Roman

So the bellmouth turned up: Good news is that its got a super thin wall thickness, so slots into the tapered part of the TB quite far. So I'll be able to make the airbox a lot smaller than I was first expecting as its a bit tight near the radiator. However the shape of the bellmouth itself isnt overly amazing, it's like its a flat outer part, then a rolled transition to a flat 45 degree section, then a rolled profile to straight pipe. Rather than the ideal shape which is quarter of an ellipse. Not sure if that makes any tangible difference however, but might try find something else similar with the better shape. It's probably this way because it's a zillion times easier to manufacture and no one notices the difference when buying one.

Sorry that's because I have no idea about anything to do with rocker arms, haha.

Oh yep, I've seen those kits for AE86 etc but not sure what fits the F series axle?

I'll get a 4age if Sentra Dave gets a 3SGTE.

When cross sectional area is that big the airspeed is super low which is why i think no boundary layer visible at that scale. and also why bends dont seem to matter as much. Using a 20 micron surface roughness as a random guess.

Soooooo with my airbox intake thingy. All is well and good, but when the motor gets to 6000rpm, datalogs show that there is a 3kpa pressure drop at the inlet manifold all the way to 8000rpm. How much is 3kpa? About 0.4psi which doesnt sound huge, but when you're working with 14.7psi atmospheric pressure that's about 3% of air (and power?) being lost before it can even get a chance to get to the throttle body. 3% of 200hp is 6hp so wouldnt complain about a 'free' gain of half that much if I could halve the pressure drop. So my first thought was, why not go from the current 3" pipe to maybe 4". But then I thought, since I no longer have a MAF, why have any pipe size at all? I could have a bellmouth straight on the throttle body for max flow. Then have a big enclosure to feed it filtered air with minimal pressure drop. This would take up a lot more space than a normal intake though, So the first things first is see if it seems feasible for space. I took a photo of the motor as straight on as I could (If wanting to do this, stand back far and zoom in, to minimise perspective distortion) and drew a rough sketch in Cad to see if theres' about enough space for a bellmouth, some space around it and a panel filter. Seemed okay so I plonked the motor back in and started on some CAD (Cardboard Aided Design) to see how much space I've got: Then roughed something together in cardboard, this is the Rapid Brototyping stage: Then copied the dimensions to CAD: Then made version 2.0: Back to CAD, made it more roundy looking: Then started working on the second half of the airbox. So now I've got a pretty good idea of the maximum available area I can work with to make it any size smaller than this. (It's pretty big and gumby at the moment) At this point, I've got two options - I can keep the intake getting air from the big hole through the wheel well area and down to the front as per previous. Orrrr, there's a 91mm dia hole behind the headlight, I could get air from here and/or here: So time to head to Solidworks and try some stuff in the flow bench thingy. TWO INTAKE ENTER. ONE INTAKE LEAVE. I've set the airbox opening to be a source of atmospheric pressure air. And the throttle body area drawing in 170 grams/sec of air (As per datalogging from a few pages ago...) When I keep the airbox diameter really large, even with shitty bends. It keeps the pressure at 101kpa right to the bellmouth. (This graph shows velocity instead of pressure, but you will just have to take my word for it.) When I try a different (simpler/smaller) design that sucks are through the 91mm entrance hole in the front panel of the car... I lose 0.2kpa straight away. Which isnt much, but it just points towards the idea that bigger is better for everything pre throttle body. (Red is good, yellow is not so good, green is less good, and so on. Read the scale damnit) For experiment's sake I thought I'd see what happens when I run the "Big" airbox entrance on an airbox that's 10 meters long. Despite what you'd think it still stays 101kpa across the whole thing, right to the bellmouth. So it seems to indicate that the length of intake means bugger all compared to diameter. Even throwing some harsh 90 degree bends in there, the cross sectional area is so huge compared to the throttle body that there's effectively zero pressure drop. Aaannnnnnnnnddddd that's as far as I've gotten. But the plan from here is to make a cardboard model of the exact shape that I'd expect to build it. Then put it into CAD, then I've got the options of getting bits lasercut or whatever, to minimise the odds of cutting a finger off trying to build something properly. This whole thing might be a big waste of time and acheive nothing at all, but it's helping keep me sane through winter so that's always a good thing. But, I'm pretty confident in my ability to quantify a change for better or worse now. So even if it's a failure it's a win, because Coupe Life

PIcs or it didnt happen I have no idea what you are talking about What car? What airbox? What hose? etc?

Mine is 2.5" all the way with straight through mufflers from Chase. Which work better than expected at keeping the volume down a bit. It's reasonably quiet when just trundling along but gets (too) noisy when you put your foot down. As per what the other guys have said a zillion times, 3" seems the go if you can make it fit. I looked at the difference in size of the bends etc and decided it was going to be an extra ball ache over 2.5" because they are a fair bit bigger radius if you use mandrel bend bits. I put a flange just before the rear muffler, so if it was too noisy I could easily swap it out. But so far it's been mostly fine, does sound a bit grotty though. If your car's gonna be slam spec then yeah I'd say you will likely struggle a bit with 3".

Ahhh okay interesting. What angle would you say the 4 links on currently, would they be parallel with the ground, up towards the diff, or up towards the body?

Have you ever driven the car with the lower 4 links down set to the lower set of holes on the diff?

Not too sure to be honest. Does your engine have standard cams still? In other news, I've been pestering Link to add an RPM based table for setting the inner/outer ratio for the staged injection - They've said it'll be included in an upcoming firmware version, yuss! As currently you can only go by MAP (Boost=MOAR INJECTORS!) or TPS which isnt too useful for NA stuff either.

Heh yep I hear ya - all good points. At this point I'm keen to go back to the staged injection manifold once the engine is back in the car, and experiment with that a bit more.

I might be missing something here, but why not make all the changes, then get cert? Or otherwise skip cert and save yourself the $$$ if it's going to be modified away from cert specs anyway?

The point is that a lot of the characteristics are similar on paper, including how much power they make from a standard engine. (+-10hp depending on verison) K20A doesnt use exotic materials or anything unavailable to any other 2 litre engine... Yet K20 responds well to mods, beams (and a lot of other things) do not. Even if you get the most agressively spec'd $$beams toda cams$$ available, it still has 10 degrees less duration than a standard Honda item. Does that not strike you as something remarkable about the K motor, compared to .5mm valve size or whatever? 70 degrees difference in duration is a shit load! And in my mind goes a long way towards explaining why basic 'breathing' mods work well on Honda stuff but not so much on beams. Nice strawman though.

Ahh yep! I remember seeing that way back in the day. I wonder if it was in the rules that they had to run a factory plenum or something. Interesting setup! EDIT: I remember some more information about this now. The motors werent 280hp, they were 250hp, due to being class limited to a 10:1 compression ratio. I remember a set of pistons from one of these engines came up for sale at one point., People wtf'd because the pistons were a bit spendy, and the CR didnt really make sense for either a turbo or NA build for people who didnt need to follow those same rules.

Yeah it depends on the shape of your adaptor manifold, whether it would suit silvertop or blacktop throttles. As blacktops have the silly shaped exit hole, silvertop a bit rounder. Yeah I think there are some bikes running bigger throttles than that. Some of the other options are trickier to adjust the spacing between the throttles, I think the GTR ones are in cast pairs? I was browsing some Honda forums and a lot of those guys run 50+mm or 60mm quad throttles, they've got off the shelf kits... but they cost a friggen fortune!

Oh yep good point! Perhaps it's even greater than 17% when you consider that the first mm or two of lift are probably useless. Main thing though was that apart from the cam specs, out of the things listed there didnt seem to be too much different going on. I'm pretty sure that they run a non square bore/stroke as well though, as in short stroke so they can do higher rpm without standard cast pistons blowing to smithereens. although that doesnt much explain how K24s seem to do zillions of revs without exploding. As they'd have a higher piston speed than an 86x86 2.0 litre engine at the same rpm. It's a bit of an eye opener reading some of the K20 forums though, man some of those guys have got shit loads to spend on building motors.

Hi, story time! Holy fuckaluckalucka the K20 motors have got so much more cam duration than a beams motor. And a bit more lift. Apart from that the other specs seem reasonably similar to the M/T Altezza engine (Comparison is against my single VVTI engine) Way smaller throttle body on a K20 which is odd. The big hp builds seem to go for gigantic throttle bodies though and 4" intake pipes. And the age old question, 20v throttles on a beams motor, or standard manifold? The standard intake manifold has 45mm diameter runners. With bell mouths on the end. In a fancy plenum with a big throttle body. Silvertop 20v throttles at the throttle plate are 43mm diameter. Blacktop 20v throttles at the throttle plate are 45mm diameter. buuuutttt a throttle body still has the throttle shaft blocking some cross sectional area when it's open, so it's effective area is more like this: So: (Altezza manifold) 45mm dia no throttle: 1590mm square of cross sectional area (Blacktop 4age) 45mm dia 4mm thick throttle shaft: 1410mm square of cross sectional area (88% area of standard runner) (silvertop 4age) 43mm dia 4mm thick throttle shaft: 1280mm square of cross sectional area (80% area of standard runner) You'd need a 47-48mm throttle body (if it had a 4mm shaft) to get a similar cross sectional area to a standard 45mm standard runner. In other unrelated news also took the yellow car for a bit of a spin to blow the cobwebs out, still going strong! (Or, at least as strong as a 3AU is capable of going haha)

Keep it as is, and then if later on you decide that it's a ball ache not being able to take passengers, add a seat. It's the same amount of work whether you do it sooner or later, but it means that in the meantime you can concentrate on the critical path towards having a running car.

Second hand value is tricky, but I'd say you could probably sell the headers.... .... .... .... .... For 1G

A workmate just bought a turbo DC2 running one of the eeeaaarrrlllllyyy links. I'm pretty sure that the scratches on the casing are from when Moses tried to chisel the ten commandments into it. His engine has been running a bit rough so I was all "sweet lets just datalog it" Oh nah, turns out you need a serial board and all this other junk to plug it in, and there's possibility that it's not laptop tunable anyway. Heh. *back away slowly*

Might dig out the yellow car for some 3AU spec lols.

What's the deal with fibreglass as an insulator? As in, I realise it's a good insulator when it's 'fluff' like pink batts. But I'm guessing that's because of the air gaps... When it's in Resin or epoxy for panels or whatever, is it actually still an effective insulator? Or is it only as good as the insulation properties of the resin or expoxy.

Friggen awesome picture! Beautiful.

Jelly of your awesome wheels, looks great.