I had a question, what differences are there with purchasing a Motordyne spacer unit, versus buying a whole new Plenum from Crawford...which is better for performance? And are there any negatives for any of them. Anything wrong with getting the spacer instead of the plenum?

 

get the spacer!

 

There are several threads on this controversial subject both here and on My350z.com, try the search function it is your friend =)

 

The short answer is a few questions. What is your goal?

If you want good performance for a fair price, get the spacer.

If you want maximum performance for ~$100 more, get the plenum.

If you do not plan on modifying your headers, cats, exhaust, etc... get the spacer.

If you think you'll turn into a mod junky (don't be in denial) get the plenum.

The above is just my opinion. YMMV.

 

One more thing to add to Neffsters post. My opinion is that a spacer creates another seem that could increase the chances of having a leak. INstead of having one meeting point (Plenum to Intake Manifold) now you have 2 (Plenum to spacer & Spacer to Intake Manifold). Now this may not be a problem for some folks but my hypothesis is that with the additional seem and the introduction of another piece of metal (Different metals conduct heat differently) it just increases the chance of leakage! Again, only my opinion. I do think for the $$ the spacer is a nice mod. I went with the new crawford cast plenum but haven't slapped it on yet because it is at the powder coater.

 

neffster
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Join Date: Feb 2004
Location: Oviedo, Florida
Posts: 3,459


The short answer is a few questions. What is your goal?

If you want good performance for a fair price, get the spacer.

If you want maximum performance for ~$100 more, get the plenum.

If you do not plan on modifying your headers, cats, exhaust, etc... get the spacer.
If you think you'll turn into a mod junky (don't be in denial) get the plenum.

The above is just my opinion. YMMV.

Okay this is what im dealing with. My G35 is stock, all I have is the HKS hi power Exhaust system. So if i install a 1/2 moto/ spacer on my G will i benifit from the 1/2 spacer? According to Neff im going to have a negative experience with the spacer on my G because I have an exhaust system installed. Need some feed back please.

This is whats really bothering me, this is what you said,
"If you do not plan on modifying your headers, cats, exhaust, etc... get the spacer". <===Why ???????

 

I have a spacer, along with cats and exhaust, and intake mods. (see list in my sig)

The spacer is easier to install.

You won't have any issues because you have an exhuast, though neff didn't elaborate I think he is saying the spacer doesn't do enogh if you have other mods, all evdidence to the contrary.

EITHER SOLUTION IS GREAT.

Use of a 3/8" spacer allows you to keep your stock engine cover / look

Starting from stock a spacer will give solid performance bump

 

The only dyno comparison of a spacer vs aftermarket plenum was the one I did a few months ago, when I first met Hydrazine. Of course more people dynoing and testing out the configurations would be nice.

There's a long thread about that day of testing in this site. In short, a 1/4" spacer with stock plenum made slightly more power up top (above 6K RPM) than a Crawford V5. The cast Crawford might make more power, but I haven't seen dynos comparing V5 to cast.

I have also detailed the exact events that occurred that day with testing, describing how the dyno was done, who did it, how no runs were thrown out, how the car was not moved once it was on the dyno, and how the runs were all completed at the same coolant temp.

The one piece of data that I wish I had was how much power on that dyno on that day the car would have made with both the 1/4" spacer and Crawford V5. On a separate dyno done last week, the car ran 248 WHP SAE.

I'm using both products concurrantly. I think they're both great.

 

You are using the spacer along with the Crawford Plenum??????
Why?

 

For the extra $100 why not go for the crawford cast plenum. $100 is not going to kill you when you are driving a $40K car.

 

Mods aren't always about just the cost. I for one like keeping my engine looking stock while my warranty is involved. The spacer does that and gives me as good of a performance boost as a Crawford. Some dynos even show the spacers to outperform the Crawford. So for me it was an easy decision to go with the Motordyne spacer

 

I already had the Crawford. Hydrazine had an offer for a free spacer in exchange for a controlled pre and post dyno testing of his spacer. Since I was going to dyno the car again anyway, I took the offer. So I got a spacer in exchange for dynoing my car.

 

So what is the Verdict on the two combined E K? Did you dyno before and after the spacer and with the Crawford on both? Any butt dyno comments?

 

Only $100 more? You can get a Cast Crawford for less than $300? That's a pretty good price. The last time I checked the Crawford cost almost twice as much as the spacer.

 

Haven't seen prices for the spacer posted. I thought they were mid $200's? NO? (And old, expired group buy prices don't count).