Ok so I couldn't find a thread on this so if one exists please let me know.
Basically I see it in this order, theres the Carburetor, TBI, the XFI, and the MPI. Looks like the XFI bridges the gap between the TBI and MPI.
Now originally I was dead set on the mopar MPI but this XFI system look pretty good. Any thoughts? Anyone using it?
The XFI is about $1000 cheaper and it self tunes, has a handheld that you can use in the future to change all the tuning in a really simple and easy to interface with way, and you can keep it plugged in to log the performance of your engine.
My Main reasons for wanting to upgrade are POWER and reliability. Here in Seattle our weather is all over the place. It can be hailing on top of capitol hill and sunny and warm at the waterfront, as well as sunny and 70 on one day and freezing the next then back again.
As far as power gains I've heard upwards of 60hp gain with the mopar mpi, anyone dyno'd this or know what the XFI might give?
Reliability here is key, from what Ive read it looks as tho the XFI is more reliable than TBI in cold starts etc..
Also there is one thing that an XFI/TBI has over a MPI. With an MPI if you have a bad injector you might not notice it until its to late due to the other injectors working properly and still turning the engine, where as in an XFI/TBI setup you'd notice it right away because the entire engine would start to run crappy.
Any thoughts/experience?
The Mopar kit includes everything you will need. The Fast XFI doesn't. You will still need a fuel pump, regulator, possibly a different distributor and also a custom intake manifold. The XFI uses a throttle body that has the same bolt pattern as a Holley 4150 4 barrel carb. You need an intake manifold that will accept a 4 barrel carb and also injector bosses. I don't see any mention on Fast's website for 6 cyl applications though. Megasquirt with used factory jeep parts is also an option. Also you can assemble your own Mopar kit using used parts and using Hesco's harness and CPS relocation kit for a fraction of the cost of the Mopar kit. Fast does make the EZ-EFI for a Jeep but not XFi that I could see.
Oh my bad,
Just got this as a reply from FAST:
"Our 30294-KIT should work very well for you. It will support up to 320HP and
is designed with the 4.0/4.2 engines in mind."
Well it has injectors at the base of the throttle body, so I see no real gain to this over a TBI setup EXCEPT for perhaps the self learning aspect, then again I've seen some of the self learned systems & I'd rather hand massage mine. Also I'll have maybe a 1/4 of the cost invested in my TBI system and that includes the programmer/EEPROM burner & chips, plus if I want to I can go to a DIS ignition for about $50 in parts. Plus my TBI system parts availability is HUGE as they are all GM OEM or "OEM replacement" parts.
It is probably a good system, I just don't see the gain for the cost other than the fact that it's a complete kit you can just order & install(at least in theory), for me I've enjoyed figuring how to make my setup work & scrounging mostly used parts from Pick & Pulls for minimum cost, now I just need to get the time to put it all on & get it tuned up... Doesn't help that I'm also working so many other parts of the SX/4 as well as putting together 2 4.6's(on for my XJ & one for the SX/4, eventually)
Ya the benefit for me is just to have a brand new system. So basically I'm looking for a system that bolts in.
I'm having a hard time narrowing down my options tho.
Although I think ideally I'd go with the crate 258 engine, 4.0 upgrade, Mopar mpi, pulstar plugs, Clifford dual exhaust with glass pack and 2 1/2" pipes.
I was just hoping someone had used the fast system, lots of info on the mpi but not he fast. It seems that in every aspect there's a trade off. IF the fast just bolts on and it's plug n play then that's cool and that might be a trade off(throttle body style vs mpi) in price vs mpi. I'd really rather buy anything new than build it. I want a 30yr old brand new car;)
I'll be putting it on a dyno, before I do the swaps and after and post the results.
UPDATE:
Ok so I FINALLY got some numbers. On YouTube there's a video of "Two Guys Garage" using the fast system. In the video they use a V8 with a carb and the fast system. With the carb it made 390hp and with the fast it made 390hp. So yea...
Well that actually makes sense as there is no reason that a FI system should make more HP than a well set up Carb that is tuned to give max HP. What FI DOES give you is driveability & accuracy of the fuel/air mixture across the RPM range as well as compensation for different conditions like barometric preasure, temperature, altitude changes, etc, with the added bonus of better emissions numbers & mileage numbers...
Ya, that being said I guess I'm back to the mopar mpi :)