LT1 or LSX?

[Ken_]

Hey guys. A question that has recently arisen in my mind is with regards to the LT1 of the early 90's and why a lot of guys have ditched the LT1 for the LSX series over the years. I've read that the LT1 was/is quite capable and was innovative for its time. Other than the 4-bolts versus 6-bolts main caps and the LT1 running out of breath in the high RPM band and a few other things, why would anyone want to swap out an LT1 for an LSX series engine? Back in the day I would race against 4th Gens in my EVO VIII and a few guys said the LSX series were stronger engines. Whether or not it is true is beyond me. All I wanted to do is race.

[demonspeed]

LS engines have a better ignition system first and foremost (just google "optispark"). Second, LS blocks are lighter (aluminum; not counting truck) vs. the GenII which only had aluminum heads. Third, LS heads are even more advanced than those of the GenII. It's also a lot easier to plug into the computer and tweak away (LT1 was not OBDII it's first four years). Combine these attributes together and one has a significantly better platform to work with. The aftermarket has embraced the LS series significantly more, too (this may also be due to the fact that the GenII only lasted from 92-97, whereas GenIII began in 97).

This is not to say the LT1 vehicles are junk. There are many people still running those engines, and there is even a race series for them.

I'm sure someone who has more LT1 experience than I could extrapolate further, but this is the nitty-gritty of it.

I'm curious as to which direction we'll see the LS go with the advent of the GenV LT series...

[Zabo]

All I can add to it is that the LS series were just easier to work on and easier to get major power gains per dollar spent.

The heads were also a special reverse cooling design (heads cooled before the block leading to higher compression ratios vs Gen I 350s) which meant that what today is a simple head and cam swap meant that you had to take into consideration how the heads were milled and modified.

The only real saving grace of the LT1 IMO was the fact that it always would have more low end grunt due to the torque band peaking earlier on a pull over the LSx. The LT4s were a more potent version of the LTx found in Corvettes but if you really want to see an oddball V8.. there was the LT5.

For model year 1990, Chevrolet released the Corvette ZR-1 with the radical overhead cam LT5 engine, which shared only the 4.4 inch bore spacing with any previous LT engine. The LT5 was engineered by Lotus Engineering in the UK headed by design manager David Whitehead, the engine was produced by Mercury Marine at Stillwater OK headed by Project Engineer Terry D. Stinson.

It was an all-aluminum 5.7 L (349 cu in) small-block V8, but was thoroughly different from any of the other Chevrolet 350 engines. The bore and stroke were both different at 3.9 by 3.66 in (99 by 93 mm) instead of the usual 4 by 3.48 in (102 by 88 mm) and it featured Lotus-designed 32-valve DOHC heads rather than the usual Chevrolet 16-Valve OHV Heads. It was hand built by specialty engine builder, Mercury Marine in Stillwater, OK. This engine produced 375 horsepower (280 kW) and 370 lb·ft (502 N·m) for the 1990-1992 Corvette ZR-1 and jumped to 405 horsepower (302 kW) and 385 lb·ft (522 N·m) for 1993 to its final year in 1995, thanks to cam timing changes and improvements to the engine porting. 1993 also added 4-bolt main bearing caps and an exhaust gas recirculation system. The engine was used only in Corvettes.

The LT5 was very expensive, and after six years of production, GM canceled the ZR-1 option. A total of 6939 were produced. The LT5 however wasn't an evolutionary dead end. Despite being discontinued, a new class of premium V8s for Cadillac and eventually Oldsmobile, the dual overhead cam V8 Northstar and its derivatives, drew heavily from the LT5's design and lessons learned from its production.

The LT5 does not have reverse cooling.

The lasting legacy of the LT5 though.. ever wonder why Northstars go through headgaskets like a fat kid goes through a bag of chips?

[demonspeed]

Originally Posted by Zabo

The only real saving grace of the LT1 IMO was the fact that it always would have more low end grunt due to the torque band peaking earlier on a pull over the LSx

This is a common misconception. The LS1 makes more power over the LT1 at every rpm -- even at the LT1's peak.

edit: I've been trying to find a dynograph but I am not having luck. I've seen them many, many years ago, so I can understand if one remains skeptical of my claim until I can prove it

[NemeSS]

Sold my 383 lt4 gtp ported lt4 heads 95 z28 back in 00 for a ls1 m6 z28. Have never looked back

[zebra]

Originally Posted by Zabo

...
The lasting legacy of the LT5 though.. ever wonder why Northstars go through headgaskets like a fat kid goes through a bag of chips?

meh... i don't think the LT5 really counts. DOHC, metric displacement, built by Lotus & Mercury. friggin sweet engine, though

[Ken_]

Originally Posted by demonspeed

I'm curious as to which direction we'll see the LS go with the advent of the GenV LT series...

This is what I am afraid of... I just got my SS and now everybody is talking about the LT1 and LF3. So will we be seeing the industry dumping LSX engines to embrace the newer engines, as well as "man, you need to swap that LS3 out for an LT1". I'd really hate that because I am just learning the LS3 and love that it has so much support, in fact all the LSXs have a great supporting base.

[demonspeed]

Originally Posted by zebra

meh... i don't think the LT5 really counts. DOHC, metric displacement, built by Lotus & Mercury. friggin sweet engine, though

Agree. That thing is out on an island all by itself.

[demonspeed]

Originally Posted by Ken_

This is what I am afraid of... I just got my SS and now everybody is talking about the LT1 and LF3. So will we be seeing the industry dumping LSX engines to embrace the newer engines, as well as "man, you need to swap that LS3 out for an LT1". I'd really hate that because I am just learning the LS3 and love that it has so much support, in fact all the LSXs have a great supporting base.

I'd surmise things won't necessarily "go away." While Ford's OHV 5.0 was last seen in a Mustang in '95, it's still hugely popular -- and SUPER affordable. I'd surmise the GenIII/IV will still have huge support yet become even more affordable and the GenV takes root. Even so, it's bittersweet turning the page.

[Ken_]

Originally Posted by demonspeed

I'd surmise things won't necessarily "go away." While Ford's OHV 5.0 was last seen in a Mustang in '95, it's still hugely popular -- and SUPER affordable. I'd surmise the GenIII/IV will still have huge support yet become even more affordable and the GenV takes root. Even so, it's bittersweet turning the page.

I just hope so, and yeah it's bittersweet just when it is all new to me. It's like starting in on a series and someone says,"Man! You are just now seeing that? That was like 5 years ago!" Anyway, it's all good. I don't see myself jumping on a 6th Gen when and if it comes along.

[Cam02ss]

Optispark FAIL, the LS platform is superior to the LT1 in every category

[OVRKILL]

^^^ yep. boat anchor.

[Bhobbs]

Originally Posted by Ken_

This is what I am afraid of... I just got my SS and now everybody is talking about the LT1 and LF3. So will we be seeing the industry dumping LSX engines to embrace the newer engines, as well as "man, you need to swap that LS3 out for an LT1". I'd really hate that because I am just learning the LS3 and love that it has so much support, in fact all the LSXs have a great supporting base.

I highly doubt the aftermarket will abandon the LS series overnight. The LS series is so prevalent that there is still plenty of money to be made building parts for them. Even when the new LT series debuts, there will be a long waiting time before people start making aftermarket parts for it.

The Gen I small block has been dead for a long time yet you there are plenty of parts made for it. With all the cars powered by the LS, it's not going away out side of OEM stuff.

[PHXLT1]

Wow why the hate of the LT1? While it is true the LS engine is a step up from the LT1 engine just like the SN95 stang they still have a huge following. The LT is no slouch and there are some serious racers still using this platform. And although the opti is not the best idea gm came up with. There have been plenty of optis that have gone 100k. I owned my car for 7 years before I changed it. I've owned my car for 12 years now and have no plans on letting it go. I love the LT. Any car can be fast with enough money and knowledge. Heck there are even fast 4bangers now. Just my 2cents.