3 replies to this topic

[Avl_Paul]

I'm being told by a local Mini guru that, while the SPI's had greater break HP on the dyno, that the driving performance of the carb versions is better. The comment is along the lines of "they just seem to pull better." I understand that the MPI was a much more refined injection system. Any truth to the claim that the carburated version of the 1275 has better driving performance than the SPI?

[Sprocket]

You have to ask youreslf, what does a carb do better than mapped electronic fuel injection? You also have to ask yourself, what does a distributer do better than electronic mapped ignition?

Carbs and fuel injection only supply fuel to the engine in speciffic quantaties at varying conditions to satisfy the demands. Its the engine that produces the power.

The only difference that should be evident is fuel consumption and emission levels. The carb is poor the fuel injection is superior.

[Avl_Paul]

I agree that a decent fuel injection system should always provide smoother performance, better fuel consumption, and better emissions but my question was in regard to performance - meaning really the torque curve over the entire range. This would be more dependent on the fuel atomization, rate of fuel injection, and fueling strategy. There are definitely cases where a poorly set up fuel injection system does not perform as well in these areas compared to a well configured carb.

For example, one can look into the SPI system at idle and see that the fuel is not being well-atomoized at idle as the flow past the throttle plate is not reachiing sonic conditions and that this could effect transient performance off the line. I'm not saying it does - just being devil's advocate. I have no prior experience with Mini's (just other vehicles). I'd be glad to hear that this guy is wrong and there is no appreciable performance difference between the SPI and a car converted back to a 1 3/4 carb setup as I'm not particularly interested in doing that conversion if it can be avoided. I'm just trying to decide whether it is worth investing in a diagnostic tool and learning this SPI system. I guess the other option is a programmable ECU - has anyone come up with a clean conversion package?

[Bungle]

my carbed mini has always matched the MPG of the MPI mini's in my club the SPI's do a little less

on a rolling road day we tryed 3 mini with stage 1 kits

carb made 69 bhp MPI 65 BHP and the SPI 64

we didn't have any standard engines to compare