Originally Posted by booger

You seem to know every thing MechEE . You ask a question ????????
And also....a post that is more than one liine....and not negitive ????
WOW !!!!!!!!!!

Originally Posted by Hydrazine

Yes, I have dynod the spacer by itself on a REVUP engine and it did absolutely nothing.

As shown on the Motordyne website dyno section, the spacer produces power almost exponentially, on a 287 HP engine, with increasing RPM (up to redline). They can easily produce 10+ HP at redline.

When a "REVUP" lower colletor (with shorter runners) is put onto a 287 HP engine, it can produce a blip of 10HP but it only produces more power in the last ~500 RPM. The REVUP lower collector loses a lot of power everywhere else on the power curve.

So the question is why would Nissan use shorter runners to gain 10HP when they could have made the top half of the plenum a little taller to gain 10+HP and not lose all the TQ and area under the curve? I don't know....

But by knowing how they traded HP for TQ it wasn't hard to figure out a better way to get both.

By switching in a 287 collector (with longer runners) on a REVUP engine, a lot of TQ and area under the curve is made. But there is a very significant rolloff of HP above 6000 RPM.

Now if a plenum spacer is also used on a 287 collector, it will add power very rapidly above ~5500 RPM. So in short, the combination of the 287 colletor with a plenum spacer produces much more TQ and average power under the curve with only a small loss (~3-5HP) above 6200 RPM. Its a very good trade.

Then there is the MREV+. I found through a lot of dyno testing that while larger spacers add more peak HP, they have diminishing returns and even start to lose area under the curve.

It is best to minimize plenum internal volume to maximize TQ but it is best to increase spacer hiegth to maximize flow area above runners 1&2 fo more HP. It is the added heigth that increases flow area to runners 1&2 for HP, but the added volume also diminishes average TQ to all the cylinders.

But why accept a compromise of one or the other? By machining down the excess material above runners 1&2 and then recontouring the inlets, it gives you the best of both HP and TQ.

Minimized plenum internal volume for more TQ and maximized flow area above runners 1&2.

That is what produces the results of the MREV+.

Originally Posted by MechEE

Excellent info. I too find it odd that Nissan would do this.

So with a modified '03-'04 lower collector (MREV+), is there still a need for a 5/16" spacer? It seems there would not be from your explanation, but on your website the MREV+ is an additional option to the MREV packages, which include a spacer.

Originally Posted by Hydrazine

Y
Getting the MREV+ and deleting the 5/16" spacer could save some money but I don't think it would be worth it.

Originally Posted by myGspot

i installed my 5/16 a few weeks back. Ran into problems duruing the install when one of the plastic spacers didnt fit on the plenum. I ended up shaving it and modding it enough to fit.

Install is not hard if you know what you doing. But due to the part that wast fitting right it took me about 4hrs to get it done.

My impressions are not great. Before the plenum spacer i had z-tube, test pipes, exhaust. At 3.5k i would feel that it pulled like no other. now with the spacer... the 3.5k pull is not there. It pulled but didnt feel any major difference. At around 6k it looks to be that it revs faster, but then again it could be just me.

May be with my mods before i cant tell teh difference, but i cant say i noticed anything major.

Originally Posted by scorcher76

Last but not least, (and maybe some of you can help me), after the spacer installation, I had trouble reconning my Z-TUBE on the plenum. Do I need special spacers for that?

Alex