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Rather simple, my question is:
Is it better to hit your max torque (and thus horsepower) at a higher or lower RPM?
If I had an engine that had a redline of 7000RPM, would it be better to reach my max torque as close as possible to the redline, or is it better for it to be lower?... If that made any sense.

It all depends on the application, for example in rock crawling you want as much torque as low as possible in the RPM band since you are not using the throttle much.

Ok, I'll give you two examples.

1: Everyday I6 car pushing about 260 horsepower. Meant to have good fuel efficiency while having decent performance.

2: High performance turbocharged I6 pushing about 400. Fuel efficiency is not as much of a concern, but we want to have optimum performance.
If that helps...

"decent" performance with 260 HP is VERY easy to do, but again, what is your market? You can make a really BIG engine with only 260HP but TONS of torque down low, it will shove you VERY quickly into the seat but run out of steam just as quick. You can also have a tiny I6 with 260 HP that takes forever to wind out to peak power and has very little torque. Again it is all about target market but for #1 I would pick a midsize (3-4L) square engine with the stock cam if possible, keep the cam a bit mild so the fuel economy doesnt go to crap.

For #2 that is a bit more difficult to say, what is this engine going in? High performance for a truck or car? Each has its own needs and each has its weaknesses.

I like hitting my max torque around the lower end of the midrange, so a 7000 rpm redline engine would have it peak around 3000. On smaller revvy engines, like the hades variants in the quark I just released (1.6-2.0 liter 4 bangers), the torque for the higher performance versions peaks closer to 5000-5500 but I try and keep at least 75-80% of the max torque available at the 3000rpm range. That's just a personal preference as I like a engine I can short shift if I wanted to around town.

Ahh for turbo engines I feel it's more about when the turbo spools then where peak torque happens. Early spool, better engine.

Microwave, usually for normal cars, having more torque on the middle and low parts of the rev-range is a good thing, as it makes driving easier for most people most of the time. Turbo engines really should spool early, otherwise they will never be on boost, something people wrongly call turbo lag.

Nialloftara, you seem to have stolen a name I use on my cars. And that engine is completely unviable on a modern car, it weighs 270 kg for heaven's sake.

It powered my full sized personal luxury coupe in the last build.http://www.automationgame.com/phpBB3/viewtopic.php?f=35&t=3684&start=50#p74758

Also hellfire has been the name for my huge turbo straight 6's for about a year now.
http://www.automationgame.com/phpBB3/viewtopic.php?f=35&t=4228&p=41539&hilit=Hellfire#p41539

oh did you mean paladin?

@Niall: he meant Quark. The Baltazar Quark is the mainstay econobox of Leo's lineup That said, I think 'stole' is probably a harsh word to be using here, as there is no evidence of intentional appropriation.

@Microwave: as leo said, if you're going to be sitting around in city traffic, torque down low will get you away from the lights without having to flog the engine all the time. For engines that spend most of their time in the lower end of the rev range, it's probably also more economical. Case in point, the Civic I'm driving was widely panned by Australian critics for its 'boring' drive, because of an anaemic lower end. That's partially because Australian critics are dinosaurs who miss the grunt of the V8s that power our resident boofhead Fords and GMs, but they do have a point. That said, for a fatass slushbox geared to be extremely overdriven for freeway economy, the Civic is a hoot to drive enthusiastically in the mountains, provided you keep it ticking over 4k rpm.

Much like my Mazda 3, anything below 4-5K and there is just NO power, it is like all 104 horses have broken legs......

Ohh that's embarrassing, guess I'll be renaming that...

Alright thanks a lot. As you can probably tell, I'm building a series of I6s meant for mid and high end cars and a series of I4s meant for low end, economical cars like hatchbacks and cheap Japanese saloons.

Alright, so taking into account what you guys said, would this be a good engine for a daily driving, economical 90s car? It has pretty low end torque and a reasonable turbo (displacement may be a little high, but it's k):

I also don't really know much about turbos, so if anyone could fill me in on whether that is a good turbo or not then that'd be great!

That seems alright, provided that the fuel economy, efficiency and costs are low it should be a very competitive engine.

That wouldn't go amiss in a sporty daily driver. For 1995 it's quite a fair bit of donk and it spools reasonably early.

Yep, it's quite overkill for what it does but I often find it really hard to make my engines have a reasonable power output.