shot up there and, custom air filter bases had to be fabricated.

Price adjusted yesterday to meet current exchange rate. (IMG:style_emoticons/default/wink.gif)

ALSOOOO... here's a lower cost set if you already have the manifolds and linkage:

https://pmbperformance.com/products/jenvey-...-ida3-42mm-pair

Those heritage Jenveys are (IMG:style_emoticons/default/drooley.gif)

Eric, have you done this under a factory airbox/filter housing yet? Already have crank-fire ignition, so this is pretty interesting.

[Eric_Shea]

Not yet Pete. Bob's was the early Sport air filters. These will bolt right up under a stock box though. Mine will probably be the first for that fitment. Putting together a system for Larry S. as well, just triple checking components. You'll still need a custom harness, ECU, Wide Band, etc. With the Holley, it will control the ignition and do it "extremely" well... something else to consider. Welcome to 2023. (IMG:style_emoticons/default/wink.gif)

[Superhawk996]

(IMG:style_emoticons/default/hijacked.gif)

OP asks A or B

Answer - you need C - and D, E, and F to make it work (IMG:style_emoticons/default/happy11.gif)

[Steve]

(IMG:style_emoticons/default/hijacked.gif) (IMG:style_emoticons/default/happy11.gif)

(IMG:style_emoticons/default/dead horse.gif)
Tons of information on MFI and EFI on the Pelican 911 Forum.
(IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/stirthepot.gif)

[Eric_Shea]

Ooooooooooooooops! Thread police! (IMG:style_emoticons/default/laugh.gif)

(IMG:style_emoticons/default/busted_cop.gif)

[horizontally-opposed]

Not yet Pete. Bob's was the early Sport air filters. These will bolt right up under a stock box though. Mine will probably be the first for that fitment. Putting together a system for Larry S. as well, just triple checking components. You'll still need a custom harness, ECU, Wide Band, etc. With the Holley, it will control the ignition and do it "extremely" well... something else to consider. Welcome to 2023. (IMG:style_emoticons/default/wink.gif)

^ Thanks, man. Looks like what I've been looking for is finally a thing…or nearly is.

To the thread police: Fwiw, I'm one who has considered MFI in the past (was priced out and went with carbs) and still thinks about MFI and EFI. So this thread is seriously interesting to me, and I learned something new that I had missed elsewhere.

For the OP: The most fun I've ever had in a 914 was a six with a 2.2S with MFI and short gears. The noises with that belt-driven mini six-cylinder on top of a flat six, the throttle response, the…well, everything. Just brilliant…until I started pricing an MFI build and tune. I ended up with Webers, which as others point out are far from bad (especially now that they're set up nicely) but I still want to get my car back to fuel injection.

MFI's cost and disadvantages mean that'll probably be with EFI. The Jenveys are seriously appealing to me because they may offer a chance do what carbs and MFI do under a factory air box. Thanks to all for the info!

[Superhawk996]

Thread police here (IMG:style_emoticons/default/busted_cop.gif) It’s all in good fun! I’ll let you off with a warning this time. (IMG:style_emoticons/default/biggrin.gif)

For anyone considering individual throttle bodies (ITBs) do your homework on the EFI tuning trade offs and drive ability issues with ITBs like PMO, Jenvy, and others. Don’t get sucked into the whole myth of self tuning - auto tuning thing. It isn’t there yet. Especially with ITBs that have a poor manifold vacuum signal.

Having said that, I’ll be doing ITBs eventually when I finally get around to taking care of induction for the 2.4L. Currently watching Bens conversion of Weber’s to ITBs on his 2.4L (IMG:style_emoticons/default/aktion035.gif)

[tygaboy]

In case anyone cares: my main gripe with Holley ECUs is that they have a proprietary CAN protocol. Just something to be aware of if you want to do cool stuff with electronics.

[Superhawk996]

In case anyone cares: my main gripe with Holley ECUs is that they have a proprietary CAN protocol. Just something to be aware of if you want to do cool stuff with electronics.

(IMG:style_emoticons/default/WTF.gif) Please elaborate. So they won’t provide a *.DBC file to read their CAN messages?

@tygaboy

[tygaboy]

In case anyone cares: my main gripe with Holley ECUs is that they have a proprietary CAN protocol. Just something to be aware of if you want to do cool stuff with electronics.

(IMG:style_emoticons/default/WTF.gif) Please elaborate. So they won’t provide a *.DBC file to read their CAN messages?

@tygaboy

@Superhawk996 - Not to my knowledge. I have been unable to find anything that would allow my Holley Dominator to talk with anything other than Holley or (their) RacePak products. There is a company called OneGauge that uses Arduino tech to connect Holley ECUs to their dash but I shouldn't have to / don't want to leverage 3rd party stuff. I can connect a MoTec ECU to an ECU Master PMU, and a Haltech dash. Not so with Holley. Again, I've not found anything, including talking with my tuner, who is pretty tight with Holley. I'd love to be proven wrong but at this point, this limitation is eliminating Holley from consideration on the Ferrari build.

Sorry for the hijack...

[Eric_Shea]

Especially with ITBs that have a poor manifold vacuum signal.

True dat. This is one of the reasons our builds got held up. Testing, testing, testing.

We built multiple adapter plates to test for vacuum signal under the ITB and the Manifolds. Our manifolds are now tapped with 1/4" ports at the top for IAC and at the base for MAP. MAP wants a more consistent signal derived from the base of the manifolds whereas IAC's are less picky so those are at the top of the manifold.

Here's the test plate we developed for under the ITB. This proved to be best for our IAC signal:


And a few we made for the base of the manifolds for the MAP signal:


By separating them even by this small amount, we were about to eliminate crosstalk and tune both circuits independently.

In practice. IAC location:


MAP location:


Do a few of these and you'll start to figure out why modern engines have so many hoses and gadgets! (IMG:style_emoticons/default/laugh.gif)