Test Pipes And Downpipes?

[scathing]

I didn't mean to have it sound quite so personal.

I'm just over the holier-than-thou mentality of Prius fans who think their NiMH batteried, aluminium, cars are somehow going to save the planet because they happen to sip a little less fuel around town...and I guess it bubbles over sometimes.

[siu_loong_bao]

Totally agree....

I just wanted to get the message across about decatting...

"If you want performance, go buy a turbocharged car"....don't opt to decat....

[Stephen Thorpe]

Let me tell you... you can have a roadside EPA test... Noise as well.

Get down the GO Road every so often and watch.

As for NO CAT, why bother?

You will not notice much difference in power

Unless you have yearly emissions tests how would you know if one is still performing well either.

Sorry Scathing... not trying to be rude... but how exactly are big wheels bad for handling and fuel efficiency? Bigger wheels (unless too big) will nearly always increase handling!

IMO... a lot of Modifications to a Skyline (including engine stuff), if done correctly can actually decrease the level of Enviromental Pollution whilst adding to the performance enjoyment.

How often is a Skyline running really, really rich?

[fcruz3r]

While a early 90's Falcodore may not be as fuel efficient as a V35 in itself, when you tally up the total fuel use with the ocean freighter that brought your Skyline here then the scales tip in favour of the local product.

that's really rich coming from someone who lists Z33, SW20 and Swift Gti on his list of cars

EDIT: In fact ignore my comment. I can see the validity of your arguement.

Edited November 3, 2009 by fcruz3r

[scathing]

Sorry Scathing... not trying to be rude... but how exactly are big wheels bad for handling and fuel efficiency? Bigger wheels (unless too big) will nearly always increase handling!

Big wheels are heavier. While replacing a cast 17" wheel with an 18" forged wheel might work out lighter, if you compare apples to apples and compare your forged 18" wheel with a forged 17" wheel (which will clear the same brakes as your stock cast wheels, and are therefore a valid choice) the 17" forged wheels are still lighter.

The extra mass increases unsprung weight, which is proportionally far worse for handling than sprung weight. Your forged 17" wheel will allow your suspension to perform better.

Bigger diameters shifts the mass further away from the rotational centre of the wheel. That increases rotational inertia. There's a performance hit in terms of acceleration and braking as a result. The extra energy required to spin them, due to that inertia, incurs a fuel economy hit. The extra energy required to slow them chews through pads faster, which means more heat is generated by your braking hardware, more brake pad dust is committed into the atmosphere, and your car consumes more pads (which need to be manufactured) over a given period than it did prior.

Wider wheels increase drag. There's an acceleration and fuel economy hit as a result.

Tyres generally have more of an effect on handling than the wheels. The main reason to go to a bigger wheel is to reduce sidewall flex, but a tyre with a reinforced sidewall and appropriate pressure get around that issue. If you have a look at most top-tier race cars (SuperGT and F1 come to mind), their tyres have a fair amount of sidewall. For most racers, the rims end up being as small as possible while fitting over the brakes.

IMO... a lot of Modifications to a Skyline (including engine stuff), if done correctly can actually decrease the level of Enviromental Pollution whilst adding to the performance enjoyment.

In Europe, the cost for rego on cars is based on its emissions these days. If it was possible to increase performance and decrease emissions, while meeting their reliability targets, the OEMs would do it.

I'm pretty sure a lot of the performance / economy restrictors serve some other purpose. Cars for the European market tend to run a tad rich in the top end to preserve and cool the engine, especially if we're talking about long-distance high speed and high RPM situations. They do have to ensure the car runs in all kinds of weather conditions as well. I don't plan on driving my car to Alice Springs, so I'm less fussed about ensuring that the engine won't overheat in 50°C+ ambient temps. I don't mind my ECU running a little leaner, which has bumped up the water temp a few degrees as a result.

If you're willing to sacrifice drive-anywhere reliability for performance and emissions, that's fine...but should your car break down its inability to move then makes it slower than a pedestrian. The parts you've broken end up in landfill, which has an environmental impact.

On a NA car, most powertrain mods increase power only in the top end, where you have more combustion cycles per unit of time and therefore you use more fuel when taking advantage of it. On mods that sacrifice low end torque for top end power, it means you need to drive higher in the rev range even when commuting.

The parts you throw away also have an environmental impact. It comes back to that Prius issue I mentioned earlier. The OEM has fitted a certain part on your car. If you've had someone manufacture you another part, then that's something else that a miner has dug out of the ground. A factory somewhere has used energy, maybe coal-fired or nuclear, to create an exhaust. Someone else has burned fuel to transport it to your location.

Your stock item doesn't just convert the exhaust gases from transportation and manufacture back into petrol, deconstruct itself back into its raw material, bury both back into the ground, move all the dirt back in to its location, and then re-plant the prior oxygen-generating and climate-stabilising vegetation back on top.

As the person who buys the product, you are responsible for a fair amount of environmental pollution by requesting the creation of that second part. You should add the environmental impact from creating the perfectly functional first part you've discarded from the car you purchased to your tally.

that's really rich coming from someone who lists Z33, SW20 and Swift Gti on his list of cars

The difference is that I wasn't claiming to give a crap about how my cars affect the environment.

I've got no issues with people decatting their weekender cars. As long as they're not sitting there in peak hour traffic breathing in, and forcing others to breathe in, the poisonous gases that come out of the exhaust I'm pretty indifferent. If your car gets used for daily driver purposes, leave your cats on and stop trying to kill people.

Removing the cats might not bring massive gains, but then hardly any NA mod does. Whether the mod is worth the risk (environmentally, medically, or legally) isn't that clear cut for me, and boils down to personal choice.

[fcruz3r]

there are other factors that come to play other than unsprung weight. trick is to find bigger wheels where the bulk of the weight is towards the center of the hub

if you look at the formula for moment of inertia, both mass and perpendicular distance to the axis of rotation plays a vital role.

[Stephen Thorpe]

too in depth for me and I love your answer and you make good points...

very little value in debating all your good work, as I think I might lose!!

[fcruz3r]

LOL.... most of us hardly see 1 track day a year so screw the physics.

I say just get the biggest legal wheels and build your engine with as much powah as your wallet can handle.

my personal opinion, try not to decat and waste unburnt fuel out the exhaust. If you must, then get a flame thrower and at least have something to show for it

[siu_loong_bao]

damn, and i was about to drag the chair out and put some popcorn in a bowl to watch....