'70 LT-1 vs 72 LT-1 Power difference?

[Mark K.]

A friend called today to say he heard of a nice original paint '70 LT-1 that might be coming up for sale and knowing that I had an interest in original paint '70-'72 cars, asked if I would be interested in this car. I have owned a '72 LT-1 and a '72 LS5 and understand the changes made versus the '70 cars. However, I have never driven a '70 LT-1 or LS5 and wondered if there is a real appreciable difference in power. Can anyone share their experience? Thanks, Mark.

[Duke W.]

Re: '70 LT-1 vs 72 LT-1 Power difference?

The drop in CR from 11:1 to 9:1 basically drops the torque curve about 10 percent across the board. The good news is that it will run on 87 PON fuel.

You can recover some of the torque curve, particularly at the low end with some ignition map changes, and if you install the 11:1 pistons, you essentially have a '70 spec engine, but it will require premium fuel.

Duke

[Gregory G.]

Re: '70 LT-1 vs 72 LT-1 Power difference?

Would a change in piston size to 10.5:1 CR bored .30 over be close in torque and HP rating as the standard 11:1 CR for a '70 LT1?

[Duke W.]

Re: '70 LT-1 vs 72 LT-1 Power difference?

That would get you pretty close. Remember that the OE rated CRs were probably a half point lower than speced depending on final deck height and the type of gasket used. An LT-1 with a true 10.5: CR would should run okay on today's premium fuel with no more than a little juggling of the timing map.

Duke

[Warren F.]

Re: '70 LT-1 vs 72 LT-1 Power difference?

Mark:

I've never had the opportunity to drive an LT-1 car. I have however owned several '70 LS5's. That 500 ft lbs of torque REALLY gives the compressing of the spine in the seatback feeling!

I liked it so much that it really spoils you, to go back to a small block car. In fact I installed a '70 LS-6 engine in one of the LS5 cars, WOW!, same torque rating, but now another 60hp.