LMM Engine Build

[Cavender]

Okay guys, I’m a newer member here. I’ve tried to learn as much as possible about these engines. But I’ve got some questions about building an engine capable of holding 1000rwhp on fuel occasionally but most of the time 700-900rwhp range 1000rwhp for a dyno event once a year.

1. Will a stock crank live a long happy life at the power I’m wanting with an AF cam?

2. Is it possible to achieve 1000rwhp with say an s484/68mmvvt? Or will it choke?

3. I’ve always heard compounds will kill the bottom end(rods). How true is that, if so will the Wagler street fighter rods work or will I need something better?

4. Are LB7 Pistons that have been de-lipped and thermal coated sufficient for my goals? If not then which pistons?

5. The LB7 pistons would make the compression ratio 17.5:1, my LMM is 16.8:1 I believe. Which compression ratio would be the best for something to drive maybe 10k miles a year and beat on regularly in the power range?

 

[Bdsankey]

1) An AF cam isn’t a proven solution to breaking cranks. Do they help on a new crankshaft? I personally believe so. I put one in my stock crank build. Personally if you’re going to spend the money on an engine build a compstar isn’t a bad investment as they are stronger than stock.

2) Yes it is possible to reach your goal on a 484/68 vgt configuration with good tuning and proper parts.

3) Compound turbos are definitely harder on bottom ends than singles. Personally if you’re going to buy a budget rod the SoCal rod is insane quality for the price and will hold ~1000rwhp. With that said, Carrillo rods are my go-to SS they will hold anything you can throw at them. If you already have Wagler street fighter rods they are rated at 1000hp and I’ve heard of them being taken beyond that threshold.

4) I wouldn’t use a stock de-lipped LB7 piston in an engine build at that power level with how available Mahle Motorsport cast pistons are. Another viable option is Fingers oval bowls. I don’t think you need a forged piston to hold that power.

5) Compression ratio on Mahle motorsports pistons with 0.075” reliefs are 16.5:1 and is a pretty good “all-around” compression ratio for a street truck.

 

[TheBac]

First off, I moved this over to the Engine Building section. There's a lot of information in this section on other people's builds that will give you more insight into what works.

Okay guys, I’m a newer member here. I’ve tried to learn as much as possible about these engines. But I’ve got some questions about building an engine capable of holding 1000rwhp on fuel occasionally but most of the time 700-900rwhp range 1000rwhp for a dyno event once a year.

1. Will a stock crank live a long happy life at the power I’m wanting with an AF cam?

2. Is it possible to achieve 1000rwhp with say an s484/68mmvvt? Or will it choke?

3. I’ve always heard compounds will kill the bottom end(rods). How true is that, if so will the Wagler street fighter rods work or will I need something better?

4. Are LB7 Pistons that have been de-lipped and thermal coated sufficient for my goals? If not then which pistons?

5. The LB7 pistons would make the compression ratio 17.5:1, my LMM is 16.8:1 I believe. Which compression ratio would be the best for something to drive maybe 10k miles a year and beat on regularly in the power range?

Just my opinions.

1) Maybe. The AF cam does help but isnt a cure, though.
2) Not sure so cant help there.
3) Carillos are a given at those power levels. Not enough info out there on the Waglers to know.
4) Mahle Performance or Fingers oval bowls.
5) Id prefer to stay around OEM compression.

How will you address your fuel system?

 

[Cavender]

This is all good to know. I already had a set of LB7 pistons given to me, which is why I have been considering them.

Truck runs good, has 205k miles.

Was hoping the AF Cam would address the crank issue. But will have to look at a new one I guess. I’ve been told an LB7 crank is better than an LBZ/LMM, not sure why or how.

As far as rods go, before I went Carrillo and jumped on the bandwagon. I have been looking at SoCal rods, and Wagler. Price being the most appealing reason. Do y’all have any insight on those? They claim 1000hp..

 

[Bdsankey]

This is all good to know. I already had a set of LB7 pistons given to me, which is why I have been considering them.

Truck runs good, has 205k miles.

Was hoping the AF Cam would address the crank issue. But will have to look at a new one I guess. I’ve been told an LB7 crank is better than an LBZ/LMM, not sure why or how.

As far as rods go, before I went Carrillo and jumped on the bandwagon. I have been looking at SoCal rods, and Wagler. Price being the most appealing reason. Do y’all have any insight on those? They claim 1000hp..

The SoCal rod will hold it but are you going to stop there? Buy once cry once is my motto. SoCal also has some of the best practices on the market and has customer service second to none.

 

[Anotherduramax]

Just my 2 cents, I originally thought my goal was 1000hp too until I got all the info on what was needed to reach my goal on here. I have sense lowered my goal to 800 tops and started a little build thread. I have yet to fire the truck up as it’s in paint now, but I’m hoping to have it out on the road in a month or two.
I went with
Brian Crower Rods
Mahle race cast pistons
Keyed cam and crank
Balanced the rotating assembly
Empire valve springs (needed with compounds I read)
Dual fuelers
45% over DDP injectors so I can still tow
Billet S484 and Billet 64mm vgt
2020 oil cooler
New oem pump

 

[WolfLMM]

I know a dude who once posed the same question you do

 

[Cavender]

Just my 2 cents, I originally thought my goal was 1000hp too until I got all the info on what was needed to reach my goal on here. I have sense lowered my goal to 800 tops and started a little build thread. I have yet to fire the truck up as it’s in paint now, but I’m hoping to have it out on the road in a month or two.
I went with
Brian Crower Rods
Mahle race cast pistons
Keyed cam and crank
Balanced the rotating assembly
Empire valve springs (needed with compounds I read)
Dual fuelers
45% over DDP injectors so I can still tow
Billet S484 and Billet 64mm vgt
2020 oil cooler
New oem pump

How did you make the 2020 oil cooler work?

 

[Bdsankey]

How did you make the 2020 oil cooler work?

You need the 2020 cooler, 2020 elbow, and 2020 elbow gasket. I’ll grab the PNs when I get home.

Edit -

12701592 (2020 L5P oil cooler), qty 1
12675428 (2020 L5P oil cooler elbow), qty 1
12676826 (2020 L5P oil cooler elbow gasket), qty 1

You will need different length bolts to secure the cooler to the block, there is a ton of info in the “Oil Cooling” tread.

 

[Cavender]

Thanks for the info! I’ve been looking into the oil cooling. I have a feeling that the oil temps play a role in cracking the pistons!