Milennia motor

[GizmoMX3]

Went to the local pull a part today. I found several milennia v6 motors ranging from 95 all the way through 2002. I've got a 94 gs. Which year or years would be the best to get? I noticed the 95-97 heads were kl31 and the newer models had kl101/ kl1a1 heads. I'm still trying to make sense of all the minor differences as there seems to be a lot of miss information. Also what ecu and air flow sensor should I be looking for?

Nate

[RX8SE3P]

well they all have kl01 cams. the kl01 heads are mis matched to the intake manifold which has square ports. but kl01 heads have a supposed stronger valve train so you could run higher lift camshafts without Issues. I'd just pick the best looking cleanest motor. shine a torch in the oil cap hole and see which looks the cleanest.

ecu and vaf depends if you have a 1996 or earlier? if you want to be really fancy rip the whole wiring loom ecu and air flow setup off the car you pull the engine from.

[wagZE]

The 02 millenia motor I run is great. I have noticed several updates Mazda has done to it.
Square can caps instead of rounded
No coolant lines running into oil pump
Kl 101/1a1 heads (must've had issues with the kl31s
And of course this one is big The oil pan is deeper under #6 cylinder, Mazda must've updated since it was so common to starve #6 for oil & kill the motor. Keep in mind you'll need to get a welder there to modify piping. Also keep in mind if your car is lowered the oil pan will rest very low to the ground. Be careful of speed bumps/ sewers or reinforce the plug part of oil pan with good welds (preferably off the car).
IMO Mazda wouldn't have changed things for the worse. Definitely recommend as new of a milli motor you can find.

[Jforce]

And of course this one is big The oil pan is deeper under #6 cylinder, Mazda must've updated since it was so common to starve #6 for oil & kill the motor. Keep in mind you'll need to get a welder there to modify piping. Also keep in mind if your car is lowered the oil pan will rest very low to the ground. Be careful of speed bumps/ sewers or reinforce the plug part of oil pan with good welds (preferably off the car).
.

Didn't know that one, do you have a pic of the differences?

[GizmoMX3]

I was under the impression that kl31 heads were better flowing than kl101/1a1? The only draw back was the weak valve spring retainers. I was planning on taking the kl31 heads off a 95 milennia in the local yard. There is also a clean motor in an 02 milennia available. I was planning on switching the heads and putting the stronger retainers in the kl31 heads while it's all apart. Is this worth the effort? Also what's the best tb to look for? I've seen kl47, kl01, and kl1c?

[SuperK]

KL31 heads are a great drop-in option if you're using the millenia or imported straight neck manifold.

They require no intake runner matching. the only working you will really can do is work the valve seat area, and swap the intake springs and retainers.

KL01 heads are great for modifying. Not because they flow better.

Ideally, you can port match the KL01 heads to the square intake runner to use the millenia or straight neck manifold.
Then work the valve seat area, as you would the KL31 heads.
The benefit of the KL01 heads are the lighter and smaller intake lifters.

You will get varying opinions on using the KL01 and using the 98+ 626 intake manifold... My opinion is it's a poor performer.
You will then get another opinion that if you port and work the 98+ 626 intake manifold, it can perform really well...
My opinion is you can do the same work to the straight neck imported manifold and see better gains.

KL47 throttle bodies work for millenia, imported straight neck, or 98+ 626 manifold.

[Jforce]

Well the 98+ 626 manifold performs better than the KL47 manifold, for me.

[GizmoMX3]

How does it perform better? What is your engine setup? Heads, cams, manifold, tb, etc.

[Daninski]

Well the 98+ 626 manifold performs better than the KL47 manifold, for me.

I'd like to know this as well. Thanks

[Jforce]

How does it perform better? What is your engine setup? Heads, cams, manifold, tb, etc.

Setup:

SS Manifold
10:1 ZE bottom.
DE D shaped Heads
KL68 TB
KLG4 Manifold, knive edged the neck.

Benefits I found:

More power in mid and high range, less in low.

+Looks better (still need to tidy things up so), stutbars fit easier, sounds also better.

Downfalls are:

-Brakebooster clearance is minimal, modification needed.
-And as you can see, not to great at the battery. But the battery will be replaced with a smaller one anyway.
-U need to plug a hole, cause it will create a vacuum leak.

I had a spacer, but i had to this to make it fit:



oh and don't do it like this -.- ,its aluminum it will grind easy use a dremel.

https://www.youtube.com/watch?v=cGWbmvhx0lE

[SuperK]

You're comparing it to the curve neck manifold found on the Xedos/millenia engines.


not to the straight neck



the curve neck is convenient because of it's easy fitment. But it hasn't been known for it's top end power.

[Jforce]

You're comparing it to the curve neck manifold found on the Xedos/millenia engines.


not to the straight neck

Well the 98+ 626 manifold performs better than the KL47 manifold, for me.

ofcourse that's what is said.

[SuperK]

Oh. The throttle body is KL47, intake manifold isn't stamped with any part number. Wasn't sure what you were referencing. Carry on.

[Jforce]

it is stamped though.

The manifold is stamped 47 right here:

[MrMazda92]

Stock for stock, here's the manifold lineup:
KL47(Millenia, Xedos, w/e): Best low end torque. Limited top end ability.
KLG4(98-02 626): Smooth powerband, but the bottom end is lacking. Top end improved over KL47.
KL31(The "straightneck" from the J-spec MX6): Low end sucks. Midrange is pretty nice. Top end is excellent.

Keep in mind, this is from my own experience with the manifolds, and the KLG4 was the complete engine in a 626. Take that one with a large grain of salt.

The KL47 and KL31 were in my own KL MX-3 with a '95 Millenia engine(KL31 cam swap, Fidanza, EGR deleted). The manifold was the only variable altered in my testing.