LT4 The C5 LS1 outran the C4 LT4 in every way ...

[Roadster Guy]

Just flipping through my new July issue of Corvette Magazine and in an interesting article discussing torque and horsepower, there are two pictures on page 55 showing the LS1 and LT4 engines side by side. The caption above the pictures reads:

"One-year only 96 LT4 sent the iron-block V8 out with 330 exotic horses; still, the all-alloy LS1 that followed outran it in every way."

I only post this because it seems to me that LT4 owners and many C4 owners are aware that the LT4 was under rated purposely by GM so that it would not over shadow the 97 C5 LS1 release. In fact as we know, most LT4's will run with the early LS1's as LT4 horsepower was closer to 350 rather that the stated 330 hp. Some LT4's will in fact outrun the LS1 when both are in stock form as LT4 horsepower did vary from engine to engine. Torque was also higher than the 340 stated.

Though you do see the LT4's engine understated performance discussed on Corvette web sites (especially this one) they do not seem to acknowledge that fact in the magazines and they appear to stick to the GM specs of 330 hp and 340 torque. I like Corvette Magazine, but it is a shame to see in a specialty Corvette mag a statement like "the all-alloy LS1 that followed outran it in every way".

By the way, this is not a poke at the LS1 which is a great engine with many advances, just a comment on the print media's apparent lack of awareness when it comes to the LT4 sometimes.

Anyway, that's all I really have to say on this. It's nothing new and it is not a big deal. Just thought I would throw it out there.............maybe I should have dropped this into the C5 forum ...or maybe not. Perhaps, in the future, as in the past, it's better the LT4 remains a little bit stealth.
RG
p.s...I figured that title would get your attention!

 

[LT4man]

I agree with you in every way. I have owned an LT4 since March 1996. I have had a lot of experience with them. Of course, GM will not admit that the LT4 was as fast as the ZR1 OR the LS1. And these magazines will not report the truth. They don't want GM ****** off at them! :L

What I think is more amazing....the fact that GM will consistently underate all of their engines. You do not see F*** of D**** doing that!

Save The Wave!

 

[Roadster Guy]

Ain't that the truth!

 

[dmd]

The thing you guys are missing is that the GM tradition of conservative ratings didn't change with the end of GenII -- the LS1 was also underrated. I had an early-production '98 6-speed Z51 that dynoed 314hp corrected at the wheels. Uncorrected it was 332hp.

I'm not bashing LT4's though. I currently own both LT4 and LS1, and there's no question the LT4 makes more low-end torque than the LS1 does.

Cheers,
Dave
polo '96 LT4 roadster, 6-speed/F45
navy '01 LS1 roadster, 6-speed/Z51
www.davescorvette.com

 

[Roadster Guy]

That's interesting dms. I did not know that about the LS1 also being under rated. I knew GM has done it with many engines previously....especially some of the big blocks. And that is what got to me about the Corvette Magazine comment...."the LS1 outran the LT4 in every way". Just seemed like an incorrect general statement to make and that a Vette magazine should know better than that. As you said, the LT4 had more low end torque. And the LS1 is really a nice smooth powerful engine. No question about it as I have driven a couple and no complaints here.
RG

 

[Aurora40]

One would expect that as they progress, the engines will just get better an better. Of course the LS1 improved a lot. It was all-aluminum, thus much lighter, and it eschewed the typical bore/stroke of a 350 for one much closer to the bore/stroke of the LT5. And the LS1 got more powerful as the years went on, gaining a few hp and a lot of torque, not to mention growing into the LS6.

I would hope Corvette motors continue to get better and better, not worse and worse, but that's no reason not to give props to a motor that was great in its time. The LT4 is pretty sweet. The fact that it's a classic smallblock in proportion and construction, yet revs to 6,800 rpm is really impressive. It sounds like the author's mistake was not in giving praise to a deserving LS1, but in not giving appropriate props to the LT4 while doing it.

 

[Roadster Guy]

Well said Aurora40. I agree with everything you said and definately the last sentence. And certainly we all want Corvettes to continue improving and evolving year by year. The survival of the brand really depends on it.
By the way, nice Vette you've got there....I am a big fan of the ZR-1. Enjoy.
RG

 

[Ominous C5]

I own cars with all of these motors. I am continuously surprised, however, with the low-to-mid range torque of the LT4. It is a fun engine.

 

[bluecoupe]

The C4 was a quantum leap in technology and performance over C1, C2 and C3 (looks and coolness aside). C5 is just a small improvement over C4 and C6 a small improvement over C5 but all of these later Corvettes are still only at arms length from each other in most categories. The C4 is a hard act to follow. GM has to stretch the truth a bit to make people want to trade up or switch over. Corvette magazines also have a stake in increasing the Corvette population.



Believe none of what you hear and half of what you see...



Frank (bluecoupe)

 

[dmd]

Couldn't disagree with you more, Frank. Power-wise, it hasn't been that big of a difference. But C5 was indeed a tremendous leap over C4, in terms of its underlying architecture. Its structure was so revolutionary that, according to Dave McLellan, Porsche and Mercedes both called back in '97 to congratulate the Corvette team on solving the problem that everyone had been trying to figure out - how to increase the strength of a roofless car's chassis without adding mass. The solution is elegant, brilliant, ingenious. It produced a huge increase in leg and footwell room, a chassis so stiff that even the convertible could be offered with Z51, a usable trunk, and no weight penalty for structural reinforcements. If you're only looking at C4 vs C5 in terms of their engines, you're missing the brilliance of C5 entirely.

C6 is an evolutionary improvement over C5, but the rebirth of the 427 will change everything.
Dave

 

[Roadster Guy]

Maybe the big jump was C5 over C4 not LS1 over LT4

It is nice to see that apparently most LT4 owners are very pleased with and enjoy the performance of this engine. You hear positives about the low to mid range torque quite frequently and that it is a sweet and fun engine.

I would agree that engine progression from the C4 through the C5 and C6 has been steady and measured and that the configuration and structural improvements that arrived with the C5 were a large leap over the C4. That being said the C4 was equally a huge advance over the C3 in many areas.

Maybe because the LT4 was a one off engine for 96 it will remain a little special and perhaps add slightly more value than say a LS1 would in the long run. The LS1 is more advanced than the LT4, but there are almost 200,000 out there and only about 5000 of the LT4's (from memory, don't have my black book with me) kicking around. In the older Vettes when there were different engines around some of the more desirable ones definately add extra value now ( LT1, 427, 327 fuel injected etc.) Ah, but all that is for another thread though isn't it........sorry guys, got meandering....
RG

 

[bluecoupe]

Couldn't disagree with you more, Frank. Power-wise, it hasn't been that big of a difference. But C5 was indeed a tremendous leap over C4, in terms of its underlying architecture. Its structure was so revolutionary that, according to Dave McLellan, Porsche and Mercedes both called back in '97 to congratulate the Corvette team on solving the problem that everyone had been trying to figure out - how to increase the strength of a roofless car's chassis without adding mass. The solution is elegant, brilliant, ingenious. It produced a huge increase in leg and footwell room, a chassis so stiff that even the convertible could be offered with Z51, a usable trunk, and no weight penalty for structural reinforcements. If you're only looking at C4 vs C5 in terms of their engines, you're missing the brilliance of C5 entirely.

C6 is an evolutionary improvement over C5, but the rebirth of the 427 will change everything.
Dave

I used to believe the C5 was a giant step up from the C4 and maybe on paper or in the lab it is but one visit to an autocross event changed my mind. Maybe a C4 creeks and groans. Maybe it doesn't hold enough golf bags. None of that really impacts the overall sports car performance. When you look at the numbers for the LT4 vs An LS1 Corvette the differences in power or handling can be measured in tenths. Definetly too close to call.

 

[6 Shooter]

The LS1 is more advanced than the LT4, but there are almost 200,000 out there and only about 5000 of the LT4's (from memory, don't have my black book with me) kicking around.

Just to be exact, 6,359 LT4 equipped Corvette's were built.

Having owned both, the LT4 & LS1 are Great Engines & Corvettes!

Later . . . . . .
6 Shooter

 

[warren s]

Spend a day at the track during a Corvette event, like the Corvette Challenge series and you can see for yourself how an LT4 stacks up against an LS1. Considering things like gear ratios and car weight being close, I have seen stock LT4s run in the very low 13s. Most LS1 C5s run there too.

Even though there are usually dozens of C5s ant every event maybe there will be 3 LT4s.

After having a C4 and C5, there is no doubt the C5 beats it in some important ways, but thats a story for another thread.

 

[Gorgon]

I used to believe the C5 was a giant step up from the C4 and maybe on paper or in the lab it is but one visit to an autocross event changed my mind. Maybe a C4 creeks and groans. Maybe it doesn't hold enough golf bags. None of that really impacts the overall sports car performance. When you look at the numbers for the LT4 vs An LS1 Corvette the differences in power or handling can be measured in tenths. Definetly too close to call.

I'm inclined to agree with dms, the C5 is a revolutionary change due to it's structure. As he currently owns both a C4 and a C5 in vert form I'm sure he can appreciate the stiffness of the C5 frame versus the C4. My C4 in vert form is a horrible performer compared to my C5. I'm not saying the C4 can't perform but the C5 is a lot more confident on the road.

But this is about the LT4 and LS1.

Leon

 

[Edmond]

I can't wait to get my LT4. I already have mods in mind to make it run faster. Right now, it's just a matter of selling the '88 and the '83 Z28 to fund the LT4.

 

[wx briefer]

I love my LT4. She now has 343hp/334torque to the rear, which is what my stock Z06 had when stock. I simply added HOT cam, long tube headers, random cats, corsa and an SLP 3 filter intake. It is very well behaved in town. The LT4 has a different feel from that of the LS6. I like both equally well and my driving is divided equally between the two.

 

[DRTH VTR]

My own observations at the drag strip would say that the LT4 is at least a match for the LS1 in power output. The few that I raced in my '97 (before I sold it) beat me by a couple of tenths. I don't suck at the strip, either. They did not beat a beginner.

 

[tlong]

My mechanic friend at Tom Jumper Chevy made an interesting comment that really sized up the difference: cylinder firing order.


The LS 1 is smoother. The LTx is old-school torque rough and rowdy.

 

[Roadster Guy]

My mechanic friend at Tom Jumper Chevy made an interesting comment that really sized up the difference: cylinder firing order.


The LS 1 is smoother. The LTx is old-school torque rough and rowdy.

Ok, now you've made me curious tlong and someone out there knows this.....what are the two different firing orders for the LS1 and LT4? And I wonder if they were different simply to make the LS1 smoother or becaue of other considerations?
RG