LeonV

Cool, always nice to get a baseline for the engine! We'll see what some properly-tuned Mikunis get you, you'll like the triples. I plan to verify my wideband at my next trip to the dyno, to see how close it is. It's a great instrument to have, even if it's slightly off. You can always scale the numbers once you've verified at the dyno. Curious point on the mixture screws. They definitely do affect the entire range, but the effect is diminished as the piston rises. They are most sensitive at idle and low speeds/throttle openings, but by the time you're WOT at mid-to-high rpm the effect is small (seemingly undetectable for all intents and purposes). This is why the needle profile must be tailored to the engine, a major pain to do when you get down to the fine details. Triples will be easier! Thanks for posting the info, Steve! Looking forward to seeing some Mikunis underhood.

Fixed that for you.

What, then tell me who gave me those socks for Christmas!

Steve, No need to burst any bubbles since you already had a baseline test done on that same dyno and can make a valid before/after comparison, right? Rest assured, however, that Dynojets inflate numbers by 15%, give or take a few percent, compared to the more accurate brake dyno.

Huh...?

For anyone running triple Webers, I recommend joining the "Sidedraft Central" Yahoo group and browsing the collection of great information. FWIW, I'm running just a stock mechanical pump on my Webers and no heat shield, although I've been meaning to make one. I don't know if you remember, but the new Webers (40DCOE 152) have relocated progression holes which may cause a problem (either high idle to maintain good driveability, or normal idle and lean spot on throttle tip-in). Some have drilled a new hole further downstream and plugged the original first hole with good success. This is documented on Sidedraft Central and probably on HybridZ as well. The 152 is nice for the fact that there are bypass screws which let you equalize two thoats of the same carb. This is a good feature. Good luck!

First off, nice job. Looks like a clean and well-done setup. Second of all (and don't let this burst your bubble), by themselves, dyno numbers are truly useless. What those numbers are good for, is comparison between cars and setups on the same dyno and preferably on the same day (for obvious reasons, this isn't always possible). It would be of more use to have dynoed the car before and after modifications, on the same dyno. For example, JustAFantaZ on HybridZ recently had his V8 Z dynoed on 2 different dynos. The difference in the results between the two dynos was 74hp (428hp vs. 502hp)! That's over 15% variation! We have to realize what dyno numbers are. This will lead to less fuss and confusion. Power or torque is calculated based on the type of dyno. There are variances between dynos, no two are the same. It is not a hard, true number although some dynos are closer than others. Was this done on a inertial (Dynojet, Superflow, etc.) or brake dyno (Mustang, Dynomite, etc.)? Inertial dynos, like a Dynojet, produce more inflated numbers. In JustAFantaZ's experience, the Dynojet showed over 15% more horsepower than the Mustang dyno! I'll copy/paste my post in the longtubes thread on HybridZ: Please, take dyno numbers with a grain of salt.

Looking good!

Seems as though you are right about that. However, if camber is to be brought back to spec (camber plates), the KPI will certainly be higher. With that said, the camber angle is the bigger issue here.

Step 1: Buy used set of Webers Step 2: Slap on said Webers to L24 Step 3: Drive Step 4: Install L28 with said Webers Step 5: Enjoy! You even have a wideband installed already, making tuning the Webers a piece of cake! The beauty of Webers is that you can make them work well on all sorts of engines, akin to the programmable EFI of today. I run 40s on my L24 and would have no problem using them on an L28. Some mild tuning would be involved, but the wideband takes all the guesswork out of it. I see nice used sets in the $700-800 range seemingly all the time. The DCOE is a pretty robust design, using ball bearing throttle shafts and piston-in-cylinder accelerator pumps. It shouldn't take more than some elbow grease and maybe a few gaskets/O-rings on a set that hasn't been beaten to death. Nothing, except a set of ITBs, beats some old school triples snarling at the command of your right foot, IMO!

IMO, installing e-fans is not an "upgrade". It adds complexity (need new dedicated electric circuit), puts more strain on your charging system, and may not even cool as well, depending on setup. The stock clutch fan works great and servicing/replacement is much easier and cheaper than putting in e-fans. If you feel the need to do it, there are multitudes of guides available online. If you search that is...

FYI, there are charging system testing procedures in the FSM, without even having to take the alternator out of the car.

Yes, KPI is measured in relation to tire centerline. JM gives good advice. I'm assuming you're trying to use Z struts because of the relative difficulty of getting Skyline parts? Sounds like a 510 or S130 strut may work better, inferring from Jon's post. The PGC10 Skyline has a Macpherson front/semi-trailing rear suspension, more similar in architecture to the 510 and ZX.

Nice work! I've never actually seen a stripped 2+2 until now.

A good thing to do while you're testing leakdown is check your plugs. Check gap and closely examine them for electrode wear. Poor running will cause spark plug electrodes to wear prematurely, so see if there is any degradation or erosion on the ends.

I would hope that you're not referring to my post as "anecdotal", unless you don't understand the reason why down-drafts are at an inherent disadvantage to side-drafts. Like I said, people make it "work". Mark is a good example of that (and knew he'd chime in ) and am not saying that his setup is "bad". I don't deny that max power numbers can approach stock SUs, but as Mark found out, this involves greater compromises in other areas. Here's a quick rundown: (1) When mounted on an inline engine, the air coming in through a down-draft carb must make a 90 degree turn in order to line up with the intake runners. This leads to a pressure drop (loss). (2) The fuel must make the 90 degree turn with the air. This leads to more fuel pooling underneath the carb. This makes tuning more difficult and inefficiencies in transient conditions. (3) The manifold geometry is forced to make the central runners shorter and the outer runners longer. This leads to a more uneven air-fuel mixture distribution and forces you to run a richer mixture in order to get enough fuel to the lean cylinders, while you dump more fuel in the cylinders that already had a good mixture. (4) Because of the manifold geometry, pairs of cylinders are tuned to differing rpm. The middle cylinders breathe better at high rpm, while outer cylinders breathe better at low rpm. This doesn't allow for intake tuning to be as effective. This is an explanation of the main disadvantages. It is not to say that those that use 4-barrel carbs are wrong, or that they should change. Everyone is free to do as they wish. If someone thinks that a 4-barrel is the bee's-knees, then so be it! I find it is good to provide information and let the end-user make their own informed decision. Good luck with your 4-barrel, azkyinc.

Things are going well! Good luck with the project, can't wait to see the Skyline again, looks like it will be better than ever! BTW, I got an S2000!

What is the condition of your transmission and diff mounts?

It would be good to double check, it's quick and easy. Check cold, drive around, check hot. If nothing helps, I'd pick a needle and start setting it at different heights, logging, and seeing the results. If anything, it's an interesting experiment!

This will increase your "kingpin inclination angle". This will make low-speed steering a bit heavier, but it doesn't look like the angle changes much (have you measured it?) so you may not notice it at all. It'll also give you more positive camber on the front, which adversely affects front grip. Again, if the angle change is minor, you likely won't notice much. This can be alleviated by camber plates, or the cheaper method of slotting the shock-tower holes. EDIT: As you can see, higher kingpin inclination angle is not beneficial. As I've said, if the measured difference is minor then you shouldn't notice much. Why the new struts? Are you ditching the coilovers? Leon

I was thinking the same...

Welcome! Look for an orange Z driving up and down 19th Ave, or around CCSF once in a while. My Z visits the city usually once or twice a week (when it's nice out). See you around!

Well there's your problem! Down-draft carbs don't belong on an inline engine, especially one with high-performance in mind. Some will be drawn to contradict me because their's runs great, but that setup is just inherently inferior to proper side-drafts. Slap on some SUs (or triples) and be done with it. People make the 390cfm "work" but that 600cfm Holley is probably no where near jetted correctly for your engine. Oh, and there is a rev limiter on the L24, it'll stop revving once you see a piston flying through your hood! An SU-equipped L24 will rev to 8000rpm just fine, just ask Greg Ira.

What I'm thinking is happening, is that your horn is shorted. When you turn the wheel, the copper contact that comes from the steering column touches the contact ring on the steering wheel and sounds the horn. I'd look at that copper contact first and see if it's touching the ring at all times. The horn circuit is very simple and there are a lot of good posts about it on this site, if you search.

It's conceivable, and I've been thinking all along that it's ignition-related. However, Zed has done quite a few tests to eliminate most variables in that scenario. The only other ignition stuff I can think of is poor grounds, but I think that's been covered as well. We should note that the spark plugs are grounded through the block, so the block must be well-grounded. Otherwise, you're robbing power from the spark. With that said, it really sounded like there was not enough advance at part-throttle but it seems as though adding vac advance didn't help, either. At this point, I would do what I can to alleviate the issue. It doesn't matter so much as to why this or that, but what can I do to make it run right. Maybe Zed's engine is not similar to other engines because there are some unknown modifications? Who knows! What I would be doing, with all other options exhausted, is seeing if I can make any adjustments that make it run like I want. I will repeat, though, take a look at your valve lash! Although no one seems to understand the importance of this, valve lash affects valve timing. If you have a tight or loose valve(s), you are putting in more/less air-fuel mixture into the cylinder, the effects of which are most prominent at part-throttle! Uneven mixture distribution can lead to misfires in certain cylinders, the effects of which would be drowned out by the other "good" (compression and valve lash) cylinders. Basically, you may have 4 cylinders firing evenly, but the other 2 are misfiring, giving you problems. An engine with the same setup, but 6 "good" cylinders will not have a problem. This really seems like one of those extensive, time-consuming, head-bashing problems that is being caused by some little, minor adjustment out of tolerance.