The OEM air duct is as squishy as a wet twinky. At high speeds the duct collapses, restricting air flow into the throttle body. In this first pic I am squeezing the stock duct, which reveals the duct had actually been pulled off the air cleaner housing when it collapsed.
I removed the OEM duct and held it up to see how it looked from the inside. Not only is the inside diameter greatly reduced when it collapses, I can't help but feel this accordian inner surface does not flow air very smoothly. Note, I am squeezing the duct, it is not out of shape from collapsing. It is only collapsed when you are driving fast, so you may not even know this is happening to you:
Here's the inside of the Mark Coplon air duct. Notice the shiny stainless steel lining inside this baby!
Installed, it looks just like stock since it is a stock air duct with a lining. But you can't squeeze this one, it doesn't collapse from air pressure, and the flow must be much smoother:
Now to test this out tomorrow!
Location: This city NEVER sleeps! Frank's back yard!
Re: Coplon Air Duct (VetBoyZR1)
Mine was actually squished together at rest, and almost closed at WOT. Mine is a 90, so it is more pronounced - but the Coplon duct certainly deals with this problem nicely. Also expands the duct by 15%! Just watch the undersurface of your hood - you may need some felt on the hood to prevent abrasion - my brother's Jeals has wear marks in this spot. :seeya
I have the same problem with mine. Every time I take my Beast out for some exercise, the air duct pop off from the left front. The stock air duct obviously collapses under WOT. Where can I get the stronger Coplon replacement?
I also had the same problem, when I went to the track it fell off 1/2 way down! and I lost the clamp!!
I bought a Mark C. air duct and problems are gone! :D
I have the same problem with mine. Every time I take my Beast out for some exercise, the air duct pop off from the left front. The stock air duct obviously collapses under WOT. Where can I get the stronger Coplon replacement?
mine original is done It also pops off on the front and it pisses me off!
I just cant ever find time when Mark has any left.
I had the exact same thing happen to me. The stock duct came off the air filter housing and was collapsing big time. My car felt like it was making all of 30 hp. Then I would pull over and it idled fine. I was really confused :confused: and very happy when I found out it was an easy and cheap fix. Marc had them in stock 2 months ago, that's when I got mine.
I was the only ZR-1 at the track. Last time the only reason there were 2 ZR-1s was because Garth Koniver came along with me! It was way too hot and humid yesterday to make a fair comparison based on speed. I was happy just to see the duct stay put. We were all off by 2 to 4 tenths, and my trap speed was down at least 3-6 MPH. I could not even break 110 yesterday. We had the East Coast Show and Go all morning, then the Corvette Challenge from 3 until 9PM. It was a long HOT day and some of our drivers were sicker than the cars from the heat. As for my car, I am considering doing a little something to pep it up a little. I'm undecided as to a P&P vs a 368. I just don't believe a P&P job is of as much value on a 405 car as it is on a 375. Isn't it funny how we can get used to a car that runs so nice and always want more? I'll be focused on some Verizon issues for a while (think it's called a STRIKE), but we'll see in a few months! So many guys getting 415's done makes me want to just go ahead and take the big leap. I've got a pile of parts sitting here next to me, so somethings going to happen soon!
PS I just heard from Mark. He is very pleased to see the feedback from his previous customers. He did not express any concern about meeting the demand for new orders, so if you were interested in getting one - go for it!
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Coplon Air Duct
