cumminsdriver635

Hey guys. Im thinking about making my own 4.5 inch exhaust. Dad has plenty of 4.5 inch pipe with couplers he got from work, and all i should need is a 4 inch downpipe. How much did moving from a stock straight piped exhaust to a 4-5 inch exhaust lower your guys EGT's? Im hoping it will lower my EGT's maybe 100-150 degrees? I really need some EGT reduction, and i think when i bump the timing to 16.5 it will help a lot, but i would like to keep them as low as i can. Also, will galvanized steel work fine for an exhaust, because that is what this is. I think it should work perfectly fine, just want to make sure though. I thought about doing this with a 5 inch stack, but I use my bed a lot, and dont want to have to worry about it every time i put something back there, so Im just going to run it out in the stock location again. So my main questions are:
1) How much EGT reduction did you guys get by going to a 4 inch downpipe/exhaust system
2) How do you like the sound(4-5 inch exhaust sound clips are appreciated )
3) Do you guys think i will lose any low end by going to a 4 inch down pipe?
4) Where can i buy just a 4 inch downpipe without the exhaust, and how much are they?

Thanks guys. Might be a little while before i get this done, but i will post a whole new thread with pictures when it does happen.

Eric

Stamey

If you have plenty of pipe, you are set. Can you get any of it mandrel bent to 45 and 90 degrees? You need a couple of 45s to get from the turbo under to the truck.
You could probably clip your existing down pipe, since you only need the flange that mates to the turbo, which should already be 4". You'd cut the flange off, mate to to your 4.5" pipe with a reducer, turn 45 degrees down, and under the truck, turn 45 degrees up, to go straight back, and then you need probably 2 45s and 2 90s to make the axle pipe and the tail pipe.
I dunno about helping EGTs. I wnet from 3.5" to 5" when I installed my twins. The twins really helped EGTs

Chris

hotmopr

What kind of pipe is it? EMT? I made mine out of EMT. and it works great. I used factory bends and welded all seams. You will need one 45 for the down pipe. a cut down 45 to start you up over the axel. then a 90 laying on the ends and cut down to go over the axel then another 45 to send you flat out the back and maybe another 45 to kick it out the side. I'll take a pict of mine and I'll put it in may gallery..

jimjawz

It would benifit your egt problem the most if you had a bigger exhaust elbow at your turbo and THEN four inch exhaust. I played this game and found that the way to lose egts is a three piece manifold and big turbo. My turbo has a non wastegated four inch dump. Check the end of my gallery on the second page for pics. Sorry its in black and white.



P.s I think banks makes a power elbow or somthing....the egt game is not a cheap one

cumminsdriver635

Thanks for the help guys

Stamey: I have quite a bit of the pipe, and i believe some of it might be just right, or very close for going over the axle, and stuff. I dont think it will be a problem. I will just buy a 4 inch downpipe, and mate to that with my 4.5 inch. Its about 4 1/8 to 4 1/4 inches I.D. so it should slip right over the 4 inch downpipe hopefully. I dont know of anyone with a mandrel bender but i think i can do enough cutting, and welding to get it looking pretty good.

hotmopr: The pipe is big conduit i think maybe? It looks like it would be great for an exhaust. Thanks for the pictures. Your exhaust looks great, and that 6 inch tip is awesome! How much did that thing cost ya?

jimjawz: Yeah, but i dont want to go with a 3 piece manifold or a bigger turbo. I personally think advancing my timing will help a lot. Your right.lol EGT's arent cheap to get rid of after youve done the obvious, like timing, exhaust, and intake. It gets expensive after that, and im trying to stay away from a bigger turbo. I put the bigger 16cm housing on, but it didnt make any difference yet, but ive heard i may not get the benifits from it as much till i start pushing more fuel.

So where can i buy a 4 inch downpipe, and how much?
How do you guys like the sound of your 4-5 inch exhaust's?

Thanks

Eric

hotmopr

The big A$$ tip came from Rip at
http://www.sourceautomotive.biz/
It was 100 bones.. Why dont you build your own down pipe? You just need to cut off the first 3-5" (shorter the better) of your stock pipe and weld on a 4"-3" reducer that you can buy at most auto parts stores. Be sure you can get the mounting bolts in the down pipe before you weld it up. You may have to lengthen the reducer or the 45 to clear the firewall and floor. First I welded the reducer on to a foot of 4". The I cut my stock end off and bolted it back on the turbo. Then I fit the reducer to the stock flange and tack welded it right on the truck. Then crawl under the truck and hold up your 45* where it clears everything and mark the new down pipe to be cut. Remove and weld fully. Then remount and start fabbing from there back. Just dont forget that once you weld on the piece that goes through the trans mount to the down pipe you wont be able to remove it with out cutting.. I used a band clamp at the trans mount and used jack stands to hold everything up in place while I was cutting and fitting the tail sections.. Good luck, Hope this helps..

JStull

i built my own too, its easy.

but if you are worried about the downpipe, i have seen them for sale several places. Rip might have a used one for sale in the bargain section of his website now if I remember right.

i picked up a 5" x 18" long polished stainless tip from summit for about $65 or so.

Jason

DRM

I was looking, and it seems they are all a bit mroe expensive now.


I sure wish I could find a sub-$50 tip option. Not for looks, I just want something with some weight to it to quieten down the "thin" sound of my new dpp exhaust.

DRM

Well, there I go making comments, then do a search and find just what I was looking for

http://www.dieselpro.net/exhaust_tips.php

cumminsdriver635

Hotmopr: Yeah. I could build my own downpipe. It would save me quite a bit of $, and i would have a REALLY cheap exhaust then.lol I might try that. Sounds easy enough. Only thing im worried about is, making the bend the right angle on the bottom of the downpipe, but how hard could it be? Also, this pipe has couplers that joins the pipe. I thijnk ill use a coupler at each joint I make, so i can just tack weld up whatever i think i might have to remove at some time, and just grind off the tack if i ever do have to remove it. As long as i dont have any exhaust leaks, ill be fine.

Jstull: Yeah. Ill have to check his bargain section. I guess i will probably build my own now though. Ill have to look at it all and see. Thanks

DRM: Its been a long time since ive heard out of you! I remember one of the first threads you made was when you had just got your truck, and was dissapointed in how it pulled, and said your V-10 pulled better. So i have to ask now. Does your CTD pull better than your old ford V-10 now? How are you liking the truck? Those are some good looking cheap tips. I gave about $70 for my 12 inch 5 inch tip from www.dieselmanor.com a while back. I think the big 18 inch long rolled edge tip would look sweet.

Thanks guys!

Eric

DRM

I will have to defer comment until I get a good auto tranny behind it and can actually get the power to the ground like it should.

cumminsdriver635

Man; as bad as i hate to say it, I hear you loud and clear on that one. The stock auto was NOT in the least meant for the cummins. Have you installed your 3k GSK yet, or not?

Eric

DRM

Nope, I need to find it and install it this weekend

cumminsdriver635

Dont speak so soon for the time bieng then because you are in for a BIG, BIG surprise with the 3k GSK It made mine MUCH, MUCH more driveable than before. You will LOVE the change. I used ot have the hardest time burnign tires coming out on the road(i have 3:55's and limited slip), and now i can come out hard, and even witht he 16cm housing, as soon as the turbo spools my back tires are done for, and if its raining, just forget about any amount of throttle at all. Let me know what you think of the 3k GSK when you get it in. I promise you will love it. Its better spent money on an automatic truck than a fuel plate if you ask me, because it really helps make up for the inneficient stock torque converter. My EGT's did go up a lot with the install of the GSK, but i think its because my plate is almost full forward, and is pretty agressive. Let me know what you think when you ge the GSK in.

Eric

jimjawz

I have a four inch d pipe just sitting at work collecting dust. It also has the adaptor already welded on.Its my old one from my stock turbo, only has about 5000 miles on it. Willing to sell.