3-1/2" THDP vs ATR Headers

[clemsgn]

On a high 10 sec car, which would be a better performance choice....ATR headers with a Terry Houston 3" downpipe (which has that flattened area to fit around headers and heater box)

or

Stock headers that were carefully port matched and pinned to the heads along with a Terry Houston 3-1/2" down pipe ? ?

Both would be used with dump open at the track, and through a 3" ATR single shot exhaust on the street

Does anyone have pics of the 3-1/2" pipe in the car or a side by side comparison to a 3"

Thanks much

 

[Sweet6]

I would wait until you are at at least 10.50s or faster. I doubt you will see much gain at high 10's. Most guys say wait until 9s for headers. But they won't hurt either.

 

[clemsgn]

ttt

Anyone ? ?

Results from switching to a 3-1/2 " from a 3" TH downpipe ? At what E.T and power level were you at ?

Another question...What's the quickest/fastest anyone's gone with ATR headers and a 3" THDP ??

Thanks

 

[GANGSTER]

why compromise?
get the atr headers and have a 3 1/2 dp made to fit.

I unfortunately found out the hard way the thdp 3 1/2 doesnt fit with the atr headers but i just had a friend cut it and fabricate it to fit with the atr headers.

only downside is the pipe is a real tight fit with the a/c box and upper a arm.

I cant believe nobody has come out with a bolt in 3 1/2 downpipe that fits with atr headers.

I have to say though, if i was to do it again, id prob go with a different header that fits the thdp or have a dp made with a 3 1/2 elbow and then step it down to 3" just to improve the flow in the elbow where the biggest gain is.

 

[azgn]

well, the Terry Houston headers and his 3.5" downpipe worked fine....sadly, they aren't available anymore

keep your eye on ArizonaGN's site (Nick)......I will soon have a new set of headers that will clear a 3.5" downpipe AND one can get to all the headbolts without pulling the headers........

 

[86brick]

Originally posted by azgn
well, the Terry Houston headers and his 3.5" downpipe worked fine....sadly, they aren't available anymore

keep your eye on ArizonaGN's site (Nick)......I will soon have a new set of headers that will clear a 3.5" downpipe AND one can get to all the headbolts without pulling the headers........

http://arizonagn.net/Headers.htm

Also, think I saw on Cramer's website that he will also be making headers....

http://www.rjcracing.com/RJC_Buick_Products/_New__Parts_Developement/_new__parts_developement.html

 

[GANGSTER]

there you go!!
thats the ticket. those are some nice headers.and they clearly fit with the thdp.

you will never be able to use the thdp with the atr headers just by flattening the pipe. by the time you're done there will be a loss instead of a gain.

 

[Russ Merritt]

Originally posted by clemsgn
Another question...What's the quickest/fastest anyone's gone with ATR headers and a 3" THDP ??

Thanks

I know people have gone faster than I with ATR headers and 3" DP but at the Nats my street car went 10.34 @ 132 with ATR headers, 3" DP, and through the ATR 3" single shot exhaust. That was with only 21 degrees timing also. It liked 26-27# boost and anymore (I tried 30#) it didn't help at all. With the Q-trim, I think the exhaust was a restriction and I would have liked to try a 24 degree chip. I know there is more in the car.... A dump pipe woulda been cool to try too during the week just to see.... But I didn't have one.

Clem, if I were you I'd do the 3 1/2" DP and leave the stock headers on and try it. Like you said they were ported, matched and I bet they would flow enough to go low 10s. Keep me posted on what you try......

 

[REDS HOT AIR]

Like Russ mentioned I believe once you go to a Q-trim wheel its time for a 3.5 d/p

I found about the same results

I went 131 mph at low timing and 24# boost but only 134 mph at 30#

thats with a 3" d/p in a 3600# GN


I will also be making headers for these cars before long

If I can find a 3.5 th d/p to use during design I'll make sure they work with it

 

[clemsgn]

Originally posted by Russ Merritt
That was with only 21 degrees timing also. It liked 26-27# boost and anymore (I tried 30#) it didn't help at all. With the Q-trim, I think the exhaust was a restriction and I would have liked to try a 24 degree chip

Hello Russ, Thanks for replying.
I'm trying to figure out what I have for a turbo. The guy I got the car from said it was a "stealth 72" but after checking, it actually has a 68mm compressor wheel. The comp housing has a 3" inlet and 2-1/2" outlet and a 55 A/R. The turbine wheel exducer is 2.54" with a 3 bolt precision .63 housing. any idea on what this is ?

To keep things simple, my current ATR headers and 3" THDP have the EGT probe and W/B O2 sensor mounted. I open the dump pipe at the track, so the 3" downpipe may not be so bad compared to corked up. (I run the ATR single shot also) Do you really think it would be worth all the time & expense to put stock headers back on and obtain a 3-1/2" downpipe ? Would I gain "that" much ? I also like the fact that I have a 3" cat to install if needed to aid at emissions time

Thanks again

 

[GANGSTER]

If you already have atr headers you are better off having someone make you a custom made 3 1/2" downpipe that will work with your headers. Thats what I did, It can be done but it has to be done custom. They just sweep it out a little further to clear the cross over and it kind of sneaks over the a arm and under the a/c box. you will need to cut away the inner wheel well to do it. then you will have the best of both worlds.

 

[Russ Merritt]

Not sure what turbo that is. Sounds like old technology and time for a replacement.

If your running out a dump pipe, why don't you get a new turbo and leave what you have? Turbonetics BB70 Q-trim .85 Precision housing would be a good choice as it would allow you to go low 10s.

With the Q-trim, a bigger DP is of benefit as Red pointed out. That's why I vote for the stock headers ported out, a 3 1/2" DP and exhaust, and a NEW TURBO! You've had that set up a while right? Time for a new combo.

Boy, I'm great at spendin money!

 

[V6 Beast]

I don't know about ATR headers, but I went 10.19@132 with stock headers and a 3" DP at BG last weekend. 10.18 at Norwalk last year. Not sure of the headers or DP is holding me back though.

Sully

 

[clemsgn]

Originally posted by Russ Merritt
Sounds like old technology and time for a replacement.

How old do you think ?

Turbonetics BB70 Q-trim .85 Precision housing would be a good choice as it would allow you to go low 10s.

Yeah, but then I'll need other supporting pieces !

That's why I vote for the stock headers ported out, a 3 1/2" DP and exhaust, and a NEW TURBO!.

I was hoping this 68mm turbo would get me in the low 10's? On Precision Turbo's site, some P trim 68mm turbos with the same size exhaust wheels, will support up to 800 HP. Even if mine is an "older" design, I would think it could get me there ?

You've had that set up a while right? Time for a new combo.

Not really. I've had this current car (grey T) for just under 2 yrs. and only have about 10 passes on it. Between breakdowns, house, kids & work, I haven't had much time for it.

Boy, I'm great at spendin money!

Yeah sure, pick me up a big turbo, converter, GN1's and a stage block and I should get it in the 9's !!

 

[twin 93 svt]

9.32 @ 144mph on a 109 block, and atr headers with a 3 inch thdp. in tsm weight, and through the muffler I might add. spend your money elsewhere!

 

[clemsgn]

Originally posted by twin 93 svt
9.32 @ 144mph on a 109 block, and atr headers with a 3 inch thdp. in tsm weight, and through the muffler I might add. spend your money elsewhere!

That's truly incredible ! What's your build up ? You do have a TR, correct ? What turbo and how much does it weigh ?

Thanks for any info

 

[REDS HOT AIR]

Originally posted by clemsgn
That's truly incredible ! What's your build up ? You do have a TR, correct ? What turbo and how much does it weigh ?

Thanks for any info

LOL

bet the details are top secret

oh yeah you need a girdle at that level