GM LT Engine

[csharg]

I have searched the forums but can't seem to find the answer to my question.. is the architecture of the LT series engines significantly different from the LS series such that it will not easily fit in the GTM? They are making crate LT4s now and that would be a pretty sweet power plant for this car.

[GoDadGo]

The LT1 and LT4 engine share similar architecture to the good old small block chevy. The LT4 was an option on the C-4 Corvette in the 1996 model year only and has larger intake valves, 1.6 rocker arms and larger port heads and intake. Again, it is very similar in size the the standard SBC, but is reverse flow cooling and has a gear driven water pump and the distributor is on the front of the engine. It has no parts that interchange with the LS platform. I have no idea how easy or hard it would be to install in a GTM because that car is way over my head. Sorry I can't help you, but I am a fan of the LT1 & LT4 engines.

Also, the LT1 / LT4 platform share the same engine mount locations as the Small and Big Block Chevy's. The transmission bolt pattern is also the same as the SBC and BBC platforms.

[carbon fiber]

I have searched the forums but can't seem to find the answer to my question.. is the architecture of the LT series engines significantly different from the LS series such that it will not easily fit in the GTM? They are making crate LT4s now and that would be a pretty sweet power plant for this car.

You have to reverse the intake to fit in a GTM, the LT4 is supercharged so that's a no-go. You could probably fit the new LT1 in if you can reverse the intake. I haven't checked these new v8s out closely so I don't know if the motor mounts/engine dimensions/etc. would work or not. The problem to me is the cost vs the readily available and cheap by comparison ls engines. Also it's not hard tp get 550hp out of a naturally aspirated ls engine and that's about all you need in a 2500lb car. Plus the cost/weight/complexity of upgaded trans/axles/cv's/etc. isn't worth it in my opinion because you can't get it to the ground. Example: FFR's GTM with 500hp ls7 does 11 flat in the 1/4 mile (on street tires) There's an 1100hp build that did 10.5 on drag radials spinning the entire way. Over double the hp for .5 seconds faster 1/4 mile run. Don't get me wrong, if you're ghoing to run 1/2 mile or mile events it may be worth it, but other than that it's wasted money imho.

[GoDadGo]

The LS motor mounts are several inches further back than on the LT1/LT4 or any other SBC or BBC engine.

I'm just about ready to reinstall my SBC into my MK-4 and a lot of work had to be done to make it happen. Trying to put the same engine in a GTM will likely require more than a fair amount of fabrication. Regarding the comment about reversing the intake manifold, I never tried it though it may be possible.

LS motors are plentiful both new and used. I think you are really setting yourself up for a ton of work going off plan to pursue the LT1/LT4 power plant of which I am a huge fan.

For the record, my build has been delayed because I'm using an engine not designed to fit in my MK-4. When you compare the MK-4 to the GTM from a fabrication standpoint, it is my untrained opinion that the money you save by going this route will quickly be eaten up by fabrication work and other modifications.

Good Luck & Hope Your Build Goes Well!

[carbon fiber]

Godadgo, he means the 2014 up LT1 & LT4, the direct injection/LS replacement engines. It looks like the intake may not be reversible and the accesories seem to be mounted where they wouldn't work with the GTM. Like I said, it's hard to beat the LS stuff at this point... At 16k for the LT4 crate engine you could buy a new LS3 and a sweet transaxle.

[csharg]

Thanks for the info and opinions. I know the new LT engines are generally more expensive, I was just curious if it would take a lot of extra fab work to make it fit. Looks like the best option is to build up an LS to get a little more power.

[GoDadGo]

I'm Old & Drive A 1995 Vette So I Need To Brush Up On Motors! Thanks-O-Million! But then again I'm the dude stuffing a SBC with a ZF-6-Speed in my MK-4! Take Care All! Have A Green Beer For Me!

[OCCPete]

The high pressure fuel injector pump on the LT1 is at the back of the intake. Because of this, it appears it would be impossible to reverse the intake, at least without a LOT of fabrication.

[GoDadGo]

Would the LS376/515 be an option for the GTM?

While it is not the latest and greatest Wiz-Bang Piece, it does produce 515 HP and a little over 460 lbs of torque. Might be a reasonable solution, but it is a carbureted set up. A sit on top F/I unit might be a great way to go. The engine is all aluminum and the low-tech option may appeal to some.

It's basically a circle track crate engine and is designed to be abused.

[crash]

Would the LS376/515 be an option for the GTM?

While it is not the latest and greatest Wiz-Bang Piece, it does produce 515 HP and a little over 460 lbs of torque. Might be a reasonable solution, but it is a carbureted set up. A sit on top F/I unit might be a great way to go. The engine is all aluminum and the low-tech option may appeal to some.

It's basically a circle track crate engine and is designed to be abused.

Actually there is a fuel injected 525 HP crate engine available, and is what we run in the FFR PDG GTM race car. Fits fine and builds good power.

http://paceperformance.com/i-7739382...te-engine.html