Post-Downpipe Questions
 

Alright, last week I finally found some time to finish installing my downpipe. Noticed a few things, though, and could use some advice.

1) 2 of the studs that attach to the turbo seem to be in slightly deeper than the other two. I tried tightening the other two, but they won't go any farther. Is this something to worry about?

2) Exhaust is leaking between the downpipe and cat. I can see it coming out. I was stupid and forgot to put back on the metal shield that used to be there. Tried to do that today, but couldn't loosen the new nut I had just put on!! Any other ideas what could be causing the leak, though? I'm using a new gasket. Everything was real tight.

3) Downpipe is glowing after a hard run. This is normal, right?

The good news is that I think my boost pattern is finally right. I took the car out for a drive today. There was too much traffic to really pay close attention to the boost gauge, but I know I'm pretty close to a 10-8-10. The sound of the turbos spooling is pretty cool, although I wonder if it would start to get annoying to me or my passenger. This is my only horsepower mod, but I don't think I noticed the car being any more powerful. Should there be a noticeable difference?

Alright, that's all. Thanks for any help/advice.

Matt

my dp never glowed, even when I still had my cat on, but maybe this is considered "normal"...or perhaps your cat is partially or completely clogged? better check it out

The bolts dont seem like they should be a problem...just make there is enought tread for the nut to sit on...

The glowing is normal...mine was doing that as well and i think whomever i have talked to said the glowing was normal since thats the first part of the pipe the air hits with pressure after the turbo's.

And lastly, you should definitely get another dp/car gasket. I got one from pettit b4 i installed my DP. That usually goes by the time u put in ur DP.

As for the downpipe glowing, it should not be, get a high flow cat or midpipe or some thing cuz the down pipe should not be glowing!!! The only thing is that you might be overboosting so watch it, im currently running a straight pipe and am having boost problems (1.5 bar boost). :eek:

for the Exhaust is leaking between the downpipe and cat, thats problally gonna be ok for a while but you should get it fixed, my brother has the same problem but it does not seem be a problem, it just spits flames occationally.

Here's some more info about the glowing downpipe:

https://www.rx7club.com/vforums/show...&threadid=5631

Thanks for the help. I checked out that link. Only the top part of the downpipe glows, so I guess that is normal. I'll keep an eye on it, though.

Would getting a high flow cat increase reliability? I am not really interested in performance gains, I just want the car to run well. For me, it is fast enough stock! But if my cat is clogged, I'd want to replace it. Any ways to check this without removing it?

By the way, I drove the car for a while last night on the highway. and was able to do the boost test a few times. Getting a solid 10-8-10. I was previously getting 10-6-8. What a difference! The second turbo really kicks in hard. Guess my pre-cat was slightly clogged.

Thanks again!

You should have below 10psi on your secondary if there is moderate clogging of cats.. You definately made the right choice with the downpipe because your previous boost reading seemed to indicate clogging. You for sure just extended the life of the motor! With your downpipe just watch for occasional spiking in cooler weather(should not be a problem if it is only mod). It is a good idea to get rid of the cat if you can get away with it. Make sure you learn about taking the proper steps in doing so. AN ECU upgrade for starters...G

Actually, I drove the car tonight and noticed the boost spiked to 12 in 2nd gear (primary turbo). Didn't think this happened with just a dp. I think Pettit included some sort of boost control pills with the downpipe, which I suppose I should install.

Completed my DP installation yesterday!:D

After reading some threads/posts on this topic I HAVE to ask.

1. how important is it to have the DP ceramic coated or wrapped? I didnt do either. Ive heard some horror stories in the MC world about wrapping pipes.....that the pipe basically rots out in a short period. ????

2. Is it possible to unthread the O2 sensor from the DP while on the car? I forgot to look into changing it........what can I say Ive been busy w/ other sh!t in my life......lol. My car has 90K miles and probably cld of used a new one. How does one know when it goes bad? Im guessing the car will run like shit????




My install:

'94 FD

All four studs came out w/ the nuts :) and chose not to reuse them. Cap bolts were a must for 3 of the 4 holes (ONLY the upper rear bolt used a regular SS hex head) for my DP.

(Brand type for the DP is unknown as the person who sold me the entire system ('used' except for the DP) advertised it as a complete Pettit system but when received the CB was made by ATR.)

Remember to disconnect the O2 sensor wire before dropping the PreCat. One of the hardest part was balancing the DP w/ one hand while trying to thread in the lower rear bolt w/ the other. Like someone else said, its impossible to slide in that lower rear bolt w/ the flange touching the housing it goes in crooked. For me the biggest problem was tightening that same bolt once all others were fitted. I had to cut off about a 1/2" off the short end of my allen key to get it in there to crank her down. The others cranked down w/out a problem. The upper rear bolt is a pain in the ass.

The cat to dp bolts proved to be the biggest pain in the rear on the whole project. The nuts came off alone at first but after fussing w/ it for about an hr or so the studs FINALLY backed out. But the threads were not good so I cldnt use them, so I fitted temporarily 10mm nuts in bolts (matter a fact I used one of the turbo housing studs and 2 nuts) I had laying arnd till my tap set arrives via Harbor Freights.

Both gaskets were in great shape and reused. No leaks from what I can see or hear and today its NOT raining so Im gonna go now and see if the 'seat of the pants' power has increased like so many say it does!!!!!!

Will the temps be any lower w/ this mod? Being its not as restrictive anymore I was wondering about that.

L8r!