THDP Slow Me Down ??

[dsa87gn]

Well, a post or two in the archives gave me this impression.
I just got my THDP and from what I've been reading it will not really gain me much, if anything, at this point. but SLOW ME DOWN ???? is that possibility for real ?

 

[Nas-T-V6]

Are you kidding?
When I had my stock combo, I put and my THDP and the difference was like night and day. Some ppl belive that a THDP isnt really good until 11's, but im not convinced. I think it was one of the best mods ive done.

 

[dsa87gn]

Some ppl belive that a THDP isnt really good until 11's

That pretty much the impression on many posts here.
Your feedback relieves some anxiety. I was amazed to read of a decrease in performance and thought it sounded a bit out of whack.

 

[CanVan87GN]

In agree with Nas-T-V6

I just put on my BG elbow and downpipe from the stocker and BOOM! The car woke up! You can still go fast with the stocker but as far as a bolt on, the bigger downpipe, mandrel bends, and dinky little elbow bye-bye, it has instant effects! PUT IT ON!

Shaun

 

[gnturbo]

Yes it WILL slow you down ,I would put it back in the box and mail it to me and I will dispose of it for you

 

[JToups386]

Q: What is a internal combustion motor?
A: A big freakin' air pump!

You want to get air in, and get air out, as quickly and effeciently as possible. Therefore, I'm still perplexed at how people would think opening up the "air exit" is going to slow them down! It's like the same theory that you need exhaust "back pressure" to perform better. Sorry, I don't buy it, and it doesn't make sense to me!

Yes, there are people who claim they slowed down with a THDP, but I'd bet the farm that it wasn't the THDP that caused it, but rather the increased airflow and boost from the bigger pipe, and therefore they created a need for more fuel, etc.
In otherwords, they gave themselves the ability to make more power, but in doing so, they need to compensate for it by raising fuel pressure and/or volume, and adjust the boost accordingly.

I've known many people who've used the THDP on TR's from stockers to 10 sec haulers, and none of them have ever said; "I wish I could go back to that finagled, crimped, stocker...!"

Now, before anyone goes medieval on me here, YES, I know that some of you have run a 300mph with a stock DP, and that's great, but you are usually the exception to the rule, based on having created a perfect balance of parts that work together.

In general, I promote and encourage the use of a 3" THDP, and would never give mine up!

 

[gnturbo]

but If anyone wishes to trade for a faster stock downpipe I will trade you plus some cash.....

 

[UNGN]

I would find it very hard to believe a THDP would slow a car down. Some cars may not pick up as much as others. I've done back to back testing between a THDP and a ported elbow/Stock replacement 2.5" and saw .05/1.5 mph gain.

Here's my test results from a test performed at Buicks @ Bristol 2001. Everything else was equal except the elbow/DP.

Ported elbow/2.5" ATR downpipe/testpipe:

11.840 @ 113.08
11.859 @ 114.66
11.836 @ 114.72

Average:

11.845 @ 114.15 (avg 60 ft 1.680)


Terry houston 3" DP/Capped dump pipe:

11.745 @ 115.36
11.788 @ 116.05
11.838 @ 115.62

Average:

11.790 @ 115.67 (avg 60 ft 1.687)

Difference = .055 seconds and 1.52 mph

I thought the THDP would be worth more. These weren't even all the runs. If I factored in the others (made it an avg of 5 runs each) the stock elbow ET would be a little closer (though the mph would stay about the same).

You can't knock a 1.5 mph increase, but it appears to help the top end charge more than the ET. The rest of the combo is stock driveline, stock intercooler with a neck, bluetops, TA49, 275/60 BFG's weather was in the mid 60's, track elevation 1400 ft or so. Your results may vary.

 

[S2V6RACER]

Originally posted by UNGN
I would find it very hard to believe a THDP would slow a car down. Some cars may not pick up as much as others. I've done back to back testing between a THDP and a ported elbow/Stock replacement 2.5" and saw .05/1.5 mph gain.

Here's my test results from a test performed at Buicks @ Bristol 2001. Everything else was equal except the elbow/DP.

Ported elbow/2.5" ATR downpipe/testpipe:

11.840 @ 113.08
11.859 @ 114.66
11.836 @ 114.72

Average:

11.845 @ 114.15 (avg 60 ft 1.680)


Terry houston 3" DP/Capped dump pipe:

11.745 @ 115.36
11.788 @ 116.05
11.838 @ 115.62

Average:

11.790 @ 115.67 (avg 60 ft 1.687)

Difference = .055 seconds and 1.52 mph

I thought the THDP would be worth more. These weren't even all the runs. If I factored in the others (made it an avg of 5 runs each) the stock elbow ET would be a little closer (though the mph would stay about the same).

You can't knock a 1.5 mph increase, but it appears to help the top end charge more than the ET. The rest of the combo is stock driveline, stock intercooler with a neck, bluetops, TA49, 275/60 BFG's weather was in the mid 60's, track elevation 1400 ft or so. Your results may vary.

Good job doing the comparison. It would be nice if there was more info like this on other performance parts.

 

[dsa87gn]

Good job doing the comparison. It would be nice if there was more info like this on other performance parts

Agreed, UNGN has posted this info several times. This info is what originally led me to buy a ported elbow from a member here. (never even ending up putting on). Figured since I got all new pipes in the engine comapartment and exhaust, I might as well do it right.

gnturbo..Yes it WILL slow you down ,I would put it back in the box and mail it to me and I will dispose of it for you

LOL. I may just do that. But let me test it out for 100K miles or so just to be sure!...


JTOUPS386..
I had the same gut feeling as you, that cars werent retuned after installing the pipe. That was part of the reason for this post.


thanks all for input....

 

[DonnieShort]

I had a stock elbow and a crappy budget 2 piece dp on my PTE52 and I could only muster a 12.280, put on a new Mease 3"dp and went 11.790. That's ½ a second at 23psi of boost. It happened for me, but your results may vary. In any case, put it on.



Donnie