Sorry I haven't been on the forum in a while. Unfortunately, while I was working on the baja video, the hard drive crashed on my macbook and I lost the sequences I put together. I'll have it done eventually, but just haven't found the time to redo the work I put into it.

Anyways, heres an update on the supercharger. I ran into a problem, that I believe another person on this forum had, where the SC didn't seem like the it was boosting enough. Turns out I had the wrong tuning installed (could have been when I was messing around with the tune to set my bigger tire size). With support from Roadrace and Hypertech, I got the new tuning installed and its hauling again, seems even faster than before.

 

"let me take a stab at it" as any engineer should know, you don't have to measure every variable in a process to know the process conditions. You can calculate compressor outlet temperatures without measuring it directly.


Break out that thermo book and freshen up RIPP.



To the OP,

Sorry about the continued hijack. I like the twin screw compressor better than centrifugals for our Jeeps. Twin screw designs provide almost instant boost where a centrifugal struggles to achieve good boost off idle. Look at Kenne Bell's success. Yea in pure race applications the centrifugals dominate but not on the street or off-road.

It is common to not use an intercooler on low boost (under 8lbs) applications with compressors that have a high isentropic efficiency. As always the key is running the proper octane fuel and having the right a/f ratio under boost.

 

Hey guys, I've been receiving questions regarding the gas mileage I get with the supercharger so I thought I'd just post up. I'm not sure that my jeep is the best example for this because I am extremely heavy, and i'm running 39" tires. Also, I am not able to tell you the impact the supercharger had on my MPG because I added the larger tires when I added the supercharger. With my tires, heavy equipment, and 5.38 gears, i'll average about 12 to 12.5 MPG highway, its a jeep, not a prius.

Now MPG around town is completely different. Now that I have the supercharger, I have a tendency to be pretty heavy on the throttle. I will tell you it is hard for me not to light up the tires at a stop light -the jeep is extremely responsive. I get about 9 to 10 MPG around town, and about 8 off road. Anyone thinking about please let me know, maybe we can hit the trail together and i'll let you give my jeep a test drive.

 

One other thing, the hypertech tuner you get with the supercharger is really awesome. Its gives to the options to disconnect the sway bar in 4HI, and run the rear locker in 4HI (worked out great in pismo). It also sets up the fan to run in low speeds, and customizable engine speeds for winching.

I've been messing around with the tunes a lot, and I found that my favorite set up for crawling. I have the throttle response set to -50% in 4Lo, and the RPM in 4Lo at 1,000. This allows me to crawl over most rocks, and have a manageable throttle.

This is a video my father did of chocolate thunder in johnson valley, with the tuning I have set up.

Chocolate Thunder - Johnson Valley - 09.22.12 - YouTubeChocolate Thunder - Johnson Valley - 09.22.12 - YouTube

 

$4k for a twin screw!!! Holly hell, gimme 8lbs please!!!

 

The $4k is before tuning or is this a diy tune?

 

haha definitely, cheaper than a hemi, but I get your point -the money we spend on these jeeps ! The power feels perfect though, comes in very steady and doesn't let out.

 

I guess I really shouldn't call it a tune -the tune for the supercharger was installed when I had the unit put in, and the unit comes with the Hypertech tuner. I talking about the extra options you can choose on top of the standard sprintex tune, kind of like a super chips tuner.

 

ive posted elsewhere on this forum that twin screw is far superior to centrifugal sc in all but WOT passes... $4k for an 8lb system is a great value. If i could squeeze a 10lb setup on 87 octane with lower comp rings when i rebuild than were talking 70% more power from idle!!!

 

I will read this whole thread later... but you just made my night! I am in no position to buy now but ill take an SC 3.8 over any NA deisel or 3.6L crapshoot... Great rig too! Subscribed.