Fiberglass fabrication?

[freebeard]

I don't like working with fiberglass either.

A Carson-style lift-off top is made from electrical conduit, chicken wire, quilted padding and convertible top material.

[serialk11r]

I completely forgot to mention that another reason the VIS tops are a big no-no is that there is a giant curved Lexan window at the back, and that's guaranteed to pick up lots of scratches. I would hate to be constantly trying to buff it out. An OEM top is better with its glass window, but they're also 3000 dollars and I have a feeling I can get something very nice and custom made for that kind of money.

It really comes down to the money. A Miata OEM style top can be had for 1000 bucks. Totally worth it, I would work with that and try to optimize it from there. MR2 Spyder tops start at 2k+, which opens up the custom work door.

I'm eyeing a car with a roll bar installed, so I can definitely make a "bikini top" like this

and add a frame to keep it sturdier. However a big reason I hated my old MR2 Spyder is the tremendous wind noise from the soft top which made my ears ring, and I really want a hard top so it is more civilized. Adding a rear window and sealing the door windows to the top is going to be impossible, so the wind will be roaring in my ears as I drive.

It's pretty funny because when I got my FR-S, I was shocked by how quiet and comfortable it was on the freeway, while everyone on ft86club likes to complain about road noise, wind noise, and a harsh ride. If I can get half the noise reduction going from the MR2 to the FR-S, I would be ecstatic.

[serialk11r]

Originally Posted by kach22i

I suspect that the MR-2 is like the Boxster in that the side intakes feed the engine oxygen. This means the rear deck louvers are for radiant heat release after shutdown.

Yes, and no. The Boxster simply has its engine hanging out underneath, and the heat dissipates from under the car. The side intakes feed the engine, and a little bit of cooling air perhaps, but they only flow a minimal amount of air.

The MR2 Spyder has two large side intakes feeding the engine bay directly, allowing venting out the top of the engine lid and through a hole in the bumper, as well as underneath the car (which is an aero mess at the rear).

The car I am eyeing has a 2ZZ swap not using the stock intake tube, which should free up some of the flow of air from the driver side intake to the vents.

The vents in the engine lid are primarily useful for venting heat while stationary, as there is a drip tray blocking most of the would-be airflow. I think I will get the VIS V line lid, as that has bigger venting holes that are louvered to prevent water from dripping onto the exhaust pipes. Or maybe I'll get the OEM style one and put louvers over it myself.

I've thought very hard about whether it would be possible to give the car a quasi-fastback by attaching stuff to the trunk lid, but because the lid is so wide and the hinge is placed where it is, I threw that idea away.

My aero checklist for this car is:
-Hardtop
-Add long spoiler to the tail to get it closer to hitting the template, the biggest one is I think the Duraflex Type W, which also happens to be one of the cheaper ones.
-Strip frunk out, add front chassis brace and use that as an attachment point for a piece of coroplast to serve as a smooth floor. The car has no underbody to speak of at the front, all the guts are exposed
-Throw out stock radiator duct, do a custom one in coroplast
-Make a rubber? grille block that's radiused and gradually increases the opening to the radiator's cross section
-Make a simple aluminum diffuser for the back, with strakes to partially seal off the vortices from the wheels. This is extremely effective on a Lotus with a flat belly, hopefully it does something.
-I will add chassis bracing to the bottom of the car, I may wrap it in PVC sheeting since it's so easy to do, even if it probably won't do much.
-Slightly fatter tires on the back to raise the rear of the car, also brings the speedometer error down and lowers rpm on the freeway.
-Manual adjust, long oval racing mirrors. This can probably drop the drag from the stock mirrors by more than 1/2.
-Lithium ion battery to allow some air to vent internally from left side vent to the rear of the car efficiently.
-Attempt to test airflow through the passenger side vent. I suspect the way the engine bay is doesn't allow much air to get through, so it would be good to block the vent off a little.

I think with all of those together, this car could be fairly aerodynamic while not looking too crazy (attracts cops :/). I would try fairings behind the rear wheels, except there are a ton of bumper screws there and I probably want to keep access to them simple and easy.

[aardvarcus]

Here is a suggestion that I seriously considered when I did my V2.0 Aeroshell. Find a local custom boat builder that does custom fiberglass work. You build the blank out of foam, carve it, shape it, etcetera. Then pay them to lay glass on it.

I ended up just doing my own fiberglass work despite having close to zero experience. The actual fiberglass part turned out well, I should have then taken it to a body shop for final bondo, prep, and paint as that part only turned out acceptably but not as nice as it should have. Darn having no patience and not much time.

[freebeard]

One of the big problems with fiberglass is, absent female mold, it's hard to control the surface finish.

My parents did a lot with fiberglass, they lined an entire [tiny] bathroom with it once. What they would do is squeegee resin out under Mylar plastic and then peel that off after it set. You could mix in micro-beads for filler. Knock down the high spots first.

Also consider a backlight from a boat-tail Riviera. Or early Barracuda.

[serialk11r]

Thanks for the suggestions. After talking with the guy who made the hardtop, it seems like the custom route may be harder than I imagined, because it takes considerable work to attach mounting bosses and fit the top to the car :/

I've noticed that for around 3000 USD I can get the Trial hardtop shipped over from Japan, whose styling I like a little more, but that price is really steep. Also trying to contact Luxurypart (a Thai shop that makes Lambo lookalike body kits for the MR2) to see if they have anything reasonable; they have one top for $1833, but you have to remove part of the windshield frame to mount it and it has no rear window, which is too crazy for me.