Which LT-1?

There is a big difference in years of the LT-1. The 70 LT-1 is really the only year that had significant GROSS HP-370 Gross HP. The 71 LT-1 with 9:1 compression was rated at 330 GROSS HP and that same exact motor in 1972 rated at NET HP was 255 NET HP which is almost exactly the same as a 73/74 L-82 with the same compression rated at 250 NET HP.

The only year LT-1 that was comparable to the L-46 is the 1970 11:1 compression LT-1. All the other LT-1's were mostly hype based off of the 1970 motor and are really just L-82's with solid lifters and the same 9:1 compression, smog motors.......Put a true dual 2.5 inch exhaust without a cat on the 73/74/77-80 L-82's and they will make the same power as a 1971 LT-1, about 250 NET HP

 

you must be referring to stats published by motor trend,I have no idea how those clowns came up with their findings .I can only sumise these clowns drove like they were on a street with a state Trooper behind them..

 

absolutely correct, the 350 h.p engine was a better street engine.the LT-1 was better with a steep gear ratio.I put an LT-1 intake on a friends 350 horse motor and the difference was astonishing we put a 750 double pumper on it and it destroyed every LT-1 I ever saw it go against.

 

I think, but won't swear, that the test was on the 1970 models. I'll try to dig up the magazine article...

 

I am going ask my question again because of the above claim and maybe somebody knows. Back in the early 70's, I put an aluminum intake billed as a Z28 on my car along with a Holley double pumper and felt a huge difference. Is the LT-1 aluminum hi-rise the same as the Z28's? Digging up the part # would be somewhat difficult right now.

 

This is not verified, however I did read somewhere that the LT-1 option was scheduled to be release for the Corvette in 1969. It was delayed until 1970 because the Z-28 " Winters" aluminum intakes were all allocated to the Camaro .
One would conclude that the Z-28 & the LT-1 both used the same intake manifold. As you say only the part numbers would verify that.

 

Since we are resurrecting this thread....The Z/28 was growing sales at an exponential rate in the late '60's. They only made about 600 in the first year '67, they made about 7200 in '68 and by 1969 they were producing over 20,000 that year. Arguably, the reason you even have an LT-1 engine at all is because of the Z/28. If you tear apart a 1969 Camaro Z/28 302 and compare the parts to a 1970 LT-1 350, you will find they are nearly identical except for the .48" longer crank stroke and a slightly revised cam spec. The reason the 1970 Z/28 came with a 350 LT-1 engine is because the SCCA racing rules changed in 1970 to allow the Z/28 to de-stroke in order to compete against 302 Mustangs in the 5.0 liter class they were already racing in. With the LT-1 350 being SCCA legal to use against the Mustang, the Chevy production line 302 was no longer needed for anything so it was cancelled and they installed the 350 cube LT-1's for the Z/28 in 1970. The 350 LT-1 just made a better more streetable package when compared to a DZ 302.

They only sold 1287 Corvette LT-1's in 1970. they sold about 7 times as many Camaro LT-1 Z/28's that year.

 

Good info on the history of the 302 and the LT-1. The fact and reality remain that the 1970 LT-1 with 370 GROSS HP with the 11:1 compression is a 1 year only great motor and remarkable that the 71-72 LT-1's with the 9:1 compression and 330 GROSS HP/255 NET HP also carry the fame associated with the 70 LT-1, when those motors are VERY similar to the later L-82's and made about the same Net HP. Also interesting that the 70 LT-1 with 11:1 compression versus the 71 LT-1 with 9:1 compression, 2 points, is worth about 40 Gross HP, everything else being equal.

 

The only difference between the Camaro LT-1 and the Corvette LT-1 is Corvettes used rams horn exhaust manifolds while Camaros used log exhaust manifolds.

 

The LT-1 was not an off the line drag race engine. It was a high rpm road race engine. Not a low end torquer.

 

The 71/72 LT-1, not the 70, is very similar to the L-82's being a mid-high RPM 350 as well. The LT-1's redlined at 6,500 RPM due to the solid lifter cam and the L-82's at 6,000 RPM. Highest torque on the L-82 is also fairly high at 4,000 RPM which is why it is considered a mid to high RPM engine as well just like the 71/72 LT-1's....very similar engines, making very similar power. The flagship 1970 LT-1 with 370 Gross HP secured the LT-1 lure for all time but was not sustained by the later LT-1's as mentioned and documented by the power levels and performance.

 

The part number for both cars was 3972114.

 

Interesting article on a 1970 Lt-1 Corvette versus Porsche..

https://www.motortrend.com/news/1970...1e-comparison/

 

Yup that about sums it up...14.4 sec in 1/4 with 4.11 gears no less and a 3,350 LBS curb weight. Compare that to late 70's L-82 4 speed with 3.70 gears weighting 3,500 lbs that could barely muster 14.9 sec in the 1/4 and you can see the gap really narrow on performance even with the 70 LT-1...the 71/72 LT-1's are pretty much spot on to the L-82 performance which is much maligned in the literature, undeservingly........

 

Thanks Mel - Motor is under my work bench and not easy to get to!

 

I found it interesting to see how well the Corvette stacks up to the Porsche in it's day. The Corvette handled as well, and in some cases better than the Porsche. Interestingly, The braking results were not published, but it appears
the Corvette would do well there as well. So the Vette out-accelerated the Porsche and tied for handling - pretty good I'd say. Only in the case of build quality was the Porsche deemed better...

 

I have no doubt that any C3 and post 65+ C2 would easily outbrake the Porsche. The C3 brakes, EVEN TODAY for the street, with 11.75 (12 Inch) vented rotors front AND rear with 4 piston fixed calipers at each wheel has outstanding brakes when functioning correctly. Add in modern high performance brake pads and SS flex lines instead of rubber at the caliper and the c3 brakes are very good to excellent.....X2 with ultra high performance (W/Y rated) summer only 17/18 inch tires.......

BTW-A late 70's C3 braked from 80-0 MPH in 244 ft. A 78 Porsche 930 Turbo (FAR superior brakes to a 1970 Porsche) which had the shortest brake distance of any car at that time braked from 80-0 MPH in 239 ft..................Difference 5 feet!

 

As long as you're not flying Hornets, I can address your question...

 

L/82 had a slightly different cam then the 350/350 hp. But the way to look at it was a lower hp detuned for power version of the 350hp engine, in the same way the 71/72 LT1 was a lower hp version of the 70 LT1. The L/82 was never as good as the 350/350 hp nor was the 71/72 LT1 as good as a 70, 2 points lost compression killed off both good engines. Then the later L/82 continued the downward spiral with extremely bad exhaust system and the ever growing extra weight the car kept gaining. You put a 3650 lb 1978 L/82 up against a 69 350hp or 1970 Lt1 it will get stomped quickly. I ordered a new 78 L 82 with 2.43 low gear 4 speed and 3.70 rear car was a big joke. My 69 Z/28 also bought new would kick the **** out of it. The new 73 454 LS 4 i ordered new was a real slug to lol.

 

Not so fast..lure again coming in here:

The 78 L-82 close ratio 4 speed with 3.70 gears like my C3 owned for 33 years now was/is actually very quick 0-60 MPH with 3,500 lbs and well documented: 6.5 seconds bone stock with the 4 speed and 6.6 seconds in 79 with L-82 with the automatic. Source Road and Track...you can look it up.


The car magazines at the time list 0-60 MPH at 5.8 seconds for the 70 LT-1 (about 295 Net HP). The 69 L-46 350/350 GROSS HP (about 275 NET HP) WITH 4.11 gears with are useless except for drag racing was 6.0 seconds.....see where this going.........?????

The mighty 70 454 LS5 can only muster 0-60 MPH of 5.3 seconds in the literature on this same car.

Take the 2-1-2 catted exhaust off the L-82 (250-260 NET HP) which I did 25 years ago and put on a 2.5 inch duals with performance timing and my 78 L-82 4 speed has a 0-60 time of low 6 seconds......NOT a 70 LT-1/69 L-46 but a lot closer than you would think to the 5.8/6.0 second times, MUCH closer.

Numbers don't lie and really focus on the true performance rather than our memories. The actual 30-40 NET HP differences is why those numbers are as close as they are in reality, the GROSS versus NET HP distorts the performance which is why you should always correct the record with crate engines and pre 1972 production engines (GROSS HP)...this ^^^^ is a great example why.

The problem with all these 350 V8 motors at the time is the Torque figures which all produce highest torque at 4,000+ RPM which is extremely high RPM in today's world..all of the LT-1's and the L-82's. Modern V6 and 4 cylinders can stomp an L46 350 and 70 LT-1 like my 2012 IS350 F Sport with 306 V6 NET HP and BIG torque at low RPM's with a 6 speed auto. The torque comes on hard right off idle and does not have to wait until 4,000 RPMs.