Divorced Down Pipes

[Poodles]

You know, I loved my DDP... I got really bored of it because I couldn't haul ass without alerting everyone within a mile :rofl:

Though scaring the shit out dumbass soccer moms driving slow and sloppy with the windows down was priceless...

FYI: I have one of the first chinese made DDP's, and it's not a perfect fitment. The newest ones on ebay don't even have the divider welded on from what I understand.

 

[Doat]

Would getting a downpipe on a stock motor increase the boost to fuel cut? I've read that most people don't hit fuel cut and is generally safe to just throw on a downpipe on a stock motor without fuel cutting problems or any other problems.

 

[jake8790]

In my experience with my own and friends supra's, yes. (Also going 3" straight pipe at the same time.) I am at sea level though in cold weather so the cars hit fuel cut sooner here.

 

[Doat]

Well I am in Houston so pretty much sea level as well and the air feels like a thick soup when it gets humid here lol. So I should also get a boost controller to keep fuel cut at bay?

 

[Dan_Gyoba]

Humidity doesn't affect fuel cut... Or shouldn't. The KV sensor detects air speed through the AFM, and density is assumed to be regular sea level air, adjusted down by the HAC sensor and up/down by the temperature sensor.

Hotwire AFMs can be affected by humidity, since the additional thermal mass of the moisture will affect the sensor wire similar to an additional mass of air.

 

[Insidious Surmiser]

You know, I loved my DDP... I got really bored of it because I couldn't haul ass without alerting everyone within a mile :rofl:

Though scaring the shit out dumbass soccer moms driving slow and sloppy with the windows down was priceless...

FYI: I have one of the first chinese made DDP's, and it's not a perfect fitment. The newest ones on ebay don't even have the divider welded on from what I understand.

I got a bellmouth DP recently that had a rounded flange on the upper part :-/ needs to be machined flat. also... DDP will alert people in a 2+ mile radius. I've been told my car could be heard ~2.5 miles out.

 

[Mikael_7m]

Just wondering guys,
but I ran a friends DDP without a divider plate for a couple of days and I was able to make full boost (10 psi) on my 57 trim just before 3000rpm.
Now i'm running a recirculated downpipe with a divider plate and I can only make 8 psi by 3000 rpm and it begins to creep as the revs increase, therefore hitting fuel cut.
Any ideas as to why they're so different? Thought it would be the same!

 

[Insidious Surmiser]

I'd imagine w/ out the divider there's a sight more turbulence inhibiting flow. pretty simple concept.

 

[Bmettie]

Humidity doesn't affect fuel cut... Or shouldn't. The KV sensor detects air speed through the AFM, and density is assumed to be regular sea level air, adjusted down by the HAC sensor and up/down by the temperature sensor.

Hotwire AFMs can be affected by humidity, since the additional thermal mass of the moisture will affect the sensor wire similar to an additional mass of air.

Humidity affects the density of the air which in turn will affect FC.

 

[Mikael_7m]

I'd imagine w/ out the divider there's a sight more turbulence inhibiting flow. pretty simple concept.

You didn't read it properly...

 

[Doat]

The question is do I order new suspension parts, Tokico Illumina IIs TEMS shocks, BG lowering springs, and bushings, or do I get this downpipe? I probably should replace my suspension parts and figure out wtf is making a pigeon sound in the rear passenger area.

 

[Bmettie]

The question is do I order new suspension parts, Tokico Illumina IIs TEMS shocks, BG lowering springs, and bushings, or do I get this downpipe? I probably should replace my suspension parts and figure out wtf is making a pigeon sound in the rear passenger area.

http://store.driftmotion.com/static/i-rearhatchbumpstopsmk3supra.php

 

[Insidious Surmiser]

You didn't read it properly...

dang, I see what you mean... got me stumped there.

 

[Mikael_7m]

dang, I see what you mean... got me stumped there.

Tell me bout it man! I can't work it out...

 

[BrandonW]

better flow? so fuel cut is happening?

 

[Dan_Gyoba]

Humidity affects the density of the air which in turn will affect FC.

But the TCCS ECU doesn't measure density.

The Karman Vortex sensor measures speed. The HAC sensor measures barometric pressure, which is independent of humidity. IAT measures temperature, which affects O2 density.

After all, what the TCCS cares about is oxygen mass, not air mass.

If humidity affected FC, then people in Vancouver would routinely hit FC at 8 PSI.

 

[Insidious Surmiser]

Tell me bout it man! I can't work it out...

you are talking about the same engine turbo, though right? I've heard all sorts of theories on the matter... maybe your divided one actually seats perfectly, so it operates as intended?

 

[Mikael_7m]

you are talking about the same engine turbo, though right? I've heard all sorts of theories on the matter... maybe your divided one actually seats perfectly, so it operates as intended?

Yeah same motor, same turbo. I don't see why my friends DDP spools much better and has no creep. Whereas mine is slower to spool and creeps. I just added more pre-tension to the wastegate today and it helped with spool time a little but it still creeps.

 

[Insidious Surmiser]

since it had no divider, wouldn't you just have a constant exhaust leak making a lot of noise?

 

[Bmettie]

But the TCCS ECU doesn't measure density.

The Karman Vortex sensor measures speed. The HAC sensor measures barometric pressure, which is independent of humidity. IAT measures temperature, which affects O2 density.

After all, what the TCCS cares about is oxygen mass, not air mass.

If humidity affected FC, then people in Vancouver would routinely hit FC at 8 PSI.

Yes but it doesn't necessarily measure speed like a MAF but also the strength of the recurring vortices created, stronger the vortices the more it shakes the little mirror and the thicker air affects the vortices created in the meter, same principle why a KV "can" be "blow thru" to an extent.