Ramjet / Megasquirt Project on my 84 K10.

[ElGracho]

Ok, so I've been mentioning this here and there for a while now, I've got it to a point where now I'm ready to give a summary of the project.

I started this really last January. I discovered the preview of the Megasquirt article in Car Craft and went searching the web. I found the MegaSquirt site and immediately had to order the parts to start building my EFI computer. This is not a plug and play deal, you actually get a board in the mail, buy a bunch of components (capacitors, resistors, etc) separately and assemble the computer yourself. The benefit is that along the way you learn how this black box really works. It's an open source project and all the designs and program code are available. There is a really good support forum too.

I started with my 84 K10. It has a vortec headed 350 I built in 1999. The engine has 50k miles. It was originally built to the same specs as the 330 hp GM crate engine, but that hadn't come out when I started building up my engine. It is a 2 piece rear main 4 bolt block. It had a Edelbrock Performer Vortec Intake and a Holley 1850 carb. It's always had plenty of power and got around 15 mpg. This truck has 3.73 gears, NP208 transfer case, a TH700R4 transmission and 32x11.50 BFG All Terrain tires. The axles and tranny were rebuilt about 10k miles ago. It also has a set of Summit headers and 2 1/4" exhaust.

I gathered parts most of the spring and summer as I researched and could afford them. I will have a complete parts list on my web page, but here's the big items:
- 87 fuel sending unit with provisions for in tank electric pump.
- 89 Camaro electric fuel pump designed for ~45 psi.
- Misc plumbing from the tank to high pressure fuel filter to intake.
- GM Performance Parts Ramjet intake, throttle body, fuel rails and 22 lb/hr injectors.
- Wiring harness from RS Autosport (really just some nice labeled wire that I added to my new AC Delco connectors)
- Serpentine belt setup from a 91 Buick Roadmaster wagon. Original small block accessory brackets might have worked, but you would have to modify the alternator bracket since the new intake doesn't have the bolt hole it used to have. This also gave me an upgrade to a 100 amp alternator.
- Two jegs 14" electric fans. As we know you get what you pay for (trademarked to Mike (Swervin) Ervin) and these were the cheapies, but Eric (ocbaud) has been using some that are similar successfully so I figured I'd give them a shot. I plan on adding a cold air intake so I wanted to get rid of the radiator shroud. I also didn't know how far the ramjet aircleaner would stick out and worried (unnecessarily) about it hitting the fan. You could use a reverse rotation fan and the original shroud.
- Lokar LS1/ramjet throttle cable.
- 69 Chevy points distributor converted to electronic with a Crane XR-I kit. Similar to a Pertronix. I have a new lockdown small cap electronically controlled distributor when I add that functionality to my Megasquirt.

As of right now, I have everything installed and the truck starts just like a new EFI engine should. I have the idle tuned better than I ever did with my old Holley and now I'm working my way up the RPM range setting the numbers in the computer to make the truck run right. The Megasquirt setup helps you with this since it uses O2 sensor feedback and will run in closed loop.

On with the pics:

Here's how my truck has been sitting since September. I'll be needing it soon so I'd better get this finished!


Here's what I started with under the hood. You can see that I'd already pulled the carb, the accessories and the water pump.


Here's the new intake installed and wired up. The white wires on the harness are the pigtails that come on AC Delco connectors. They are hooked to color coded and labeled wires to the terminal board under the hood which has a cable that goes to the ECM inside the truck.


Here's the other side. The fuel gage is just in there for testing. The wiring mess on the firewall is partly for this EFI swap (the stuff around the board with the three relays on it). The red wires running across the firewall are actually from my A/C swap, powering my amp and powering my ACC circuit since something in the fusebox keeps it from working like it should. I'm ebarassed to let anyone see that, I'll be cleaning it up.


Here's my serpentine belt drive and more detail on the air cleaner.


Electric Fans.