Plenum heat reduction, more power

[beemer]

On the 3.9 motor under the plenum cover is a jacket cover assembly which is heated by the engine coolant. This comes from the intake manifold and exits to the radiator. Temp after start up goes quickly to 190 degrees. After installing a aluminum slug in the hose with a .062" restriction the intake temp lowered to 90 degrees + -, no detonation on hot days and more power felt. The engine gets a cooler more dense air charge. Carl...........o&o>................

 

[redrover51]

Hi Beemer.....is this jacket intended to dissipate heat, and where does the heat go once it is plugged? If the heat is re-directed, or exchanged at a safe location, the procedure does appear to have long-term merit! I will also give this a try if you have determined the over-all factors governing heat-dissipation factors within the perameters of the operational service quotions of the 3.9 engine specs.......

 

[beemer]

heat jacket

Redrover, the heat jacket is a block of alumimum mounted right under the throttle butterfly below the TPS to add heat to the intake air, the plenum will burn your hand it's so hot, not the best way to have dense air. On carbureted engines it helped in vaporizing the fuel and run leaner for smog. Once the engine is at normal temp there is more than enough heat coming up thru the manifold as well as from the radiator blowing across the engine. I'm only talking about lowering the coolant flow not blocking it completely so during cold starts and cold weather the plenum will be warm. It's flow is like your heater hose, if blocked there is no harm to the engine cooling system. The cold ram air that i installed made a difference, so why heat it to 190 degrees?
This will be the next "test project" after i rebuild the 5-speed. Carl....o&o>...

 

[redrover51]

very perfect explanation....thankx

 

[beemer]

looks stock, passes smog

Redrover51, everything is 3.9 but the short block, it's a 4.6 litre. The next thing to replace (test) is install a 20 AM mass air meter from a 4.6, i'm running the 3.9's 5 AM that feeding a 4.6 motor. I got e-mail returns from rpi and rimmer but they won't state torque or hp gain numbers. Maybe the difference is above 4,000 rpm only? Carl........o&o>...........

 

[redrover51]

Hi Beemer...I am jazzed that you are energetic enough to persue excellence of performance to the degree you have. I have found that with every new engine mod comes a new problem, or co-efficient that needs attention. As I get older, my focus is maintenance with moderation. I believe these very european Land-Rovers are designed for "upper-established income brats," and all of us "off-road cats". therefore, I restrict the modification levels for my rig, to satisfy the basic remedies for going into the bush as often as my schedule allows. I think that research and development will take you down some interesting and expensive roads.....and I will try to be there if you need my assistance, but I do not have the expertise that you obviously have with engine-mods, so I will not try to develop a thread based on these periferies. But...I want to know how well your mods stack-up when you are finished with your rig! I live in Tennessee...where do you off-road?