Splitting a lot of hairs here.

Damn, not bad. Exhaust too? I only ask because how were the AFR? I thought I read, intakes and full exhausts weren't the greatest to run alone.

That wasn't a claim, hence the question mark, he was asking :tup:

K&N drop ins plus PMTs here and very happy with them, 80-90% performance of the best CAI's (like the G3) at 30% the cost.

For those really worried about fowling the maf's with the oil, it's over oiling when recharging them that can do it, so just sell or toss the filteres every 20-30K miles and buy new, that's what I do, or more accurately, plan to do and they're not expensive so problem solved. :tup:

I've done oil analysis's with k&n's. My numbers showing contaminants that you'd get from dust and road debris were no higher than any other car. In fact they were under the average. Longest I had one, re-oiled twice, was 40,000ish.

Cleanable oil type air filters are nothing new they existed in the 40's and 50's, but when the superior disposable paper filters came out they went the way of the dinosaurs .

Same as the straight razor being replaced by single edge blade to the multi blade disposables today.

When you had car and motorcycle intact tracts or airboxs that were very restrictive or poorly designed in the past, the early vehicles of the 80's and 90's did benefit quite a bit from the external oil type filters.

But once the vehicle manufacturers strived to get as much HP and efficiency out of a particular engine design, they paid a lot of attention to the intake system design and based on having a good performance and pollution controls.

This is why you only see marginal gains from just changing you intake.

If you intend racing or tracking your car then, you can go all out, then you can really see a lot of HP gains from the intake and exhaust combos.

Basically with the oiled air filters , you have companies that are trying to sell you on technology that's outdated.

You even now have aftermarket billet oil filters, with cleanable mesh screens that are now being posed as superior to the best disposable ones.

It was with the OEM exhaust off of a Nismo 370, stock headers and cats.

Only thing we did was put the filters in.

According to the widebands on board and the wideband at the tail pipe, AFRs were exactly the same, it just traced higher on the MAF volts (a tiny bit) because it was pulling more air, and the ECU compensated by adding fuel, exactly as the system is supposed to work in open loop.

With the non-nismo exhaust, maybe there would be a difference in the gain you get from the filters, but I really doubt it.

Your theory has some serious flaws. Not the least of which is, why would a company make an outdated product that lasts the life of your vehicle. K&N could make WAY more money by convincing you that rechargeable air filters didn't work and were bad for your car and offering the alternative which you had to replace every 10k.

Obviously this has occurred to you yet but you're in a sports car forum. We generally want our cars to perform as well as possible. Even if it's only a few HP.

To say nothing of the fact that OEMs changed to paper air filters because it lowers maintenance costs and reduces warranty claims, when you're comparing a paper filter to the oiled filters of yesteryear... Which have very little in common with a K&N or the like.

Point is, does going to an oil filter lower the life expectancy as compared to a super thick 'Extra Guard' style paper filter? I feel comfortable saying "yes".

It probably does lower it, from around ~300K miles before the rings are gone to around ~225-250K miles before the rings are gone.

I could not care less about that difference, and I don't think anyone driving a Z today would or should, unless you really care that much about the next owner (or the one after them, or the one after them)...

Besides, the oil pump, VVEL system or rod bearings will probably go before the rings do. Just sayin.

This could be talked to death.

Bottom line:

Want a handful of horsepower? Buy K&N or the like.

Want an engine you can tell yourself will last longer and don't care about horsepower? Buy the thickest damned paper filter you can find.

Everyone's happy! :tup:

^^ makes sense. I think we can close this up :)