Redbaronxj

Im running 31s with 3:55 gear ratio. I havnt hooked up a air fuel ratio gauge yet ( I know dumb right). But I plan on doing it soon so that would def. help let me now what's going on to. I moved the iat sensor in the air filter piping before the throttle body. I know cooler temps on the iat can cause them to run richer. Where did u guys move your iat sensor too? But really I guess I need to just what it comes out to when I refill, just trying to prepare myself for the disappointment lol

BBuchta

I've found I get much better gas mileage with the AIT seeing heated charge air temps but with a reduction in power. With the AIT seeing cool intake air temps I get more power and less gas mileage. When out of boost I see the same MPGs I had prior to the supercharger.

CrawlerXJ

When is boot kicking in? What rpm or mph? Meaning, off road, you can see boost (power) right?

BBuchta

I've never needed boost off road as of yet. Boost off road typically means excessive wheel spin and possible breakage of things if you suddenly catch traction. The exception I see to this would be deep sand and maybe mud. On my jeep the throttle has to be pressed about 60% or more for it to start seeing boost. This only occurs on paved roads during rapid acceleration and up steep hills. Mine has enough power that if you enter boost without the steering wheel straight you are almost guaranteed to fishtail sideways at any speed, this is with an LSD which works great on the street to prevent the one wheel spin but not so great off road. Will be installing a selectable rear locker soon or modifying the clutches in the LSD soon.

I would really like to see a SC on a manual transmission. Looking at the dyno and based on my butt dyno I think quicker acceleration could be had by shifting sooner instead of at redline. TQ and HP peak at about 3500 RPM with this supercharger and things fall off towards stock as it continues to rev. When it hits 5000 RPM the power level is just above stock. I'm thinking about installing a manual shift controller and shifting at about 4000 RPM and think that will bump acceleration times even further. Its not a supercharger issue because the boost level doesn't change. I think that it being a single cam old school engine built for TQ limits its high end potential. I have thought about a ported head but am happy with the performance I have now. From what I have heard the safe limit on this supercharger is 14K RPM. With the pulley I have now it spins just under 14K RPM when the engine is at 5K so if I could limit the engine RPMs back down to 4K I could go with a smaller pulley, make more boost and still keep the SC RPM under its max.

CrawlerXJ

Sand One of the main reasons I got it.

CrawlerXJ

So, power band is 1000-3500 RPM I am hearing?

I wonder if the M90 has higher RPM?

BBuchta

M90 has a lower max RPM than the M62, but it moves a higher volume of air per revolution. It produces less TQ and more HP on the V6 engines they were installed on. BUT our engines were never meant to rev, if 5 pounds of boost makes a 5-10 HP difference at redline more boost wont help. The 4.0 can't inhale enough air at that RPM unless it had a higher flowing head and maybe a different cam, which both would probably cause low RPM TQ to suffer.

CrawlerXJ

My M62 arrives tomorrow

So, what do you think the power rpm is on the M62? You said 3500 was max. What's lowest? Can you raise the 3500? This would help when your on the highway for a passing gear "boost".

BBuchta

The boost of the supercharger is linear it produces the same amount of boost at all RPM's. The engine on the other hand breathes based on its air intake and exhaust. Any mods (high flow air filter, cold air intake, header, cam, free flowing exhaust ect.) changes how the engine breathes and ultimately its output. The supercharger helps a huge amount when passing, it gets moving much faster than stock. After having mine for many miles now I just keep tweaking and wondering what other mods can be done. More boost isn't always the answer, an engine that breathes better will make more power and show less boost than a restricted engine with high boost levels.

CrawlerXJ

You said it taps out at 3500 rpm. I wonder if my head will help there or is that a pulley issue? Or?

BBuchta

That's why I would like to see more supercharged jeeps on the dyno. The one dyno we have is from a completely stock jeep. (The one I'm referring to is a few pages back) I wouldn't say it taps out, but it does peak around there, but it also stays well above stock power levels up until redline. The stock run shows it peaks around 45-4800RPM. Maybe the power band on mine is different, maybe yours will be different to. I don't know until we get more dyno runs. Its not a pulley issue or even supercharger related. I'm curious to see how a higher flowing head, rocker rollers, ect will affect it.

CrawlerXJ

Ya, I wonder how my LS1 big valve head will perform. If that will help?

coloradoinsane

my dads 1998 Wrangler is a 5 speed manual. I installed a supercharger on it as well. It performs much better than my XJ with the Auto.

CobraMarty

I put the IAT sensor in the adapter that bolts directly to the intake manifold, I drilled and tapped a new hole. Now I watch it with my scangauge and it shows me my 'charge' air temp. The colder the more 'dense' the air, the better, the more power.

The head will help as will the cam.

Redbaronxj

Boost doesn't really come with rpm or mph it's more about the the throttle body position seems like anything over half throttle I start to build boost no matter what rpm but below half it's still in a vacuum. Mine seems to pull good until about 4k then u can tell it seems like its not pulling as hard. Are u guys running a different pulley for more than 5-7lbs? Anyone running water/ meth