Magnuson SC and proper gearing

[Yoinkers]

Why force an up shift at 4500 rpm? This engine has 6500 of them available. Use them!

X2. wind it out to the end.

I will say, the whole "lift to shift" thing with these power mods is a fairly awful problem for an expensive power upgrade.

[JeepLab]

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The truck is very well done. I like the rack a lot.

Are all your parts steel? flares, rails, armor, rack, bumpers, tire carrier?

If so, you may want to consider the 4.88s. expecially if you dont spend much time on the highway.

[jt1911]

Everything is steel which is why I mentioned the weight thing with the rack. I don't have the exact figure on tool weight added, but it's obviously several hundred pounds. The only thing I weighed were the Method rims which with headlocks came in at 31lbs each. I don't remember what the KM2's are per tire, but I had read your (jeep lab) previous post on wheel mass did try to keep the combo as light as I could.

With more time behind the wheel today, the 4.56's were for sure going in but I was thinking about 4.88's. The question is do I get the SC installed and wheel it with the tune that's installed a the time, or go ahead re-gear and set the tune up with 4.88's?

I'll throw another wrench in the plans; do i stay with stock exhaust and air intake or upgrade? Not that I need it, but I like the looks, but how would a snorkel effect the tune on this SC?

[JeepLab]

Everything is steel which is why I mentioned the weight thing with the rack. I don't have the exact figure on tool weight added, but it's obviously several hundred pounds. The only thing I weighed were the Method rims which with headlocks came in at 31lbs each. I don't remember what the KM2's are per tire, but I had read your (jeep lab) previous post on wheel mass did try to keep the combo as light as I could.

With more time behind the wheel today, the 4.56's were for sure going in but I was thinking about 4.88's. The question is do I get the SC installed and wheel it with the tune that's installed a the time, or go ahead re-gear and set the tune up with 4.88's?

I'll throw another wrench in the plans; do i stay with stock exhaust and air intake or upgrade? Not that I need it, but I like the looks, but how would a snorkel effect the tune on this SC?

1. Those have to be the lightest beadlocks on earth, and the KM2 is 70 lbs. Ive never heard of a 30lb beadlock. Im not saying its not, Im saying if it is, Its super light.

2. I say gear after SC. Dont worry about the tune. The tune is for air fuel mixture in the engine. Your gear change will not effect it.

3. Stock exhaust vs. aftermarket is no difference in performance as far as my testing has shown. If someone else has better info on it give us a chart.

4. Mag planned for a snorkel, so dont hesitate to use one if you want to. BUT keep in mind, even if your snorkel is installed correctly, if you hit a bump in the future and somehow loosen it, you will allow water into your engine through the connection to the snorkel.

[gbaumann]

So let me know if I get this right.

SC + AUTO + 35s + 4.10 gearing = highway passing in 4rd gear?

SC + AUTO + 35s + 4.56 gearing = highway passing in 3rd gear?

Now, this all brings further questioning

1. Is your speedo calibrated perfectly?

2. What is the RPM you cruise at if doing 80mph?

baumann, Ive read your posts a bunch of times now trying to get clear about how to help the OP in this thread. Since you have the auto with the mag and we dont, your experience above ours in this case because of your AUTO transmission.



Here is what I think about your situation, not Jt1911's.

I think are geared right. 4.10 for 35s with the SC is PERFECT gearing. If you had 4.56, you would feel overgeared. If you have never been overgeared, take it from me. It sucks. Do not feel like if you did it over again, you'd do it different. The grass is always greener on the other side of the fence. I promise, you are on the greener side of the fence. Being overgeared, turns your supercharged truck into a pig on the highway. I dont care how much horsepower you make.

If you had 4.56 with 35s on an Auto, you would be at 2700 RPM at 70 MPH! Your truck would struggle to get to 80, and would be gasping for air there at 3500 RPM. You would almost be forced to go to 37s.

Just my position. take it from a guy who geared twice.

With 35s and 4.10 gearing with automatic trans I'm running around 2,700 (2,750?) at 80 mph. That's in 5th gear, of course.

[gbaumann]

X2. wind it out to the end.

I will say, the whole "lift to shift" thing with these power mods is a fairly awful problem for an expensive power upgrade.

Well. . . I don't mind winding her up now and again and I'm fully prepared to drop a hemi in if the 3.6L S/C blows up. But I don't want to sprint down that path. Remember that we're running open deck aluminum blocks with iron sleeves. The bottom end of the pentastar is by all accounts rock solid and built to take forced induction. The heads and the upper deck aren't. At least not in the Jeep version. They will accommodate forced induction but we need to be careful. Static compression ratio is, I think, 10.5:1. With 6 to 8 lbs of boost you can quickly get north of a 14.0:1 effective compression ratio. That's O-ring head gasket territory and closed deck block architecture land. Oh, and that kind of cylinder pressure would LOVE 100 octane fuel. When these motors are in route from Pentastar to Masarati where they are fitted with twin turbos they first stop off at Ferrari where the cast blocks are machined and they receive different heads. I've read that the cylinder walls are fortified and the sleeves are thickened which reduces displacement to 3.2L. I think some of this technology is rumored to be headed for a few Chrysler products in the future. I even heard that there could be turbocharged Pentastar RAM pickup truck. So what does all of this have to do with gearing?

I was originally attracted to the MAG SC because of the flat torque curve and how quickly it developed power in the RPM band. I want that power at lower RPMs to be transmitted to the road. As I push down on the accelerator I want to be pushed back in my seat. Not downshift two gears. At 65 mph I want to drop one gear and disappear! I would love to get the throttle open more in higher gears so the motor has to develop the power the SC is capable of producing. With my 4.10 gearing, 35s and an auto trans, I'm mostly using 3rd gear to find power. The trans will hold that gear and let me open the throttle so the SC can develop power. And it's quite awesome! I would like a little of that awesomness in 4th gear too. I was wondering if 4.56s would get me there. But from what I've read in this thread I don't think new gears are the answer. I think I have a good ratio and need better transmission control.

[jt1911]

Jeeplab, as far as the Methods…they were weighed on my scale in the house. I will say, that I put 50lbs on the scale to verify the weight and the beadlocks came in at 31lbs roughly. Not to say that I didn't screw something up by how I placed the wheel on the scale, but it read 31-32lbs. Thanks for the all of the info. I'll keep you posted on how the SC instal goes. Anyone else, please feel free to chime in, the more info the better.

[JeepLab]

Jeeplab, as far as the Methods…they were weighed on my scale in the house. I will say, that I put 50lbs on the scale to verify the weight and the beadlocks came in at 31lbs roughly. Not to say that I didn't screw something up by how I placed the wheel on the scale, but it read 31-32lbs. Thanks for the all of the info. I'll keep you posted on how the SC instal goes. Anyone else, please feel free to chime in, the more info the better.

Method Race Wheels confirmed it. I talked to steve there today. 32 lbs for those beadlocks.

That is an incredibly light beadlock.

Really good wheel pick. Bravo!

[jt1911]

Good deal, glad I wasn't off on my weights. Since having installed them, I've checked the torque settings every day and for the most part they are holding. Now if I can just get all of my baja design lights wired up. Anyone have a weather pack connector crimping tool?