ZebraFord

Anyone have any advice for me regarding CR with boost? The goal for the truck is to be quick and torquey. The kind of power that pins you back in your seat and makes you grin. I've already got a lightning blower that has been ported for it and all the stuff to do the swap. I'm going to do a built bottom end to handle the power. Curious if I should
1. Go stock lightning compression ratio at 8.4:1 and run 16 pounds of boost (8 lb lower)
2. Bump CR to 9:1 and run less boost
3. Bump CR to 9:1 and still run 16 pounds of boost while hoping that my tune is spot on and probably lower timing as well.

Only constraints are that I still need to be able to tow and haul stuff with the truck. Also, pump gas only so 93 octane is the best I can get here. Thanks for any input

jprevat

iTrader: (1)

I would go with option 2 and then you have the option of swapping the lower out if doesn't have enough juice for you.

2thousand5.4

8.4:1 and 16 pounds will make the most power out of the 3 if the tune is right. Lower compression "increases" combustion chamber size so you can cram more air and fuel in there. 16 pounds on an 8.4 is physically more air then 16 pounds at a 9:1. But, at the same time I think you will have to spin the blower faster at an 8.4 than a 9.1 to achieve 16pounds of boost. I could be wrong tho. Cam profile is going to have a big impact on your towing and hauling preformace as well

jprevat

iTrader: (1)

If you are correct will the m112 be able to spool up that high?

2thousand5.4

I'm honestly not sure. I want to say yes tho. It will probably be close to maxing it out

ZebraFord

Thanks for the advice guys. I think I'll start with 9:1 CR and then go from there with pulleys. Yes the M112 is capable of that. It's not rare for lightning guys to run 8 pound pulleys and make 16-17 pounds of boost. It gets hot pretty quick if you're on it a lot, but for just cruising around it really picks up a lot of torque. I'm gonna talk to my tuner about it before I start just to confirm. My understanding is that 8.4:1 will be a little slower "out of boost" and 9:1 will be a little better "out of boost" but probably will restrict how much boost I can actually run

jprevat

iTrader: (1)

That would probably be the direction I would go in. You do a pretty fair amount of towing so I would think that may heat things up a bit but I could be way off.

Cmanjr

From my understanding lower boost generally can make it more reliable too anyways, so having the higher CR couldn't hurt if you're running lowery boost with it. So that meaning you really can't go wrong.

But maybe I'm looking at this wrong, maybe someone else will chip in on whether I am or not lol.

DrillRig52

I've currently been thinking very hard about a budget minded single turbo setup. Either buying the complete hot side from CGfab, or flipping the factory manifolds and having someone do all the plumbing work. Thinking about 6 psi, so that I have some extra power without having to rebuild everything around it.

Everything else would stay factory, only needing to upgrade injectors, MAF, fuel pump, egr delete, and exhaust.

ZebraFord

You're gonna spend more money on it than a lightning supercharger swap. There's a full swap for sale right now for only $1500. That's a steal