Going compounds on lml few questions

[Josh154]

Hey guys finally going to add some air to the lml. Grabbing a used sdp kit to pair with my sdp pipes I currently have. I’ve never ran compounds, ran modded vgt and s369 on lmm so have some questions.

I know most stock motors making big power are on s400 singles with big sticks. Seems like I see a lot of cracked pistons and windowed blocks coming from compounds. Is this coming from drive pressures and torque down low? I plan on billet s480 with a 1.32 housing to keep the hit more mellow and power come on later but are drive pressures still high?

I’m on stock manifolds and lb7 up pipe. Is now a good time to upgrade to some pro fab manis and up pipes with extra flow? Will these relieve some good drive pressure and to help keep that stock bottom happy?

I need to get some parts powdered to match the rest of my current parts. I want to powder the stock turbo cover. I either need to purchase a stock cover to get powdered, or if I’m going through the work should I just go ahead and do a 64mm wheel and cover for the stock charger?

Who’s got the best deal on a billet s480? I did some searching and seen forced inductions was good cheap option. I’m not seeing it on there website though.

Also, oil drain. This needs to get tapped into aluminum upper oil pan? What’s best method of going about this? Can I leave pans attached? Read something of somebody adding 2 extra qts of oil before drilling and draining afterwards.

Thanks in advance for the help! Y’all are awesome here.

 

[S Phinney]

Yes install the return in front of upper pan under the balancer. Run a 12 an return. If you are keeping your stock vgt in place you could use that 480 or run a 475/87 with vband turbine. You will need more fuel if you want to feel the power. Stock injectors just don’t have enough available. The rods won’t last long unless you detorque it. I have a few of those trucks running around.


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[Josh154]

Yes install the return in front of upper pan under the balancer. Run a 12 an return. If you are keeping your stock vgt in place you could use that 480 or run a 475/87 with vband turbine. You will need more fuel if you want to feel the power. Stock injectors just don’t have enough available. The rods won’t last long unless you detorque it. I have a few of those trucks running around.


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I was hoping you’d chime in. Seen you’ve posted about quite a few lmls with compounds. I plan to add some 100%s in the future. How soon I’m not sure, probably another year after compounds go on.

Was really leaning towards 480, it should make less tq correct? Or at least up a little higher in rpm and not hit super hard to bend rods? What about 1.32 vs 1.15?

What about drive pressures? Why do I see a lot of cracked pistons with twins?

 

[S Phinney]

Using a 480 I would go with the 1:15 housing. The only trucks that I have had cracked pistons on should have cracked those pistons. Only one of those was at a power level that shouldn’t have expect the customer seemed to think you could run at wot for miles. He super heated those and melted five pistons valve reliefs. Next day just normal driving one cracked. Cracked pistons come from one of two things. Excess temperatures like what I mentioned or excess cylinder pressures usually from excessive timing. With the larger injectors you will see the power potential but the tuning will need to be conservative unless you want to build it very soon.

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[S Phinney]

The previous photo shows what happens with fuel and timing that will create the power that most people like to see.


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[Josh154]

What’s top end going to be like on a 1.15 vs 1.32? What kind of boost do they usually make? Drive pressure on the 2?

I’ll mainly do 100s to keep pulse down and probably keep it at 700.

Also keep stock compressor wheel or swap it for a 63.5 and cover while I’m powdering?

 

[S Phinney]

We haven’t ran a gauge to measure drive pressures. Boost with stock engine and camshaft was around 75 with 60 overs. Stock injectors was seeing 58ish. With the 480 and 1:15 you will still be able to make great power. The stock charger will be the limiter. Go to a 66 stage three modded charger like one Dans Diesel has. It doesn’t loose any drivability or towing capabilities.


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[Josh154]

We haven’t ran a gauge to measure drive pressures. Boost with stock engine and camshaft was around 75 with 60 overs. Stock injectors was seeing 58ish. With the 480 and 1:15 you will still be able to make great power. The stock charger will be the limiter. Go to a 66 stage three modded charger like one Dans Diesel has. It doesn’t loose any drivability or towing capabilities.


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So is a 480 or 475 either safer on rods?? Will a 480 make 700 the same as 475 just with lower drive pressure?

Is upgrading the stock charger to a 64 billet going to be better or is turbine side holding it back?

 

[S Phinney]

A stock/475 will make over 700 with stock injectors. The 480 will make more HP and a modded vgt will be better with drive pressure. It will be based off a 37 or a 40 garret turbine. The one I spoke of is off a gt40 turbine. With a 480 it will make close to the 1000 range.


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[Josh154]

Obviously that’s not going to happen till a built motor. So realistically I’ll run around at 700 for a while. Will I notice a difference at 700 between the 2? A box 475 is much cheaper and that money could go towards injectors.

 

[S Phinney]

Go ahead with the 480 with what you plan to do. That will save money later.


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[Josh154]

Sweet. Seems like most lmls I’ve seen are 480s. Does a 64mm billet wheel and cover on stock turbo do anything or don’t worry about it unless I do a full drop in with modified turbines?

 

[S Phinney]

Save your money and do the drop in later.


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[Josh154]

How about manifolds and up pipes? Worth it or not?

 

[S Phinney]

Uppipes are since they will increase airflow. If you can get a deal on the set do both manifolds and uppipes.


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[Dm23]

I am by no means an expert, but do you have a built trans at all? I dont see it in your signature. And most of the time a lot of the guys on here will tell you to run bigger injectors before going with compounds. I am in the same boat as you for twins. Forced inductions is actually having a sale, if you go to there instagram post from one week ago they have there sale listed, hopefully the sale is still going on. I have a 65mm in the valley and plan to do the s480 over the top as well, with the 1.15 A/R. and 100% overs.

 

[Josh154]

Nah stock trans for now. She’s went 12.9 stock turbo full weight. Dropped pan and cut open filter this summer a year after drag strip and everything looks mint. I don’t beat on it. Been to the strip once with her. I’ll go out this summer, my dad just bought a new Audi sq8. V8 twin turbo so I’m sure we will go out this summer. As long as I can beat him once I’m happy lol. Trans will get built though forsure.

100%s are next. I’d rather pop the trans than the motor.

 

[Dm23]

Even if you did go twin and injectors first, you wont be able to put that power down on a stock trans. And with that power your trans build will be sooner than you think. Im just trying to help. Good luck.

 

[Josh154]

Well found a 475/96 1.32 local for $400. Might just snag that. Should still make more power than my sportsman can take me and be better than stock charger

 

[TheBac]

Cmon Josh, you've been here a while. You're smarter than this. You've got to build the trans to match the power output.