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ZR8ED Two Piece Belly pan project


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Thanks for the run down mate!

 

I wouldn't have thought of doing the flat bottom plate without seeing your prep work and I wouldn't have thought of using expanding foam or even how to cut it - so thanks for sharing your information!

 

It would make my project a lot smoother!

 

I have learn't the hard way that it is so much easier to get the plug right instead of trying to get the copy right as you start close to the beginning again when you are trying to fix up the copy - can be very tedious :-)!

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I have been receiving loads of emails regarding my pan, and if I have plans to continue it further back, and rebuild my rear diffuser. I had a large rear diffuser until I had the rear fascia designed and built which made it unusable and in need of a major redesign. I removed it and have not gotten back to it.

 

1 I don't have any measurements of my current pan, and if I did, it would not likely help much, as my VG30ET conversion is a complete "one off" and I made the pan to fit around it, the oil pan, and of course my air dam is now a "one off" so the front measurements would be quite different. I still have the old pan that I could measure up if someone wants it.

 

2 I do plan on rebuilding a rear diffuser, but I will leave it alone for now and just "think" about it, and how I would design it this time. Mounting would be very straight forward as I would use some of my original mounts at the differential, and there is lots to mount to on the fascia (rear roll pan)

 

3 I do have plans to fabricate a pan that joins the two floorboard frame rails, but those plans are on hold until I redo my floors and rails. It is too much work to build it, only to change the mounts when the floors/rails are all redone, and most likely modified. I am enthusiastic about attempting it, and seeing the effects though. I'm not sure where they will start and end, that will all depend on clearance around the tranny, exhaust etc.

 

4 I have not tested the new pan at high speed. My old pan though did work fantastic, and noticeably improved stability well beyond reasonable speeds. I fully expect the same results.

Cooling issues were never a problem with the old pan, they actually improved with the use of the pan. Overall, I do not expect to see any noticeable improvements over my last pan. Time will tell. Some testing will happen at a future club track event. I'd love to see it in a future windtunnel event, but that will not likely happen, as my results would not be all that useful to the majority of Z owners. It would be cool though.

 

5 No I'm not a bodyman, engineer, tinsmith, etc though I do work in the automotive field, and I have lots of links to the world of Z's, but mostly I just love working and customizing my Z, and I like to do things differently for the sake of being different. Anything I do with this car is totally do able by someone willing to take their time, research, plan, and have reasonable tools and a place to work on it.

 

6 No the car is not for sale.. well never say never, but not for any reasonable price.

 

Thanks everyone for the support and comments!! :)

Scott.

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  • 1 month later...

A month later and a few highway runs under my belt:

 

Well, the pan is working pretty well. I did some trial runs around the block to see if there were any clearance issues, but it was after a few highway runs, that I tried a few fast turns (lefts and rights), when I discovered a slight rub under hard left turns. I had painted the inside edge of the airdam, and an aluminum bracket that holds the upper "flare extension". I found that the tire rubbed slightly and rubbed off some of the paint. It took a few turns before I could track it down, until it rubbed enough to see the wear. A little bit of dremelling on the passenger side bracket, and all is well. I have shaken the car down pretty well, and have not had any rubbing/shifting/scraping etc. It does not make any noise while driving (for anyone concerned about the thickness of the aluminum causing it to flex and make noises while driving)

 

I do have a couple of speed runs completed, and have not had any ill effects. I do not have enough seat time yet to determine if the larger pan is any better that the old one. It is nice and stable at speed just like the old pan. I was at my Z clubs yearly show/shine last weekend, and I have a few pics that I will link up (from other members that posted photos from the show) It was partly cloudy which always helps a black car. hehe!

 

Scott.

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Pic as promised.

 

zfest280z.jpg

 

Austin. I wonder if it is the splitter part (sticking out infront of the airdam) that is causing you some of your issues. Definately try some careful testing. We don't need another John C. story about feeling like your going to go airborne. You could always remove/cut the front part off, and make it end at the airdam. May not have to scrap the whole thing.

 

At my clubs car show, I met up with a friend who copied my original bellypan, who specifically mentioned how happy he was with the difference in handling. Makes me think that unless the pan is angled the wrong way (tilted down towards the back of the car), that a basic pan should not hinder or reduce the performance of the car. This makes 4 cars that I know of using a front belly pan (cars I've driven or sat in) that have a pan similar to my old pan.

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At my clubs car show, I met up with a friend who copied my original bellypan, who specifically mentioned how happy he was with the difference in handling. Makes me think that unless the pan is angled the wrong way (tilted down towards the back of the car), that a basic pan should not hinder or reduce the performance of the car. This makes 4 cars that I know of using a front belly pan (cars I've driven or sat in) that have a pan similar to my old pan.

The issue with splitters is angle change/nose dive/suspension compliance/whatever you want to call it. My SWAG is that most street driven Z's are way too softly sprung to really utilize the downforce a good splitter could generate. Cary might chime in if he's reading this thread but I believe that one he tested was driving a Z with 450 in/lb springs into the ground. It was a lot bigger than Austin's, for what that's worth. I think the prime area where you would feel instability would be under high speed braking.

 

One solution is to add a raised center section that is say 1" higher and tapers down to the flat area with the rest of the undertray. If done properly with a diffuser in the back this can actually increase airflow under the car and into the diffuser, thereby increasing downforce and makes the splitter much less pitch sensitive. Not legal for most lower racing classes, but it's a good idea...

 

Some examples:

http://www.mulsannescorner.com/dallaralmp10.html

http://www.mulsannescorner.com/nasamaxdm139.html

http://www.mulsannescorner.com/couragec60-05.html

http://www.mulsannescorner.com/lolab2k40-1.html

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.................................................... Makes me think that unless the pan is angled the wrong way (tilted down towards the back of the car), that a basic pan should not hinder or reduce the performance of the car............

 

Interesting comment. Mine is deliberately angled down towards the back so the airflow will have to speed up and so drop in pressure, Bernoulli's thing or whatever it is. I posted a pic and description of what had been done here a while ago.

 

The car has not been tested at really high speeds but on one of the circuits I go to there is a kink I've taken at ~200KPH which is a bit of an aero test. Can't fault it so far, steering is completely neutral there and the car rock solid. The car does have a front splitter and a rear wing too.

 

But if yours is working then no problem, I don't claim to be an aero expert :)

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The issue with splitters is angle change/nose dive/suspension compliance/whatever you want to call it. My SWAG is that most street driven Z's are way too softly sprung to really utilize the downforce a good splitter could generate. Cary might chime in if he's reading this thread but I believe that one he tested was driving a Z with 450 in/lb springs into the ground. It was a lot bigger than Austin's, for what that's worth. I think the prime area where you would feel instability would be under high speed braking.

 

550s actually. And you could feel the splitter from about 35 MPH on up. We really needed to balance it out as it would cause the front brakes to work too well at speed. It really needed an equally large wing in the back. Sorry to say we have no real data other than the feeling and how deep we could go on the brakes with it on.

 

The car was setup so that at speed it would be level and have rake as we went onto the brakes. Under power it was slightly nose up but still seemed to help.

 

Cary

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Scott,

 

I've been following this thread and have a question - I think I know the answer but wanted your thoughts. I'm still trying to understand to aerodynamics of our Z Cars.

 

Why didn't you carry the belly pan forward of the front edge of the air dam?

 

Thanks for sharing your project!

 

Al Keller

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Al. There are two main reasons why I did not continue the pan forward of the airdam. The primary reason was pure streetability. My new airdam is almost a low as my air dam was with the rubber strip attached. It is also further forward (away from the front wheels) So I was taking into account getting up driveways etc.

 

Second reason and also a big part of the desision, was that I have a very streetable suspension setup, and from what I understand there is not enough of an effect to make it worthwhile to figure out and setup/build. The car needs to be pretty low, and at least have a very stiff suspension setup to be able to take advantage.

 

Scott.

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More seat of the pants commentary.

 

Front of airdam is approx 4" from the ground. (mirrors are stock)

 

Ok on to the commentary: I logged a good 800km's on the Z yesturday on a day long Ontario Z Car fall cruise through north eastern Ontario. What a blast.

 

Seat of the pants description. No issues other than one of my holders came loose on one corner giving me less than 4" of clearance. It may have rubbed during some particularly bumpy sections. Zero issues with the car wanting to be like an airplane, though it did feel like a rocket ship passing in a few areas, and going through some fast S's, W's, L turns and maybe even a Q! hehe

 

I think that pretty much wraps this thread up. Got a Q? PM me. I'll add to the thread if anything pertinent comes up.

 

Thanks,

Scott.

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