3.6L build opinions

This came up in another thread but its an interesting idea (at least to me) so I decided to start a different thread. I did the math and using a 199cid crank and a .030 overbore the engine displacement becomes 215.6ci (3.6L). Using 4.0L rods, and silvolite hypereutectic pistons with a 11.5cc dish, an a MP .043 head gasket. I came up with a CR of 7.50:1 and a quench height of .068". This is my first attempt at these calculations so I'm not completly confident that they are accurate. On desktop dyno 2000 this engine, along with larger valves, and a 260h cam makes 245hp@5500 and 266lb/ft@4000. This would be a much faster reving engine, and because the 199 crank is forged it would have a much higher redline. And with a CR around 7.50, a large amount of boost is an option. What do you guys think? Would it be worth it to try this?

A destroked engine based on the 4.0 block with a 3.00" stroke crank and 3.905" bore (0.030" overbore) would be sweet and make for a fast revving engine, especially with a forged crank. The only problem with your proposed setup is that the Silvolite pistons won't work and here's the reason:

Deck height = rod length + stroke/2 + piston pin height + deck clearance

Assuming that you're using the 4.0 rods, let's substitute some numbers into the equation:

9.453 = 6.125 + 1.50 + 1.581 + deck clearance
Deck clearance = 0.247"

So the pistons will be nearly 1/4" down the hole at TDC. Not viable, but there is a solution. Get a set of custom forged pistons made (if you're supercharging, they'll be far better than Silvolite cast units anyway) with a pin height of 1.828" so that you're left with zero deck clearance. If you then use a Mopar Performance P4529242 head gasket, quench will come in at 0.043".
I suggest that you go for an 8.5:1 CR and use 8psi of boost. That way, off-boost response will be more lively than using a 7.5 CR. The only detail left is to calculate the piston dish volume that you'll need to get an 8.5:1 CR:

CR = cylinder volume/total combustion volume + 1.0

Displacement will be 215.6ci or 3533cc (3.5L) so cylinder volume is 588.8cc.

7.5 = 588.8/total combustion volume
Total combustion volume = 78.5cc

Total combustion volume = combustion chamber volume + head gasket volume + deck clearance volume + piston dish volume

Substituting some numbers into the equation:

78.5 = 56.7 + 8.8 + 0 + piston dish volume
Piston dish volume = 13cc

In summary, this is what you'll need:

4.0 block (not decked)
Eagle forged 6.125" rods with ARP rod bolts
199 forged crank
Custom forged pistons with 1.828" pin height, 13cc dish, and 0.931" piston pin bore
2.02/1.60 big valve head (not decked)
Crane 753905 cam

With ML header, 2.5" exhaust, K&N intake, Flometrics 68mm billet TB, and custom chip, this setup would produce 238hp @ 5500rpm and 257lbft @ 4000rpm in naturally-aspirated form.
With 8psi of boost from a Vortech centrifugal supercharger, you're looking at outputs of 363hp @ 7000rpm and 318lbft @ 5000rpm. Woohoo!
Balance the whole bottom end to ensure maximum smoothness and enable the engine to survive 7000rpm. Use Mopar Performance HD main bolts and 258 main caps for maximum strength.

How would the valve train survive at 7000rpm? I thought you couldnt really go much above 6k with out having problems with the hydrolic lifters and pushrods.

This sounds like fun motor project if you had the money to throw at it...

AARON

I'm the guilty party who brought up this set up. I would keep it bellow 6k but I skip the blower and go with the turbo witch is what i intend to do. With the turbo you can realy pound the boost but keep the rpms low witch allows you to double the 8psi that the blower will do and turbos can be built cheap. I would also toss the 4.0 rods and get some aftermarket rods and find a good combination of rods and pistions that would work well. I haven't had a bunch of time to work on it so I dodn't have all the details but when i get time i'll post my results. BTW any one know where i can find a use borla header that may be beat up since i need a good stat for my turbo manifold.

Good point about the hydraulic lifters not surviving 7000rpm. Crane have a 274/284 degree solid lifter cam so that'll get around the problem. The stock timing gear also needs to be upgraded to a Cloyes dual roller.
The rods that I was recommending are the Eagle forged I-beam rods for the 4.0, not stock cast 4.0 rods. Use ARP rod bolts for strength.

REDXJ4FUN said:

BTW any one know where i can find a use borla header that may be beat up since i need a good stat for my turbo manifold.

Click to expand...

Why not use a stock manifold to start off with? The mounting flange is 1/2" thick so there should be no problems of it being easily warped. I dont know the materials you are going to use but I found this webpage that basically explains how to do a turbo manifold for the cheap. http://www.sdsefi.com/techheader.htm

AARON

I could do that but since I work with stainless for a living its kinda a personal thing i guess plus stainless holds up much better in high heat stiustions but a steel one would work.I could make y own flange out of stailess isnce i have a cnc punch at work or just have it lasercut by a friend.