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beatle78
10-18-2006, 02:25 PM
I think I know, but I want to make sure....

p.s. I have the '01 LTR which I believe is MPI....

What I think:

MPI = fuel injectors
TBI = glorified carburator

is this correct?

thanks

east tx skier
10-18-2006, 02:43 PM
I see where you are coming from, but I think the response you will get is that TBI is much more than a glorified carburetor. TBI offers start up and ease of operating advantages over a carb for starters. From an performance standpoint (all else being equal), there may be less of a distinction. In other words, you can get lots of horses out of a carb'd engine.

But if you conduct a poll (or find the thread where the question was posed, "which would you rather"), you'll see that fuel injection, no matter the variety, carries the day.

/owner who is perfectly happy with his carb boat.

bigmac
10-18-2006, 03:04 PM
I think I know, but I want to make sure....

p.s. I have the '01 LTR which I believe is MPI....

What I think:

MPI = fuel injectors
TBI = glorified carburator

is this correct?



Throttle-body injection is significantly more sophsiticated than a carburetor. The difference between that and multi-port injection is the way the fuel is delivered to the cylinder. With the latter, it's delivered directly through an injector, as opposed to dumping it into a manifold. That method of delivery is the only similarity between TBI and a carburetor.

the legend
10-18-2006, 03:04 PM
Mpi=multi Port Injection-dry Intake-best
Tbi= Throttle Body Injection-wet Intake-good

pilot02
10-18-2006, 03:32 PM
Throttle-body injection is significantly more sophsiticated than a carburetor. The difference between that and multi-port injection is the way the fuel is delivered to the cylinder. With the latter, it's delivered directly through an injector, as opposed to dumping it into a manifold. That method of delivery is the only similarity between TBI and a carburetor.

For clarification, Neither TBI or MPI directly inject fuel into the cylinder. In the case of TBI all fuel is injected at a centralized point (old carb location) whereas in the case of MPI it is injected just before the intake valve. Both provide superior perfomance over a carb as far as driveability and fuel efficiency though MPI is significantly better than TBI since there's no ability for fuel to pool in the manifold and the fuel charge delivered to each cylinder is equal thereby preventing the possibility of the farthest cylinders running leaner than the center cylinders.

88 PS190
10-18-2006, 03:39 PM
MPI = fuel injectors
TBI = glorified carburator


If you want to be technical both are glorified carburators.

End goal, proper mixture of fuel and air in all cylinders when its supposed to be there.

Carb, air flow sucks metered fuel. To ensure proper mixtures/volumes carb must be jetted, varied temperatures change air density and therefore that can throw it off.

Injection, use sensors to determine the metered air volume/density inject proper amount of fuel for proper mixture.

Then they've mentioned the TBI and MPI.

MPI is better, though if your injectors start going out it can be a pain to replace them all.

beatle78
10-18-2006, 07:53 PM
thanks guys.... I didn't mean to downplay TBI... I would take TBI or MPI in my boat, I was just trying to understand the difference a little better.

Here's a modified statement:

TBI = no fuel injectors
MPI = fuel injectors

:)

Archimedes
10-18-2006, 08:03 PM
And note, contrary to what my dealer said ("errr the motor in that X-1 is carbuerated..."), all of the MC motors are MPI, including the RTP-1.

André
10-18-2006, 09:18 PM
And note, contrary to what my dealer said ("errr the motor in that X-1 is carbuerated..."), all of the MC motors are MPI, including the RTP-1.
Did your dealer really said that???
Sad,really sad...:(

JimN
10-18-2006, 09:31 PM
Tell your dealer to go to training so he doesn't cause more problems for MC than he already has, not to mention the fact that his being totally clueless is a disservice to his customers.

88PS- actually, the MPI isn't a glorified carb since the fuel and air don't mix in the throttle body. As Will said, the MPI is a dry intake and that makes a big difference in efficiency and performance.

WOW! I can't believe the dealer said that. What makes him think he's qualified to sell new boats?

the legend
10-19-2006, 09:20 AM
to correct your statement, tbi has two injectors.thanks guys.... I didn't mean to downplay TBI... I would take TBI or MPI in my boat, I was just trying to understand the difference a little better.

Here's a modified statement:

TBI = no fuel injectors
MPI = fuel injectors

:)

beatle78
10-19-2006, 09:26 AM
kool, thanks guys...... did MC ever sell any motors with TBI?

LTR = MPI
MCX = MPI
LT1 = MPI

Tryin-again
10-19-2006, 09:28 AM
kool, thanks guys...... did MC ever sell any motors with TBI?

LTR = MPI
MCX = MPI
LT1 = MPI


Yea...Mine is - 98 model :rolleyes:

the legend
10-19-2006, 09:29 AM
Mc was the first tow boat to offer EFI, AND YES MC OFFERED A TBI UNTIL THEY REPLACED IT RECENTLY W/ THE RTPkool, thanks guys...... did MC ever sell any motors with TBI?

LTR = MPI
MCX = MPI
LT1 = MPI

east tx skier
10-19-2006, 10:29 AM
If memory serves, the predator was the TBI motor until 2004 (replaced as the Legend pointed out, by the RTP).

Archimedes
10-19-2006, 11:44 AM
Did your dealer really said that???
Sad,really sad...:(

Oh yeah, I can't make this stuff up. Over the phone as I was calling around for a leftover X-1 and the salesman at the dealer I wound up buying from said that. I couldn't tell from the MC website whether the RTP was MPFI or TBI, so I asked him and that's when he said "no that motor is carbuerated". I was about to ask why Mastercraft put a 1993 motor in the X-1, but I knew he was wrong so I just let it go. Probably a warning sign I should have paid more attention to at the time.

tdaines@hotmail.com
10-24-2006, 07:51 AM
One thing that I've been wanting to do is switch my 84 SNS over to TBI. It needs a new carb anyway, which runs around $500+. A Holley marine TBI system is only $900+.

Has anyone done this? How hard was the job and how were your results? On my last SNS (83), I just put on a new Holley 4160 that had tremendous results - turn of the key starting, and flawless operation right out of the box.

If anyone has any experience in this, I'd love to hear about it...

TIM

BrianM
10-24-2006, 09:08 AM
One thing that I've been wanting to do is switch my 84 SNS over to TBI. It needs a new carb anyway, which runs around $500+. A Holley marine TBI system is only $900+.

Has anyone done this? How hard was the job and how were your results? On my last SNS (83), I just put on a new Holley 4160 that had tremendous results - turn of the key starting, and flawless operation right out of the box.

If anyone has any experience in this, I'd love to hear about it...

TIM
I would just put on the 4160 and call it a day or sell the boat and upgrade to a '94 or newer that already has fuel injection.

From what I have read about the Holley Projection systems they are tough to set up and require a fair amount of tinkering. Search for it on Google and you will find lots of discussions on it. That along with performance that is only really as good as the carb anyway equals why bother. Switching over to a newer style TBI system would be very expensive.

rcnjson
10-25-2006, 10:19 AM
Has anyone done this?

If anyone has any experience in this, I'd love to hear about it...


Tim,
You may be interested in this. I am going to do my own JYD (stands for junk yard dog) EFI conversion to my boat. I am using mass air parts from mustangs and F-150's. I've got the A9L computer and engine harness, mass air meter, injectors, pump and lines already. I am currently working a deal for the intake, rails, and TB. I should be into fuel injection for under $500. I will probably post updates as the project progresses.
Jason

JimN
10-25-2006, 10:36 AM
How are you going to reprogram the ECM to deliver the correct amount of fuel under load? I wouldn't want to bet that it's going to be right as is, but you may get lucky.

rcnjson
10-25-2006, 11:05 AM
Jim, it is safe to bet that it will be correct no luck involved. Mass air measures the amount of air the engine needs at all operating ranges save for WOT in which case it just dumps fuel. An engine is an engine and it is not smart enough to know that it is in a boat or a car or a garbage truck for that matter. There are very easy ways to tune the amount of fuel that you need with the mass air system without touching the computer. Increase fuel pressure with the same pulse with in the same injector will deliver more fuel if needed. Reduce fuel pressure means less fuel, too low will cause problems with fuel atomization. If the tune requires even more or less fuel than the fuel pressure adjustment will provide, change injector size and recalibrate mass air meter done deal. I have run the stock computer on stock cars and supercharged cars and 600 HP nitrous cars with no problems all of these motors had different fuel requirements and the same system works.
Jason

rcnjson
10-25-2006, 01:27 PM
I forgot the 3800# convertable that ran 11.20's off the trailer with a JYD (see previous post) T64 turbo setup and you guessed it... STOCK COMPUTER.

If you think that I just woke up one day and just decided to do this you would be wrong. I know every pitfall that you are going to bring up. Engine rotation direction Check
Roller vs non-roller block, cam, dizzy Check
O2 sensor Check
...
I am driven by people who tell me I can't
k