So I've paid up for a nice stainless downpipe. Did some searches and there's a lot of talk about wrapping them.



Is there really that much underhood-heat-reduction benefit from wrapping? The biggest thing would have to be just getting the precat out of there. Is there really a big benefit from the wrapping the downpipe also? This pipe is really a nice piece of work, I guess I would prefer not to wrap it and I'm trying to justify not . . . but if I get some really good pro wrap arguments, I guess I'll do it. Also, any reasons not to wrap?

i always wrap the dps and manifolds. even ceramic coated units. i knoticed a 10deg drop in oil temp after wraping the manifold and a slight drop in water temp specialy in stop and go traffic. my biggest drop came from venting the hood.

Here's my "pro" argument.......

It's effective at keeping underhood heat down to something just cooler than molten lead. Remember that a rotory engine exhaust is about 30% hotter than a typical piston counterpart. Obviously stainless won't rust, but it does nothing to reduce the radiant heat, which will bake all the plastics, solenoids etc. The more you can keep the heatsoak and baking down...the better for everything. It's relatively cheap, easy to do (particularly if the DP is off the car) and there's even a marginal performance benefit...although I can't imagine you'll be able to tell. It also tends to quiet the exaust a little too IMO.



Several years ago I did mine in DEI 2" wrap and sealed it with their silcone sealant/paint. http://www.designengineering.com/pro...asp?m=sc&cid=3

One roll is plenty for the DP, even overlapping 50%. I had enough left over to do the inlet and outlet of my hi-flow cat. Together it also significantly reduced radiant heat to my transmission casing and inside the car via the tunnel. In additon to "sealing" the wrap, that silcone coating keeps you from getting ichy if you ever have to work around it. IMHO, forget their ties and just buy some decent stainless worm-gear clamps. Fold the ends of the wrap into a "point" or "triangle" for a cleaner look.



FWIW, in July I can get off the freeway and pull into my shop. In the time it takes to run it up on the lift I can grab the wrapped downpipe with my bare hands. I doubt you could do that with just heat-coating.



My "con" argument........



It's a minor PITA to wrap the DP on the car, and you can't get right up to the flange at the engine end because of the bend. You have to wear rubber gloves, a long-sleeve shirt and eye protection while doing it. It's really a PITA to apply the sealant with the DP on the car. It's not as pretty as heat-coating.

All the stuff will run you about $80.

Ok, sounds like the benefit from the wrapping is significant and my DP isn't on yet, so I'm going to do it.



Thanks both of you for the advice.

Post up any tips you come up with and some pictures if you have time.

Should I post pictures onto this thread or is there someplace better where people can find it.



I had been hoping to find some pictures of finished wraps but didn't in searches. When I looked in the garage area there didn't seem to be any way to do a search for a specific modification. I looked at a few cars in there but didn't find any downpipe pictures. If there are any in there it looked like it would take a car by car hunt checking each for mod pictures, tedious.

banzai-racing.com. go to their cars and check out their FD. he has a single turbo 20b and the downpipe's wrapped if you're looking to see what it should look like

I wrapped mine & am glad I did. Will have to agree with others who have said it tended to keep underhood temps down.



Something else I do. After I have been out driving around in mine for awhile & pull into my garage at home, I pop the hood & let the car cool down that way. I figure that at least the wiring harness, solenoids & control stuff under the hood won`t bake nearly as bad & possibly last longer. Just what I do anyway. I spent too much time, money & effort to not try & take care of my car. I really enjoy driving it & want it to be as trouble free as possible.



YMMV.

Yeah, just post then up here in your thread.



I wouldn't worry about pictures. Fortunately the FD DP has no weird curves and is pretty straight-forward. I think the instructions suggest soaking the wrap in water to make it more pliable. I never did that because I didn't want to wait for it to dry before spaying on the sealant, but it probably would have helped.

I'll look at that. It doesn't seem like it would be that difficult but since I've never wrapped any exhaust I have been wanting to see an example before I start.



thanks

not a problem man

I've got the DP wrapped and sealed now. I soaked the wrap for a few minutes before applying which I think helped to get it on tight without bunching or puckering in it in any places.



This method should be helpful if you don't have an assistant handy:

After I got started it seemed easier to sit the DP up vertical and turn it to apply the wrap. After getting about half way done turned the pipe over sitting it on the other end and continued to turn the pipe working upward the rest of the way.



I used the 2 inch wrap and cut a V on the side on my first pass when the wrap was going to hit the oxy sensor port. On next pass I got the port in the middle of the wrap and put in a small slit lengthwise with an Xacto knife for the port to poke through.



Used the silver colored DEI sealer.



I like the worm clamp suggestion. They definitely aren't going anywhere.



The DEI package instructions said something about overlapping up to a quarter inch and it not adversely affecting the pipe. Is there really any issue here with hurting the pipe? 50% overlap was mentioned above. I assume people have run with overlaps greater than the quarter inch DEI said and haven't a problem. I'm not even sure what they are talking about adversely affecting the pipe unless they mean warping the pipe from uneven heat retention.



[attachment=46765:dp_1.JPG] [attachment=46764:dp_2.JPG]

If the downpipe is decent quality, you shouldn't have to worry. I overlapped mine about 50% because I realized I had plenty and rotary exhaust is hotter. That same pipe has been wrapped that way for ~6 years with no issues. The only difference is that in my case, the DP is mild steel, so I coated it first with the sealant, wrapped it, and then coated the wrap with sealant. Stainless doesn't need the initial coating and should be even stronger for the heat.

Looks good. Nice job on going around the O2 sensor too.



FWIW, I used the left-over to wrap the inlet and outlet to the cat too.

Also, if you didn't have it plugged before hand, I'd clean the threads of the O2 sensor port of any sealant before installation.

I had the O[sub]2 [/sub]port taped up. Thanks for the help.

Nice job! What size of roll did you buy? I read that you used the DEI 2" wrap, but was it the 15' or 50'? The FAQ says that for a 2" wrap you need 60' per linear pipe foot.

I had a 50' roll. Based on what I had left the 15' wouldn't have been enough. I used a bunch of the sealer too, about half of the spray can, it gave it a tough hard texture when it fully cured.

???

If I understand that correctly, that means you'd need a 180 feet of wrap for a 3 foot long (3 inch ID) downpipe?

DEI sells it in a 50 ft. roll. As mentioned above I had alot left over, even after overlapping 50%.

I'm guessing he meant 60", not 60'?

I like to use bailing wire to tie off the ends it looks cleaner than clamps but thats just me.

Is the DEI wrap tough enough to wrap the exhaust manifold with? I've heard a lot of these products just fall apart because that area is so hot. I'm wondering if I should assemble a heat shield around the turbo section and wrap THAT, so there's some air space between the two.

If your talking about the FD stock twin turbo exhaust manifold, I'd think it's shape would be impossible to wrap. You could have it heat-coated. Companies like Jet-hot can do it.

For reference, this is what your stock exhaust manifold looks like (random picture..not mine):



http://img641.imageshack.us/img641/9194/manifold201.jpg



]

unwrapable!