what would be the best diff to replace the old one in my 1200 coupe ie 120y or newer.

Ps Ive just put the A14 engine in with a webber and extractors off the old A12 and it has heaps more power than I expected. Does anyone know what the stats are for the A14 in
comparison to the A12 and A15.

Andrew

A12 - 69hp
A14 - 83hp
A15 - 69hp

Huh? A15's had a much lower peak power and heaps more torque. Also thev were measured in different ways (DIN versus SAE), plus A15's had tighter pollution controls and lower
compression.

Effectively an A15 has slightly LESS power than an A14, but more potential due to extra capacity. The A14 revs much harder than the A15 in stock form.

You're probably somewhere around 90-95 horses at the crank with the weber and exhaust, and maybe 70-75hp at the back wheels (based on usual experience). Getting much more than this
depends on the compression ratio and cam that the engine's got in it (standard - red or green grind, or performance).

A 1200 ute diff would make it go harder again - 4.11:1 instead of 3.9:1. They're also supposed to be a little stronger, although I dunno why.

Funny, I have had 1200's with different HP ratings. My '72 sedan had 68 Hp and some of the others were 69 HP. I wonder what the difference is. Also the 1979-82 A14's have 65 HP
in the US.

they're stronger coz they have bigger diametre axles and bigger bearings

Justin

Countries introduced different "pollution controls" at different times which has a significant impact on horspeower claims. From my expereince here in Oz, Australian models generally lost
around 20% of horsepower as of 1st Jan 1977 due to such measures, then about another 10% in 1985 with the introduction of unleaded petrol.

A lot of cars STILL get different horspower claims in different markets, eg: Aussie spec 200SX's claim 147 kw, but japanese spec claim about 160kw. American non-Turbo 240sx's I've got no
idea on....

Suffice to say that the A15 is massively "undertuned" compared to earlier A12's, and this can be resolved either by using A12 cams or by getting someone to grind some new profiles on your
existing ones. Putting A12 cams/carb (yes the A12 carb jets were generally bigger too) and distributor (dont foprget this when you hot up a motor) is a sure way to increase power on your
A15, whereever you are - and a good way to get factory like response with a horsepower boost.

Factories spend a shitload of money trying to make a good power curve for their cars and YOU out there don't have the resources to do the testing they did....

People take note of this. I reckon 1 in 3 people at best would get a performance benefit out of a hot cam - because all the other related components need to be optimised to match. This is
without the more complicated stuff like matching gearing, or tuning exhaust or header lengths....

For instance, if you did the same to an A14, you would most likely end up going backwards.