LT4 Vs. LS9

[bk2life]

Originally Posted by colorado80439

LT4 or LS9 Also would consider an LS3 with low profile supercharger

how much power do you need, and what type of car are you building for what type of driving...
looks only, car show killer, or something actually going to be used and abused?

[colorado80439]

Originally Posted by bk2life

how much power do you need, and what type of car are you building for what type of driving...
looks only, car show killer, or something actually going to be used and abused?

Pretty much all of the above, small amount of road coarse time, street and cruising on canyon roads, distance trips a little bit of show. I'm at 7500ft so N/A take a back seat, 6-700 horse similar torque

[colorado80439]

My big concerns are fitment and drivablity issues, what difficulties are there with fuel management of LT4 vs LS9, who has a front runner with power steering that works, supercharger efficiencies and/or cooling issues, ecm looks like the LT4 is more involved with electrical control, vacuum pump are they needed for a DSE brake booster and if so who makes one thats not loud and obnoxious

[thedugan]

Jeeze, LS9 short blocks are worth big bucks these days....

https://sdparts.com/i-24507973-chevr...ong-block.html

I hope it's just a typo where the 9 key was sticking.

[samckitt]

Originally Posted by thedugan

Jeeze, LS9 short blocks are worth big bucks these days....

https://sdparts.com/i-24507973-chevr...ong-block.html

I hope it's just a typo where the 9 key was sticking.

$100,000! Can't be right.

Pace Performance has it for $13,556.xx
https://paceperformance.com/i-622022...ance-6-2l.html


Why do you only get 6 ignition coils?

[camcojb]

Originally Posted by samckitt

$100,000! Can't be right.

Pace Performance has it for $13,556.xx
https://paceperformance.com/i-622022...ance-6-2l.html


Why do you only get 6 ignition coils?

I'd guess they have the three coils already mounted to the covers in engine assembly. They leave out the far left coil as it covers a valve cover bolt, the others don't. They throw the other two coils in a box. Kinda lazy but I get it lol.

[srode1]

As far as fitment the LT4 high pressure pump will mean you probably need to modify the firewall for clearance, for the pump and the electrical connections. That's the price of direct injection vs port injection. I'm sure you've read the other technical differences and that the LT4 has more torque earlier making for a flatter power curve too which is an advantage in any application IMHO. The wiring on the LT4 isn't really complicated, just plug stuff in and it works and it's gone in lots of cars so there's plenty of information on front runners.

[rpol78]

My understanding is you have more ECM options with the LS and more options for making changes. I do like the LT4/LT5 engine with the direct injection. It just depends on what you want to do in the future.

Originally Posted by thedugan

Jeeze, LS9 short blocks are worth big bucks these days....

https://sdparts.com/i-24507973-chevr...ong-block.html

I hope it's just a typo where the 9 key was sticking.

Hmmm... Makes me wonder what my LS 396 engine is worth (LS9 block/LS9 CNC heads, Callies Magnum custom crank, Callies Ultra rods, JE custom pistons, Kong 2650).

FWIW - This is going in a '67 Chevelle.

[colorado80439]

Originally Posted by rpol78

My understanding is you have more ECM options with the LS and more options for making changes. I do like the LT4/LT5 engine with the direct injection. It just depends on what you want to do in the future.



Hmmm... Makes me wonder what my LS 396 engine is worth (LS9 block/LS9 CNC heads, Callies Magnum custom crank, Callies Ultra rods, JE custom pistons, Kong 2650).

FWIW - This is going in a '67 Chevelle.

Very nice, Kong 2650 LSA blower on an LS9, with a dedicated SC pulley who's front runner is that?

[rpol78]

Originally Posted by colorado80439

Very nice, Kong 2650 LSA blower on an LS9, with a dedicated SC pulley who's front runner is that?

Thx, It's the GM modified LSA accessory drive 19417908. It has the same spacing as the corvette accessory drive with the LSA SC pieces added to it. Unfortunately it doesn't look like it's available as a kit any more.

I ended up having to use the Holley A/C compressor mount with a Sanden SD7B10 since I couldn't get a GM compressor to clear the main cross member. I'm still trying to work out the A/C lines on it.