5.0 V-8 EFI or 5.0 V-8 MPI ?

[Stinger]

I'm deciding on two boats. Both are the same make, model, length, weight, and options except that one has a 5.0 V-8 EFI 240hp Merc. and the other has a 5.0 V-8 MPI 260hp Merc. The boat with the EFI is $300.00 less than the MPI. What's the difference in performance between the two and the price?

 

[snapperbait]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Hi Stinger... The EFI model is most likely a throttle body injection (TBI) which has two fuel injectors connected to the throttle body which looks a bit like a carburator where as the MPI is multi port fuel injection which has eight fuel injectors located on the intake manifold... <br /><br />Performance wise, both perform well, but the MPI will give you a bit more power in the mid through upper RPM range and may give slightly better fuel economy at cruising speed but the difference is so minor that it would be difficult to detect..<br /><br />MPI can be more costly to repair if the need were to arize simply because there are more parts to go bad (injectors mainly)...<br /><br />For the $300 extra, I'd take the MPI since the price difference on the engine alone is about $800-$1000 more for MPI...

 

[Doug Durako]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Snapperbait----thanks for the clarification on fuel injection. I have just a simple question here so I did not want to start a new thread.<br /><br />How much would true MPI increase the horsepower of my Chevy 350, and how many millions of $$ would it cost to convert?

 

[snapperbait]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Well DDboater, it definately ain't going to be cheap and it's really not worth the cost and hastles involved to swap out (I'm assuming you have TBI) TBI for MPI... As for a ballpark figure to convert, at least $1500 bare minimum.. Probably more like $2000 and up...<br /><br /> You might get 20 HP and 1 or 2 MPH at Wide open throttle if your luckey...<br /><br />There are a few little things you can do to add extra performance to your TBI that would likely bring a TBI setup to the performance of an MPI without the cost of swaping systems...<br /><br />A free flowing flame arrestor like a K&N arrestor is one thing that may make a noticable difference in performance and economy.. Along with an engine compartment that has good airflow to the engine... <br /> http://www.cpperformance.com/products/Fuel_Systems/085.asp <br /><br />A throttle body spacer is another little mod that can add a few extra HP.. http://www.turbocity.com/TBIPowerSpacerInst.htm <br /><br />A mulit spark ignition like MSD and a high output coil is always good for supporting good combustion as long as there approved for marine use... http://www.msdignition.com/ <br /><br />These are the EZ bolt on ways to gain a little without costing you an arm and a leg...

 

[Boatist]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Snapperbait<br />I agree with everything you said with maybe one question. I feel MPI less costly to repair, true there are more injectors to fail but I find they rarely fail and a single MPI injector much cheaper than a TBI injector to replace. I know nothing about the marine engines but baising my thoughts on the auto engines.<br /><br />So what do you think MPI or EFI cheaper to repair?? Have you seen a lot of MPI injector failures or mostly cleaning??

 

[Doug Durako]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Snapperbait---forgot to mention---my 350 has the standard carburetor. So it's cheaper/easier for me to go with a bigger carburetor and new intake manifold? I've got plenty of room and good air flow in the engine compartment.

 

[snapperbait]

Re: 5.0 V-8 EFI or 5.0 V-8 MPI ?

Boatist.. Generaly I'm dealing with performance auto applications where I won't change just one injector but rather start with a fresh set in which case two TBI injectors are about $160 for OEM.(original equipment) injectors and a set of eight OEM. injectors for MPI applications start at $235 for a set and go up too $400 or more depending on the Lbs. per hour of fuel rating... Thats my reasoning for added repair cost... <br /><br />I suppose it's acceptable to replace one injector on an OEM. non-hi-performance MPI set-up so it would be less that a TBI injector... I'm just glad the marine engine manufacturers have stuck with the old speed density systems and have stayed away from using Mass air flow systems.. Talk about something costly to repair... <br /><br />DDboater, you can upgrade to an EFI/TBI system.. There are a couple aftermarket systems specifically for marine use that start at about $1000 complete with everything you need to convert it, and they will work with your current intake manifold as long as the intake is for a four barrel carb..... <br /> http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=112599&prmenbr=361 <br /><br /> http://www.turbocity.com/EFIApplBoat.htm <br /><br /> <br /><br />No more rough cold starts, just hit the key and go.. More fuel effecient too..