[Deakins]

Originally Posted by 1998Z28

More maintenance, probably, but a street driven car is not going to be buzzing around at 9,000 rpm all the time. If we drove around at redline in anything, I'm sure we'd see more problems.

We would, but you are missing the real issue with ultra high RPM engines. Sure, the act of turning the engine more RPM accelerates wear, there really is no getting around that to some extent. However, the main issue that you are overlooking comes from the sacrifices that one must make to enable the engine to operate at the RPM at all. If you were to crack open an old NASCAR R07 built by say Hendrick Motorsports, you would be looking inside a marvel of engineering optimization that could turn up to 10,000 RPM for hundreds of miles, essentially worry free.

Now if you installed that engine in your Camaro, and never exceeded 6,500 RPM how long do you suppose that it would last? When it failed, what would fail and why? I can tell you that likely the engine would suffer a broken (dropped) valve relatively soon. Not due to a faulty valve, not due to the valve being cheap (a single valve costs anywhere from $120-$200 depending upon features), but that in order to operate and survive at 10,000 RPM the mass had to be reduced an extreme amount.

This led the engineer to procure a very light and strong Ti alloy valve and spec the stem just large enough to survive the expected cycles required during the race of which the engine was designed to complete. If the stem was thicker it would have more mass...more mass means more valve spring pressure....more spring pressure means more valve stem...more valve stem means more mass...and so on. Also, Ti is not like steel; it will fatigue in some aspect during all operation hence, there's no free lunch in high performance engines when you go to Ti components.

Now, you will say "but that's racing and GM spec's our cars for street use" and they do, for a specific number of miles, driven under a specific set of circumstances. On top of that, mechanical and material engineering can only go so far with mass reduction, performance at elevated temperatures, and fatigue resistance. Couple all of THAT with the bottom line at GM and you will see that with increased RPM capability regardless of operation; maintenance and costs go up 10 out of 10 times.

[1998Z28]

Yes, but OHV engines have inherent problems with valvetrains that are greatly reduced with OHC and smaller, more numerous valves. If NASCAR permitted OHC engines, I doubt you'd see pushrod engines for very long on the track.

[oldman]

Originally Posted by 1998Z28

More maintenance, probably, but a street driven car is not going to be buzzing around at 9,000 rpm all the time. If we drove around at redline in anything, I'm sure we'd see more problems.

My Integra Type R comes stock with a factory fuel cut of 8600 RPM, I've been running a stroked sleeved 2.2 liter with a Jun III can and peak Hp is just about 8800 RPM and I shift at 9600 RPM. The engine has been over 10,000 at least a thousand times over the last two decades. I also have the original engine, original bore with light weight rods 280,000 psi bolts, light weight 12.5 forged pistons and the same cam above peak HP was about 9400 RPM, shit at 10,000 RPM. The engine has gone 180,000 miles and I've just finished a re-ring with total seal rings (still stock bore, stock bearings, stock crank, stock bearings). Just in case my teenage son blows the current engine up, which he tries on a daily basis. So with VTEC you basically have 4 complete cam for one engine. I there is a rare two stage VTEC that would be 5 cams.... Oh HP is about 275 HP on 2400 lbs. Guys with the K20 to K24 are at 310 HP NA on 2000 lbs in hatch. My 2015 SI supercharged is at 450 ish engine HP on 3000 lbs.

I will point out that the last Vipers do at least have a true cam overlap changes that really helped (cam in a cam). No not VTEC but least it is true overlap manipulation not this pretend variable valve timing which is just simple cam phasing.
http://www.hotrod.com/articles/how-t...ts-horsepower/

I did a lot of racing back in the day with Toyota 2TC and 3TC hemi, these were OHV, with dual 45 side drafts and shimmed rockers to prevent them from walking, I'd pin the 10,000 RPM monster tac at shifts about 9500 actual RPM. bout 210 engine HP from 1.9 liters. The OHV heads could take more N20 or boost vs the DOHC Japan only 3TG heads. I can't say these were 100,000 mile engines, I'm just pointing out there was a least OHV engine in a street car that would rev.. Crazy world back then, the racing all went to Puerto Rico where they did a lot of Toy and Mitsu 2.6 liter racing. And yes my Corolla was about as quick as my 440 Dart.

Note mine but this is how crazy the OHV hemi got:
https://www.google.com/search?q=3tc+...3cMDqWSiHV_nM:

http://hmongbuy.net/video/vNIxImBJFS4