BIC Divorced Downpipe or Cheap Ebay Divorced Downpipe??

[755hp]

Hey guys, so I just lowered my Supra on Megan EZ Street Coilovers and dropped it almost 2 inches; now I'm scrapping my downpipe/exhaust in/out of my driveway. It caused the gasket seal btwn the turbo and downpipe to separate slightly (corner bolt between the turbo and exhaust manifold wasn't fastened properly come to find out...).

Anyway, I don't know why I wrote all of the previous sh*t above; I guess I'm trying to say that I want try another downpipe (this time divorced dp). I ran a DM open downpipe a few months back a loved hearing my wastegate crack open at WOT. Ohh, so yea, now that the gasket seal separated slightly, I can hear my wastegate cracking open AGAIN and I am now reminded of the SAVAGERY that can be heard at WOT!

So, what option would you guys choose?:

- Cheap Ebay DDP: http://www.ebay.com/itm/Toyota-Supr...Parts_Accessories&hash=item2a1bbb5572&vxp=mtr

or costly $400+

- BIC Performance DDP: http://www.bicperformance.com/images/ddp_new.jpg

Based on my knowledge from an MAE Fluid Mechanics course I've taken last Fall 2013, I'd say the Cheap Ebay option is not the best choice because there isn't a "Separator" piece btwn the exhaust path and wastegate path that would aid against exhaust flow disturbances (back pressure/turbulence). Not including the wastegate valve/flap hitting against the dump tube of the downpipe.

But then again, I'm not sure; maybe it would be alright...?

 

[themadhatter]

I've seen a few ddp's pop up on eBay that do have the separator.

 

[JDMMA70]

BIC hands down

 

[RazoE]

BIC. I was hitting boost instantly

 

[Doat]

I have the Justspeed Ebay DDP and the fitment is not all that great it's a real bitch to tighten the bottom left nut next to the manifold there is no room to get a socket you barely have room to get a wrench and in order to get a good grip you have to get under the car with a stubby wrench. Also I am not sure if they flatten the flanges. I wish I had gotten a BIC DDP I plan to order one in the near future with the flex part.

 

[super51fan]

Why not raise your car a bit and machine the flange on current down pipe and get a toyota gasket. I feel open air is only ok on big turbo high boost set up. IMO Kind of gay keeping up with minivan and hearing open air waste gate. Just sayin

 

[SideWinderGX]

Why not raise your car a bit and machine the flange on current down pipe and get a toyota gasket. I feel open air is only ok on big turbo high boost set up. IMO Kind of gay keeping up with minivan and hearing open air waste gate. Just sayin

You had this exact opinion over on SupraForums as well. While everyone is entitled to opinions, everyone is not entitled to their own facts, and you are an idiot for continuing to ignore those presented to you.

Regardless of how fast someone's car is, a divorced DP will spool a turbo (all else being equal) faster than a bellmouth downpipe. BIC proved this in back to back dyno runs. No one cares what you 'feel'.

 

[755hp]

You had this exact opinion over on SupraForums as well. While everyone is entitled to opinions, everyone is not entitled to their own facts, and you are an idiot for continuing to ignore those presented to you.

Regardless of how fast someone's car is, a divorced DP will spool a turbo (all else being equal) faster than a bellmouth downpipe. BIC proved this in back to back dyno runs. No one cares what you 'feel'.

Ohh man, thanks! I don't think he meant to be offensive though (I hope not); then again how does he know if I'm as slow as a minivan. You got a ride in my Supra two weekends ago SideWinderGX; tell me....did that feel like a minvan to you?? Lol

And I thought that a "bellmouth" type downpipe was the best flowing downpipe... Hmm, so would the Cheap Ebay downpipe be a better performer over the current DM bellmouth type??

 

[755hp]

Why not raise your car a bit and machine the flange on current down pipe and get a toyota gasket. I feel open air is only ok on big turbo high boost set up. IMO Kind of gay keeping up with minivan and hearing open air waste gate. Just sayin

I'm currently running a GrimmSpeed MBC set to 11psi (+/- 1psi depending on weather) staying away from fuel cut. I've got an Apexi Intake, full DM downpipe and exhaust (looking for another Dp), Megan EZ Street Coilovers and AEM Wideband afr.

And I might be upgrading to a ct26 57trim (puffing white smoke out the tailpipe now w/ stock turbo). Plus I got a Lexus AFM off Ebay and 550cc injectors which I purchased off SidewinderGX two weekends ago.

Case-n-Point: Once I get this downpipe (along with above mods installed), theres no f**kin way any minivan will be able to keep up with me....if so, then I will be a disgrace to my Supra-ancestry!!

 

[MK3pizzadriver]

I would stay away from the Ebay DP. I just had to return one because the build quality was so bad that two of the turbo's mounting nuts wouldn't even go on without them hitting the pipe or welds. And the divider plate is really flimsy. Compare the BIC divider versus the Ebay one:

BIC

Ebay

If you get the Ebay one, cut the middle part of the gasket out. It probably won't line up anyways (lol) and the CT-26 is open between the wastegate and turbo, so there's nothing to seal there. It'll probably just burn up and clog your cat lol.

BTW, both the bellmouth and divorced pipes are advertised on BIC's website as "turbo will spool 13psi at 26-2800 rpm, and keeps pulling hard up to redline" with the exception that the divorced pipe spools the turbo "much quicker than stock"

You should do a dyno run before and after to see what gains you see vs. the bellmouth. With all that flange area where the divider is being somewhat of an obstruction, seems like it won't be really all that much vs. the completely free-flowing bellmouth dp. But I'm really interested in seeing dyno gains vs. a remerged divorced pipe.. divorcing to air is sorta cheating lol.

 

[JDMMA70]

All I have to say is Toyota ran a DDP on their GroupA race cars.

 

[gats]

^ yep...

 

[755hp]

All I have to say is Toyota ran a DDP on their GroupA race cars.

Ohh, what?!?! Clearly, there is some magic to this "DDP" that I've not yet seen before!

My guess (in terms of fluid mechanics): A bellmouth Dp causes exhaust gas turbulence in the "bellmouth region" before it reaches the 3" Dp section. As the turbo is spooling up (wastegate closed) exhaust gases are swirling around the wastegate region (below turbine exhaust outlet) as well as trying to flow into the 3" Dp section. Then when the turbo hits full boost (wastegate opens) the flow of wastegate exhaust gases try to merge into the existing exhaust gas stream causing turbulent exhaust flow (in the bellmouth).

If you think about it, the bellmouth is the sharpest bend in the whole exhaust system (at least w/ my DM Dp and exhaust); and it occurs right after the turbo. Plus, fluid characteristics (velocity and pressure) change when you go from a bigger cross-sectional area (bellmouth) to a smaller cross-sectional area (3" Dp section). The smaller cross-sectional region forces the fluid to increase its velocity; it does so by placing pressure ("back-pressure") to the source from which it came (in this case, the engine/turbo). This is what delays spooling response from the turbocharger.

Instead, a DDP keeps the exhaust and wastegate flow separate therefore keeping each flow consistent (uninterrupted, smooth, laminar, etc); as a result, turbulence (therefore back-pressure) is kept to a minimal.

This is just my guess....based on my MAE 335 course.

 

[JDMMA70]

Good observation. However I wouldve thought it was more obvious to the benefit of a DDP.

 

[Doat]

That's why I thought the DDP is beneficial because it keeps the flow consistent for the exhaust and wastegate and doesn't clash together and cause turbulence

 

[DeMoN2318]

I have the BIC DDP. Install was VERY simple and straightforward! Noticable difference from a BIC bellmouth DP...

Only thing I will say, I wish I had the wastegate dump recirculated instead of open... Although it is cool to hear the wastegate scream at WOT...it gets pretty annoying when cruising around at partial throttle

 

[Doat]

my ebay DDP is open dumb it sounds mean on start up but when cruising it's not that loud imo I look forward to days where it's not so hot I can roll the windows down and just listen to the exhaust. At highway cruising speeds it doesn't bother me at all I can barely hear my exhaust over the music.

 

[MarkIII4Me]

Only thing I will say, I wish I had the wastegate dump recirculated instead of open... Although it is cool to hear the wastegate scream at WOT...it gets pretty annoying when cruising around at partial throttle

That shouldn't be, since your wastegate should be closed at partial throttle and open when set boost pressure is reached. That's how boost is regulated. Unless your turbo reaches full spool at partial throttle. I only hear my ddp once I hit full boost at around 4500rpm during a full throttle pull. Give a listen to my dyno pull in my signature. You can hear the whistle of the ddp only at the very end of the pull.

Here's a pic of my BIC DDP. I specifically requested that he mandrel bend it out of a single pipe, even the last 15 degree angle which he usually doesn't bend. So it's one of a kind. I think I show it off in every DDP thread. lol

 

[DeMoN2318]

^^ Interesting

Maybe my spring is weak.

but, I would expect the wastegate to open some under any amount of boost

 

[MarkIII4Me]

The wastegate flapper doesn't need to open very far to regulate boost, so it should stay shut up until just before your set boost is reached. If it even opens a crack it will definitely slow your spool considerably. What I believe is happening is that your DDP's divider isn't mating completely to the hotside of your turbo and causing an exhaust leak from the divorce pipe. I used to have this whenever I drove around whenever the engine was cold. Once the turbo got hot enough the metal would expand and stop the leak. I'd image this to be worse for most ddp owners as I shipped my turbo hotside to BIC so he could get the fitment as tight as possible.