Difference between a 3.2 and a 3.4

[DohertyCM]

Just curious what the difference was in reliability and performance between a 3.2 and 3.4 motor..?

Intake systems?

Is the difference just stroke or bore?

What can you upgrade a 3.2 motor to? 3.8? 3.6?



Just tossing some bread in the water to see what bites...

Chris

[Shawn 357]

.2

A 3.4 is generally a 3.2 with 98 mm bore instead of 95 mm. You can run a different intake if you want.

[Jeff Alton]

Shawn is right, stroke is the same (74.4) but the bore is increased. You can use the standard Carrera intake or go will something a little more wild like ITB's or carbs or even MFI. But you can also use all those intake choices on any displacement motor you want.

Cheers

[JeremyD]

pretty sure about 3.7 is the max you can go - check LN engineering.

How big is your wallet?

[Bobboloo]

As Shawn said 98mm P+C on a 3.2 motor gives you 3.4. The stroke stays the same. You can with an even bigger bore but that will require cutting the spigots on the engine case. I believe you can take a 3.2 up to 3.7 with a big bore 102mm P+C kit.

[Jeff Alton]

Yep, 3.7 with some parts from LN Engineering. Charles, the owner, post frequently in the engine rebuilding forum.

Cheers

[Bobboloo]

Boy I sure type slow. To more posts before I hit the post button.

[DohertyCM]

how about reliability...I know the 3.2 is a tank and just keeps going and going..does the 3.4 have the same reputation..?

[Jeff Alton]

No reason a 3.4 can't live like a 3.2. (hope so, I just finished my 3.4!) The 3.2 has a couple of weaknesses, valve guides and head studs. Both can be remedied when the motor is apart for the 3.4 upgrade and should provide better service than the originally fitted pieces.

Cheers

[Bobboloo]

I've never heard of any problems.

Provided you replace them with Mahles you should expect the same lifespan as the stock.

Now I have heard that if you mix JE pistons with Mahle cylinders then you will have a shorter lifespan.

However, Charles of LN Engineering claims that JEs have a comparable life span when used with his cylinders. He designed them to match the JEs thermal expansion rate so this allows you to run a minimal gap which translates to a longer lifespan.

[Quicksilver]

Mahle makes P&Cs in 3.4 (98mm), 3.5 (100mm), and (special for Andial) 3.7 (102mm). LN Engineering makes cylinders from much better materials in the same sizes but they use JE Pistons. The 3.4 cylinders from both manufacturers will slip into a stock case. The 3.5s and 3.7s require that you bore the case opening so that they will fit.

Mahle pistons are the gold standard for quiet operation and long life. The LN cylinders are made from vastly improved materials so they are stronger, have double the heat conductivity, and have quite a bit more cooling fins per inch. My 'perfect' combination would be Mahle pistons in the LN cylinders. In the 'normal world' my choice is the LN cylinders with the JE pistons. I would expect a minuscule increase in piston noise until it warms up but otherwise the improvement of the materials in the LN's cylinders is the big selling point.

Most builders recommend switching to a twin plug system when you go to a 3.5 and pretty much require it for a 3.7. With the 3.4 you can go twin plug which makes it easier to raise the compression but it isn't that important for a 'stock type' replacement.

Fun facts about the displacement changes:
- The stock 3.2 liter is actually a 3164cc motor.
- The 98mm 3.4 liter upgrade will get you a 3367cc motor. (6.4% increase)
- The 100mm 3.5 liter setup will get you a 3506cc motor. (10.8% increase)
- The 102mm 3.7 cylinders end up as a 3647cc motor. (15.2% increase)

[89911]

I used Mahle 3.4's and twin plugged my engine. The Mahles aren't cheap. About $4500 a set. If you start with solid 3.2, add the upgrades and hit all the area's needed for improvement (rod bolts, valve stems, cams, intakes, valve springs), you can have a rock solid engine thats output equals or surpasses a 3.6.

[sp_cs]

whose got the best prices on Mahle 98mm barrels and pistons?

I have thought going QSC/JE via Supertech - just need convincing about longevity.

Cheers