zredbaron

NapaBill (or anyone else that can help!): I just got some A/F data from some dyno runs: Also, my power is very bumpy below 3500 rpm. From being too rich in that range, I assume? (BTW i think that strange red peak from my first run was from timing not being in the right place and giving false readings...but what do I know?) I am going to get the biggest chokes I can fit in my 40DCOEs, and I am thinking the following changes might be in the right direction: 34-->36mm chokes 130-->145 main jets 180-->195 air corrector jets F11-->F2 emulsion tube 65.F8 idle jet? * 40 accell. pump jet ** * idle jet will have to experimented with all of these other changes. ** this is what's in the car. I was advised that since I go super rich once I hit the throttle and then lean out as the engine builds rpm I should go smaller. Thoughts? I know I'm not supposed to change too much at once, but a lot of these were calculated, and I was *hoping* with that A/F graph you might have a feel for these adjustments....and possibly verify or adjust some of these numbers...of course, if I do get all these jets, I plan on experimenting with different combinations of what I've got to see what makes her happiest... Thanks!

yeah, it seems pretty high to me too. the numbers aren't from a timing light, but from the potentiometers on my ignition, which are probably quite crude. but i can say that the car made the most power wherever its at right now...

Here's my advance curve: I'm not quite sure what you're asking for, Dan. Are you asking for the above plots with it's respective power curve for each run? Regardless, no...the curves on this post are all I have. I just did run after run playing with the settings on my ignition to change its advance plot. If power went up, I'd make the same change again and kept doing it until it didn't like any more changes. As for carburetor changes...here's what I think I am going to do for next step. I am reasonably confident because following that guide I found (link further up this post) produced a lot of numbers that were recommended to me on this post: 34-->36mm chokes 130-->145 main jets 180-->195 air corrector jets F11-->F2 emulsion tube 65.F8 idle jet? * 40 accell. pump jet ** * idle jet will have to experimented with all of these other changes. ** this is what's in the car. should i go smaller, dave? We've talked about main choke sizes...but what about the aux. venturis? Do they have various sizes? So...before I invest in the expensive chokes and yet another set of jets...and possibly another dyno run, I have a few questions/concerns for those following this post if you won't mind: I am concerned about changing too much at once. Should I start with some **recommended** jet sizes to go with bigger chokes, or should I just get the chokes and see how it responds? Does anyone know if the above changes will mean I might not need a smaller pump jet? Dave240z recommends smaller accel. pump jet, bigger mains, richer emulsion tube. Dan recommends actual numbers: I understand that a lot of this is guestimation, but the guesses follow a similar trend, and my on paper calculations agree that I need bigger mains, air correctors, emulsion tubes, and main chokes. So...I assume that changing all of this will require changes with my timing? Or will that timing plot I have stay relatively the same? I am not willing to spend $150-200 on a dyno refinement every time I want to see where a jet moved my mixture and/or timing. If the timing doesn't require a lot of change, will my butt dyno be able to refine any further corrections? I do have one of those G-meter accellerometers, but I can't get a curve from it, just peak hp and peak G forces under accelleration (it comes within 5hp of the dyno). Thoughts? Comments? What I really need is a dyno shop with a butt ton of jets. Any ideas? Thanks yet again, fellas. After your responses I think I'll put whatever my then current inclination is on the Weber post and ask that NapaBill guy what he thinks with the jetting...

thanks, jon. yes, i definately have a positive deck height of .025" -- i measured it myself. i pulled out my old nissan competition catalog (circa '99) which is where i bought my stroker kit. it has a table of compression ratios. using a 2mm gasket, the ratio is 10.29:1. using a 1mm gasket, the ratio is 11.54:1. i have the 2mm gasket on my block, but with the head shaved... 10.3 < my car < 11.5 is probably the case... (those are the numbers for an E31 head) yes, i saw that weber post, and have been participating in it. unfortunately it hasnt been helping me as much as i had hoped...everyone contradicts each other. which is why i put my info in this thread since this group has always seemed to know what they are talking about. as for exhaust...i have headers, 2.5" pipe, and a flowmaster. not much restriction there. i even have the headers wrapped and a heat shield under the carbs. i also have an airbox and 'cold' air routed from in front of the radiator. ill put up a pic soon. hell, i might just update a website like ive been meaning to and put the link up.... oh, and i found 'pump jets' in my weber book...ill look at the numbers in my carbs tomorrow. i dont think ive ever pulled em out before...

As usual, you guys never cease to amaze me. I get several replies the SAME day, and give me hope in tuning my investment... Yes, my Webers are still 40mm. They have 34mm chokes in them. as for compression ratio, i don't know. it's probably fairly high, its an E31 head, and it looks like sunbelt shaved it some. how do you measure compression? i did the dyno pull tuesday using 100 octane gas. I haven't tried pump gas since I dialed in the timing curve. Dave: thanks a lot for your input. I'm a little thrown off: I don't remember coming across said "accelerator jet." I pulled out my weber book, and again, can't find a jet with that name. Do you mean the idle jet? I have found the idle jet controls how the car transitions between light pedal and heavy pedal. Jets: 180 air correcion jet 65.F8 idle jet 130 main jet F11 emulsion tube according to a website i found online, http://members.aol.com/dvandrews/webers.htm i can calculate all the jet sizes i need based on the main venturi size and cylinder displacement. here are the numbers i got from these calculations. 185 air correcion jet 135 main jet F2 emulsion tube 60.F8 idle jet would it be a reasonable guestimate that the numbers my car would like might be slightly higher than the calculated on the basis that my head probably flows better cam is a little more aggressive than the "average car" that they used for their formulas? here are my thoughts for the first jets to play with...I'll get the 135 main jets and the 185 air correction jets. I'll only make one change at a time of course. I'll probably see how each jet affects the car independently...and then I'll see how they work together. or am i missing this completely? thanks again.

Sunbelt head installed....finally! According to their printout: stock (head before any work) port flow: .......................intake.................exhaust .425" lift...........158.9 cfm...........110.2 cfm .525" lift...........163.5 cfm...........118.4 cfm (.525" lift never reached with the cam i had in it) final port flow: .......................intake.................exhaust .425" lift...........180.6 cfm...........129.3 cfm .525" lift...........201.6 cfm...........145.1 cfm according to sunbelt, 200cfm by their flowbench (flow pro) is 225cfm by anybody else's (super flow). The cam Jim set me up with has a lift of .520, and powers from 3500 - 7200. Cam lobe duration is 290° for intake, and 274.8° for exhaust (yeah, that seems ridiculously precise to me, too). It should also be noted that Jim said the L6 motor doesn't start making any 'real' power until your lift exceeds .550". Damn. My old head produced 157 rwhp, and this one produces 197. Quite a dissappointment considering my investment. On a positive note, it pulls hard to around 7250 rpms and sounds absolutely beautiful. Any thoughts on why my rwhp is 50 hp < similarly built engines? Valve lift and carb tuning are issues....but 50hp? Not sure what's going on under 3500 rpms...I've been meaning to call sunbelt but haven't got a hold of them yet. Jetting? Cam lobe?

Again, this was my setup with 40DCOES (3.1L): I swapped my idle jet to 65.F8 and the car is A LOT more driveable. It still isn't perfect, but transitioning between little pedal and a lot of pedal isn't nearly as picky.

clicking? can you describe it in more detail? if it can be described as mettalic rattling, then you might be hearing detonation....

bump. i just got my e31 head from sunbelt, am putting it on tomorrow. the printout i received showed the following data: stock (head before any work) port flow: .......................intake.................exhaust .425" lift...........158.9 cfm...........110.2 cfm .525" lift...........163.5 cfm...........118.4 cfm (.525" lift never reached with the cam i had in it) final port flow: .......................intake.................exhaust .425" lift...........180.6 cfm...........129.3 cfm .525" lift...........201.6 cfm...........145.1 cfm according to sunbelt, 200cfm by their flowbench (flow pro) is 225cfm by anybody else's (super flow). the cam jim set me up with has a lift of .520, and powers from 3500 - 7200. i think the duration is around 280. this is the max lift (valve-piston clearance) you can put in a 3.1 stroker without cutting valve reliefs into the pistons (using a 2mm gasket). the stroker kit produces a positive deck height of .025". hopefully i can dyno the car this week and let you know what this puts to the ground with a 3.1 LD28. i have pics, but won't post until i have guidelines since i remember john coffey saying something about sunbelt not liking that. john coffey, my 3,4 exhaust ports do look "funny" (but why do that only to cyl 3 and 4?)and i have single springs. all in all, i'd say ~225cfm per cyl is pretty damn good for an e31...i cant wait to hear and feel it!

i would recommend avoiding clumsy distributors and electronic ignitions. for as much/less than a high end electronic, you can get a more capable direct ignition setup. check this out: http://www.electromotive-inc.com/products/xdi.html the kit was $500 in 1998, not sure what it is now. my kit is the hpv-1. the later model was hpv-x. either one of those you can probably find for a few hundred i would imagine. evidently the next generation just came out, but does the same thing my unit does. the xdi is $850 (dont know why its higher, dont know whats new) no shit, from the ignition and its timing curve alone, i gained 15% hp and 19% torque on my 3.1L with triple webers (using av gas). (dynoed results) if you arent racing in a class that requires a distributor, do it. best of luck!

here i was, thinking i was going to start a good thread again, but NO! datfreak already beat me to it! so...this is my 3.1 L28 setup, and here's how it runs..... i am running the 40dcoes, and here is my current setup: 34mm chokes (main venturis) 180 air correcion jet 55.F8 idle jet 130 main jet F11 emulsion tube my mixture screws are happiest 3.5 turns out from bottom, and the idle speed screws are about 3/8 of a turn past contact with the fuel lever....spring....mechanism....thing. haha. currently, my car dives if i try to transition between very light pedal and more pedal. the hesitation passes, and the car picks up accelleration a moment later. above 3000 rpm this is not a problem. i am under the impression this is a problem with my idle circuit being too small. can anyone positively confirm this for me? some say its the idle circuit, but NapaBill says throttle plates....? according to a website i found online, (http://members.aol.com/dvandrews/webers.htm) i can calculate all the jet sizes i need based on the main venturi size and cylinder displacement. here are the numbers i got from this calculation. 34mm chokes (main venturis) 185 air correcion jet 135 main jet F2 emulsion tube 60.F8 idle jet (f13? f8? f9? here's what it said about the Fs:) Weaker Normal Rich F3 , F1 , F7 , F5 ,F2-F4 ,F13 ,F8-F11-F14,F9 , F12 , F6 can anyone confirm or deny these calculations in their 3.1L? also, i have been told that 34mm main venturis might be too big, that 32mm might be more appropriate, since smaller venturis allow better atomization when not at peak horsepower. the car is to be autocrossed... and one more question, how much will porting/camshaft selection affect the jetting requirements? the cam i am using has .525 lift and has power from 3500 - 7200 rpm. my head's intakes flow 200 cfm (from sunbelt, which they say is 225 cfm by anyone else's flowbench). e31 head, av gas. no, i dont know the power, yet. just put it on. ill post that to my old thread when i dyno it. it may be a few weeks, but it better not be! as usual, your infinite experience is always appreciated....

hey guys. i've been having some bad luck with my autometer fuel level gauge. the fuel level runs down much faster than the fuel is actually being used, and i can't get an accurate indication. at first, the problem was that the guage i had was expecting 0-90 ohms from the fuel level sender, when in fact the Z sender sends 10-73 ohms. well, i got the right gauge (10-73 ohms) and put it in, and now the problem is even worse. my theory on this is hard to explain. if you look at the gauge itself, you can see that the level change is not linear. by this i mean the display from 0 - 1/2 is longer than from 1/2 to full. also, if you look at the nissan fuel level sender itself, you can see that the level change in the potentiometer's windings is not linear since the tank is not rectangular in shape. my guess is that the gauge is expecting a linear signal (like a fuel pressure would be) and is correcting for the fact that tanks arent linear. so basically two non-linear corrections is compounding the matter and making it something worse, like logarithmic or exponential. or....i could be over thinking it...haha.... is anyone using an autometer guage? anyone figured out how to get around this? or does it work right for you? if so, whats your setup? universal fuel level sender? any help would be appreciated. thanks!

thanks for the info... so....are you telling me i should mount it where the heater hose mount is in this picture?

hey guys...i was wondering if anyone has installed a knock sensor in an L28, if so...where? here is where I put mine... this is an old pic, but its where i installed the knock sensor. it doesn't seem to be doing its job. if my octane is less than ~97, i hear the detonation warning sounds under load. i am using the electromotive hpv-1 direct ignition setup. (and btw, i finally get my sunbelt head this week )

Haha! How did I know I was going to get an answer like that, John? For some reason I thought you were carburated, but silly me, I should have known that I have no clue what the hell you have done with that ridiculous car of yours... Any reason you went with the Motec EMS over the TEC-3? Also, 65mm...thats way too big for 3x2 TB, right? So how exactly are you set up? Do you have a picture of this engine of yours?

No problem, Jon. Also, those numbers will be solid sometime next week. He's got my head, and will run numbers and such soon. I will formally have the cam specs next week sometime, I'll post em when Jim gets back to me. Also, I opted to get exactly what JohnC had done to his head (ouch -- $$$$), except in an E31. Again, assuming the .534" lift will clear. Is your power from the 3200 - 7200 band too, John? 3500-7500? Higher?

Okay, Jon. I spoke to sunbelt today. Their quote, not a final price, is $450 for the cam, and the price includes a set of the single springs. The quote is good for any grind that they have engineered before, if anyone wants a unique, never before attempted grind, the R&D brings the price up to $1500. If you do end up calling, mention that Jim knows what cam he's putting into my E31 head, and that you want the same one, as it clears the 3.1L kit if you use a 2.0mm gasket. Again, the lift was in the neighborhood of .525" (maybe it was .535"? i dont remember for sure), and duration was such that the power band was 3200-7200 RPM. Their number is (770) 932-0160. Good luck! -Mark

haha, figures. i'm an idiot, go ahead and shoot me.....

Just wondering, not really interested in doing it myself, but has anyone dropped in say, a two rotor wankel? You know the kind, add a twin turbo and you get something ridiculous like > 200HP/L.... Hey, they don't call it HybridZ for nothing....

Thanks Dan, I'll have to reevaluate all my hoses next time I get a chance. I'm glad billzbear pointed it out, so thanks bud. And no, there were never any hard feelings. I don't plan on running past 7500 either. Where did you get the 8500 rpm figure? I don't think my diesel crank setup would like that very much... Is that about right for the other 3.1L guys? No one goes past 7000-7500, right?

hahaha, easy john. by the way thats the second time you've cracked me up today. i read one of your older replies to the gas mileage thread....6 gallons per hour...i love it! even better was that no one seemed to notice, everyone was so proud of their 30mpg... i assume that was a typo about the temperature, billybear. if it were a couple hundred degrees, there would be some serious problems. the water temp in the radiator isn't even a couple hundred degrees. and by the way, the hoses topic is not what this thread is about. i will reply in case any silent readers are wondering or confused, but lets keep this post about performance head and camshaft stuff, shall we? feel free to email me if you have further comments or questions about that stuff or my setup. i will be the first to admit that my hose setup needs revamping. thats not a fuel pump you see at the bottom, its a pressure regulator. my fuel pump is electric (nissan competition) and it mounts near the fuel tank. the two fuel lines you see are both sending fuel to the carbs, there is no return line. yes, im sure they are a bit warm there, and yes, I plan on moving them. i also think i'll take out the pressure regulator, i dont think i need it with the nissan comp pump. you may be right about the intake manifold getting warm, particularly sitting at stoplights and such, but at speed i would bet it is negligible (johnC, what does the racer's voice say?). the pistons i have came with the 3.1L overbore kit i got from nissan (more or less flat tops). my ignition is direct, no sloppy points--three coils and a controller. thats it. (which is why the distributor has been replaced with a blanking plate, and you see not spark plug wires, they are on the other side, and short) electromotive ignition allows me to plot an advance curve that changes with rpm (electromotive hpv-1). i am an electrical engineer and i stand by their design over msd, crane, etc anyday of the week (if anyone wants details why, email me). i literally experienced a 19% increase in power from this ignition (dynoed, have the printout to prove it). i attribute this to the advance curve that you can dial in, and the fact that my timing was mildly retarded on the initial run (to protect the engine since the e31 head brings high compression with the stroker kit). as for the valve float at high rpms with only one set of springs...this is engineered by sunbelt, reputed to be the best in the business. they have a cam lobe design that doesnt require firm spring pressure in order to hold the rocker arm in contact with the cam lobe. just believe, buddy. they're that good.

the first thing you need to ask yourself is how much do you want your Z to perform, and how much $$ that is worth to you. do you want a basic stock job, or do you want a sweet ride? a top head job can cost $3000+. you can get a basic assembly and cleanup for $500. i am by no means an expert, but a competent head shop will be able to to a head job on just about anything. however if all they see is v8s, then they may have to spend some time getting setup to handle a straight six on their bench, and this time will come as a cost to you. the common advice that floats around is to not short yourself when it comes to a head job. all of your power is made from your head....gas and air come in, exhaust goes out. how easily this takes place determines how fast the crank can start the next revolition, which translates to speed. the best advice ive come across for a head job is dont get the best you can afford, go to the best shop you can find and get it done right. just to give you an example, i have a very poor head on a 3.1L stroker with headers and triple webers. i put a mere 157 hp to the wheels. a well built head puts 250hp+ at the wheels. i am going all out on the head ($3k) and fully expect to see a 100hp difference from the head and camshaft alone. in my case im shipping my head 1500 miles. if you are interested in a performance discussion, check out the thread titled "NA 3.1L head and camshaft questions" good luck, and enjoy the ride!

Haven't really considered anything. To be honest I had forgotten about it. What do you do? I think the exhaust option sounds the most appealing, how exactly do you pull that off? Drill a hole and put in a check valve, or what? On another note, I'm shipping out my head to Sunbelt tomorrow. Whoever told me a while back that the 3.1L stroker kits have a .025" positive deck height was right on the money. I measured it: exactly .025". Translation: I can put in a cam with ~.520-.525 lift (using a 2.0 mm gasket). I wasn't told the duration, but was told I would have power from 3200-7200. And yes, JohnC, Jim is using what he learned from your R&D, I will have single springs in the head. He expects a little over 200 cfm per cyl., and thinks my 40mm webers will be just fine if jetted and choked properly... And Jon, I just realized I forgot to ask about buying a cam individually! I'll get back to you, I promise! I know you mentioned before that you were unsure about swapping out a cam that might be .500, but heres the .525 we always wanted. I was really impressed talking to Jim. Plus, with less spring pressure thanks to their lobe shapes, thats even more power to the wheels!

billyzbear, The hose is going into my intake manifold, #2 cyl. I used to have a breather, but it made a mess out of my engine bay. A mechanic told me that I should let my engine suck it out for me. I never really liked the idea that much, mixing that mess into my gas/fuel, but I blindly trusted him. Thoughts? I've got a 3 point strut brace. I had it chromed but it was flawed so they're doing it again. It will be on soon. What's the problem with retaining a little heat in the valve cover? And by the way, I'm working on getting a TWM cold air intake. The K&N chrome is pretty, but cold air will help a lot, and I won't have to mess with blankets and such. Thanks, the brakes really hold up. I fully recommend Ross and his MML kits. They are very sturdy parts, and he goes out of his way to set up up the way you need to be set up.

Jon, I was told almost as a side note, that the cams accounted for $500 of the cost of the head. I'm not sure if that was for the custom-grind or regardless if they had to grind it or not. I do think I remember the custom grind being about a 6 week wait, regardless of time of year. I would think that if you wanted to, they would let you just buy a cam, but I'm not sure. I won't be calling them back until next Monday, as the man I really need to speak to (Jim) won't be back until then. You want me to ask if he'll sell a cam as is? Sounds like Jim has all the knowledge for the L6 motors, it wouldn't be hard to get a little clarification for you. Who knows if the $500 included something else, it did seem a tad high to me...