LT5 Engine

[enkeivette]

Tell us uncle Glenn, wtf was up with this engine? GM decided to do a DOHC for the Corvette in the 90s and... what the hell happened to it?

Can these things even be modded? Is the bottom end SBC based? It looks like they're more expensive than LS engines on E-Bay.

http://www.streetfire.net/video/corvette-zr1-with-427-lt5engine-just-idling_80032.htm

[94cobra69ss396]

Tell us uncle Glenn, wtf was up with this engine? GM decided to do a DOHC for the Corvette in the 90s and... what the hell happened to it?

Can these things even be modded? Is the bottom end SBC based? It looks like they're more expensive than LS engines on E-Bay.

http://www.streetfire.net/video/corvette-zr1-with-427-lt5engine-just-idling_80032.htm

I remember reading about this my senior year of highschool in 1989. The LT5 came in the ZR1 Corvette which was made from '90-'95. The LT5 has nothing in common with previous SBC engines. My buddies dad had a '95 about 5 years ago but sold it. I'm sure you can add power to them but not sure what's availble to do so.

[kdracer73]

Here is a exploded view of the LT5.


http://www.zr1netregistry.com/ZR1_engine_blowup.htm

It was built and designed by Mercury Marine I believe.

Most of the design lessons led to the Northstar motor development.

[Vettezuki]

Here is a exploded view of the LT5.


http://www.zr1netregistry.com/ZR1_engine_blowup.htm

It was built and designed by Mercury Marine I believe.

Most of the design lessons led to the Northstar motor development.

It was built by Mercury, but designed by Lotus. Yes, that Lotus. I've heard of modded ones running deep into the 500WHP NA, but I don't recall what was done to them or how. As I recall, (and this is way off memory), the dimensions of the block are still SBC. That was the restriction that was given to Lotus, so *probably* there are some easy interchanges for internals.

It was always expensive and if you had trouble with it, the dealer couldn't even deal with it, had to go back to Mercury.

[jedhead]

The bore centers are the same as SBC. The bores are smaller because of the aluminum liners. So the store was increased to keep the 5.7L displacement

http://www.zr1netregistry.com/LT5tech.htm

Bob

[enkeivette]

So basically it's a Gen 1 Northstar, longer stroke smaller bore than a SBC and stay away from it?

[Vettezuki]

So basically it's a Gen 1 Northstar, longer stroke smaller bore than a SBC and stay away from it?

It's certainly going to cost more to make more power out of. But if you're looking for something a little more exotic, smoother and higher-revving, it's pretty slick.

[Vettezuki]

So basically it's a Gen 1 Northstar, longer stroke smaller bore than a SBC and stay away from it?

Didn't realize the LT1/4 was a 4" bore.

LT5 3.9x3.66
LS1/6 3.90x3.62
LT1/4 4x3.48

[BADDASSC6]

LT5 was where ligenfelter(misspelled) made his mark he had NA versions that were in the mid600s. He use to rock the magazine top speed runs in them. good motors, but expensive and rare. They went away because with improved modeling programs GM can reach the it's target power goals with OHV engines that are significantly cheaper to produce. It also makes it easier for aftermarket manufactures to design replacement heads.

[enkeivette]

Didn't realize the LT1/4 was a 4" bore.

LT5 3.9x3.66
LS1/6 3.90x3.62
LT1/4 4x3.48

Pretty sure all SBC excluding yours and the 400s were a 4.0. Typical first oversize is 4.03 (mine) second 4.06

[big_G]

No one mentioned that there is NO room in the bay to work on it. One guess where the put the starter motor?...In the galley beneath the intake manifold! I've changed a few. How about the fact that the engine weighs bore than a BBC with cast iron heads...Great in its time...but an engine that complex better make north of 600 hp. to justify itself.

[94cobra69ss396]

Pretty sure all SBC excluding yours and the 400s were a 4.0. Typical first oversize is 4.03 (mine) second 4.06

Nope. The 265 (3.75), 283 (3.875), 305 (3.736) and 307 (3.875) all had smaller bores.

[enkeivette]

Didn't even know the 265 and 307 were Chevy engines. I totally forgot about the 283. Did all of the 305s have smaller bores? I always thought the late 305 C3s were just shorter stroke motors.

[Sonic03SVT]

Ive seen a few examples of some street driven 400+ c.i. stroker LT5s with some head work and such...600ish hp is not unreasonable, but would certainly be cheaper with an LS motor or even an LT1/4 based engine. Fun stuff, but ultimately a niche motor.