...no pun intended... and that relates to the fundamental engine design...i.e. ohv vs ohc engines. "cube for cube" OHV engines tend to produce more torque at low revs compared to a similar size ohc engine. This effect is enhanced when OHC engines contain say 4 valves per cylinder vs the standard 2 valves per cylinder for older ohv designs. That's why turbos and higher revs are used to develop torque and high end power in OHC designs. The reverse is then true...engine braking is far more noticeable in a push rod ohv engine than say a modern multi valve ohc design of similar or higher power output for same displacement. My 2.2 turbo CRDI Santa Fe develops more power and torque, albeit at different rev points than the venerable 4.6V8 of my previous P38. ...however, keeping to the 60kmh limit descending the Range from Toowoomba, the P38 would comfortably hold to 55kmh in 3rd gear (high range!)at comparatively low revs with feet off brakes and accelerator. The Santa fe...approx same weight... has an 8sp auto. To maintain 55kmh on engine braking, it needs to be in second gear and the tacho is showing close to 3500rpm (3800 rpm is max power, 4500 rpm is the red-line). An LS3 in the front end of the RRS might be the answer!
Reply With QuoteI reckon you guys are missing the basic difference of petrol v diesel. Diesel engines have no inlet manifold vacuum, and turbo chargers actually mean manifold pressure. The turbo is pumping air in negating any engine braking. Larger engines use Jacobs type brakes to alter valve timing to make the engine work as a compressor, and even these can have an effect on engine life. Engines fitted with an inlet manifold help stop the turbo feeding more air in when not needed, my l322 td6 is awesome when in sport mode coming down the hills at the back of Cairns. I have run an exhaust brake on a Perkins T6.354.3 for many years in my 4x4 International with no adverse effect(it really makes people look twice when roaring into the car park!!). I have no intention to put one on my old defender though. My two bobs worth from a layman.
Originally Posted by Daryn1996
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