I was just wondering if getting a motordyne spacer and a crawford plenum would be a good idea on a non-turbo Z. I read up on both of these items and I see substancial gains with each application! But for someone who already has a plenum and also a spacer, could u recommend what would be a smart move.

 

Motordyne products always have proven performance gains. Really can't go wrong with them.

 

+1 for Motordyne products ( iso spacer is my best mod , the best notesable butt-dayno upgrade so far ,for me at least )

 

I can not say that I understand your post. Are you trying to say you already have a spacer with a stock plenum, and would like to know the benefits of adding a Crawford Plenum? Or, are you trying to ask if adding both(Crawford Plenum/spacer) to a stock Z would be a smart move?

Here we go again with that "wording" issue...

 

You would not run both the Crawford plenum and the spacer together. They physically wont fit.

 

Doing both of them together isn't an advantage over just one by itself.

Take note of the dyno plots here.





The 1/2" spacer and the Crawford plenum perform almost identically. In fact, I would bet they are even more similar than what the plot shows due to simple dyno run to run variability.

So given that the 1/2" spacer and Crawford plenum are essentially identical, that allows you to do an equivalent "apples to apples" comparison of the 5/16" spacer against the 1/2" spacer (or Crawford plenum).

So take note of the differences between the 5/16" spacer agains either the 1/2" spacer or the Crawford plenum.... There isn't all that much of a difference for peak power. And this fact shows that there is a point of diminishing returns as you continually increase plenum volume more and more.

In fact, it not only shows the peak power has an asymtotic limit, it also shows that plenum internal volume has an optimum point with respect to area under the curve.

See the other plots and analysis here for more info on peak values and area under the curve. http://motordyneengineering.com/dynos.htm

When the MD spacers were in development a 3/4", 1/2", 3/8", 5/16" and 1/4" spacers were all tested and compared.

In all the testing it was found that the 3/4" spacer actually performed less than any of the other spacers. The peak was down and area under the curve was down.

So it is possible to make it too big for optimum performance. Not to mention there will probably be fitment issues. I think the Crawford plenum is pretty much maxed out for fitment under the hood.

So I recommend just doing one or the other.

 

No.

 

^Hahaha. Right on.

DavidV. Concise.

 

Thanks alot hydrozine, u pretty much summed up my question. Thanks again!
Thank u all for your help!!!