Leon

I can guarantee you that a cam with a duration long enough to open the intake valve through 64% of an engine cycle will make no horsepower. No magic required. A turbocharged engine will make more power higher in the powerband with a longer duration cam, because of an improvement in high speed cylinder scavenging. This improvement comes at the expense of low end volumetric efficiency because of gas reversion and a higher percentage of unburned fuel. Higher lift equals higher flow, there is a point where increasing lift won't gain more power and that's when port area is overwhelmed by valve curtain area. And typically, the cam you choose doesn't depend on intake and exhaust sizes, it's the other way around. An experienced cam grinder will likely be able to head you into the right direction when choosing a cam as Xnke mentioned. Point is, the PO has much research to do, but the info is there (especially if you search the archives). A cam grinder will help, but some background goes a long way.

That cam would make negative horsepower, you'd have to push the car to move it.

Very minimal if not dyno tuned. If tuned right, then expect to gain in the neighborhood of 6hp compared with a stock manifold.

I'll definitely second that. I've thoroughly enjoyed watching that series, it's very well done.

I'd use the MSA 6-1 header if they're both in usable condition. It should have better scavenging than the 6-2, but on a street engine performance gains are minimal. Therefore, go with the one in better shape (straight flange).

I completely agree. They were 3 zombies feigning enthusiasm. I wanted to like the show, but it really was awful especially when compared to the British version. I am not optimistic about personality or chemistry improvement with the hosts. Tanner Foust just screams d-bag IMO, it's very hard for me to listen to him. It's something about his fakeness and "I'm better than everybody else" demeanor.

Going off of "avoiding accidents is the best safety device of them all" I would say that a safe car is not the largest you can get. Longer braking distances, slower steering response, and larger girth will tend to get you into more accidents.

My 2 cents: When "designing" an engine, you have to look at the big picture. There is no magical r/s or b/s ratio that turns something into a great race engine. It is a combination of design parameters that gets you there. As shown, you can have wide ranges of r/s and b/s and still get great results. What matters is how the system is put together. The first thing you do when you want to design an engine is analyze exactly what you're going to use it for, and progress from there. e.g. You're building a race engine. Let's say you build it for autocross. Since autoX courses are usually low speed and tight, you want to maximize area under your power curve at the engine speeds that you'll mostly be seeing (dictated by gearing). Let's assume you want performance in the 4k-7k rpm region. What do you need to do in order to maximize engine performance in that region? You start with a given parameter, and begin designing around it. You have plenty of space for a straight six in you engine compartment so let's start with that, rules of different race organizations will tend to dictate this part. You also take advantage of the 6er's favorable harmonics (in comparison to V arrangement and 4 & 8 hole engines). We picked an engine type and cylinder count, now come engine parameters: bore, stroke, rod length, compression ratio, valve timing, intake and exhaust lengths, among many, many other things that you must make to work in concert with one another. Any choice will have trade-offs. Basically, it's a lot more complex than just finding a couple of magical ratios. Those ratios have to work with the rest of the engine. What works for one, won't work for another.

Get a Volvo.

Thanks, it sounds pretty good from the outside, but inside the car it's loud as hell! Maybe I'll just fix the exhaust leak at the manifold and keep it. Those twice pipes are enticing though. Sorry to get off topic, your pipes sound great!

Sorry about that! I'll make it a little more visible.

I'm so torn about exhaust options for my 260Z. I've been wanting to get the twice pipes but since the current exhaust is too loud for me, I'm not sure if I'll be able to handle them. I love the sound of the twice pipes though! Here's a clip of my 260Z that I got last month. Sorry about the loud noise at the start of the video. http://s518.photobucket.com/albums/u345/LeonVin/RLS30-004406/?action=view&current=P1010942-1.mp4

That is called a Bricklin. SV-1 to be exact, a very interesting car actually!

Great work, Stepan. Looks like you put some good, quality time into it!

I'd rather have the "mostly" 2.5 inch exhaust because that will give you less pumping losses than a true 2 inch, given it's not completely cobbled up. It's simple fluid dynamics. A 3 inch exhaust pipe won't hurt anything, a 5 inch won't hurt either (except for ground clearance). Once again, read the sticky I linked to earlier. BTW, higher exhaust velocity = higher frictional/pumping losses.

Read the sticky.

http://www.classictube.com/store/index.cfm http://www.classictube.com/store/index.cfm?fuseaction=product.display&product_ID=117593 Obviously, bending and flaring them yourself is a lot more cost-effective.

http://www.youtube.com/watch?v=13JK5kChbRw I couldn't resist!

The reason for my reply was that you sound as if you are complaining about your lack the knowledge on the subject. Instead, educate yourself (from the right sources). Here is my game plan: read, understand, test, analyze results. You can theorize all you want, but in the end, you're going to have to physically do something about it. When it comes down to making modifications you have to understand that failure is part of the game. I try to make my approach nondestructive when it comes to valuable parts for two reasons; (1) it costs $$$/time to replace and (2) those gains are likely to be minimal in the scheme of things. Sure, bore out a 45mm Weber to a 50mm but what will that really get you? Want to find out, then do it. Alternatively, use a 45mm carb and focus on something else, maybe it will be more worth your while. That's what it takes.

I keep telling you (and anyone else that's interested) to buy that engines book and read it. Invest in knowledge. Seems nobody ever takes up that offer. I guess that's the difference between someone that knows what they're doing and 1000 monkeys trying to write a novel...

Those wheels are definitely not the originals and did not come from the factory that way. I'm not sure on the claim that only 2 Z432s being in the US either, as I know the owner of one and have seen it with my own eyes. Maybe I'm just lucky... FYI, the original 432 wheels look like this:

Nope, that works for both. I'd imagine the addition of a spacer would simply mean a longer shank length.

Sure, velocity in an ITB system will promote mixture homogenization but so will the shape of the runners, combustion chamber and pistons. Thus, velocity is not as important in an injected engine versus a carburated one as I said in the original post. When you say "real high performance injection" I'm assuming that you're speaking of F1 and other race-only engines, where rpms are usually (very) high and there is plenty of velocity in the intake to keep the mixture atomized. I don't think they are very concerned about low speed operation and fuel condensation, at least compared to street applications. Plus, those runners are usually pretty darn straight. Port injection is just fine, and much better than carbs (as you've shown), for street and race engines as it has proven in countless applications. Notice I never said anything about needing larger runners, I think you've misconstrued my statement. Yes, it is correct that carbs do need bigger runners to flow as well as ITBs, but that's not what I said. Here is the last part of my post: As you make a runner bigger in a carburated engine, the velocity of the mixture decreases, therefore you have more fuel condensing in the tract. With a port injected ITB setup, fuel atomization is not dependent on manifold velocity, therefore you can utilize larger runners without detrimentally affecting performance or driveability. That's what I meant by that statement, nothing about matching performance.

Whether it's a Z or a Triumph or a bike engine, the same principles apply. As this thread discusses, the header and the collector pipe are the tunable aspects of the exhaust system. You're talking about tuning the secondary/collector length. This is what you would do with any engine's exhaust. Trust me, buy the Heywood book and read it. You will have many more revelations reading that book than browsing the internet or consulting engine builders...

Intake velocity is much more important in a carburated engine where the air-fuel mixture must travel from the throttle body all the way to the cylinder, through the manifold. This is because at higher velocities, pressure decreases and the fuel is better atomized. As velocity decreases, pressure increases and the fuel begins to pool in low spots and on manifold walls. The need of the fuel to vaporize is also another reason why manifolds are heated, at the detriment of performance. If you go with ITBs, manifold velocity will be less important when compared with carburated engines. That is another advantage of port fuel injection, you can have big runners that promote flow yet fuel delivery is not affected as it would be with a large-manifold, carburated engine.