I'm sure this has been discussed in the past here, but not sure as a straight comparison. At the NCRS events I have been to it seemed like the big block owners walked a little taller (haha). But so do the LT1 owners.

Which is better? LS5 454 power or the LT1? Does it depend on which year of each? Let's here your opinions.

 

Having owned neither type of engines, can only go on what has been written.
The LT1 was the highest small block HP and torque engine of that era, and most would agree that it handles better than a big block because it is lighter.
For shear gut wrenching torque, don’t think anyone would argue that a LS5…or any big block for that matter… can’t be beat.

 

i have owned both and yes, for sure, it does depend on the yr of the engine (assuming no machine shop rework). while GM was fighting with the EPA regarding their CAFE numbers beginning in the late 60's early 70's, the engines started to become self imposed strangled items. according to the Corvette Black Book, for instance, in 1966 the 427 engine (thought by at least 1 "motor" publication to be the best engine ever built by GM) it had a stated hp rating of 425hp while the 327 max h. p was rated at 350. in 1967 the 327 remained the same. but the 427 was rated at 435hp max. it remained the same in 68 and 69 for the 427, but the 350 ci was introduced with a max of 350hp. 1970 saw the introduction of the 454 with max hp at 390 thanks to pollution restriction increases. 1971 the hp of the 454 was stated sat 425 while the base 350ci engine started at 270 stated hp and a max h.p. in the LT1 AND the ZR1 models only of 330hp. with EPA restriction in creasing in 1972 yr production max 350ci hp was 255 and the 454ci engine was 270 and the serious stated hp decline was on. the 1973 454 actually got a bump up to 275 hp while the max stated hp of the 350 ci dropped to 250. 1973 hp for the 454ci was 270hp with the 350ci max at 250hp. the 454 engine was not available in the corvette beginning 1975 and the 1975 350ci was rated from the factory at 205hp max. horsepower continued to fall hitting a low point in 1978 with only the 350ci offered and a max stated in the L82 engine of 220, before a slight increase of the hp in 1979 at 225 at 225 and 195 respectively. the 1980 was similar and the 81 was only offered at 190 max hp for a 350ci block. interesting ly enough i remember hearing (unsubstantiated by me) that the EPM was really crunching down on the auto manufacturers in the later 70 and early 80's regarding the CAFE (corporate average fuel economy) and that GM had actually seriously considered eliminating the Corvette from their line up to meet their number. with the exception of 1982 however corvette production has existed for public purchase every year.

 

I'm not disputing the decline in horsepower ratings over time, but you have skipped over the fact that from 1970 to 1972 the method to measure power output changed. Up until 1971 the output was stated as "gross" power; from 1971 and onward the output was stated as "net" power. 1971 is in both camps because that's the transition year that GM provided both measures.

You can't compare the 1970's LS5's 390 hp to the 1972's LS5's 270 hp as equivalent measures to show a 120 horsepower drop. The 1970 net rating was likely ~305 hp and conversely the 1972 gross rating was likely ~345 hp; 1973's net 275hp was likely ~352 gross hp.

 

I have and still own both, a 1970 390hp coupe and a 1970 370hp LT-1.
when both were pure stock the 454 with 3.08's would out perform the LT-1 with 3.70's in a quarter mile, but just slightly. The LT-1 is a high rpm engine and is severely choked with those stock exhaust manifolds. Put some headers on the LT-1 and it's a different story. 390 hp 454 starts crap out around 5500 rpm. LT-1 just getting started.
Bullshark

 

GM went from a gross to net horse power rating system between 71 and 72. Even though the advertised ratings dropped significantly in 72, the engines themselves were all nearly identical those used in 1971. The net ratings were supposed to be more accurate real world numbers than the previous gross ratings.

The 1971 Chevrolet ratings dropped in comparison to the 1970 numbers because GM lower the compression ratio of all their engines for 1971, in anticipation of the introduction of catalytic converters and lead free gas coming in 74-75. Leaded gas can't be used with catalytic converters because it fouls the converter, and when lead free gas was first introduced it was only available as a lower octane regular grade fuel. The lack of mid and premium grade lead free fuels in the 70's necessitated the lower compression ratios. So unlike 1972 when the ratings changed significantly, but the actual engines didn't, there was a real change made between 70 and 71 that did cause the ratings to be lowered.

Performance wise a same year LT1 and LS5 were pretty close to each other, it's just that they achieved the results differently. The LS5 was a torquey but somewhat mild engine while the LT1 was a high revving, beast that loved to scream but could also be a bit finicky (with solid lifters and all that).

 

I have/had both engines in a C3. 68 350 hp 327 and a 70 BB 454 LS5. I really don't know which is quicker accelerating. I think it might have been the 68 350/327. It has a 3.73 differential, compared to the 70 3/08:1. The 68 is much much lighter. The AiM shipping weight for the vert is 3050 pounds if I remember correctly. The LS5 is...my opinion....a cast iron pig. It weighs about 650 pounds. 650 pounds is too much weight for the front end of a smallish C3. And then add weight for the AC.

I've modernized both cars. The 68 now has a ZZ4 SB engine and a Tremac 5 speed. My 70 now has an all aluminum BB, vintage air in lieu of the factory AC, and a Tremac 5 speed with a 3.73 differential. I think the 70 will be faster....630 hp at 7000 rpm.

 

The LT-1 is also a better curvy road car. The LS-5's extra front end weight makes it push into corners with understeer.

 

Thought the topic was engines. No curves at the dragstrip..... at least not intentionally! 😁
I agree though, LT-1 handled better. That is until I installed Ridetech suspension,....and a 540 all aluminum BB with 750hp. LT-1 has to stay stock. Even if I'm not a NCRS guy.
Bullshark

 

Do you want to impress folks who go to NCRS events, or do you want to enjoy driving your car? I'd vote for LT1 for the later, especially a Gen V LT1.

I s'pose you could do both, but from these photos, it looks like NCRS forgot to fill the stands with an AI-generated audience. So I'd focus on what you enjoy the most.

https://www.corvetteforum.com/forums...ton-posts.html

 

I'm not so sure I agree.

Because the engine in a Corvette is mounted behind the front cross member, even the heavier big block cars usually had a near perfect 51/49 weight balance, and the higher rate springs, larger front sway bar and added rear bar included with big blocks, more than compensated for any handling difference between the 2 engines.

Road & Track road tests from the 60's and 70's showed a 65 396/425 4 speed convertible with power brakes but not steering at 3570 pounds and a 51/49 front to rear balance, and a similar 67 327/300 convertible with 4 speed, PB and not PS at 3540 and 49/51. Most 68-74's have a similar weight balance. Where the 70-72 LS5 cars differed was usually in the amount of optional equipment. Most 70-72 (and 73-74) big blocks often tended to be loaded with things like air conditioning, power steering, power brakes, power windows, etc, which all add weight and effect the weight balance.

If you're talking about a Chevelle or Camaro, then dropping the extra 100 pounds of a big block over the front crossmember makes an already nose heavy car even more nose heavy, but that's not the case with the Corvette. And there's nothing wrong with understeer either. Understeer is much safer for the average driver and easier for them to anticipate and control. Oversteer, where the rear of the car wants to come around, is a more dangerous situation for most drivers to deal with which is why most cars are designed to lean toward an understeer condition.

 

I agree as to the fact that where the Corvette is carrying the extra weight, that of the "big-block" vs. the "small-block" (and this difference can be reduced greatly with just the utilization of a set of aluminum cylinder heads; this even as provided for by GM) isn't going to change the handling as dramatically as might another chassis produce; and an added benefit of the big-block is the greater ease with which the understeer issue can be reversed into oversteer with the simple addition of more throttle!

Scott.

 

Thank you! I'm A-OK with being taught about these sorts of details. I've heard/read that about BBs and assumed it was true - and having BBs, they feel heavy but I've not driven a SB C2 or C3 in 40 years to compare with.

 

Anyone that thinks a 454 with 308 gears will be faster in a 1/4 mi against a LT-1 with a 3:70 is dreaming.
..

 

The old saying goes" there is no substitution for cubic inches" While a small block LT1 is a desirable vette and the big block vette seems a have a much wider audience.

 

I do dream occasionally, but mostly it's related to a nice *** and big tata's 😁
Tell me, what do you base your statement on? What do you think a completely 100% stock 1970 LT-1 turns in a quarter mile? Vs a stock 1970 BB 390hp. Like I said, I own both and have raced them on the strip multiple times wheel to wheel. Toss those small port stock exhaust manifolds and then, I agree. 👍

 

70 to 71 LT1s had a 2 point compression change so theres that for the HP difference as well as the Net vs Gross. The weight of a 68 verte is 3500 at least, with my fat *** in mine it was 3700 at teh track so theres that. Handling wise for a big block and a small block its about 200 to 250lbs total difference and if you change the intake and the water pump from cast to aluminum including and especially the heads then the weight of a big block is pretty close to the small block and once the springs correct for the weight you dont really feel a difference. I know I dont.

So if you are looking for just comparisons for comparisons sake the LT1 was a cool engine back in the 70s and 80s. We all loved that the small block was bad *** but it still has no torque compared to a big block. And once you see a big block stuffed into a vette and hear that nice rumble, theres no other choice......

 

Again 3:08 verses 3;70 in a 1/4 mile makes a big difference & yes I have had a few 70 454;S and a few 70 LT-1'S. most 454;S were 3;08 & the LT-1'S were either 3;70 or 4;11

 

Define what you mean by "which is better". Are you talking in a qtr mile?, are you talking overall driving experience? Both examples most likely will yield different answers. In 1970, Car & Driver (or Motor Trend, can't remember which) did a direct comparison between an LT-1 and the Porsche 911. They concluded that the LT-1 was the perfect balance of power and weight providing handling and performance capabilities that was the closest rival to the 911 by an American car company. Those handling characteristics go right out the window when you drop a big block in there. In '71, one of those publications did a shoot out between an LT-1, an LS-5 454, and a base model small block. Again the results were predictable, the LT-1 was a great all-round performer, the LS-6 was a monster of torque designed to go straight fast, and the base small block was a great handling car w/out the power of the others.

As for which year is the best for performance, hands down 1970. The LT-1 was a 370hp small block that was said to be underrated. What's not to love about that.The big blocks also had the most HP that particular year.

 

Good thing they never road raced those horrendous L88 cars...God a big block would have sucked on the track and in Le Mans!!

https://rmsothebys.com/auctions/mo15...dnart-le-mans/