The Great R33 Intercooler Dilemma

[Ryno]

Actually looking at that graph again the 68mm line is deceiving as it's not peaking at the same high boost as early in the rev range and that's probably why it looks to be falling away from 160rwkw.

The 100mm Takashi cooler clearly hits the wall at around 260rwkw of airflow though, and starts losing out to the PWR cooler from 180rwkw.

[Dose Pipe Sutututu]

Higher boost will:

1. Increasing boost will increase the cylinder pressure (how can it not?)

2. Increase the intake temp

3. Lead to higher chance of knock/detonation, far more prominent with 98 Octane PULP vs 105 Octane United E85

4. And potentially, show more in efficiencies in the intercooler system

In relation to point 4, think about wind resistance, or rather the power to over come it, is velocity^3 (If my memory is correct) - so it's not linear, and as such I would not expect an intercooler pressure drop to be the same from say 15psi to 25psi if the core itself is reaching it's limitations.

1. Run less timing, more boost.

2. Get a better FMIC

3. Run less timing

4. Yes, but safer way to tune, get a better FMIC

Back to my point, you just can't say "Running 25psi on PULP? That just be asking for trouble IMO. Most people keep to a more sensible 18-20psi and turbos that hit the sweet efficiency there"

[R31Nismoid]

Your argument about 25 psi of boost is relevant but is probably confusing the point a little.

It may be easier to think of it as the airflow limit of the intercooler... By using a larger turbo you could run into these same issues at a lower boost purely because the cooler can't flow the required amount of air.

You can see from the above graphs, the 68mm cooler starts being a restriction (compared to the other two) at only 160 rwkw of airflow... That really is quite significant and I imagine most people that have that brand of intercooler, would make some decent gains by swapping it out.

Yeah without a doubt.

You are adding more heat at 25psi on small turbo than 15psi at big one, either way.

There is definitely a bit to consider here, and its a good topic, that's for sure. Money does tend to get you gains in this space (where other times it won't).

The Blitz has always done well.

[R31Nismoid]

1. Run less timing, more boost.

2. Get a better FMIC

3. Run less timing

4. Yes, but safer way to tune, get a better FMIC

Back to my point, you just can't say "Running 25psi on PULP? That just be asking for trouble IMO. Most people keep to a more sensible 18-20psi and turbos that hit the sweet efficiency there"

Yeah I can, you're much closer to the edge of knock/detonation - that point is irrefutable - due to what I outlined.

Sometimes it's not just a case of pulling timing (loads of factors involved).

[R31Nismoid]

Actually looking at that graph again the 68mm line is deceiving as it's not peaking at the same high boost as early in the rev range and that's probably why it looks to be falling away from 160rwkw.

The 100mm Takashi cooler clearly hits the wall at around 260rwkw of airflow though, and starts losing out to the PWR cooler from 180rwkw.

Indeed, looking on my phone I hadn't noticed that...

Well spotted.

[Dose Pipe Sutututu]

You have a much greater chance knocking with more timing than more boost less timing, provided your IAT are lowish.

Most tuners would choose loads of boost and low timing than loads of timing less boost, provided the turbo can provide enough puff.

Saying you can't run more than 20psi on 98 is incorrect.

[hypergear]

From the results I've posted earlier. the High boost reading is the boost pressure before the cooler. The lower boost reading shown boost level after cooler measured after the throttle body is the actual boost level.

[Pr0x1mity]

we're going to use a good core and make up some piping. We're hoping to not have any tight bends so hopefully it flows a bit better than the cooling pro one.

[Kinks]

I bought a Blitz return flow for my GTT. Plenty of people making great power with them. I'm sure it is much nicer internally than a ling long brand (including Cooling Pro).

It is possible that return flow piping has a bit more backpressure and puts a turbo out of its happy zone, as jet_r31 said. But if it does, you'd have to be on the edge of the efficiency cliff regardless, I would think!

Generally speaking, boost is purely a measure of restriction, it doesn't tell you how much air is flowing through the engine simply how hard the turbo is trying to shovel air in. That's why a big turbo running 15psi produces the same power as a small turbo running 20psi - the small turbo has a flow restriction in the turbine which causes backpressure, and you need to shovel more boost into the intake to make up for that turbine backpressure. The big lazy turbo lets all the exhaust gas flow out easily and consequently doesn't need to try as hard shoveling air into the intake to flow the same power. The big turbo will also heat up the air less (due to the lower boost), and since there is less backpressure the end gases leave the cylinder more easily and you get a better gulp of fresh air for the next compression cycle (which also gives you more power - your VE is better because you just reduced an exhaust restriction with a bigger turbo). Same reason why external gate produces more power - the gas flow arrangement is much better than an internal wastegate (which is a compromise for cost and compactness).

If you ran a pressure sensor on your manifold upstream of the turbo you'd see how much total exhaust restriction (including turbine) your engine is pushing against. Correlating FMIC pressure drop, exhaust backpressure, boost, IAT, timing, and power is a complex undertaking though, there are a lot of variables and you need to only change one at a time to understand what's going on.

Tao has put some interesting information up about his experiences with different cores and piping but the simple fact that others are making great power with return flow coolers means you can't categorically say that return flow ruins your change of making decent power. There is a bit more going on than that.

[Pr0x1mity]

The point is that people running turn flows are making OK power still but have noticed a trend of changing to a true front mount and making a decent bit more.

300kw OK in my daily, but we're going to find more. The setup made 383 on E85, however I have a 25/30 with VCT adjustable cam gear and such so we'll have a fiddle. I still need stronger valve springs and to get some cams reground.

[samw/skyline]

On 11/27/2015 at 6:05 PM, kingtube69 said:

My Blitz made 289kw yesterday - Told it was a restriction because the pipes run on the hotside of the engine. I would probably end up going Plazmaman in the next couple of months to be honest.

Hate to revive this old thread so I apologize. King were you running stock piping on your setup at the time you posted this or was some of your tubing getting sucked shut like I've heard it can on high boost and had to be replaced?

[GTSBoy]

The only pipe that can get sucked shut is the turbo inlet elbow.....as it is the only one under suction when hauling. The pipes after the turbo are all.....wait for it....under positive pressure.

[tridentt150v]

And when you are chasing higher power/boost/and airflow that front pipe is the first one you replace with a hard pipe - even before you start upgrading.  So really its not an issue...cos its gone.