Fuel Injection – Page 15 – Not Your Average Engineer

January 6, 2011January 6, 2011

Looking for a properly sized throttle body with sensors and fuel injectors already installed

The spare set of carbs from Phil came in the mail yesterday. They are making my lab smell pleasantly of gasoline and solvent. One of my labmates is also a gearhead. He’s loving it. The others aren’t saying anything yet. I guess that gas smell hasn’t traveled all the way down the lab.

Taking some measurements from the carbs, I found the following:

Throttle body outlet measurements:

Outer diameter: 40mm
Inner diameter: 37mm

Throttle body inlet measurements:

all wonky because they are tapered to receive the plastic airbox

I’ve been poking around looking for 37mm inner diameter throttle bodies with sensors and fuel injectors already installed but have come up short. It seems like the Moto Guzzi Breva 750 throttle bodies might be the right size. There is an auction on ebay for a set. They have a sensor but don’t have any injectors as far as I can tell. There is also a Suzuki Burgman 400 throttle body that ebay indicates might be the right size. Looking at the microfiche, the Burgman does have fuel injectors. I wonder if anyone on the IPCRC might have an extra set laying around… The microfiche doesn’t tell me enough to figure out what angle the injector body is at compared to the throttle body and if the throttle body has any strange turns like the fuel injected VT750 throttle bodies do.

My google-fu is obviously weak because I haven’t had any luck finding a list of throttle bodies for common vehicles and their dimensions. Does anyone know where I might be able to find such a list?

December 29, 2010July 1, 2020

Throttle bodies for sale or rent

I’ve been poking around more looking at available throttle bodies online. Brand new after market throttle bodies run as cheap as $131 from JC Whitney. Once I get my hands on a set of PC800 carbs, I can start looking more in earnest at available automotive throttle bodies. Maybe I can even find one that has the injectors already integrated. Seeing all of the options on JC Whitney makes me hopeful that it will be easy to find what I need and inexpensive, too. Alternatively, like I’ve mentioned on here before, I’ll gut out a set of PC800 carbs and use the throttle bodies from them. There is a set on ebay at the moment for $185. That seems a bit high. Hopefully a less expensive one will come along.

As an airbox replacement, I’m thinking about some K&N universal tapered filters. Maybe I’ll throw a filter minder on, too. I might grab a filter wrap as well.

December 27, 2010July 1, 2020

A book to get and some other fuel injection odds and ends

A friend recommended I pick up a copy of Four-Stroke Performance Tuning as I get ready to put fuel injection on my PC. That’s the book that he used 10 or so years ago when he put FI on a Datsun engine. He also suggested that I might point the injectors up toward the plenum to improve atomization.

One person on the IPCRC suggested that I fit a vacuum-operated fuel regulator to decrease flow to the injectors at high vacuum (low RPM). I need to investigate this more to see if this would be worthwhile to pursue or if modern injectors can give me precise enough fuel delivery for lower RPM operation.

It seems that there are two types of injectors. One is standard and the other is a pico injector. Picos use less power according to someone on the IPCRC. That is good for our power-starved PCs.

This project will be taking a back seat for the next month or two as I have several conference papers to produce in short order. Hopefully by June I will have some plans put together and parts ordered. I’d like to go to next year’s TGPCHPCMY2KMR+11 ride with working fuel injection. And a rear rack. 🙂