C3 Lt1 Engine History

[John G.]

I am wishing to understand more about the LT1 option introduced in 1970 was there someone in particular responsible for this package? what is the full make up of the package? did the specifications other than comp ratio change over the years 70 t0 72? are there articles anywhere to read on this option
thanks john... down under

[Roy V.]

Re: C3 Lt1 Engine History

John, I sent you a pm

[Joe C.]

Re: C3 Lt1 Engine History

I am wishing to understand more about the LT1 option introduced in 1970 was there someone in particular responsible for this package? what is the full make up of the package? did the specifications other than comp ratio change over the years 70 t0 72? are there articles anywhere to read on this option
thanks john... down under

There was not any one particular person responsible for the introduction of the LT1 engine in 1970, but rather, it was the fruit of "committee work".
In reality, the LT1 is a hybrid which combined the best elements of the Z28, and L76, with the extra cubic inches of the L46, together with a smog cam. The responsible party for this design bears the initials "E.P.A."

[Vincent F.]

Re: C3 Lt1 Engine History

along with this option came the 2 1/2 in exhaust, larger fuel lines and pump, m21 or m22 trans, I dont beleive the m20 was avail for this package, heavy duty U joint clamps,radiator and shroud,I'm sure there are more.

[Terry M.]

Re: C3 Lt1 Engine History

Vince,
When I suggested a larger fuel line for LT1s here a while back I got some serious negative reactions.

[Mike E.]

Re: C3 Lt1 Engine History

M20 was available with LT-1--my 30k mile car with original 3.36 rear end has M20 from the factory.

[Steven B.]

Re: C3 Lt1 Engine History

In '69 there was a large spread on LT-1, ZL-1 and other Corvettes in Car & Driver or one of the more popular auto mags that is very interesting. They have a '69 LT-1 and speak of it being available in 1970. I have it packed away somewhere and will liook for it. Atthe time I paid more attention to Zora's white HT ZL-1 with Americans, Kustom sidemounts, etc.

[Vincent F.]

Re: C3 Lt1 Engine History

stand corrected Mike,m21,m22 was not avail in the base engine car.

[Vincent F.]

Re: C3 Lt1 Engine History

Mike, yours must be pretty rare with that combo,more of a highway cruiser, mine is the 2.20 with 3.70 rear

[Terry M.]

Re: C3 Lt1 Engine History

Actually it is not all that unusual -- there are a fair number of M20 LT1s on the survey in all three years. They have the best of both worlds. With a 3:36 ratio and the "low" first gear one gets dig off the line, and the 3:36 gives one relatively low (for the time) cruising RPM.

[Steven G.]

Re: C3 Lt1 Engine History

Was (c-60) a/c option available on LT-1's ? Steve

[Terry M.]

Re: C3 Lt1 Engine History

During 1972, and only later in production -- after 10 or 11K serial number.

[Warren F.]

Re: C3 Lt1 Engine History

John,
As I recall, Duntov and company wanted the Corvette to compete in SCCA B production. American Motors was eyeing this as well and was fielding the AMX for this category. I had heard that the LT-1 option Corvettes were made to compete in this racing segment.

[Steven G.]

Re: C3 Lt1 Engine History

The LT-1'S have a really cool looking hood, add an emission pump, no a/c, so the L-46, are really the coolest, especially during hot summer days. I WONDER how much H.P. loss occures due to the emission pump, I was told 5-8 H.P. loss, if that is true, by H.P.comparison there is about 12-15 H.P. difference, LT-1 (with emissions pump) vs L-46 (no emissions pump) instead of 20. I guess race cars back then did not consider a/c needed. Steve

[Dan P.]

Re: C3 Lt1 Engine History

The LT-1'S have a really cool looking hood, add an emission pump, no a/c, so the L-46, are really the coolest, especially during hot summer days. I WONDER how much H.P. loss occures due to the emission pump, I was told 5-8 H.P. loss, if that is true, by H.P.comparison there is about 12-15 H.P. difference, LT-1 (with emissions pump) vs L-46 (no emissions pump) instead of 20. I guess race cars back then did not consider a/c needed. Steve

Steve-

I've owed a '69 L46, M21, 3.70:1 coupe and a currently a '70 LT1/ZR1, M22, 4.56.1 coupe. There is a big difference in how the engines rev and pull. Twice the L46 fell on it's face when the lifters collapsed on the top-end (probably a good thing) as it hit about 6k. I'm usually very intent on eyeballing the tach, but the 350/350 left me feeling like I needed more "ooomph" on the top end so I kept my foot in it. On the other hand, the solid lifter LT1 will just keep pulling, so it's imperative that you monitor the revs.

I loved the '69 though. The L46 is a great all around engine, but I prefer the LT1's sound and ability to rev. If you need technical proof of the difference, here's a simple equation: LT1 + M22 + 456 posi = WoooHooo!