Getting air to Turbo

[Dynoroom]

Rex get's it.............it's all pressure ratio in blown engines. IMO the only issue in a turbo motor is back pressure. If your back pressure is significantly higher than your boost pressure it will only get worse at altitude (pressure ratio is higher to reach the same boost), other than that it will not show you any power. The compressor discharge temp is always the same at a given shaft speed assuming inlet temps remain constant. If you're not running a charge air cooler the ram effect might allow you to make the same power at a lower boost level, but who doesn't run a charge cooler?

 

[landracing]

I have updated my formulas to allow for boosted applications. This formula works from Target MPH, engine RPM and VE to come up with a sizing, then add the boosted application on top of it.

http://www.landracing.com/formula/hoodscoop.htm

Jon

[landracing]

Rex and Dyno,

It would seem that in a perfect world, we would love to have the turbo point out to the front of the motorcycle. However since the turbo sits low and SPACE is a major issue and our turbo's sit behind a very fast rotating tire kicking up salt and is blocked by said tire and the frontal area where a radiator is can be sealed off, we have an issue.

So plumbing something down to the turbo seems logical to me, but those really fast turbo busa guys seem to be doing one hell of a job just pulling the air in from the side of the fairing. Some with and some without air filters on there. And I have not heard any of them complain about salt injestion issues. Which just makes it that much easier, works for them why make a big deal out of reinventing something that may or may not work and a serious nightmare plumbing it.

have another question later on pipe velocities that will be another topic.

Jon

[Dynoroom]

I guess you misunderstand me Jon. You're right, the turbo can pull air from any direction, as long as you don't try to draw it from a duct that is too long or too small.

[landracing]

Gotcha, yeah I was under a different impression.

Jon

[panic]

"I have updated my formulas"
Excellent, thanks, I'll link it to my page on atmo vs. boost.

[Sumner]

.............. but who doesn't run a charge cooler?

Us.........  .

We should put that picture on the Kugel Firebird page on your site and thanks for the turbo info,

Sum

[Sumner]

I have updated my formulas to allow for boosted applications. This formula works from Target MPH, engine RPM and VE to come up with a sizing, then add the boosted application on top of it.

http://www.landracing.com/formula/hoodscoop.htm

Jon

That works good,

Sum

[landracing]

I got some help to work in a radius edge for the opening as suggested in a previous post. We will see what happens with that. A good work in progress.

Jon

[panic]

Re: "It doesn't have to be."

Especially on a bike - you should take air from the highest pressure source  available, which may be at the headlight bucket, alongside the fairing, etc.

Re: "Dumping into a huge plenum is as effective as trying to calculate a resistance free path"
Right - after the proper inlet size, you can use any diameter and shape you need (round, oval) to get good flow as long as it ends and expands into a big box. The turbo compressor inlet is not tapered up to the box X-section, but intrudes into the interior and ends in a stack and bell for best efficiency.

[Rex Schimmer]

Jon,
If you do run some sort of piping from your front inlet to the turbo you really should make the piping as large as you can, again because of the boundry layer. As the air flow thru your inlet tube, especially at high velocity, the boundry layer gets thicker which effectively reduces the diameter of the inlet piping. So small inlet, again based upon engine air requirements with larger piping to reduce both the air velocity and the boundry layer affect.

Rex

[Mark Scott]

Jon, I am in the same camp as you are in for ducting air to the turbo inlet. I suggest you take some time and look at Rich Yancys Budweiser Hayabusa. He uses the air duct on one side of the fairing into a large plenum, ducted to the turbo inlet. It looks like a first class fabrication job for sure. He has everything inside of the bodywork. I cannot tell if he uses a filter or not. The question I have is about the installation is the 90 degree elbow at the turbo inlet. What is it or who makes it? I assume the inlet is approx 4" dia. and the flex hose he uses in typical NASCAR quality air ducting hose. There are several good articles on the net, and reprints of articles with the fairings off his bike. Rich is a talented guy, and I spoke with him at Maxton last year waiting in line, and he is as friendly and knowledable as everyone says. Good luck, Mark