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Building 3.6 with forged internals

piroman683

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Just curious if you did any type of dyno testing prior to tearing down? Would be curious to see what kind of improvement is made going forged, and possibly adding more boost? Obviously, the goal is longevity!

I've been driving my maggy glad more since the weather is nicer, and I absolutely love it, but everytime I push it past 4k rpms I start to worry. Currently have 7k miles on set up with daves small pulley tune.
how much boost are you generating with the small pulley? When I first installed my SC the tune Magnuson sent me resulted in about 22.9psi of absolute pressure at full boost (8.2psi of actual boost). In their more recent tune I hit 27.1psi of absolute pressure (roughly 12.4psi of boost) and with the updated tune the truck deffintely moves faster.
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I'm using @DAVECS2 to tune the Jeep. Once I get it back, we are going to datalog an push the power up slowly.
 

cmb396

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how much boost are you generating with the small pulley? When I first installed my SC the tune Magnuson sent me resulted in about 22.9psi of absolute pressure at full boost (8.2psi of actual boost). In their more recent tune I hit 27.1psi of absolute pressure (roughly 12.4psi of boost) and with the updated tune the truck deffintely moves faster.
I honestly do not know. IIRC, I think @DAVECS2 said it was around 10lbs?! Maybe he can chime in with an answer.
 

dcmdon

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No need to lower compression on modern engines... Your just giving away power. 11.3:1 is pretty standard and not high compression. Maybe compared to old technology and older motors it is but in todays technological age its not.

The weak points for sure are the wrist pins on these motors, as well as, the rod design for a boosted application. Hence, why I went and made custom Rods and Pistons for factory replacement. If anyone needs a set I have a set ready to ship today! Complete factory replacements all beefed up and rated for over 900whp application.
There is need to lower compression if you want to maximize boost and power.

But no need if you are only going to boost it mildly. (which is how the majority of these systems seem to be set up.). Especially if you maintain some kind of knock sensing system to pull boost and/or timing if knock is detected.
 

bullitt5897

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There is need to lower compression if you want to maximize boost and power.

But no need if you are only going to boost it mildly. (which is how the majority of these systems seem to be set up.). Especially if you maintain some kind of knock sensing system to pull boost and/or timing if knock is detected.
Lowering Compression reduces the efficiency of the motor. For example:

on a VQ37 (Nissan V6 which is similar to this motor). We have an 11:1 compression ratio and a displacement of 3.7L. At 20-21 psi the motors make about 800-900whp. Now drop that compression down to say 10:1 and it now requires 24-26psi to make that same power level.

11:1 Comp: 38-45 whp/psi
10:1 Comp: 30-38 whp/psi

The only time you should be decreasing the compression on a modern engine is when you are trying to affect change on your power delivery and power curve to match the Forced induction application and fuel availability.

Working with one of the formula Drift teams on their engine program they ran 14:1 compression and boost because they were only running a specific race fuel and could squeeze out a few extra whp in their application.

I have run v6 engines in low compression and high compression boost configurations for years. Factory compression should only be lowered if you do not have access to premium fuel or octane boosters (short term use).
 

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bullitt5897

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Further more in a supercharger application the frame size of the supercharger has a tighter window of boost in which is its effective range. for the jl/jt sized maggie superchargers and the rotrex superchargers you are going to be under 20psi of boost in most applications. Lowering compression will force you to the top end of that range and will add extra stress and strain on components.
 

JarHeadLV

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GREAT post and info here! I'm curious if you don't mind what's the expense to "build" your 3.6L motor for the supercharger? I've also been considering a Magneson supercharger for my 23 JT, but don't mind spending a little extra cash to extend longevity.
 

bullitt5897

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I still have a set of rods and pistons if anyone is in the market.
 

Pauliboy

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I still have a set of rods and pistons if anyone is in the market.
Are you able to give me a Price and availability for shipping to Australia? What HP did you make in the end on yours? I'm currently sitting at 253rwKw with Magnuson and 81mm pulley on my 2020 JT
 

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bullitt5897

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Are you able to give me a Price and availability for shipping to Australia? What HP did you make in the end on yours? I'm currently sitting at 253rwKw with Magnuson and 81mm pulley on my 2020 JT
$2k shipped to australia
 

AzOldGuy

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This has been a good read. Hope things are coming together for you.
 

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how much boost are you generating with the small pulley? When I first installed my SC the tune Magnuson sent me resulted in about 22.9psi of absolute pressure at full boost (8.2psi of actual boost). In their more recent tune I hit 27.1psi of absolute pressure (roughly 12.4psi of boost) and with the updated tune the truck deffintely moves faster.
I was getting 10psi with the 81mm pulley
 

Pauliboy

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how much boost are you generating with the small pulley? When I first installed my SC the tune Magnuson sent me resulted in about 22.9psi of absolute pressure at full boost (8.2psi of actual boost). In their more recent tune I hit 27.1psi of absolute pressure (roughly 12.4psi of boost) and with the updated tune the truck deffintely moves faster.
I was getting 10psi with the 81mm pulley
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