Ram Air

[kymbo]

Before I start modifications to my R35, I thought I would first put some information and a question out to everybody.

Every high performance car I have had in the past has responded incredibly well to a forced cold air intake, in a position that creates increasing positive pressure from increasing speed.

The standard circular air inlets to the air boxes are tiny and appear to be power restrictors. Ever wondered why, when you watch a GTR on U Tube, the GTR is killing its opposition up to 200 KMH, past that it just seems to flatten out with the other car suddenly catching up?

That outcome is typical of air restricted race cars. At high RPM the air velocity is limited to a maximum volume. Common in the past with cars that have MAF sensors, because the MAF sensor has a limit on how much air it can measure to adjust air/fuel/timing etc.

The dummy air intakes (one only side cut to flow air to the oil cooler) at the bottom, on each side of the intercooler intakes are either a styling afterthought or there for a purpose. Surely not just for an oil cooler intake? Maybe the 2012 model will hook up these intakes???

My intention is to create a lightweight alloy system that is 'plumbed' to the air intakes at the air boxes, with a tapered (funnel) affect to the air box that will also have enlarged diameter inlets, which will add increased volume, pressure, velocity and colder/denser air to the air boxes. I will use a K & N air filter to help the final flow restriction point.

The only problem with this type of mod is, how to measure the power increase because a Dyno can not replicate the massive air pressure on the factory inlets at say, 200 KHM. My only explanation is, past cars that I have done this to experience a manic increase in top end thrust that slams the rev limiter every time!

The aftermarket cold air intakes that are currently available are limited by the fact they use the standard air box inlet sizes and are a different size to each other, which would give different pressures to each turbo. Or they are located in a limited positive pressure air zone.

MY QUESTIONS ARE:

1. Has anybody done this to an R35 before and if so, what happened.

2. What is the opinion of the tech guys who read and add to this forum.

3. Will the standard MAF sensor be able to read and adjust for the changes.

Regards, Kymbo

[StealthX]

Alot of work for minimal gains.

first port of call for any performance turbo car is an exhaust system, then increase boost pressure and some sort of tuning device.

An R35 is no different.

[kymbo]

Alot of work for minimal gains.

first port of call for any performance turbo car is an exhaust system, then increase boost pressure and some sort of tuning device.

An R35 is no different.

OK,

I already have a Willal Titanium mid pipe and intend to fit the balance of the Willal system with the air intake system.

I should have also asked, does the Cobb tuner have a program for this type of mod.

Kymbo

[Mendoza]

There's some good reading on autospeed's website on cai's "eliminating negative boost" is the article. It seems like a worthwhile change to make, should give better response aswell.

http://autospeed.com/cms/article.html?&A=0629

They also experienced a problem with it detonating under hard acceleration from ecu tuning problems.

[StealthX]

OK,

I already have a Willal Titanium mid pipe and intend to fit the balance of the Willal system with the air intake system.

I should have also asked, does the Cobb tuner have a program for this type of mod.

Kymbo

You wont need to adjust AFRs from a cold air intake like you are planning. So long as the air flow meter isn't moved or modified, it'll still read the same, the 'ram' affect of this mod will be minimal. How many times do you expect get the chance to drive your car above 200km/h anyway?

Not worth it. Get the Cobb tuner and some adjustable wastegates, and up the boost, that way you'll have gains everywhere in the rev range, not just at 200km/h+. Alot less hassle too...

[fungoolie]

The effect of the increase in pressure is minimal compared with the effect of the cold air you are getting in. I recently saw an analysis on it and the pressure increase at ludicrous speed is the equivalent of the air density increase as a result of a drop of only a degree or so in temp. On top of all that you only get to tap this effect at highly illegal speeds. By all means grab cold air at a point that does not have negative pressure but don't bother going far out of your way to try and increase the intake pressure.....

And agree with Turbo X-Trail. The MAF doesn't care where or how the air is sourced. It simply reads rate of the mass of the air flowing through it....

Edited November 30, 2010 by fungoolie

[kymbo]

Thanks for the feedback guy's

Very much appreciated.

"Mendoza" I especially appreciate the negative boost article, thanks!

I will update you on the results!

[lachlanw]

a zx12r can generete nearly .4 of a psi of boost at over 200kmh . hardly "massive" as you worded it .

yes it will do something . weather its worth it or not is a different storey

[Cowboy1600]

I don't think this is entirely worthwhile on a boosted engine.

I rigged up a CAI (removed inner left headlight and ran pipe straight to airbox) in my Datsun 1600 which was running a warm 2L with a single 32/36 down drought Weber (in a modified standard airbox) and the difference was most noticeable. For starters the thing made power for almost another 1000RPM which was significant! And beyond that it had more grunt off the bottom and got better fuel consumption by roughly 15%. Not bad for a $20 piece of 100mm flex hose from a hydroponics store

But this was a naturally aspirated engine. It's not possible to actually get a "ram-air" affect on a turbo'ed engine. As long as the air box is well fed, gains with such a set up are going to be probably zero. Unless your current setup is sucking heated air from the engine bay or it's substantially restricted via poor quality filters or too smaller intakes, benefits from a custom CAI for a boosted engine will be slim to none.

[kymbo]

I have decided not to hook up the lower air intakes to the air boxes, because I will need the dummy right hand side intake to flow air for a future front mount transmission cooler.

Negative comments about Turbo engines not benefitting from cold rammed air are incorrect.

Many manufacturers of after market air intakes, that mount forward in the front bumper to pick up larger volumes of cool air are Dyno proven to produce more power and other benefits, the below is a quote lifted straight of the 'Speed for Sale' website regarding the AAM sports air intake. Check out the site, go to air filters and read about this and other brands. Harmon have proven an extra 8 AWHP with this type of system.

"The AAM Competition Premium Sports 2.75" (70mm) and 3.00" (76mm) Version 1.5 Intake systems are designed to increase air flow to the GT-R's turbochargers by replacing the restrictive factory air boxes in favor of free flowing external air filters and smooth, one-piece, lightweight aluminum intake pipes.

For factory equipped GT-Rs, the 2.75" V1.5 Intake the complete intake upgrade. Increased throttle response, lower IAT temps, quicker spool up, as well as an increase in accessible power are benefits of pairing our 2.75" Intakes with factory turbochargers, with no custom tune necessary."

Think about it! A Turbo gets bloody hot and 'sucks' the air. Make the air colder and give more volume from added pressure to enhance the turbo suction, it is going to help. I have ordered the AAM system and should have it 9 days. The only thing missing is the 'Ram', but even so they do work.

Have a look at the intake diameter of the small snorkel in front of the OEM air box. At high long duration RPM it is a restrictor. As we now know, the 2011 GTR will have 390 Kw standard. Nothing like having simple built in elements that can be upgraded at a small cost, to keep ahead of the power game with Porsche!