Does a downpipe make a difference? Part 2

[bshotts422]

.

[chaser27]

You need a ; after

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[scubasteve711]

Originally Posted by Mike@Stratified If you can get before and after logs in similar conditions on the same road I'd be really interested in seeing them.

I'll try to incorporate some fixes into the tune for any over boosting before I do the DP so that I can do a 1:1 on the tune. I'll definitely do a before and after!

[btstarcher]

Wonder where that data is..... @Jtaylor;

[Jtaylor]

Originally Posted by btstarcher Wonder where that data is..... @Jtaylor;

Give me a second

[MS3inDC]

Originally Posted by spdandpwr Wish this was done on the same car. Not that my anecdote is scientific, but as someone who when from a @superskaterxes; tune with intake, sri, and cbe to that same tune with a catless dp and step lower sparkplugs, I felt a huge difference. To gauge the difference, I used a car race as my control. Before I was neck and neck. After catless dp, I pulled a car length with each gear. After a revised tune, I pulled slightly harder still.

I'm gonna give Ant the benefit of the doubt and say that he just pushed your tune further after you had mods to support it. Ant is a very careful tuner.

I was one of the first to have a Superskaterxes RichTune, and with every revision the car pulled harder. He's tuned me from intake and internals only all the way to fully bolted, and with each revision the car came alive more and more. At this point and power level, all that he can do is "change the curve" unless I run some form of alcohol or go BT.

[Mfinlay04]

I did my DP solely for more WGDC head room. I was maxed out 95-99% even with my 3 port EBCS and only gettings 16 psi over 5.5k. Since my dp i've been able to hold a little more boost towards redline, but a k04 is gonna be a k04

[btstarcher]

Still waiting LOL

[g00s3y]

Another reason I love my OBX exhaust, $510 shipped for the whole TBE, and everything was awesome.

[Mazdazilla6]

@Lex; I know you've talked about using cats to prevent the stock turbo from smoking, but wouldn't this be contrary to that? You talk about how well the oem cat flows so wouldn't that mean it is really just covering up the smoke rather than provide an increase in back pressure to keep it from smoking? I'm not trying to call you out, just looking for some clarification.

In my experiences my car used to slowly sip on oil when I had the stock dp and after I threw my catless dp on it still slowly ate oil, the only difference being that now I see smoke.

[iammike]

Originally Posted by Mazdazilla6 @Lex; I know you've talked about using cats to prevent the stock turbo from smoking, but wouldn't this be contrary to that? You talk about how well the oem cat flows so wouldn't that mean it is really just covering up the smoke rather than provide an increase in back pressure to keep it from smoking? I'm not trying to call you out, just looking for some clarification. In my experiences my car used to slowly sip on oil when I had the stock dp and after I threw my catless dp on it still slowly ate oil, the only difference being that now I see smoke.

Any cat will provide some extra back pressure. How much I wouldn't begin to be able to tell you.

Also, yes, I believe a cat does more to mask the smoke than actually stopping the problem in the first place. That's just my opinion though.

[Lex]

It's a little bit of both. There is definitely more back pressure with a cat versus without a cat. Then smoke might be cleared up a bit more with having a cat in the way as well. The purpose of the cat is to covert CO to CO2 and it will do little to actually prevent the smoke from exiting the tail pipe once it is burned. The backpressure is preventing the pressure differential between the CHRA and turbine housing from being too large in turn preventing some of the oil from exiting the CHRA and burning in the first place.

The more effective methods to stop smoking is to increase vacuum at the crankcase (Mazdas OEM fix) run a higher idle to get higher vacuum, and run a thicker oil.

[Yatta]

I get a deal on a CPE catted dp and now wonder if it was because of this post having a gutted stock secondary already wondering if I should wait, which brings me to my second question, a catted/long DP (elimination of second cat) should weigh less then the stock combo? how much less? these comparisons are for dyno results but that might not be the whole picture? I suppose if I install it I could weigh it and weigh the DP/TP combo it replaces.

[Cheapspeed]

Originally Posted by Yatta I get a deal on a CPE catted dp and now wonder if it was because of this post having a gutted stock secondary already wondering if I should wait, which brings me to my second question, a catted/long DP (elimination of second cat) should weigh less then the stock combo? how much less? these comparisons are for dyno results but that might not be the whole picture? I suppose if I install it I could weigh it and weigh the DP/TP combo it replaces.

Definitely not enough to make a difference. That's splitting hairs.


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[Snip]

Originally Posted by Lex The more effective methods to stop smoking is to increase vacuum at the crankcase (Mazdas OEM fix) run a higher idle to get higher vacuum, and run a thicker oil.

And upgrade the oil restriction bolt to one with a smaller diameter hole (on the stock k04 that is) so lesser oil goes to the turbo.

I believe damond motorsport sells them
Stock turbo, oil restrictor banjo bolt

[Lex]

Originally Posted by Snip And upgrade the oil restriction bolt to one with a smaller diameter hole (on the stock k04 that is) so lesser oil goes to the turbo. I believe damond motorsport sells them Stock turbo, oil restrictor banjo bolt

If the problem can be resolved without restrictors I prefer this. I like the CHRA to get as much oil as possible without having it end up on the turbine side.

[El Beaner]

I want to thank you @Mike@Stratified

I was on the fence a lot between getting a TP vs a full DP - then had a local mention this post and it solidified my decision and I went TP only.

[anodizedeeznutz]

@Undertaker;


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[Dimenus]

Originally Posted by Mfinlay04 I did my DP solely for more WGDC head room. I was maxed out 95-99% even with my 3 port EBCS and only gettings 16 psi over 5.5k. Since my dp i've been able to hold a little more boost towards redline, but a k04 is gonna be a k04

I've had a similar experience since adding my Axleback as well.

With a full DP and axleback, my k04 isn't even trying very hard to hit load targets at redline (especially on pump).

So yes, powerwise you might not gain much, but having the extra headroom on the stock turbo is nice. I don't really know if not having to use the full wastegate decreases load on the turbo, but it makes me feel better lol.

Edit: The Corksport ABE has no muffler though so it is definitely loud.

[iammike]

You sissies running catalytic converters and stock downpipes are missing out on the fun of scaring Prius drivers at WOT.

[El Beaner]

Originally Posted by iammike You sissies running catalytic converters and stock downpipes are missing out on the fun of scaring Prius drivers at WOT.

Coal Rolling is better

[Cheapspeed]

Originally Posted by iammike You sissies running catalytic converters and stock downpipes are missing out on the fun of scaring Prius drivers at WOT.

I still dump with my high flow cat and not just at tip in.

[himurax13]

Originally Posted by iammike You sissies running catalytic converters and stock downpipes are missing out on the fun of scaring Prius drivers at WOT.

Meh, I am over that.

[Cheapspeed]

So.. @Mike@Stratified; @Lex; and @jbmazda6;

We should be seeing a dyno comparison with tuned stock dp vs tuned cpe catted dp yes?

[himurax13]

Originally Posted by Cheapspeed So.. @Mike@Stratified; @Lex; and @jbmazda6; We should be seeing a dyno comparison with tuned stock dp vs tuned cpe catted dp yes?

On the same car?

[Cheapspeed]

Originally Posted by himurax13 On the same car?

Yes.

[btstarcher]

@jbmazda6; did you guys do any before and after dyno comparisons?

[jbmazda6]

Originally Posted by btstarcher @jbmazda6; did you guys do any before and after dyno comparisons?

Im hopping on the dyno saturday. We will have to determine what significant gains are. I would say 15+hp to even make it worth buying. Thats just my opinion though and I believe I will achieve that Saturday. I will be writing up a full review of everything in my journey thread and will post up just an answer here.

We will also have to look at differences in temperature and humidity. Even though the dyno "corrects" for that, the car still runs differently in different weather (not a boost based tune) so that will have to come into consideration.

Thank you everyone (who is interested) for being patient.. the time has almost come.

[Lex]

Originally Posted by jbmazda6 Im hopping on the dyno saturday. We will have to determine what significant gains are. I would say 15+hp to even make it worth buying. Thats just my opinion though and I believe I will achieve that Saturday. I will be writing up a full review of everything in my journey thread and will post up just an answer here. We will also have to look at differences in temperature and humidity. Even though the dyno "corrects" for that, the car still runs differently in different weather (not a boost based tune) so that will have to come into consideration. Thank you everyone (who is interested) for being patient.. the time has almost come.

We were able to get better stability before knock with the DP installed so the knock threshold was pushed out further. We will see the exact comparisons very soon.

[himurax13]

Does the stock dp in this conparison have a race pipe?

[jbmazda6]

Originally Posted by himurax13 Does the stock dp in this conparison have a race pipe?

No, full stock exhaust

[himurax13]

So both the cats then? I think it would make more sense to have a racepipe/nator midpipe installed since that is the easier/cheaper option than a full downpipe install. Not to mention you should remove a cat in order to use a stage 2 OTS tune.

[nb6179505]

But effectively tp with oem cat is comparable to long catted dp stage 2 ots should be attainable

[Cheapspeed]

Cpe replaces both oem cats with 1 high flow cat.

[jbmazda6]

The title of this thread is "does a downpipe make a difference", all but ONE of the options for the speed6 is a long downpipe so replacing the downpipe generally means replacing both cats. Its not saying whether a test pipe or downpipe is better. I have an opinion on that but dont feel like even touching on it until I see the numbers saturday.

[himurax13]

Well downpipes usually eliminate both cats or replaces one of them with a high flow cat. So if the purpose of this test is to compare a stock downpipe and midpipe to an aftermarket downpipe with no cats or one high flow cat, I suspect that a 15 HP difference will be seen and I doubt anyone will disagree with that.

Most of the arguements I have had involves a stock downpipe + race pipe/NATOR midpipe vs any aftermarket downpipe, catted or not on a stock turbo.

Seriously, who is going to tune with both stock cats in the car?

[jack_hammer]

Originally Posted by himurax13 Most of the arguements I have had involves a stock downpipe + race pipe/NATOR midpipe vs any aftermarket downpipe, catted or not on a stock turbo.

I have seen dyno charts that show a stock dp/gutted test pipe can make comparable power to a full catless dp. Not the same car, day, weather, and moon cycle, but the results were there just the same.

They are buried in old threads, though, and I'm not going to search for them.

[AnubisFSU]

So... What happened to all these test results.

[JgamB]

With so many people going to mid turbos, I can offer some data that won't mean much to the K04 crowd. Better than nothing I spose...

Same dyno, similar mid ~70F temps for all pulls. The E85 K04 setup was 68mm intake and test pipe only. The BNR S3 pulls were Gutted UPPER DP and stock test pipe vs ATP long catless. The results were impressive - so I would use the same train of thought we typically use for intakes - if you might go bigger later, you may as well go full 3" out the hiney now, unless you're concerned about expediting K04 seal failure.

[Cheapspeed]

I'm stuck around 320whp on my 3076. High flow cat, resonated testpipe, and stock catback. Also, low compression in cylinder 3. But I'm definitely leaning towards opening up the catback now. I keep reading that I'm leaving about 15hp on the table, which seems to line up with your numbers.