5 replies to this topic

[Kerrin]

After looking at FAQ

my 1275 spi engine (12AEF77) has 63 Bhp 10.1:1 comp ratio.

I got a spare engine today (12A2A) which (I think) has 50hp 9.4:1 comp.

Anyone know how the engines differ, is it just the compression ratio or is the cam valves or are other areas different.

K

[taffy1967]

I know the Cooper engines always had more torque?

[THE ANORAK]

don't rely on rovers stated BHP figures for the SPi, there is a rumor that either the carb coopers figures were quoted low or the SPi figures were quoted high to make the injection models look like a "step forward" when in reality most SPi can't make the "quoted figure".

i don't know the details, but i have heard the rumor.

but i do think the main difference in the engines is the cam shaft, i think ???

Edited by THE ANORAK, 14 January 2007 - 09:53 PM.

[Billy]

I know the sprite head has tiny ports and a hif 38 hence being low powered
I can do pics of the tiny ports with a decent'ish 12g940 tomorow if anyone wants
the sprite head is also lacking the locating rings for the inlet manifold

[Kerrin]

Great thanks for that, dont worry about photo's. I will take off the exhaust manifold tommorrow, and compare the engines.

I dont actually know if the engine is out of a sprite so will check the rest of the engine number tommorrow.

I have three engines, so just trying to work out which one will be best to use for a fast road motor.

The third motor is a 12H D12 metro which may be the best option so far.

[Sprocket]

Cooper SPI and Cooper Carb, both 63hp.

Non Cooper SPi and Non cooper Carb 53hp.

Non Cooper Carb engines have engine numbers 12A2BG03

Injection engines have engine numbers, Non Cooper, 12A2DF75 low compression, Cooper, 12A2EF77 high compression

Cooper engines were 10:1 CR, Non Cooper were 9.4:1 CR. Coopers run 3.2:1 final drives and Non Coopers run 3.1:1 final drives, carb or injection. Coopers have a sportier cam.

Cooper SPi has a slightly richer acceleration enrichment than Non Cooper SPi. The Cooper is less efficient but accelerates that little bit quicker. The 10hp difference comes from a combination of the cam, the CR and the Richer fueling.

Injection does not make the car more powerful, just more economical and into the bargin, a lot cleaner.

Those figures relate to the 1992 onwards 1275 engines fitted in Minis, not any other 1275