Howell EFI Install: We Upgrade A Classic C10 With Modern Horsepower Fed By The Easiest EFI Install Ever

Howell EFI Install: We Upgrade A Classic C10 With Modern Horsepower Fed By The Easiest EFI Install Ever

(Words and photos by Matt Graves) – LS engines are absolutely the hottest thing going. You cannot deny their presence and effect they have on our hobby. They are currently being dropped into everything from C10s to Austin Healeys. I consider them not a Chevy engine but a universal power plant, only limited by your budget and dreams. When it came time to get our C10 powered our immediate choice was a 5.3L truck LS engine. The holy grail of truck engines is the 6.0L, but they cost considerably more. Yes, the 6.0L has a 4” bore so you can drop those Holy Grail LS3 heads on them and go. But the lowly 5.3 can make tons of power for half the money and there are literally thousands of them in the junkyard.

We knew we wanted to build up our engine from more than stock. A quick call to John Bouchard Engines in Nashville, TN and we had a 5.3L coming together. If there ever was an expert in LS engines, it’s John. You may remember him from Horsepower TV and have seen the various LS engine combinations he’s built for the show.  John is a young guy with an old school methodical approach to building his engines. He has all the power combinations in his head, carefully hand assembling each one.  We told John our goal was 400-425hp, which is very easy to do on a 5.3. Our combination is running .040 pistons, stock crank, custom Bouchard ground COMP cam and Summit Racing roller rocker upgrade. Pace Performance sent us the super cool looking Holley Mid-Rise EFI intake, 24lb Holley injectors, and rails with the door open and closed by an Edelbrock 90mm throttle body.

But the point of this story is EFI. There are so many options these days on EFI systems for LS engines. After some research we soon realized one of the easiest systems out there is Howell EFI. One of the reasons we love the Howell system is the use of the GM OE ECU. You get an ECU and you’re getting millions of dollars in engineering research. It’s rugged and can survive anything, giving you full OBDII diagnostics just like any modern car and it can be mounted in the engine bay.  So pick up the phone and call Howell.  Give them all your engine parameters, cam specs, injector size, intake set up, make and model the engine came out of, and what OE sensors you have. This is key, so make sure you grab all the OE sensors from your junkyard engine. Howell can even keep the emissions setting so you can pass the sniffer test if you’re running cats. They can also set up the ECU to turn on your cooling fans, A/C and more, programming it to your exact needs, and making installation a breeze.  No more spending 2 hours setting up a blank ECU and hoping you get it right.  If you do end up needing to tune it, tuning software programs are available, as well as plenty of shops than can fine-tune your program. But out of the box fit, plug it up and run? Howell wins that game hands down.

Follow along as we install Howell EFI on our C10 –


Our candidate 1970 Chevy C10. This is a clean driver truck that was in desperate need of more powah! We’re delivering with the LS combo fed by Howell EFI.


5.3L Truck LS Engine with Holley mid-rise intake and Edelbrock 90mm throttle body. Make sure your engine has all the OE sensors installed. The Howell system is designed to work with the OE fuel injection sensors. Engine built by John Bouchard Engines.


LS engines just fall right into a C10 chassis. The engine is backed up by an American Powertrain prepped TREMEC TKO 5-speed.


If you’re scared of wiring, the Howell EFI system will help alleviate your fears. It’s very simple and straightforward to install. Everything is clearly labeled.


The heart of the system is the custom programmed GM OEM based ECU. Using the OEM ECU gives you OE tested rock solid reliability. Simply give Howell your specs and they will set it up for you, programming it for A/C, cooling fans, turning off the anti-theft system and more. It can also be fine tuned by many aftermarket tuning software programs if needed.


All the connections are clearly labeled. This is the fuse panel for the system. The only loose wires you have to hook up are 12V switched, 12V battery, a few grounds, fuel pump wire and your fans. That’s it!


There are 3 relays in the system we ordered. One for the EFI fuel pump. Two for the dual fans we are running. The ECU will turn on the fans at the temp you specify to Howell using the OE temp sensor.


We mounted our ECU inside the fender to keep it clean. The OE ECUs are very rugged so if you wanted to mount it in the engine bay it will be totally fine. We also found a spot close to the battery to mount the relay bank and fuses.


The LS engine harness could not be any easier to install. Just click and go. The connectors only fit one way so it’s a pretty brainless installation. Luckily for us….


Fuel pressure is extremely important on a properly working EFI system. Make sure you use a good quality fuel pressure regulator and a gauge. We set ours at 43 psi to meet the requirements on the size of injectors we are using.


On the bottom end we installed oxygen sensors on each header collector. We picked up a set for a 2002 Chevy Silverado with a 5.3L. Make sure you get the ones BEFORE the cats, not after. The plugs won’t match up since we aren’t running catalysts in the exhaust.


One of the trick features of the Howell system is the universal OBDII data port complete with check engine light right beside it! You can check codes or perform tuning with the compatible tuner software.


The final touch was a K&N cold air intake for 2002 Silverado we had lying around. With a little modification it fit perfectly. The mass air sensor adapter in the kit made it the right choice. Once we buttoned everything up and checked the fuel pressure the motor fired right off! Using Howell EFI was a game changer for us especially for LS engine projects we have in the future.


Howell EFI

(810) 765-5100


Pace Performance



John Bouchard Engines

(615) 752-9924


American Powertrain



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