bigjohnson

Any links on placing the MDX Crank in the 3.2?

mrsteve

iTrader: (1)

I don't think anyone has just done the MDX crank swap. The people running the 3.5 have a completely built short block.

Although I have been told that the crank swap is possible. The only problem is crossing your fingers and hoping your compression ratio stays below 12:1.

According to EricL's calculations you should be. Somewhere in the high 11's:1.

Basically you'd need to pull the engine and swap crankshafts. Then do a compresion check. If you are above 12:1 you'd need to upgrade rods and pistons to decrease your CR.

Ant7701

or you could use different head gaskets to increase/decrease ur compression ratio a little..

EricL

Static compression is not related to dynamic compression *and* a compression test will not tell you compression ratio. You’d have to CC the head – or get the information from a vendor -- to get the combustion chamber volume with the pistons that you planned on using, and then use some math to include the swept volume. In addition, depending on the rings and condition of the bores, you could actually “read” lower cylinder pressures with a higher compression setup. IOW, doing a compression check will NOT give you the static or dynamic compression ratio of an engine.

Compression Ratio = (Combustion chamber volume + swept volume) / (Combustion chamber volume)

If you put in the crank, you have to change the rods too...

The high compression is predicated on CLS pistons, and you'd need some high-octane gas – at a minimum.


Here is an “Engine Compression Ratio Calculator” link:

http://www.csgnetwork.com/compcalc.html


Here is a link that explains some of the aspects regarding compression ratio, dynamic vs. static compression, and effects of cam timing with compression:

http://e30m3performance.com/myths/mo...comp_ratio.htm

mrsteve

iTrader: (1)

^^

81brettkeith

never seen another one but mine runs pretty good. You will have to have a spacer machined because the 3:7crank is shorter then 3:2. Also I don't know if they make better Management Systems then they did 3 or 4 years ago when I put mine together but I always have a random misfire check engine light cylinders 1 through 6

81brettkeith

Stock 3.2L block
MDX 3.7L crank,rods,intake manifold and T.B.
3.5L pistons TL
if you're assembling this it all goes together quite nicely it's not until you try to mate the engine and transmission that you realize the flywheels not even engaged because of the shorter crank. Machine shop charged me like 150 to fill the void.
With the block .30 over, a port an polish, (critical)cat deletes(this is where most power was hiding on mybbuild)AEM cold air, i had to weld steel plates on the front and rear of my collectors and mufflers because i blew/burnt out every place of my Tunabe gold medallion exhaust where the exhaust changed directions. .
could use some advice on management system or tuning help advice

Karanx7

iTrader: (2)

14 year old thread, bud.

81brettkeith

so wtf are you doin init

johnboy1313

Telling you to pull your head outta your ass.