Leon

Ok... Maybe as a baseline, but not a final design. You need to design the collectors for resonance at your design rpm with your valve timing. The pipe must be big enough as to not rob horsepower. You can't just make a blanket statement like that and expect everything to be sized perfectly.

Really sounds like an ignition problem to me. I don't know what car/engine you have (L28ET?) but it sounds like it could be the black ignition box if you are using a ZX dizzy.

I just installed my 40DCOE carbs on my Z so I'll put in my 2 cents... #1 & #2 Set your timing for about 34* with mechanical all in. I am not using vac advance, it is likely dead anyway. This means that you are probably around 15-20* initial depending on dizzy and rpm. #3 You need to use as little return spring as possible. Stiff springs will wear your bearings quicker. Make sure there is no binding in your linkage and that it moves freely. Then set up your linkage so that it is self returning. I am still in the process of doing this and has been my biggest challenge. The car starts and runs great but getting the throttle to return to idle without heavy springs has been taking some time and tinkering. #4 Set your idle rpm after you set dizzy advance and then make sure that no progression ports are uncovered. After that set the mixture. Once that is set you can play a little with the speed screws to balance the carbs and get the idle down. Make sure the progression ports remain covered! Mine can idle as low as 500-600 rpm if I want them to (and if I can get the linkage to return). #5 I thought I'd bring up the PCV system as well. I got a K&N filter for the valve cover breather, but I'm still figuring out how I want to do the rest of the system. The simple solution would be do route the lower hose to a catch can and vent to atmosphere or to a PCV valve connected to one of the ports in the intake. The elegant solution that I found while searching is what stonehenge69 did on his stroker. He utilized a PCV valve threaded into the block and a hole threaded in each runner so that the crankcase vapors get equally distributed and the carbs are easier to tune, while keeping the PCV system intact. I've been scouring the net for linkage and PCV solutions and I'll post results when I get that stuff figured out.

I did notice you changed it up and stacked the tips and solved that problem nicely, but it does take some more work in order to do it as you've shown. The way MSA intends to have the system mounted with the tips arranged horizontally does require cutting unless you want to hang the pipes low and leave that empty hole there. It's a good looking and sounding system, especially for the money, it just takes more work to make it the way you want to make it. As for the sticky, it's a great resource especially when people start throwing the words backpressure and velocity around without knowing the true dynamics involved. I hope it helps!

Combustion chamber design is a big part of it, along with spark plug location. You can't do much about the latter, so the former is altered. A smaller, more efficient chamber allows for a more controlled, repeatable and faster burn. Modern pent-roof chambers with central spark plugs are more efficient in this sense, thus you see the higher compression ratios that cars run today.

Thanks for posting this, maybe we need a dedicated twice pipes thread? Ray, nice work on the pipes, a sound clip would be awesome! I keep going between two exhaust options, since I have to replace my rusty, leaky one. One option is the MSA twice pipes hooked up to a stock manifold. They sound great and are low priced, but fitment issues are a big complaint. Also, I like the horizontal tips but don't like the fact that you have to cut up the stock rear valence in order to fit them. Overall, they still seem like a good value if I install them myself. My second option is using my Clifford header (6-2) and having a set of pipes made, similar to Chris's system. I have access to my buddies MIG but don't trust my welding skills enough to do a proper job. I'm thinking of just going to the shop and getting a quote for a close copy of that system, meaning true duals (or maybe use an X-pipe) with four glasspacks, two by the driveshaft and two at the end. The header has twin 60mm collectors so I'd probably go with 2" or 2.25" pipes. When I decide and get it done, I'll be sure to post something up. Again, thanks for the thorough write-up and everyone's input.

Summit would be a good bet.

Here is a bookmark I had: CZC Another site: MMS You can probably find other lists and sites by doing a search here, on google, etc.

Triple

Double

I had a busy weekend. Finally installed my Webers along with new studs, a new manifold gasket and exhaust flange gasket. First start was Saturday, 2:30am. Plenty of stuff still left to do. Adjusting throttle linkage, lots of engine bay cleanup is needed and that exhaust manifold bothers me (air tubes, ugh). I have a Clifford header in the garage, but I need to have the flange straightened.

What condition are your carbs in? Old SUs tend to leak around the throttle shaft when the bushings get worn. This may be causing a vacuum leak which leads to the lean mixture. It may be a small leak, but it will affect the mixture. Check by spraying starting fluid around the carbs. If you hear any changes in sound as you spray over the throttle bushings then there is definitely a leak. My thought is if you have a properly tuned, good set of SUs (e.g. ZTherapy rebuilds) then you should be good to go.

The physics are awesome, but I'm with you on the standard car stuff. I did see an S30 in the used lot after I bought my first car, but obviously I didn't have the monies . I did manage to get a Countach, KPGC10, and Mercedes 2.3-16 from the used lot. As far as driving goes, I like to turn all assists including ABS off but remember to set your brake balance correctly, or else you'll go twirling off course. I use the interior view once in a while, and I like that you can change the zoom level. My old GTDFP wheel seems to be holding up pretty well. Overall, it's a great game, but I've been into the series since the first one came out so I may be a bit biased!

If your Z was originally an auto then it came with an R180. If manual, then R200. Here's a good reference: http://atlanticz.ca/zclub/techtips/differential/index.htm

***Admin edit*** ...it is very unlikely that his R200 came with LSD since most of them were open differentials. The LSD came much later, and then only in the 300ZXT. Unless it's some rare comp piece, it's unlikely to be LSD. It would be much easier to install the 4.11 R180 than putting 4.11 gears into an R200. All you have to deal with are those pesky drive-shafts.

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!