Monday, April 20, 2009

Breathing Better

Some people remove the stock airbox and install the so-called "mushroom" type pod filters in an effort to get more air into the engine. The added intake sound is cool too... but is this the best solution to getting more air into the RB26?

Nismo Z-tune...uses the stock airbox - albeit with a special carbon fiber air scoop built into the hood directing air into the airbox - not like the standard "snorkel" which standard cars have. But other Nismo tuned cars (recently anyway - the 400R apparently came with dry pod filters) use the standard airbox, although with a high performance Nismo air filter. Mine's too - uses the standard airbox, although with their oiled "wet"-type air filter.

So - what do these tuners keep doing this? I think that, besides the reassurance that the filtering capacity is maintained (as various reports say the pods may not filter as well as they should, depending on who makes the pod filter), cold air might be the reason why.

Cold air, being denser than warm air, contains more oxygen, and therefore the potential to unleash more energy than warm air. Pod filters do all their sucking of air from air trapped in the engine bay (unless you have a vented hood - see the 400R), which suggests that this might be their main drawback.

So, there is an argument for cold air. What about any kind of "ram-air" effect? I'm still doing my research, but apparently turbo engines don't benefit from this, as the turbines suck in the air they need. However, it would seem that creating positive pressure in the intake system would allow the turbos to kick in that much earlier, if they don't have to overcome any negative pressure in the system.

So - I have the standard airbox. But when you look at the system closely, most of the air being sucked in through the airbox comes from the underside of the leading edge of the hood.

This means that I need to increase the flow of air into this area. Short of building a tube that funnels air into the box directly (like the R34 Z-tune), the best I can do is to get more air into the general area.

Two ideas come to mind: the "hood top molding" option that Nissan offered, and a modification to a radiator gril panel. The hood top molding is a slim piece of plastic that is attached to the leading edge of the hood, creating an area of positive pressure, which forces more air under the hood (otherwise these kinds of areas have negative air pressure - the leading edge is too slim, and the air gets split).

My idea is to take a cheap aluminum radiator panel, and cut a flap, bend the flap down and have air coming through the grill (where the GTR emblem is) be funneled up into the snorkel area.


You can see the lines where we cut in the alum radiator panel, first line here.

Two lines as so

My friend Thomas at work using the saw

So finished - we reattached, bent the flap down, and then used
foam cushion to prevent air from leaking out

slightly better angle
You can somewhat see the snorkel we created.
And the result? Definitely not placebo, the engine DOES respond better. Always having air coming in means less or no hesitation when I step on the gas. Of course don't know if the car makes more power, but definitely more responsive.

Saturday, April 18, 2009

Repainting My Track Wheels

With the help of my friend Thomas (who has obviously been very kindly sponsoring me onto Camp Zama, where the Auto Shop is...) I have been working on repainting my track wheels. Also, we took the opportunity today to do a little mod to improve the air flow into the engine (see next post).

A little history. A few years ago, I bought the four wheel set - standard R33 GT-R alloy rims - off of Yahoo Auctions. Looked pretty good from the photos, but when I got them, well let's just say that the seller overestimated his painting skills. But no matter, they were my track wheels, so I really didn't care how they looked. But as they got dirtier and dirtier, it occured to me that I could probably do a better job painting (based on the excellent result from painting my front lip spoiler).

So, two weekends ago, we took the tires off two rims, and proceded to prep them.

We decided to sandblast, sandpaper and use a grinding wheel on one. After a few hours, we realized that 1) the sandblaster was working, but very slowly - too slowly, 2) the sandpaper was also inefficient, and 3) the grinding wheel caused too much damage.


Grinding wheel

Then someone more experienced at the shop told us we should try using paint remover. Which we did, last weekend. While Thomas was indexing my plugs - see previous post - I managed to finish the two wheels. We also removed the tires from the other two rims.

Here is the prep:

Here's how they look when the paint remover begins working - see the bubbling?

After all the paint was removed, the wheel was sandblasted again, and then set on the "paint stand."

Almost forgot to tape up the valve stem.

And so here goes the first layer of paint - heat resistant black! (up to 600 degrees C - recall last time at Fuji Short Course the paint on my calipers melted?)

Stay tuned to see how well they turn out...finished removing the paint from the other two wheels, so they will be prepped and painted during my next visit. I wonder if I should put some red/orange/green pinstriping on the wheels? Just kidding.

Saturday, April 11, 2009

Indexing Spark Plugs

I didn't really believe it, but it really works!

Don't have any good photos, but indexing works. Indexing is the concept of arranging the spark plugs to face the same direction - usually with the electrode gap facing towards the intake valves, or the exhaust valves. Although I was skeptical, I went ahead and ordered a copper washer kit designed specifically for this purpose, and gave it to my friend Thomas to try out on his engine (R33 GT-R as well), last week. He immediately reported pretty good results - but I remained skeptical.

So, while I prepped two of my alloy wheels for painting (see next post) Thomas indexed the plugs in my engine.

And guess what - just like he said, the engine DOES run better - a bit. A little bit smoother, a little more responsive - at idle, definitely smoother and the exhaust sounds a bit better. And on the road, the engine responds a bit more aggressively - making the car easier to drive on the road.

I posted my results onto the GTR forum, but no one seems to care. It's either the placebo effect for BOTH of us, or too subtle for most people. But any little bit, adds up, and the cumulative effect is well worth it!

Sunday, April 5, 2009

Titanium Brake Shims

So another day at the Auto Shop at Zama. Today, decided to install the titanium brake pads that I got from the U.S. Made by a company called TiSpeed

The theory is - titanium is much worse at conducting heat than steel, so having titanium shims in between the brake pads - which get hot during braking - and the pistons means reduced heat transferred from brake rotor to pads to the rest of brake assembly and eventually to the drive boots.

As you may recall, last track day my brake use on the Fuji short course resulted in melted paint on the front calipers. There was slight fade at the end of the day too, signaling how hot the brakes got.

So, did some research - need to somehow block the heat, and provide ventilation and cooling. Already have the Nismo wind deflectors to the brakes, but I will be ordering air cooling hosing to supplement and ensure adequate cooling as well.

But first, titanium shims. Before installation - here is what the titanium shims look like:

Process to install is relatively straightforward. Remove wheels, take off clip holding brake pads in, unbolt the guide pins, squeeze down on pads to retract the pistons, remove pads, then reinsert with titanium shims. Bolt everything up, then make sure you pump the brakes before driving away... pedal went to the floor after I pulled out of the bay, luckily grabbed the parking brake to prevent from running into the wall behind me.

Fronts - before:

...and after:

Rears after.

Will report on how good the brakes are after the next track day at Fuji on May 5th. So far in daily traffic use, no real difference - maybe some more squealing, or is that the brake pads?