I have an 84 Z28 with the L69 motor in it. Just wondering what the differences were between a regular 305 and the 305 h.o.

I dont know all the differences but higher compression is one of the reasons.

Well to start off L69 cars came with better gears 3.73, dual snorkel intake better manifolds, bigger converter, flat top pistons, for 9.5.1 compression, better camshaft too... I think thasts about it , well they also had differnet metering rods and hanger in the car..Kevin

Compared to LG4:
Better exhaust from heads to rear bumper. Better cam. Better air cleaner. Higher compression in '83 and '84 only. Different carb and PROM tuning. Knock sensor.

Heads are the same, intake manifold the same. In '85 & '86, pistons (and therefore compression) the same, & LG4 also had knock sensor w/higher compression. Gears may or may not be the same. Converters also varied.

So does my lg4 T/A '86 model have flat top pistons. Also can I improve that compression in any way?.. So correct me on what I've come to believe. The least amount of cc's in the combustion chamber determines comp. ratio?

RICHRAD
You have the 9.5:1 compression ratio. The amount of the cc's determines your compression ratio. Right now your heads are 58cc stock and you could mill them to a lower number to get more compression.

Basically, get headers and exhaust and a better cam and you are there.

82 LG4-145 hp
83/84 LG4-150 hp
85-87 LG4(9.5:1) 165 hp

Now is that horsepower (hp) or brake horse power (bhp)? And what is the difference between the two?

I don't know the entire answer to that, but the manufacturers have been using SAE hp since the 1970s, which means hp in the car at the flywheel with all the accessories' parasitic drag accounted for. So, if you took an 86 LG4 and added about 30 hp to its SAE (or net) hp--to account for the loss of hp caused by the water pump, alternator, air conditioner, etc.--that would give you its dyno hp.

That works out pretty accurately, too. I read a mag article where they took an LG4 out of a Camaro and put it on a dyno stand and it produced 197 hp.