When do we know that the problem is in the air?

[MetalMania80]

I thought about the whole, with Kia Stinger 3.3T - Ultimate Performance HFC Downpipe + Mid Pipe Combo Kit. and catback.

Can I reach 500-540 hp (crank) with stock exhaust?

 

[Thomby]

I thought about the whole, with Kia Stinger 3.3T - Ultimate Performance HFC Downpipe + Mid Pipe Combo Kit. and catback.

Can I reach 500-540 hp (crank) with stock exhaust?

I've considered it too given the 46hp / 62tq gain they show, but others have been skeptical of those gains. That coupled with the stories of guys breaking turbo studs or having oil smoke has kept me from pulling the trigger...if you do it make sure to soak the studs in a penetrant, preferably overnight and a few times over.

Stock exhaust should not prevent you from hitting 500-540 crank. Of course there will be some combination of boost & timing that lands you at (say) 490hp on stock exhaust and (say) 510hp on aftermarket exhaust, but if you follow the established path of intake/plugs/E30 and work your way up the maps you should be in the 450-500 crank range.

See how it drives, maybe dyno it there, then decide whether you want to go CPI (or WMI) for that extra kick.

 

[Corleone1]

I was assuming by "more air" you meant "freer flowing intake" based on the mods you described, at a given level of boost. And I think the answer is that the convoluted stock routing probably has some restriction that any open airbox (or sealed box + snorkels) eliminates. If there were further room for improvement, you can't beat a cone filter on the turbo itself.

If you're asking more generally if the engine is limited by the amount of air, that's easy: if you aren't fuel limited (quantity or knock), you're air limited. But that really means turbo limited (either via self-imposed boost limit, or thermally...not a physical restriction between turbo and engine).

So if your logs show zero timing corrections, you're "air limited" by your conservative boost limit. If you have mild corrections, you're air limited by your octane. And if you ran BEF+E85+CPI/WMI with the turbo cranked to the max, you'd be air limited by the size/efficiency of the turbo itself (and exhaust manifold restriction).

Agree!

 

[Corleone1]

If you should go for a better exhaust there is some alternatives:

1. Take off secondary cats, keep the rest, maybe a 10-15 hp gain. Easiest to do and still pass emissions
2. Keep secondary and go for catless DPs, you should still pass emissions and this make a difference at higher rpm, like +4000 and up, probably, just a guess... 15-25 hp
3. Complete new system with catted 200 cells DPs and rest as a free flow exhaust with 1-2 silencers. Will also pass emissions as I have had this before. Just a guess but maybe 20-30 hp some depending of how aggressive tune you run
4. Complete larger system, bigger catless DPs with 200 cells cat after DPs, will pass emissions also. Its preferable to have cats at more distance from turbos as exhaust gases will be cooler along its trip. This is what I have, right not no cats at all but they going in after Dps. Guess is 25-35 hp at a heavy max tune

DPs change takes time and can be tricky, stock locknuts isnt a play, you need to grease them up day before and it can takes that you warm them up (induction heater) also to get them lose. But its doable. If a pin bolt breaks there can be needed to drop the engine not fun: I have done it...

Warning if you will change DPs: Never use stock nuts, not even new ones, you have to buy copper nuts so its possible to take them of again.

When I did change exhaust from stock to a free flow 2½" system (stock DPs) I did get like 2-3 more Psi from 4500 rpm, so there is a bigger resistance from that rpm telling us there is a restriction that kills flows at higher rpm.

 

[MetalMania80]

What do you think about NGT Performance Primary Cat ?

I tried different BEF, such as Race (ign18), E85 and Race ign19. For me, the best works JB4 BEF Race.
Maybe is not the faster one, but I feel the boost and the car feels the most steady.

I'm not convinced to open intakes. I have one from BMS, but I'm unsure if they make a power difference.
I asked Terry do they have any performance comparison between BMS Intakes vs stock boxes + sport filters (I have K&N)+ new BMS High Flow Silicone Turbo Inlets, but no response so far.

For me is not easy to make E30-40, pure E85 is a dream. We don't have it in Poland. I have to buy pure chemical ethanol and mix it with gasoline. The advantage is that pure ethanol has an octane rating 112-113, so my E30 is 97.8 or 99.3 depending on what fuel I mix it with. Drawback, I have to order and keep it in my garage, and fill a tank with it at the gas station using a funnel and is not cheap.

I haven't considered changing the exhaust, but now, knowing what you all have explained to me, I think of it—it would give more power and be safer for the engine.

Thanks a lot for your patience and explanations,
Best !!

 

[Corleone1]

I bought my catless DPs from Poland and Much Boost. I don't think they have chatted ones. Before I had these like Ngt with 200 cells big difference to stock

 

[Corleone1]

Agree, always turbin that is the biggest resistance.

I also think that bigger turbos need to have a full build if it should be worth it. I know that we all get used to the power we have with our cars but I still feel its really enough for a daily driver, strong, fast, easy to drive, nice to look at and a very good handling IF... you have changed springs.

You need go up in power like the GTR´s we run with +1000 whp, well, we get used to them also but you just don´t have to drive for a week and they feel crazy again. I drove last week as I put it of for the winter. At full Map it is crazy, it is bang when shifts in, it spin at all 4 even when 4:th gear with goes in and with some sideways sliding. This even as we have a programmed Syvecs antispinn that I just can put it of by the PC, not in the car like stock, its really dangerous. My friend, Europe's best tuner, Tony spun at all 4 in 280 km/h in log, not healthy... Every guys that I have had as a passengers, Lambo and Ferrari guys, understands nothing... what happened they say.

That´s what life is about! Cars handles like we treat them! No other daily´s do that, who can they be...?

 

[Corleone1]

I have to put up a pic... sorry if I stole the thread...

 

[MetalMania80]

I saw this video posted by Thomby. Turbo is the biggest restrictor in our cars. I understand that by releasing some restrictions afterwards by making DP (catless or sport cat like 200-400 cells), we make it easier for our turbos and gain additional power.

 

[Corleone1]

Yes, thats right. Also... if you take in more at intake side... more has to get out.

 

[MetalMania80]

Okay. I did some research, and opinions are quite different. In my understanding, making the end part, let's say with cat-back, gives me sound and maybe a few HP. The biggest gain will be with DP. What about secondaries/mid-pipes?

 

[Corleone1]

Hotter exhaust is a bigger restriction as it has a lot more volume. As longer back exhaust gases travels, the cooler = less volume it is. Thats why always the restriction is:

1. Hotside/turbin (and manifold)
2. Dp;s, more resistance with cats #1, a lot less wo. (If you look in in stock Dp´s and compare to aftermarket cat less you understand why it takes power, area stock is about half or under the area from aftermarkets.
3. Next cats #2 and rest of the system
   
   So yes, you are right, that why I do cat less DP;s now and will put good cats at where stock cats #2 is located. It cats run to cold they work less good. But I will fill up with gas when I then go for the yearly inspection (instead of E) and drive it really warm before. New cats are also better. Right now I am thinking of to use the stock secondary for the emission test and then again take them of for just a pipe. Stock cats is like 3-400 cells and really restricted so the work good. At GTR I did pass with 100 cells at the place our secondary is placed. So should not be a problem.
   
   If you go all the way with full cat less it will still go quiet when driving normal but at WOT a Stingy sound from the back and... its possible that you need a tune for that so it don´t over boost a lot by increased rpm. That what we work with right now. That also tell us how much more flow there is wo restriction from cat;s , I got around 8-10 psi more than with cats but has a stop of course right now until we solved this. Boost regulation is by air mass and stock ask for much more mass than engine can produce as the restrictions take care of that. Wo cat;s and free flow exhaust the ECU asked air needs to go down as the rpm with much flow will rise boost to much. Soon it´s done. Probably more power at 18 psi than 22...

This Dyno I found for years ago, not mine.

Below is my exhaust, run quiet and is a right thru all the way. Best to have as big silencers at the back as possible, its also important to let the end pipe go in inside the end tips.

 

[Thomby]

This Dyno I found for years ago, not mine.

That's the dyno from the HFC downpipe/midpipe sales page. When I asked about it in the past, people who had them seemed skeptical, and the fact that they don't change the much tighter restriction upstream of the turbine makes me skeptical.

But I haven't seen any before/after dynos from actual users to confirm/deny it.

 

[Corleone1]

Yes, seems a bit to much difference. But every difference is good....

 

[MetalMania80]

Thomby, so having in mind the video that you posted, everything relating to the exhaust system is a little bit of a scam- restriction is in turbo, so power gain from all these modes (DP, secondaries, cat-back) is little if any?

Do I think correctly?