Changed my air box

[vilant]

I switched my air box from this aftermarket one
http://www.zr1.net/forum/picture.php?albumid=217&pictureid=1687
to this mostly original air box
http://www.zr1.net/forum/picture.php?albumid=217&pictureid=1685
I had the original plastic bottom, but was missing the screws and top piece. A big thank you to Dave J. for giving me his old air box (actually only ended up using the screws, Dave. Have everything else if you would like it back) :handshak:. The top piece I did have turns out (after some looking for the original) to be an aftermarket for a 94'-95' ZR-1. They say it will fit a 90', but it turns out it doesn't quite make it. The shroud that is on top, keeps it from sliding all the way down so the screws can catch. Look at the one on the right.
http://www.zr1.net/forum/picture.php?albumid=217&pictureid=1688
So I drilled out the rivets holding it on, and wah-la, it now fits.
http://www.zr1.net/forum/picture.php?albumid=217&pictureid=1684
Problem is the paint is missing where the shroud use to be. I colored it in w/ black marker for now, lol. But eventually I'll take it to a friend, have it sanded and repainted. You can't tell unless you stick your head down in there and look.
http://www.zr1.net/forum/picture.php?albumid=217&pictureid=1686
Once I have the holes filled in where the rivets were and repainted, it should look just like an original 90' air box top. I'm sure I could just sand down the piece and paint it myself, but I can have it done cheap. Quick, easy way to turn the 94-95 part to a 90.

[Kevin]

looks good. i have my stock one kicking around somewhere, i'm running an open one now

[GOLDCYLON]

Looks good.

[Paul Workman]

Looks nicely done!

I had one of those (SLP?) "Claw" intakes on my 95 LT1 car. Intuitively speaking, it looked to have some potential over stock, but never dyno'ed it to actually see if function = form.

The stock intake on the LT5s is an area worth exploring, far as improvements go. Case in point: The vacuum is so great that often the accorion tube will collapse at WOT, in spite of an open lid box (I discovered).

1) The collapsing screams "impedance" at the opening of the tube; enough so that there is a pressure drop within the snorkel sufficient for outside air pressure to collapse the unsupported tube. And, when applying principles of "laminar flow", it would be difficult to find a surface with greater impedance than that accordion style tube bridging between the filter and the intake horn. (This was addressed on the C5 and C6 with the smooth carbon fiber bridge instead.) Installing hoops keeps the tube from collapsing, but does nothing for (theoretical**) surface impedance/internal pressure drop.

2) The "Coplan" sleeve insert does provide a bridge over the accordion surface, which has to be an improvement to flow (I'd bet a ham sandwich on it!).

**Note: I have to leave it at "theoretical" based on observation and basic flow principles. But, w/o actual quanitative measurements of air pressure or velocity to prove it, quantification is stll "at large".

So, from a flow dynamics point of view, the "Claw" appeals to my sense of flow, compared to stock. Sure would be interesting to see some "before and after and back again" dyno comparison of that system and stock.

I'm just sayin. This is a topic I'm studyin' up on at present, in conjunction with increases in TB area, is why all the elaboration. (Don't mean to steel the thread:p)

P.

[XfireZ51]

One indicator of inlet performance would be how close to 100kPa you get at WOT.

[Paul Workman]

One indicator of inlet performance would be how close to 100kPa you get at WOT.

No agruement, but a simple vacuum gauge in the intake horn, as in a "before and after" test, would be easily done as cheap test...methinks. No?

P.

[vilant]

Thanks, guys, I don't know if it looks good, lol, but it will when I have it painted.
Paul, the claw was still connected to the air horn via the accordian. Are you saying the accordian would collapse at WOT w/ the original air box but not the claw? Or either, because of the accordian? How did you find out it was collapsing? And where do you find the insert your talking about? It would be interesting to see what the difference is between the two on a dyno. I have both, but it costs $150 for 3 runs on a dyno at the shop near me. Not sure I want to spend that to quell my curiousity though, lol.:cheers:

[Kevin]

The accordion will collapse matter what set up you have. You can check by watching it while you open the plates by hand. You will see it sick down. The coplan duct is no longer available, I know because I bought the last one from him at bg a few years ago. It's a stock looking duct with a an aluminum insert in it. Back in the day we also used a coffee can...but I can't remember the last time I saw a metal coffee can.

Before buying the duct from mark, I went through several factory ducts and due to the under hood heat they get soft and suck closed under acceleration. I remember thinking Keith's black car had bad injectors when we saw his dyno numbers, mr. Haibeck saw that his duct was collapsing. Mr. Haibeck sells hoops to keep this from happening.

[XfireZ51]

I bought this one for mine. Tough to install but it's pretty stiff and smooth. Also reasonable at 44 bucks.

http://www.ebay.com/itm/ZR1-ZR-1-LT5-LT-5-Intake-Connector-Duct-Stiffener-/310059954936?pt=Motors_Car_Truck_Parts_Accessories&hash=item48310372f8&vxp=mtr

The MAP sensor is effectively giving you a "before and after" since before is 1atm. Of course you need a scan tool to read it.
I learned this year that Marc removes his air filter also when he runs the car in addition to removing his mufflers.

[GOLDCYLON]

Yep thats identical to the coplan insert that's made out of metal. Don't forget the haibeck hoops also solve the collapse problem. Both are nifty little mods

[tomtom72]

:o I used a section of dryer duct to solve the collapsing issue, maybe I got some smoother air flow in the deal. It was a cheap backyard fix. If you have some patience you just buy one section of 6" duct if I remember right and cut it to length first. Then you join the seam, then you squash it to an oval shape so it fits inside the OE duct. That's the part that takes time & patience to get the fit just right so as not to loose too much flow. As a "insurance" policy against future collapse of the metal duct I took a framing joinery flat plate, that was large enough so that after I bent two opposing right angles, and used that to support the final oval shape. I screwed it in place driving the screws in from the outside of the duct. I used standard peanut framing screws for that as they're only 7/16" long. I have had that in the car since 05 and it seems to work great!

Like I said it will take some time to get the oval just the right volume & shape as when I was done shaping it I used wire-Eze to get it inside the OE duct. LOL I should have waited for the guys Dom used to come up with theirs, it would have saved me the time! LOL

:cheers:
Tom

[Paul Workman]

Thanks, guys, I don't know if it looks good, lol, but it will when I have it painted.
Paul, the claw was still connected to the air horn via the accordian. Are you saying the accordian would collapse at WOT w/ the original air box but not the claw? Or either, because of the accordian? How did you find out it was collapsing? And where do you find the insert your talking about? It would be interesting to see what the difference is between the two on a dyno. I have both, but it costs $150 for 3 runs on a dyno at the shop near me. Not sure I want to spend that to quell my curiousity though, lol.:cheers:

I didn't realize the "Claw" retained use of the accordion tube. Too bad - a missed opportunity, methinks.

Yes, the accordion, otherwise unsupported, will likely collapse at WOT even if attached (in my case) to an open K&N filter box.

I learned on this site that collapsing was an issue with the hose, and it occured at around 5500 rpm or so. That too was my case: fell flat on it's nose at 5500 rpm.

Killing two birds w/ one rock, or sleeve, as it were, I used a strip of 16ga aluminum cut approx. as wide as the tube is long and approx a foot or a little more long and shaped it into an oval to fit snuggly on the inside of the hose. I trimmed the lenght to overlap enough so I could pop-rivit the seam. Works like a dream, and I knew it the first time I went WOT and it pulled hard to 7000+ rpm.

Not wishing to beat a dead horse, but some go to all the trouble of routing out the inside of the air horn at the same time the TB is opened up to 63mm or so and not address the accordion hose seems counter productive (to me). Certainly the TB effort works - well known fact, and maybe porting the air horn helps too. But, I have an idea that to go to that extent and NOT address the flow across that accordion bridge piece can't be as affective as it would be if it was smoothed out. And, when I look at the C5 and C6 filtered air intake tubes - i.e., smooth - it seems like that issue was finally taken into account.

Dyno time is expensive, no question. And, dyno time is further increased when there is any significant increase in output resulting from a physical change, as the tune may need to be tweaked to be keep everything in balance after the change. However, it would be interesting to test this and other ideas to see what is valid and if so by how much. It gives me an idea for possibly a funded dyno session setup for the purpose of exploring this and other power adder ideas. After all, the Registry helps sponsor certain social events, why not a a "tech" event that consists of a specific, formal set of experiments in order to quantify validity? Just a though.

P.

[vilant]

But, I have an idea that to go to that extent and NOT address the flow across that accordion bridge piece can't be as affective as it would be if it was smoothed out. And, when I look at the C5 and C6 filtered air intake tubes - i.e., smooth - it seems like that issue was finally taken into account.

Dyno time is expensive, no question. And, dyno time is further increased when there is any significant increase in output resulting from a physical change, as the tune may need to be tweaked to be keep everything in balance after the change. However, it would be interesting to test this and other ideas to see what is valid and if so by how much. It gives me an idea for possibly a funded dyno session setup for the purpose of exploring this and other power adder ideas. After all, the Registry helps sponsor certain social events, why not a a "tech" event that consists of a specific, formal set of experiments in order to quantify validity? Just a though.
P.
I don't doubt a smooth duct = smoother air flow. The question is: Is there any noticeable change in engine operation or performance between the ribbed vs. smooth duct? Not so sure you could really acurately prove it. Maybe a "tech " event is the way to find out. We need to get a list of things to test, then find a shop to rent for the day, and get enough people to split costs and test different theories. I would be into doing that, I would test air boxes, ducts, and coil packs. I'm looking into Marc's hoops to prevent the collapsing issue (even though this hasn't happened yet). :cheers: