I recently heard someone say they put a turbo on a Jeep. Is that something done very often and if you have done it what performance boost is there i.e. city driving or highway driving. What are the possible downsides to that?
That would be "2 Fast" and "2 Furious"!
Actually I do know someone who wanted to do it to a 4 banger... but I don't think there is any practical purpose to it in a Jeep (off road).
-- JimG
80' CJ-7 258 CID 35" BFG MT on 15x10 Centerlines D44 Rear, Dana 30 Front. SOA 4.56 Gears, LockRight F&R Dana 300 w/4:1 & Currie twin sticks Warn X8000i w/ dual batteries
A turbo doesn't kick in until there is some exhaust velocity (at the higher rpm band). On a Jeep, you need all your torque at the low end. There are several brands of belt driven superchargers that will give you a much better torque curve for the way Jeeps are driven than a turbo.
I think the one that I heard it put on was a four cylindar and not all Jeeps are driven off road. My CJ tries to get stuck in mud up to the doors but most of the time I'm driving it to work on the highway - call me crazy but I drive my 21 year old Jeep everyday. (er-except when the radiator is out or something)
A turbo will work way better than a supercharger on an off road vehicle. There is no boost till the engine sees a load. I had a turbo on a 4 cyl. in a Trooper. With the stock gearing and stick shift it worked very very well offroad.
erm. A turbo builds boost at higher rpm based on exhaust flow where superchargers are belt driven and based on demand. Turbos are best for flat out racing and highway performance. Superchargers are best for increasing low end HP.
Eggshually an exhaust driven turbocharger creates boost based on the temperature and volume of exhaust gas, or more correctly the differential in both of those across the driving side of the turbo. Engine load has very little to do with it in that if you lug your engine in a high gear you are not gonna get more boost, you'll just risk cooking the turbo. Although you *could* get useful boost at crawling rpm by using a teeny tiny turbo, it is far easier to do so with a mechanically driven supercharger. A supercharger can generate boost at pretty much idle rpm if desired.
Ahhh, this is why you install a B&M hopped up automatic transmission and launch the thing by standing on the brakes, floor the gas, then release the brakes. Except of course on really big turbo motors which either ignore the brake pedal or rip all the rubber off your tires, or both.
Porsche never really had that much trouble with turbos, other than scaring the heck out of new drivers on the older ones when they released the high pressure on the outlet side with a simple popoff valve...about like a pistol going off in your ear.
The turbo wastegate limits max boost via signals from the ECU.
The pop-off valve or blow-off valve doesn't limit power, but protects the impeller/ turbine assembly and intake system from harmfully excessive pressure and stress. When the throttle plate slams closed, the turbo is still spinning a gazillion rpm and providing boost. The pop-off valve dumps all the high pressure air into the atmosphere, resulting in that loud Pro-Rally noise. A bypass valve is much more civilized and dumps the air via a hose back into the inlet to the compressor.
I agree that turbos aren't usually suitable for off road use. Some are, like this non-Jeep application, which is unfortunately out of production:
I have had a couple of high performance turbo cars and just loved them.
John Davies Spokane WA USA
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