RB26 -7 upgrade suggestions for optimum performance

[Hadouken]

Short of scouring the depths of sau to find the thread that compares the sizes to the 3 dumps, I personally have done no testing. And I don't recall seeing your test results posted anywhere either.

But luckily I don't have to test it if someone has already gone through the efforts in the past to compare them and give us forum members the results.

So I see you are getting frustrated, which happens every time someone corrects you so I'm not really bothered.

All I know is that you don't want 32 dumps and you do want 33 and 34 ones.

[Borci88]

4 minutes ago, Hadouken said:

Short of scouring the depths of sau to find the thread that compares the sizes to the 3 dumps, I personally have done no testing. And I don't recall seeing your test results posted anywhere either.

But luckily I don't have to test it if someone has already gone through the efforts in the past to compare them and give us forum members the results.

So I see you are getting frustrated, which happens every time someone corrects you so I'm not really bothered.

All I know is that you don't want 32 dumps and you do want 33 and 34 ones.

 

I'm not interested in arguing with you nor am I getting frustrated. I feel like we're saying pretty much the exact same thing only I'm saying 34 are not as good as 33, but it is negligible. I haven't posted test results because nobody listens on this forum regardless (thus why it took Piggaz and others pushing hard to convince people stock cams are the best for years before anyone agreed), I have done 20+ turbo swaps in the last year or so and the owners either choose to keep their stock dumps, or go HPI. I've seen stock 34 dumps go up to 370rwkw on E85 so they're not really a restriction in the grand scheme of things. 32 dumps yes while restrictive, will be fine for his power goal, which is what I was originally replying to, in that he doesn't NEED HPI dumps.

[sneakey pete]

That's all well and good if you only care about peak power. However you have to wonder what effect the the size of the dumps will have on midrange power and transient response etc. Personally i'm of the opinion of bigger is better and would try get a cheap set of Tomei or HPI's

[Piggaz]

Eh, ditch it all restrictive shit and put a single on it ?.

 

But people buy R34 dumps for a reason. No one "upgrades" to R32 or R 33 dumps. R34 dumps are the biggest and get sold for cheap. They're bigger then anything else stock. Do some measurements and come back. It's the "cheap upgrade". 

[TXSquirrel]

So here is my take away.  Aftermarket dumps will not make much of a difference if I am targeting, let's say 320rwkw.  However, I can get more power at mid range and perhaps reach 320rwkw earlier because they do flow exhaust air better.  I can live with that.

But then here is my speculation.  If I also get manifolds ported, they may create an early lag that offsets any early gain from aftermarket dumps.  My reason is a more restricted manifold exit creates more back pressure but also higher velocity air flow, which can churn turbines faster...?  But then how about the air turbulence created by mismatched port sizes between a manifold outlet and its turbine inlet...?

[Trex]

2 minutes ago, TXSquirrel said:

So here is my take away.  Aftermarket dumps will not make much of a difference if I am targeting, let's say 320rwkw.  However, I can get more power at mid range and perhaps reach 320rwkw earlier because they do flow exhaust air better.  I can live with that.

But then here is my speculation.  If I also get manifolds ported, they may create an early lag that offsets any early gain from aftermarket dumps.  My reason is a more restricted manifold exit creates more back pressure but also higher velocity air flow, which can churn turbines faster...?  But then how about the air turbulence created by mismatched port sizes between a manifold outlet and its turbine inlet...?

You don't want back pressure in a turbo charged car. The quicker air gets to the turbine, the quicker it starts moving.

[TXSquirrel]

1 minute ago, Trex said:

You don't want back pressure in a turbo charged car. The quicker air gets to the turbine, the quicker it starts moving.

I look at this issue like pinching a water hose.  When a water hose is pinched, there is more pressure, hence a higher velocity water flow, eg. restricted manifolds.  When a water hose is relaxed, there is less pressure, but water flows with lower velocity, eg. ported manifolds.  So there is always a catch, and then the question is, which scenario spins the water wheel faster...?

[Trex]

I understand what you're saying, I see it being very dependent on the whole setup. Honestly i shouldn't have commented as i don't have enough first hand knowledge on the subject.

Theory goes; smaller rear housing = quicker spool being that it is the road less traveled. The smaller vs larger rear housing is very well documented.

A lot of people used to complain about lag with a fmic being so large, and piping so long, and debate the use of 2.5" vs 3" . Most people i have spoken to who are honest (not trying to justify money spent) will say that there wasn't a difference in response. 

[GTSBoy]

23 minutes ago, TXSquirrel said:

I look at this issue like pinching a water hose.  When a water hose is pinched, there is more pressure, hence a higher velocity water flow, eg. restricted manifolds.  When a water hose is relaxed, there is less pressure, but water flows with lower velocity, eg. ported manifolds.  So there is always a catch, and then the question is, which scenario spins the water wheel faster...?

 

It's very simple.  Porting the manifolds increases the flow capacity (ie bumps up the max power they will flow) whilst stealing from the bottom end, for exactly the reasons you say.

[r32-25t]

I have -7s making 348kw at the wheels and the manifold haven't be touched, I wouldn't port the manifolds until going to -5s 

[sneakey pete]

Bear in mind the "squeezing to make it faster" Mostly takes place in the exhaust housing itself.