NAS D90 300tdi exhaust?

[Chris Cox]

I have been working on my project 90 quite a bit recently, and got ready to mount the exhaust on the engine/chassis. Boy was I pissed when I realized that the rear silencer is supposed to sit where my fuel tank is! Guess I should have realized that. I read that ECR uses a NRP exhaust for their 300tdi conversions that just mounts to the head pipe. I emailed NRP, and have gotten no response. Since they are more than likely going to be expensive as hell, I am just going to get an exhaust made, by cutting off the flanges on the 300tdi exhaust I have, and using them on new pipes. My question is, what kind of muffler do I need to run on this thing? I don't mind paying premium price for the best muffler, as the exhaust is going to cost me practically nothing to build. Also, the 300tdi exhaust uses 2 silencers. I should only need 1, shouldn't I?

Thanks for your help.

Chris

[Buckon37s]

Take out the silencers all together. Totally unecessary. If it was my truck, don't put on a muffler. The turbo cuts up the noise quite nicely and the diesel is not loud to begin with. If you think you have to, I have had good results with dynomax. You do not have to spend a lot of money here, just get a very free flowing muffler. Summit Racing is a good place to start.

P.S. if you think I am kidding about the muffler, drop your pipes at the first connection and drive around. You will be surprised at the lack of sound. And you will get the lowest EGT that way.

[JimC]

Chris-
do you have any bits of the NAS exhaust left over? I need a cat. Mine is rattling like crazy. I only need a used one to tide me over until I do the diesel thing like you.

[Chris Cox]

Sorry Jim, sold that stuff long ago. What problems could arise from not running a muffler? I will probably add one anyway, as I do enjoy being able to hear. :grin

[Buckon37s]

Hey Chris,

Like I said, after you finish your install drive around without any exaust except for the down pipe. If you are used to dealing with gas engines all your thinking needs to go out the window. Turbo Diesels are not loud without the muffler, in a matter of fact there is amost no difference. You get that cool Borla sound but pocket the $600. As to your question about problems, there are non what so ever. EGT's are your new cancer. You need to watch that guage wherever you go. You will notice a difference with no muffler. As much as 100 degrees in similar driving conditions. Just try it. If you don't like the noise, you can get a high flow that fits the demensions you need for cheap, they work fine. Good luck!

[Buckon37s]

BTW:

I forgot, dump the rest of the pipe exiting the rear of your vehicle and just turn the pipe out and down and blow it out the side 2.5 ton style. That way you can trow away all the annoying over/under link around gas tank hit on rock headaches.

[Chris Cox]

David, thanks for the help. I will probably just get the thing running, like you said, and see what it sounds like. 99% of my experience with diesel engines is on heavy equipment, where it DEF. makes a big difference having a muffler.

Thanks

Chris

[Buckon37s]

If I can I will get a few pictures posted of some different exause rout options. So you can pick the best for you.

[Gkase]

Chris,
what did you end up doing about your exhaust?
George

[JimC]

He sold the truck, so I dont think he ever solved it. I just grafted the NAS rear section to the TDI midsection just forward of the a-arm crossmember. That eliminated the rear silencer, but noise isnt a problem. Exhaust shop charged me 15 bucks for the job.

[Gkase]

Thanks Jim...that helps!

[cbass]

Jim, If you want a stock cat, I have the y-pipe from our rover. It has both cats in it, but I don't know if they're burned up already or not. If you want them, I'll give them to you for free if you pay the shipping. I can either cut them out of the y-pipe or if you want the whole y-pipe, I can mail that too although there's a crack at the flange that bolts to the exhaust manifold. Let me know. I can get pics tomorrow night if that will help although don't be expecting much. When we pulled it off, the truck had 88,000 miles on it so they're fairly old.

[junkyddog11]

There is a rear tank exhaust for a 300tdi (the later models had a rear tank instead of the side tank) I have one at the shop but I'm not sure I'll use it as the silencer is about 8" in dia and 26 " long which seems like a little overkill as, like Buck says, they are pretty quiet with a straight pipe.

The last conversion I did used a 10" flowmaster grafted into the stock head pipe and the rear tank Tdi tailpipe section. Sounds good and relatively cheap. Be carefull of to much back pressure unless you want burnt exhaust valves....get an EGT guage. All the stock silencers get in the way of underdrive / overdrive units which seem to be so popular right now.

[TDI Guy]

Matt, what model flowmaster did you use? How does it sound and do you have a part #?

[artm]

110 Tdi:

Was driving down route 3 towards the Cape last weekend and see something flying behind me. Thought it was a tire tread I ran over but I was pretty careful and didn't see anything on the road. Pull over to see if I had a flat and didn't.

Come back Monday, Wednesday start taking out the radiator. Get underneath the truck and notice that the middle section with the muffler is missing! That was the debris I saw.

Funny thing, a little while after the debris incident I thought the engine sounded a bit louder than normal. Not much louder but a very slight increase over a broad speed range above 55 or so. It did concern me as I thought it was from the engine. Must have been from the missing muffler.

So, yes, they are quiet without a muffler at all. That's reassuring as I plan on fitting 3-in pipe straight through.

[ECR]

I read that ECR uses a NRP exhaust for their 300tdi conversions that just mounts to the head pipe. I emailed NRP, and have gotten no response. My question is, what kind of muffler do I need to run on this thing? Chris

Chris, we used to run NRP years ago. They custom made us some tail sections that would bolt to the Tdi front pipe and mount to all the NAS pick up points on the chassis. However since NRP changed hands or somthing (don't really know what happened there) we just use SS pipe that we put together here. So I don't know if the guys at NRP now would even know what we used to use.
As for mufflers, I agree with Buckon37, forget them or run a small straight through silencer. Whatever you put on make sure when you hold it up you can look right through it to the other end, otherwise you will get higher EGTs when you run hard. In my own rig I run a cat and a small silencer. I personally can not tell a noise difference in the noise from my truck on basically no muffler and when it had a V8 type of muffler (don't run one of those by the way, too restrictive).

Oh man... I just read this was a WAY old thread. Oh well, I'll leave the popst anyway. Sorry for the old news.

[Gkase]

Mike,
Not old news! All very valuable to me as I am facing this exhaust thing right now...
George

[JimC]

Cbass - thanks for the offer, but my request was back from my pre-diesel days - more than 2 years ago...

[cbass]

Cbass - thanks for the offer, but my request was back from my pre-diesel days - more than 2 years ago...Haha yeah, I guess it would help if I looked at the post dates!

[TDI Guy]

Mike, who sells a small straight through silencer? I need one..