Were you measuring the material thickness of the front air horns to get this 10-11mm number?

 

thickness of the fronts differs from the middles, and rears

stock i believe i right around .600" but I'd have to measure again

If after you had milled them they measured 10-11 mm (~.400"), its definitely more than Motordyne does.

 

Guys, to be honest, I don't recall exactly. I was under the impression that 10mm and 11mm was close to the Motordyne specs, if not right on the mark. Maybe I am wrong, but I remember seeing a picture where a guy measured the front runners on an MREV2, and I'm going my memory of off that.

Willey, how do you think the increased volume of my lower collector affects gains? Do you think the extra work that went into mine actually yields less gains than the MREV2?

 

I've milled mine down to about 0.440"-0.450".

 

Dave, are you also installing an Aramid gasket?

 

I dont think the volume is the concern but the even flow of the cylinders. That is why MD has a specific spec on how far they mill the front cylinders down.

Overall volume has been shown to be beneficial at higher rpms but not so much on lower end. All in all, i wouldn't say that it hurts all that much. The other parts to what motordyne does that haven't been done do help with the flow characteristics too though.

 

Nope. I don't doubt these "cooling" gaskets work in keeping the intake manifold cooler, but IMO intake air temp is far more important then the temp of the intake manifold. The air spends a fraction a second in the intake manifold before it's combusted. It just doesn't spend enough time lingering around to heat up. Addtionally, the ECU is setting the parameter based on the air coming in at the MAF. Anything past that is a bit of a moot point.

I installed my modifed plenum this afternoon. Only took about an hour. I reused all the gaskets too Unfortunately it's cold and wet out and everytime I tried to punch it in 2nd at 3000rpms, the tires would just spin. Otherwise, the car drives fine. Hopefully tomorrow it was dry off a bit.

 

^i was wondering about these aramid gaskets as well DaveB. After installing Mrev+5/16 spacer i have noticed that the upper plenum is completely cool to the touch all the time now (except for after letting the car sit for awhile obviously) I am wondering if the lower plenum is just as cool. If it is then this would leave me to believe the aramid gasket is really keeping things cool. If its not then its the 5/16 spacer thats keeping the plenum cool.

 

It's not the spacer because I've had a MD spacer for about 4 years and my plenum gets very toasty in the spring and summer It don't worry about the hot manifold because what really kills the performance is the crappy density altitude conditions (high ambient temps and humidity, low baro pressure).

 

After about 10 days of driving now I can post my experiences with this manifold. I usually wait at least 7 days to post my observations because it's my experience that it takes most any late model ECU about 40 or so strarts to fully take advantage of intake/exhaust modifications. So far, I've driven in 25 to 70 degree conditions with DA conditions varying from just below sea level to around 3000'.

Here's what I've noted:

1) There's definitely a bit more throttle response from 1500rpm to 3000rpms. This is great for around the town driving. Nothing earth shattering. It's like adding another HR y-pipe.

2) The engine feels more refined, flexible, and willing to rev above 5500rpms. Instead of feeling a bit truck like in the high rpms, it's a bit smoother.

3) There's no real change in induction noise.

4) No driveability quirks. MPG is the same.


Modifications I made to the manifold where:

1) Shaved the front two air horns down with a 40 grit flapper disc. Horns milled down to about 0.440"-0.450".

2) Random orbital to knock down the casting grain a bit on the exterior surfaces of the six air horns. These surfaces were no polished completely smooth. Completely smooth is not a good idea.

3) Polished out some of the rough casting edges around a few of the airhorns and cleaned up some casting flash on the inside of the runners.