Project: Tuned Port Fuel Injection (TPI) on my boat

[jones3935]

I'm not much of a fan of carburetors to start with but have a bit of an affection with TPI cars. My boat is a 1990 Maxum SCR that was originally equipped with a Merc 5.0LX with a quadrajet. I bought the boat with a worn out motor. I pulled the motor, completely rebuilt it. Went back with a Comp Cams custom spec marine camshaft and upgraded the cylinder heads. Since this is a cruiser, I wasn't going for speed but rather power to bring the boat on plane in a timely fashion. I fought off the urge to change to fuel injection at this time but was very pleased with the performance of my new motor. The next season, my quadrajet gave me some trouble and that was just the excuse I needed to make a change. The intake manifold I'm using is 1990 model year specific commonly found on Camaro, Firebird and Corvettes. Here are the steps of my project. To avoid the conversations on the safety topics... Safety was #1 priority. While I am using am automotive intake manifold, I'm using sealed marine distributor, marine starter, marine alternator, marine inline fuel pump, USCG approved fuel lines, etc etc

Hope this thread ok here, as I don;t appear to be able to post on the project thread.


Stock setup - Quadrajet

Off with the crap , I mean carb

Tuned Port Injection

Mocked up

Not what you'd expect to see when you open the hatch

eprom burned with a initial tune. Using moates.net memcal adapter.

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Took the (Painless Wiring #60203) harness apart and reconfigured to route forward

Milled and drill/tapped the exhaust manifold for a O2 sensor (5/8 hole, M18x1.50 tap)

Started off with 24# injectors but changed to 19# for my 5.0LX

EGR Block Off Plate

Getting close to a finished Project

 

[AChotrod]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Very cool and looks great but shoulda been a LT1












PS Im a big LT1 guru.

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Very cool and looks great but shoulda been a LT1

PS Im a big LT1 guru.

LT1 was strongly considered but I wanted a setup that what was era correct for my boat. Everything is 90' model

 

[Tail_Gunner]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Intresting approach.....How did you get that manifold on vortec head's???? How rich are you running. Sounds good tuned port with vortec head's...should be a strong low end puller.

 

[thumpar]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

How did you eliminate the O2 sensor?

 

[Scott Danforth]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Thumpar,

looks like a pre-vortec head (12 bolt intake). if you notice, he machined one of the cylinder ports on the manifold. O2 will be reading only one cylinder vs the average.

My concern running that close to the valve is the high temp on the O2 sensor along with the intermittent flame front. Since the 90-92's were speed density, once your done tuning, you could eliminate the O2 sensor.

 

[thumpar]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Yep I missed that part of the post. :facepalm:

 

[Tail_Gunner]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Ahh me bad i guess my imagination ran a bit wild there. The OS port should be fine but it will account for only one cylinder..Just a fun project it pretty cool to see that tunnel ...tuned port sitting in a boat.

 

[Walt T]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

What was the cost of the set up?

 

[Scott Danforth]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Walt,

used TPI setups on craigslist, or your local salvage yard are going for about $200 complete with wiring, ECM, distributor, injectors, etc.

if you watch, you can even find them with the high flow runners, throttle body and inlet air foil (common TPI mods)

the TPI intake setup is a great low RPM torque setup.

Jones, are you keeping the O2, or just using it for initial tuning?

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Intresting approach.....How did you get that manifold on vortec head's???? How rich are you running. Sounds good tuned port with vortec head's...should be a strong low end puller.

Those are 90' heads (Pre vortec) 58cc chamber and 1.94/160 valves (stock heads was 1.84 intake valves) ECM tune is for stoich, 14.7 I will be swapping in a wideband o2 soon to see where it really is. According to the plugs, the a/f ratio is real good.

Ahh me bad i guess my imagination ran a bit wild there. The OS port should be fine but it will account for only one cylinder..Just a fun project it pretty cool to see that tunnel ...tuned port sitting in a boat.

Yes it will account for only one cylinder but the TPI systems are batch fire anyways meaning all cylinders are treated equally by the ecm. I LOVE the way it looks in there.

What was the cost of the set up?

I had most of the parts on hand but depending on how hard you shop the parts, hitting up craigslist/ebay, id say it could be done from $800 to $1400

Walt,

used TPI setups on craigslist, or your local salvage yard are going for about $200 complete with wiring, ECM, distributor, injectors, etc.

if you watch, you can even find them with the high flow runners, throttle body and inlet air foil (common TPI mods)

the TPI intake setup is a great low RPM torque setup.

Jones, are you keeping the O2, or just using it for initial tuning?

I'm keeping the 02 permanently so that the system will run in closed loop. I've got 70 miles on the system and the 02 seems to be doing great.

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

The absolute hardest part to this project was the thermostat housing. Notice it can't bolt to the intake any longer. I fabricated a plate in front of the water pump, mounted my housing vertically like the Mercruiser LT1 powered boats.

 

[Scott Danforth]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

jones, would a T-stat base like this help?

Holley Performance Products PowerCharger Thermostat Housing Adapter?90845

Especially if you went with a closed cooling half-system

 

[Tail_Gunner]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

Those are 90' heads (Pre vortec) 58cc chamber and 1.94/160 valves (stock heads was 1.84 intake valves) ECM tune is for stoich, 14.7 I will be swapping in a wideband o2 soon to see where it really is. According to the plugs, the a/f ratio is real good.


Does the painless system have the ability to do knock counts....gezz 14.7/1 is extremely lean for a boat. I pushed my little 4.3 to 13/1 and only from 2500..3700 rpm...

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

jones, would a T-stat base like this help?

Holley Performance Products PowerCharger Thermostat Housing Adapter*90845

Especially if you went with a closed cooling half-system

I strongly considered building something similar until I ran across this LT1 setup, and then decided to emulate it.

Those are 90' heads (Pre vortec) 58cc chamber and 1.94/160 valves (stock heads was 1.84 intake valves) ECM tune is for stoich, 14.7 I will be swapping in a wideband o2 soon to see where it really is. According to the plugs, the a/f ratio is real good.


Does the painless system have the ability to do knock counts....gezz 14.7/1 is extremely lean for a boat. I pushed my little 4.3 to 13/1 and only from 2500..3700 rpm...

target a/f is not for WOT or heavy load conditions. There is at least a dozen tables for varying coolant temp, map, tps, voltage that affects over all a/f. Once i have the wideband in, I will know for sure. For now, I'm simply reading plugs closely and really like what I see so far with no signs of detonation.

Yes, it does have a knock sensor present and the ability to pull timing based on knock count.

 

[JustJason]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

ECM tune is for stoich, 14.7

You want to be roughly 20 to 25% over, and run in the 17 to 18 to 1 window. Or else your valve train is going to grown into a garden of beautiful tulips. You will likely have a little bit of flatness in the holeshot as well.

Remember, stoich is for efficiency, not building power. You need to be well over stoich to allow the engine to build the peak torque it's capable of. But you also need the extra fuel to cool the valves, and help keep pre-ignition and detonation at bay.

Aside from that... All that work for a 5.0? man o man o man.

 

[Scott Danforth]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

You want to be roughly 20 to 25% over, and run in the 17 to 18 to 1 window. Or else your valve train is going to grown into a garden of beautiful tulips. You will likely have a little bit of flatness in the holeshot as well.

Remember, stoich is for efficiency, not building power. You need to be well over stoich to allow the engine to build the peak torque it's capable of. But you also need the extra fuel to cool the valves, and help keep pre-ignition and detonation at bay.

Aside from that... All that work for a 5.0? man o man o man.

I think you have that backwards

17 to 18 :1 is lean.

you want to be under the 14.5:1 to start getting rich.

you need fuel to pull load. Stoich is just where everything is balanced (no change in load, no change in RPM, etc.)

 

[jones3935]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

You want to be roughly 20 to 25% over, and run in the 17 to 18 to 1 window. Or else your valve train is going to grown into a garden of beautiful tulips. You will likely have a little bit of flatness in the holeshot as well.

Remember, stoich is for efficiency, not building power. You need to be well over stoich to allow the engine to build the peak torque it's capable of. But you also need the extra fuel to cool the valves, and help keep pre-ignition and detonation at bay.

Aside from that... All that work for a 5.0? man o man o man.

Yes, as stated above, the stoich is base line for the ecm. The dozen or so additional tables add or subtract from that based on engine conditions.

I've drag raced for the last 18 or so years of my life and built many of sbc's. As I'm sure you know, the 5.0 shares the exact same stroke and rod length as the 5.7 The only difference would be in the bore size. I prefer the smaller bore for fuel economy, the thicker webbing as a result of smaller bore for durability and concentrate on my parts combination to improve efficiency to make up for number of cubes.

I love my 5.0 :lol:

 

[JustJason]

Re: Project: Tuned Port Fuel Injection (TPI) on my boat

I think you have that backwards

17 to 18 :1 is lean.

you want to be under the 14.5:1 to start getting rich.

you need fuel to pull load. Stoich is just where everything is balanced (no change in load, no change in RPM

Lol... Yup. Thinking about to many things at the same time. But the point I was trying to get across was the same. In a boat, you want to be 20 to 25% over stoich.