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I'm new to this group on the net but not new to auto performance. I will say I'm a big GM man, I have owned many different cars and trucks, from Trans Am's with 4.6's to my 97 Grand Prix. Out of everything you can do to an engine a great thing you can do is port and polish. For you how don't know what that is it boils down to making the air for the intake flow easily to the head and into the combustion camber. With most engines the areas around this flow is okay, but not perfect, you can buy kits that will fit a small drill and smooth the areas out, but not to smooth (I won't get into all the details.) To get to the point when I have done this to V8's or V6's I get about a 10 to 20 hp gain depending on the engine, Its just an idea for you all to try, and no I haven't gotten my engine apart....yet, so when I get it to that point I'll send an update.
 

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Just FYI, the 3.3L can be ported and polished to a 3.9L. the 3.9L engine that comes in Caravans are the same 3.3L but bored out. Though it's a very strenous and complex task, but maybe the paybacks are worth it!!! I would love to see someone try it first before I tried it.
 

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you mean 3.8L? don't know of any 3.9's in the caravans.
the 3.9L dodge engine is a Truck engine that is a 90 degree Vee, the 3.8 is a 'car' engine with a 60 degree Vee
 

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I could swear that my dad's Caravan SE seats a nice 3.9L, but I'll check and let you all know.
 

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If it is the same set of heads as in the 3.8L, why don't you find a set of them and refinish those and then bolt them on?
 

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3.8L vs 3.3L. the increase in volume comes from Bore and Stroke, not port and polish. (no, i am not talking about some cheezy porn video.)
the 3.8 have a longer piston stoke and a larger diameter piston. if you want to upgrade to 3.8, then you need to rebuild the engine with a 3.8 crank, Pistons & connecting rod, and a honed out block
 

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First of all, porting and polishing doesn't increase the displacement of the engine. All it does is smooth the air passages. The engine will remain at 3.3L.

To increase displacement you would have to employ a technique called stroking or overboring. This is where the cylinder bores are cut wider than stock. New pistions are installed, as well as piston rods and sometimes a new crank.

Secondly: It is a 3.8L no such thing as a 3.9L in any current Chrysler product.
 

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Discussion Starter #9
There are a lot of site on the internet to show how to port and polish your intake and heads, but I would practice on some old engine parts before you try it on your engine.
and while I'm on the topic please note I notice the intake and heads seem to be aluminum and you need a special tool kit for aluminum.

Oh, and to bore and stroke your engine would be a good way to increase engine size, but with out increasing your value size or the at least a bigger cam (cams in this case) you won't see a big improvement.
 

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Secondly: It is a 3.8L no such thing as a 3.9L in any current Chrysler product.
Untrue. Pick up any Dakota or Durango V6 and you got yerself a 3.9L Magnum. with 175 hp and 225 lb/ft of torque.
 

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i am in the process of having my heads shaved, valve-jobs and i am porting them also. i have also be told by my chrysler mechanics to expcet a 20-30 hp gain, so we wil see that happens. i am hoping by the end to be in mid 15's. i am also looking for a TCM, PCM from a Vision, supposedly they have a slightly more aggresive program. same HP numbers etc, but they programing to get there is a lil more aggresive.
 

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accleration times for 3.5L intrepid and vision are the same, top speed in vision is lower, I don't know why, either drag or ECU restrictor
 
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