2.5 downpipe for cheap

[summit]

I just built a 2.5 mandrel bent downpipe for a 83 carbed car for $45. very similar to the 84-85 hot air cars. I started out with an 84 GN, so I know how hard it is to find upgraded parts for them. more details in the before black section.

hotair downpipe article

Greg Kring
Arlington, Tx
2002 BG super 16 winner
Ex Buick owner

 

[tb3]

the 2 90 degree bends in the middle are a tad lil bit sharper than I'd like, but nevertheless, its gonna flow/look quite a bit better than the stocker being its true 2.5 all the way down.

get some of those turbo flanges with the built in wastegate from rjc racing and weld it to your new custom dp, and you my friend, could make yourself some $$$ by selling them to the hotair crowd.

 

[BRAD_PADGETT]

[get some of those turbo flanges with the built in wastegate from rjc racing and weld it to your new custom dp, and you my friend, could make yourself some $$$ by selling them to the hotair crowd.[/QUOTE]

The stock turbo elbow is only 2 inches wiide. This means your pipe wil not have a real impact on flow. Put the rjc turbo plate on your downpipe and you will greatly improve the flow. I noticed a big difference when I put on my integrated downpipe. There is no need to go bigger either due to the limitations of the hot air turbos. There is a market for your idea. Nobody builds integrated downpipes at and an affordable price. I had to pay way too much money for mine. Good luck- Brad

 

[summit]

well the carbed stuff is a different bolt pattern on the elbow than the 84 and up turbos so the RJC and terry houston style elbows won't bolt up. I have a terry houstone stub wastegate on the shelf and tried it first even though there is no way this car needs that much wastegate control and that large of a puck would probably cause fluctuation issues.

As far as making them I don't mind these one off deals for the experience, but am not setup for production. I used aluminized tubing, but you would want to go stainless for resale. About double the cost of materials which is no big deal, but fittment would have to be better and a TIG would be a must.
Stainless materials-$75, integrated elbow and wategate arm-$140, that would get you to $215 in materials alone for a 2.5 stainless downpipe. Add in a cash business markup of 25% on parts to get you to about $270. Even 4 hours of lightening fast hand fabrication at a cheap $25 an hour would be a grand total of $370. I spent a solid 8 hours doing this one, but was also installing a new turbo as well. I don't see why places like ESP who were tooled up at one time don't crank out a few more. I assume there is a CNC mandrel bender program out there already setup for the hot air cars?

 

[BRAD_PADGETT]

If you built one for $400 people would take you up on your offer. Some would pay more. I paid $850 for mine which was custom welded together with various parts primarily carbon steel. Here is a pic. Take care- Brad

 

[tb3]

hell, now that i go back and look, yours is pretty comparable to mine. mines all stainless and is 2 piece (i can have it off in 30minutes), and it woke my car up like a pissed bull, course much of that has to do with flange eliminating the elbow i would think.

at $40 cost (plus the rjc flange) even if you marked them up 200% or so, they'd still be super cheap, and you'd make a nice profit. the hotair guys ought to be all over this. course, we tend to be a strange bunch

 

[BRAD_PADGETT]

TB3- The same guy built mine and yours. Take-care. Brad

 

[turbonut85]

And just where do the rest of us get one???? Sign me up!!!

 

[1985_ttype]

is it possble to cut ta one that is for sale and get tha other piece to make it a two piece.what is tha rjc flange??hw much did ur cost TB3?thank you write back asap...

 

[tb3]

TB3- The same guy built mine and yours. Take-care. Brad

sorry about that brad, i should have used a quote, i was talking about the one summit built. I think his looks pretty darn good.

yep, me and brads where built by the same guy. (and a big thanks to brad for his help, those are the pics you took btw). these 2 dps are works of art in my opinion, perfect fit all the way down with no mods needed and they don't come close to anything. i even still have plenty of room for my kirban control arm bushing heat shield. the only thing i have to remove to take it off is: up pipe, test pipe, and the one bolt in the plastic wheel well that holds it to the body.

problem is, this was kind of a one-off deal that was offered awhile back. since the guy didn't have a jig, he used brads car for the mold. nobody else was able to pony up the price at the time, and yes it is pretty expensive, i would pay the price again tommorow. even with the largest bolt on turbo offered for our cars (t33) the 2.5" pipe is still slightly larger than the outlet on the exhaust compressor housing, so something as big as a 3" is way overkill imo, plus, every 3" pipe ive ever seen, there is some cutting here and there that needs to be done to get it to fit, or, it is extremely close to other parts that it can hit when the engine torks.

its all in what your goals are i guess. i was running stock dp before i installed, and i had already installed poston headers and up pipe and hooker exhaust, which did make a differance in lower response for my car, but when I added the 2.5 dp and eliminated elbow, the car was able to finally wake up and breathe, i got almost 3 more psi of boost and overall response was incredible differance

 

[BRAD_PADGETT]

And just where do the rest of us get one???? Sign me up!!!

The truth is you cannot get a downpipe like mine and TB3. Both of these downpipes were built by a guy near me. The problems with this setup is the high cost and more importantly the process. In order for my exhaust guy to build this downpipe my car has to be in his shop. I did a one time favor for TB3 last year. I am not in the downpipe business. The RJC flange can be found on their website for $129. This eliminates the need for the restrictive turbo elbow. The second main reason is the cost. I paid $850 for my downpipe(my flange cost $45) which puts the cost at $950 today. The point is we need to get someone to build our downpipe at a reasonable cost. Take-care. Brad

 

[cool 84]

Those downpipes look very nice. It makes me wonder why they didn't catch on considering our hotairs need a better downpipe worse than the IC crowd. My Lee Thompson 3" pipe was pretty inexpensive but I had to buy a $450 external gate to use it.

 

[tb3]

does your lee thompson have a big dent knocked in it so it would keep from hitting the control arm?

 

[cool 84]

does your lee thompson have a big dent knocked in it so it would keep from hitting the control arm?

No dent. It fit very well, not even close to rubbing. I eventually modified it to fit the Kenne-Bell headers and then I ran into issues with it rubbing the floor board. FWIW, it was a 3-piece bolt together unit.

 

[stage1and2]

rjc racing flange $129.00

does anyone have the part # for the rjc flange ? would like to get one for my hotair. thanks kirk.

 

[BRAD_PADGETT]

The flange is the same for a stock 84/85 & 86/87 turbo. Only the nipple for the 86/87 is longer. For the hot air setup. cut and reweld the nipple shorter. RJC racing is a vendor on this board. Good luck. Brad

 

[FJM568]

Here's a partial pic of my 3" TH-style DP. It started out life as a 2 pc Action Fab DP that bolted to the stock elbow. It was then modified to fit the TH-style elbow. It actually fits quite well. Real tight, makes changing plugs an ordeal. Motor has to be cold to do it.

Not a real good pic, though. Motor is out of the car right now. Soon to have a roller cam and get back on the road...I could probably get a pretty good pic of the DP with the motor not in there.

Had it built maybe like 6-7 yrs ago...First one, TH-style that is, if my memory is correct...It was built by a very well known TB vendor that wanted to see what it would take to build one. After making mine, he didn't think he could make them and still have it affordable enough to sell...