72 Riviera Fuel Injection

Prepare to spend a lot money and time. Do not waste any of either on Holley's Pro-Jection, which is halfassed at best.

, go read the whole site.

Just curious if anyone has tried Edelbrock's port FI. I'm not really looking to buy, but it looks a lot better than the Holley setup just at a glance.

nate

I would be inclined to go grab one of the older throttle body injection systems off of a big block Chevy truck from the early nineties, I think that's when Chevy was doing TBI. The older ECMs are fairly hacked, meaning that it's easy to get the software and build the equipment needed to fine tune the internal settings for other applications. The big block TBI system will already be fairly close because the motors are similar in displacement and probably fairly close in power output. The throttle body itself is fairly simple, so adapting it to the Riv manifold should be straightforward, and the low pressure of the stock fuel pump is what the TBI will need. The biggest hassle will be plumbing a return line to the tank for the TBI's built in precision fuel pressure regulator.

There's lots to learn at

JazzMan

"JazzMan" wrote

I notice that they'd normally use a steel pipe to run the return line to the fuel tank. Wouldn't it be easier to regulate fuel right on top of the fuel tank? Just run a vacuum hose there?

Some pumps use the output from the return line as a cooling jacket and some tanks are designed with a well that fills from the return line to act as a cornering baffle keeping fuel on the pickup when turning corners with low fuel in the tank.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Holley Pro-Jection is not a waste of money and if anybody tell you it sucks then that person does not know much about the Holley line or had a shoddily installed system.

First off - The Projection system comes with many levels and price ranges.

Second- The Chevrolet system was in fact of Holley design.

How can someone bitch about gaining better performance, better mileage, and eliminating the known problems of carbs.? Must be a financial reason!

I installed my projection back in 95 and I have not had a problem with it. I went from 10mpg no-matter-what to being able to achieve 20mpg. This is in a built up and lifted International Harvestor.

For the money spent, there is not a better bargain out there than the Pro-Jection system. Others claim to be better but fail to explain why it is better. Simplicity is better than complexity.

DieInterim

With the systems I'm familiar with, fuel pressure at the injector is varied in proportion to the manifold vacuum, this keeps the pressure across the tip of the injector relatively constant and therefor easier to control. The tank is too far away and there would be too much lag for the pressure to be precisely regulated from there. The GM TBI systems normally have the regulator built into the TBI right at the injector. To regulate pressure fuel has to go somewhere, that's why the need for a return line.

JazzMan

Also the return line helps prevent vapor lock on cars with low pressure fuel systems by keeping the fuel moving, that way when the engine is running the fuel doesn't sit by the front of the engine and heat soak, it is always circulating and cool fuel is always being brought up to the front of the car.

nate

My '99 Mazda did away with the return line because-I am told- it heats the fuel in the tank and upsets imissions.

probably screwed with *evaporative* emissions. I can see that. Also probably unnecessary with a high pressure FI system with the pump in the tank; it would take a lot of heat to vaporize fuel under 50-100 PSI. Only issue is how to regulate pressure; I don't honestly know how they would do that, but there are some mechanical regulators for carbs that don't use a return line so I would assume that something analogous would be available for FI.

nate

That is why my carbed CJ7 has one, didn't think it was as much of an issue with FI engines.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 (More Off Road album links at bottom of the view page)

Newer computing capabilities allow the ECM to control fuel mixture even with constantly varying pressure differentials across the injector tip, so there's no longer any need to keep the pressure differentials minimal with a return line regulator system.

JazzMan

JazzMan wrote: The biggest hassle will be plumbing a return line

But a lot of high-performance 60s and 70s cars ALREADY have a fuel return line, because continuously circulating fuel helped prevent vapor lock. My 69 Coronet has a return line, for example.

With EFI other than the most primitive TBI which might be able to use the stock mechanical fuel pump, the biggest problem is getting a good high-pressure supply and a fuel/air separator system. Just running a HP fuel pump straight from the tank won't cut it, because fuel tanks for carbureted engines aren't baffled and the pickup can suck air for a few seconds at a time anytime the tank is less than half full. Carbs don't care because the float bowls won't empty in a couple of seconds, but MPEFI won't tolerate fuel pressure dropping to zero going around corners, under acceleration, under braking, or going over rough spots in the road.