I always thought that the LS3 and LS7 shared the same physical outside dimensions. I'm looking at a new project and the newest ND MX-5 Miata seem nice. I have an LS7 crate engine today so I spoke to the guys at Flyin' Miata, who normally use the LS3 for their swaps, about using my LS7 and got this answer:

So what about the larger crankshaft diameter? In what way does it affect the physical outside dimensions of the engine?

I could always get the 376/525 LS3 crate as they normally do but I really like my LS7 and would prefer to keep it, it's a rather special motor.

Thanks,

 

They ARE the same physical outside dimensions. The LS7 has a different crank, but that does not affect the major dimensions AFAIK. If you're going dry-sump, then yeah the oil tank might be an issue. Miatas do NOT have much room under the hood.

 

That's what I thought as well until I got that from FM. I have asked them to clarify but have not received an answer for a couple of weeks. I actually just sent them another mail to remind them.

I would prefer to keep the dry sump, I need to see if it's possible to fit a custom tank maybe somewhere above the passenger foot rest. Or else I'll just convert to wet sump and then it's done.

 

All the LS blocks and heads are dimensionally same. Different accessory configurations could change some measurements, but has nothing to do with engine type.

 

The LS7 crank snout is longer, but that's really all that I could tell. There is a conversion kit out that uses the C6 balancer, LS7 bolt, LS3 oil pump and timing cover, and a spacer that goes between the balancer and the balancer bolt to take up the difference in crank snout lengths

 

Thanks, yes I've seen those wet sump conversion kits around, as said I would prefer to keep the dry sump but as I'm not gonna build a track day car it wouldn't be much practical issues going wet.

 

With the dry sump, the LS7 will be slightly shorter in overall height than a wet sump LS3. Basic external dimensions otherwise the same. Go to the link below and scroll down to post #13 for a pretty detailed breakdown on the differences otherwise....

https://www.corvetteforum.com/forums...3-and-ls7.html

 

Thanks, I'll hope that somebody at Flyin' Miata will get back to me and clarify what they said.

 

Im in the middle of swapping an Ls1 out for an LS7. Its been a perfect bolt in affair besides the oil pan (dry sump vs wet sump) and the crank snout length being slightly longer. (which doesnt matter since its still behind the front of the balancer anyway