bradyzq

My comment about running from that tuner is based also on the facts that you should be able to get those numbers on a STOCK L28ET at those boost levels, as well as the erroneous torque data on the dyno sheet. With 320ft*lbs of torque and your gearing, you should be able to spin the tires all the way through 2nd gear and get a mighty chirp in 3rd. On the street at least. Maybe not on a prepped strip. Those timing (and performance!) numbers are just not something you should end up with after dyno tuning your car. It sounds to me like he is afraid of tuning your car, for whatever reason. Once you get this sorted out, you will absolutely not believe how much faster your car will be.

Wow. Those are incredibly low numbers. Your EGTs must be through the roof, and your car must fall on its face when you get above 100kpa. I concur with CamH. His timing numbers look much more reasonable, assuming you have decent quality fuel available. You have what looks to be a very potent setup, and if the heading on the dyno graph is right, a topnotch ECU (Motec). The tune, however, is horrible. Your car is so far from detonating that it is not an issue. Run from that tuning shop. With all the abilities of the Mainline dyno (I have a Dynapack) and the Motec ECU, you should have been able to drive out of there with a 90%+ tune.

Hi, There is something very wrong with your dyno graph, and the data. I did some math for you, but I had to make some assumptions, which should be very close. I am assuming you have a 3rd gear that is approx 1.3:1 I am assuming you have a final drive of 3.7:1 (even if it's a 3.9, it's only 5%ish off) I am assuming your tire radius is approx 1 foot (0.3meter). On the dyno graph it says motive force is 3998N. That is what is measured at the roller. That converts to 900 pounds force. And if your wheel is 1 foot radius, that equals 900 ft*lbs torque at your rear hub. Divided by 3.7 equals about 240 ft*lbs coming out of the tranny. Divided by 1.3 equals about 185 ft*lbs coming off the flywheel, NOT 320 ft*lbs! The 185 ft*lbs number makes sense based on your hp graph. 185 hp and torque also make sense for you 1/4 mile numbers, but they don't at all for your engine on 13psi with your turbo. You should probably be around 350whp on 13psi, maybe a bit less, but not 185! Not trying to dump on you. Just saying that something is definitely awry with your setup. It should be killer. And I'm sure it will be soon. Prepare yourself for 11 second passes!

I have a Dynapack, and yes, I love its consistency. And I agree, on 4wd cars, it can take awhile to set them up, especially if you have to jack each corner separately. But if you're looking for actually tuning, not just a baseline, that's no problem because it just adds a few minutes to the bill, and even if it is just for a baseline, that usually has a fixed (not hourly) price. IME, my dyno reads slightly higher torque early on in the pulls than a Dynojet might, so your torque peak numbers might be higher if they are at low RPMs. But HP numbers are not any higher than anything else out there. Of course this all depends on how hard you load the car during the pulls. Generally, I use 2 seconds/1000RPM.

So you're saying fueling, timing (assuming your MS is controlling spark as well), and boost are not the same. Not a valid comparison, IMO. If you're trying to show that the stock ECU is a weak link, fine, but if you really want to show what tuning can do, show us a graph with the boost and injectors the same as the original ECU.

Anyone? Bueller?

Hi All, It has been a few years since I last drove my Z, and I recently dragged it out of storage. It started right up on the first try (after 2.5 years sittingBTW) ! But now it seems the rear carb or cylinders 5 and 6 aren't doing much. So I pulled the carbs off and set the throttle stops (only the front carb had been closing it seems), checked the fuel pressure, adjusted the valves, cleaned and gapped the plugs, timed the engine, and took a compression test. A couple of the valves were off (at least by Z L24 specs) but not by too much. But when I timed the engine, I noticed that my timing pointer is graduated (has many points, not just one for 0degrees), and my crank pulley only has 2 marks. The pointer is on the alternator side of the engine. This is different from what I expected, which was a single pointer, and many marks on the pulley. Then, when I took the compression test, dry, with cold engine, because it doesn't want to start right now..., I got these results: 1: 195psi 2: 195psi 3: 205psi 4: 195psi 5: 195psi 6: 200psi This is higher than spec for a 240Z. The car has an N47 (MN47?) head and there is still significant metal below the "N47" so it hasn't been milled. Engine is L24 032144. Basically, I'm unsure what engine this is. It's been in my car for 15 years, and it came out of another Z, but it was a 280Z and it had fuel injection on it! I'm leaning towards it being a Maxima motor, but the 200psi compression numbers seem high for that. So, where can I find Maxima L24E compression and other data? I've looked through the stickies on heads and L series dimensions, but no luck... Thanks, and sorry if this post is a bit long...

I have that issue somewhere! It's an NA orange 71 with triples and a Supertrapp, and all the goodies (5speed, diff swap, swaybars, lowered, and running sticky tires for the day A001R's, Racer Brown cam, headers, etc). The gist of the story was whether the old 240Z could keep up with the "new" 300ZX Turbo. I think the ZX got smoked in all tests. But of course it was much more civilized...

Have you tried Elgin Cams? http://www.elgincams.com They have a Mercedes section (and Datsun!) Copied this from their site. No affiliation, BTW... MERCEDES BENZ PROFILES We have the following stock masters for regrinding Mercedes cams. If you do not see your model listed below, we can still regrind your Mercedes cams but please allow another week. 190 SL 230 S 300 E 190 D 240 D 300 SL 220 S 1958-59 250 300 TD 220 1964 250 CPE. 380 SL 220 4 CYL. 280 SE 450 SEL 220 D 280 TWIN CAM 450 SEL HYD. 230 SL 300 D 6.9 V8 PERFORMANCE CAMS AVAILABLE FOR NEARLY ALL GASOLINE MERCEDES CAMS. PLEASE CALL FOR SPECIFICS. If the bearing journals are worn undersize on your Mercedes cam, it is still possible to save it. If the cam towers are still in good condition, we can build up your worn journals with chrome plating and then grind them back to their proper size. If your cam towers are worn oversize or are out of round, the dealer can occasionally supply underzise cam towers and we will grind down your bearing journals to fit these towers.

Try increasing the gain on the profec. You might have to tweak (probably lower) the duty cycle (main boost setting) after you've adjusted the gain.

You're right. I don't think there are enough outputs for that, BUT you CAN do a wasted-spark ignition (3 coils, each coil firing 2 plugs) with their standard multipoint injection (fire all injectors at once). It is MUCH more important to have fine ignition control than fine fuel control. In addition to that you can use a more accurate (toothed wheel bolted to crank) triggering system than a distributor. If you are already using a crank trigger, and are only using the distributor to, uhh, distribute the spark (not as a trigger for fuel and spark to the Haltech), then you are getting there, but your poor coil is working 3 times as hard as if you had wasted-spark. It's not very expensive to get the needed parts, and will be well worth it if it's well tuned. HTH.

Not that I really thought about it overly hard, but for routing, if you can fit a 3.125" single exhaust, you should be able to fit the trio of 1.5" pipes glommed together. If you separate them, it should be easy to find space, but much harder in terms of extra pipe bending, etc. For exit, I was thinking of a horizontal triple exit in the center of the rear valence under the bumper. Of course, this goes with a fuel cell occupying the former spare tire compartment.

Daeron, You have no need at all to apologize. If anything, you are trying to keep the peace! BTW, I just noticed in your previous post (#15), you typed 6-3-1. I have been trying to get the conversation going about a 6-3 setup, with 3 pipes out under the car. I'm pretty sure you just made a typo there though. But in case you were thinking (and maybe johnc was too) that I was talking about a 6-3-1 header, well, I wasn't!

Hi All, I have (had, actually, as most of it was long ago) a very high level of math education. I find it very strange that I had to type that sentence, BTW. Dyno time is not an issue either, as I have one right behind me as I sit. (chassis, though, which would make it harder for 30 minute header/exhaust mods). I am a dyno tuner. I must admit, though, that 95% of the cars I see are already built, and all I can do is optimize what's in front of me. So I don't design exhausts... But, as I posted in the first paragraph of this thread, this was to be a hypothetical scenario. I'm not trying to get a radical exhaust system designed for free through this forum! And, yes, I understand that this topic is a deep one, and that one must experiment to get it right on a specific application. But there are general trends and guidelines. A long tube header may work better one a given engine than on another, but it should have a similar relative effect on both (like for example improving high RPM torque). Finding out, or even just discussing, that trend was all I was after. Read my questions. They were all very general in nature. This was not an accident. Then, when 6-2-1 and 6-1 headers were introduced into the mix, I asked more general questions, in an effort to position the hypothetical 6-3 header relative to the other 2, and flesh out the discussion. Apparently I didn't do a good enough job, since the whole idea of 6-3 got buried.

Beans of coolness! Glad to hear it's been resolved. Now you can get on with the tuning!

I'm with you on the misinformation front. But I don't see any signs of this thread degenerating to of those "This is the Best" type threads, which are thankfully not allowed here anyways! I reread the thread and came up with the above quote as the trigger. It's where I had difficulty, and is the reason I asked the questions I did after you posted it. My logic is as follows: Effective scavenging removes more spent gases from the cylinder thereby allowing more space for fresh mixture to be ingested. More ingested mixture is synonymous with increased volumetric efficiency, which means more torque where the VE is improved. So I came to the conclusion that better scavenging equals more torque. For the 6-1 with its one broad area of increased scavenging to be able to make more power than the 6-2-1, it must be at higher RPM than the 6-2-1's areas of optimized scavenging. But then you say that the 6-2-1 can give a broader range of power than the 6-1, despite its two narrower areas of optimized scavenging. This seems to contradict your 6-1 comment of higher power, with a broader range of optimal scavenging.... Unless my max scavenging => VE increase => torque increase line of logic is wrong. If I've missed something, I apologize for the WOB. Cheers,

I hadn't thought of that! Assuming equal wall thickness of the tubing, the piping would weigh a whopping 80% more than a single 2.5" exhaust. If the exhaust is short, the actual weight gain could be quite modest, though.

Quote: Could one conclude in a general way that 6-2-1 is best for low-midrange torque, 6-1 for higher RPM torque, and 6-3 ????? (maybe REALLY high RPM torque)? No. OK, then, what, if anything, could one conclude in a general way about the above? Quote: The longer the primary and the fewer primaries with which it merges, the more a cylinder will feel like it has its own dedicated exhaust pipe, right? You're assuming the optimum is to have an individual pipe/exhaust for each cylinder. That's only (in rare cases) true for forced induction engines. Not really assuming that, actually. And that would be in VERY rare cases for turbo cars , as we would talking one turbo per cylinder! For blower cars, I can think of big dragsters (like Funny cars, etc). For normally aspirated engines there are huge benefits to wave tuning using multiple cylinders to work with each other. Yes, I understand that. It's what made me this thread! Quote: And this would be ideal for top end torque? No. Where, if anywhere, would this setup be ideal? Quote: Any benefits anywhere else? Yes. Where would there be benefits then? I appreciate your taking time to participate in this thread, but I get the feeling you'd rather be doing something else. Simple "Yes" or "No" answers that immediately require followup questions are frustrating. Or... you could just be messing with me. I hope it's the latter! So, reply or not. Either is fine.

Could one conclude in a general way that 6-2-1 is best for low-midrange torque, 6-1 for higher RPM torque, and 6-3 ????? (maybe REALLY high RPM torque)? The longer the primary and the fewer primaries with which it merges, the more a cylinder will feel like it has its own dedicated exhaust pipe, right? And this would be ideal for top end torque? Any benefits anywhere else? All of this is on the assumption that all needed development work has been done!

I somehow thought you would reply! And I notice that you used a very small font when mentioning the 5-cylinder exhausts. I am addicted to the sound of free-flowing Audi engines, 10V NA, 10V turbo, and 20V turbo. Got 'em all and none have stock exhausts. Back to the discussion: I remember seeing pictures of Ferrari 365GT4/BB exhausts with a trio of tips per side. I wonder what that sounds like, and why it was done. Also, if I understand this correctly, if you have a X into 1 collector, where X is the number of cylinders the engine has, the pulses would be evenly distributed by definition, strange odd-fire engines notwithstanding. Right? BTW, Audi made a factory equal length (or close to it) 5-1 header on their 20V NA engines in 1990-91! So, I guess my next question is this: Is the fact that the exhaust pulses are even distributed enough to maximize the benefits (scavenging, smoothness, tone, etc)? Or, does the length of time (in degrees here) make a difference too? In an equal-length 6-1 header, it would be 120 degrees spacing between pulses. In a 6-3 equal length header split as above, it would be 360 degrees spacing.

Hi, Neat car! Couple of things you might want to consider: You mention that you have no traction in 1st and 2nd. This means your setup cannot get the torque to the ground. By going with a 4.11 over a 3.36 rear end, you are adding 22% more torque to the wheels. They will still be overloaded and spin even more! You say that your car is sluggish down low with little grunt. Not matter what your diff is, when you shift to 3rd, your revs will drop by the same amount, so staying up high in the revs is a transmission ratio issue, not a diff issue. Of course, your biggest change will be the addition of the LSD. Hopefully you hook so well with it that you shoot out of the hole like crazy. Good luck with the car!

Hi All, Warning: this is just a dream/crazy idea I'm throwing out here for discussion. I don't think it has any practical use in the real world. But it's different.... After reading through that fantastic thread about flat-plane cranks and 180 degree headers over in one of the V8 sections here, I got to thinking. That's sometimes a BAD THING. With an L series, we can't have 180 degree headers into a dual exhaust. But we can have 360 degree headers into a triple exhaust! 1 and 6 into a 1.5" exhaust, 5 and 2 into a 1.5" exhaust, 3 and 4 into a 1.5" exhaust. That would have slightly more cross-sectional area than a 2.5" single exhaust, and, mufflers notwithstanding, could occupy a space only very slightly larger than a single 3" exhaust. Why would one want to do this? Why not? In theory, the exhaust pulses would be evenly spaced. They may even be too far apart at 360degrees. The sound might be ridiculously cool, or not?! There _may_ be power gains to be had. It shouldn't be too hard to do, especially on a racecar. You could even use a standard 6-1 header and cut off the collector, then fab your own twisted 2-1 collectors. Waadya think?

Duh, brain fart. Sorry!

You make no mention of the turbo setup. For example, a small turbo that spools (and dies) quickly will probably not like a cam with much overlap since it is all over for the turbo before the cam wakes up. You'll just blow a fair amount of boost out the exhaust. More info needed.

When a wideband is exposed to reaaaallly rich exhaust, it can show a false lean reading sometimes.