Roman

Intradesting http://www.corner-carvers.com/forums/showpost.php?p=931366&postcount=111

Yeah I've got a good GPS unit that I can use to measure gear pulls or whatever too, but I only ever really use it on the racetrack where I can measure consistent results in a similar way... I find if going along random stretches of motorway or whatever, a slight dip or rise in the road can make just as much difference as anything else so it seems too tricky to get meaningful results. Where as a scatter plot of MAF readings or temps or whatever, you can accumulate data over multiple runs to verify your findings a little more thoroughly. Drag racing is a cheap form of dyno though, at the Oldschool drags day it ended up costing me about $5 per run down the strip I didnt make any changes on the day, but if going to a similar event with a few different intakes to try or whatever is a pretty good way to measure 3rd gear pulls etc.

I cant wait to get a tunable ECU one day and just be able to adjust the damn thing instead of playing around with smoke and mirrors hahaha. But there are still useful ways I can analyze physical changes to the motor, which is cool! Dyno time is expensive so it's good to have other options for tinkering and seeing what works etc. I guess I can buy a wideband in the meantime, and run it in parallel with the narrowband. That would have definitely answered the question today as to whether it was a MAF signal or lack of air causing the difference.

Yeah its just an air mass graph but in order to make more power, you need more air so they go reasonably hand in hand. On a previous engine I had an apexi pod filter setup with a really nice pipe back to the throttle body. Dynoed at 150hp at the wheels, with a horrific loss of low rpm power. I eventually found a factory airbox so fitted that... Dynoed at 170hp at the wheels with a whole heap more low/mid range power. but no one had figured out how to datalog the factory ECUs back then, so thought I'd try again to see why. The MAF sensor needs to be fitted in the correct size pipe though, cant go bigger or it would definitely make the engine run lean. But yes, there are three possibilities here - one is that the engine is sucking in way less air, so lower readings. One is that there is turbulence or something causing the MAF sensor to read a lot lower. The third option is that there's turbulence or something that causes the MAF to read lower, AND less air to suck through. Based on the way the curve has changed though I'm guessing it's an airflow / tuned length issue though rather than solely a MAF problem, as otherwise I wouldnt expect the 'dip' to move up or down the powerband. I guess the way to isolate it is to try again with a different length of pipe on. If the readings stay about the same, it's likely a MAF signal issue. Thinking about it some more I am a bit skeptical that a tuned length before the throttle body could make so much difference, but I dont see why the MAF readings would be so much lower than with an airbox.

My car has a live axle... But to pass cert I had to have 0 degrees camber up front, as factory alignment is positive 1 degree. Makes any plans for low at the front a bit of a mish, depending on tire/wheel/offset/etc.

The 'Japanese' style is pretty much the only thing people seem to do now, I dont think I've seen a dumpy or bolt ons for 15 years haha. Have a search in the project section here, there are a few very cool KE70 projects kicking around already! Also, google 'Motorfix'. I would say they are the most hardcore KE70 fans on the planet haha. Also if you're planning on lowering it some more, which I wouldnt reccomend. Have a read on the camber laws and tire laws. Makes it pretty well impossible to have a road legal example of what you're likely planning.

Pic from the drags: Okay so now that's out of the way, back to being a nerd. Soooo it seemed to show some improvements since I had a play around with the airbox, but it's still using the same airbox if you know what I mean. This is what it ended up looking like: I've been kinda wondering though how much of a loss I'm getting simply from the airbox and filter itself. So I thought I'd experiment with using just an airflow meter housing (at exactly correct diameter to the other one) and a length of PVC pipe on the front of it with a fairly crude bellmouth made by heating and bending the end. No air filter or anything, which is not something I am keen on but for the sake of my very dubious science I thought I'd drive around enough with it to get some comparable data to the airbox. First impression, is that sweet effing jesus the induction noise is loud! I think it's louder than the exhaust which is fairly obnoxious already. Intake temps were up, the motor was pinking at low load, (From the temperature increase?) and at full throttle.... Hmmm hard to tell either way, which is why datalogging is good. It also wasnt much fun to drive as I was paranoid about getting rocks in my motor. But anyway, when looking at the graph and comparing to the airbox, the (surprising) results speak for themselves! Essentially the engine now makes the power at redline that it previously used to below 6000rpm. So for whatever reason, a straight piece of pipe with no air filter, flows less air than an air filter box which has to pull through a filter and around a few turns. To be honest I'm really surprised to see such a difference (especially a difference in the opposite direction to expected) Wizard magic! Time to put the airbox back on hahaha.

Autospeed has articles on this subject proving that its worthwhile. If you have the scoop at an existing high pressure area within existing vehicle profile then theres zero difference to drag apart from removing several thousand litres of air per minute from an area where the high pressure is causing drag. Example, front radiator panel area behind bumper or whatever. Agree that a ling spec bonnet scoop or whatever is probably no good. But in case of carina the bonnet is a low pressure area anyway with no flow.

What i mean is that a smaller engine only consumes a small mass of air per minure. So with a smallish cross sectional area of the scoop you can maintain positive pressure in the scoop at a lower speed. When you are huffing in 2000hp worth of air you need a huge cross section to keep positive pressure. So a lower power engine gets a bigger % of gain from ram air.

Yeah i guess regardless of motor size you get 2hp or so worth of air. So more beneficial to low power cars. Or things as above where youre going for 10/10ths

Bahahaha!

The flat earth is suspended on an essential layer of backpressure.

Interesting that they mention power loss when going to 3" exhaust from 2.5".... Oh god not this again

Aahh so just some gif files from my thing before.. Big gif files so click the links. http://iforce.co.nz/i/1dm2kvwj.4fd.gif http://iforce.co.nz/i/tmwz3uk3.fvw.gif Most of the air spills back out of the big trough thing so could probably keep downsizing it until that stops happening. Or keep lowering the vehicle speed to see how big it needs to be to work at XYZ speed.

My engine isnt peaky. Well, it does make max hp right on redline. But thats because it needs a higher redline, not that it feels gutless at lower rpms. The throttle response is already good. Factory manifold is a negligable restriction, it's got bellmouths in the runners already, and the runners are a larger cross sectional area than blacktop 4age throttle bodies. When your throttle(s) are wide open, it doesnt really matter where they are? I dont need to change the harmonics because they're already designed for the motor and gives it a good powerband. The packaging is worse, because quads wont fit properly. Better looks in the engine bay is irrelevant to me. It wont sound any different because I'd have it in an airbox regardless. I get 8l per 100km when driving it like normally, and I drive it on gravel roads etc so good filtration is mandatory. I think I've done about 8,000kms in 6 months so far, and last air filter change there were all sorts of insects/debris/etc stuck in the filter. Open throttles or anything like alpha N mean compromises I'm not willing to make to filtration or fuel economy or whatever. Either way it's a pointless conversation because I've got zero intention of going to quads even when I get an aftermarket ECU Going to keep running a hotwire MAF as well if I can

It's been proven already that longer the runners the better for these motors, even glenn's ones with ~190kw atw run long curved runners to get enough length. Apart from how it sounds, and how it looks (which is irrelevant because I'll never run open throttles anyway) What do you think is going to be better about quads? And in your mind how much better is it going to be for the $2-3k expense. When I had quads before it was about a grand in parts from memory, to get bolted to side of motor. Not including ECU / tuning / etc.

Going from 2nd to 3rd throws away some of my powerband, why would I want to do that.

My idea: Leave it as is Your idea: Remake everything. Yep sounds difficult

Yeah I've seen that vid, its easy enough to vary the flow between runners like that with a time dependant analasys. But yeah there are too many variables and assumptions to use it for anything apart from cool animations. But as per my rant above, knowing the MAF sensor value in grams per second gives me some useful info regarding what's good for anything upstream of the throttle body. It's a real life value which can be applied to known pipe sizes etc. Rather than making assumptions about how much flow/volume/blah blah comes from the valves/cams/etc. which is what's required to reinvent the intake manifold which is already good. Everything I've done so far (not much) seems to point to that the bigger the pipe the better, for minimising pressure drop. Which is useful info. Rookie - As I've mentioned briefly before, my car used to have quads on it. But to get a runner length that's good with a straight pipe, I had to cut some of the bonnet support things out. This caused an irrepairable bonnet warp and I had to source another one before painting the car. Having a bonnet cutout or whatever isnt an option for what I want with the car. If the car needs bent intake runners then the only real advantage of quads over single TB is that you can have a much larger plenum volume and no step down to the diameter of the single TB. Which is beneficial, but if I had $2-3k to throw around then I'd be buying tires and other things first.

Hey cool article! Thanks

Oh so as per above. It's obviously a good plan to put an air intake into a high pressure zone. I've Been wondering if there's any benefit to making a 'trough' type thing, that collects and holds air slightly pressurised for the intake pipe to pull from. If the amount of air coming is greater than the amount of air going out then it should build some pressure. So... If you've got a certain mass of air flowing out of a hole in the back of a box/trough, (known value as per airflow meter readings) then if the trough is still lower than atmo pressure when the car is going 100kph then you just need to keep making the box bigger. So I started out with a box 100x100 with an outlet that's sucking 170 grams per second of air. Tested at 100kph... Lower than atmo pressure in the box. Made it 100x500. Still lower Made it 100x1000. Now gets to about atmospheric. (This could fit in the car, could take up the whole lower inlet panel thing) I then drew some piping and an airbox type thing off the back of it, to represent air filter box. To see if that could get slightly above atmo. Yes and no, the trough thingy gets above atmo but having a 72mm dia hole outlet is where the pressure drop happens. Increased the size of this, and increased the size of the box to 200x1000 Now it's getting above atmo pressure inside the airbox at 100kph... However it was above atmo pressure by something like 0.001 PSI. Haha. Not bad I suppose if it means you could get the entire inlet tract including air filter for 'free' in terms of restriction. It seems the name of the game is to make any pipe pre-throttle body as bigger diameter as you can get away with. In my case I'm stuck with a MAF sensor that needs to be inside a certain diameter pipe and it's got a 72mm throttle body so those seem to be the bottlenecks. I wonder what the intake pressure drop is at the moment IRL... I've really gotta get a pressure differential gauge at some point for nerdy experiments like this. I guess another thing is that 170 grams per second is peak airflow meter reading, but because the engine operates through a powerband it's only reaching this at certain speed/rpm combos. It would only get to this reading currently at 50kph, 80kph, 130kph, ~185kph. So at the real life 100kph MAF reading it may very well make positive pressure there. Even if it only did so 'off peak' it just means it would broaden the powerband instead of increasing the peak. I might run it a a few more times at the grams/second rating for the rpm it drops to on gear change. And yes I realise this all seems stupid compared to just getting a turbo or supercharger. However engine bay simplicity is a set in stone goal for my car. If I made a contraption as per above it fits into a part of the car that's currently unused and completely out of the way of everything else. (and doesnt cost me any money hah)

Yeah it's got the modelling stuff. Jeepers, Ansys looks pretty hardcore. Might check that out another time but just learning solidworks is enough to fill my brain to the brim currently! And my knowledge of engineering type stuff is the bottleneck anyway, not the software. I'll put that on the to-do list!

Hey so one thing I've been wanting to play with in solidworks is some of the flow modelling stuff. For sake of learning the program I thought I'd draw up an intake manifold / throttle body / piping / air filter / air scoop / etc. Then play around with some stuff and see what changes. For my motor I know: Intake runner lengths, diameters Approximate plenum size/volume Throttle body diameter piping diameter How many grams per second of air the motor currently consumes at full rpm/throttle with the current length/size/etc of inlet tract (as per airflow meter readings) So what I've been thinking is that it's probably outside the scope of what Solidworks can accurately acheive to try and model the pulses as each cylinder sucks etc. As although you can make time dependant flow it's not going to accurately represent an engine well enough. So what I was thinking is that I've got a known Grams/second at a known pipe size (start of airbox) so perhaps I could model some different intake configs upstream of this (as realistically I'm not gonna build a new plenum or anything anyway) and see if I can minimise the pressure drop. Or, since ideally I'd want to acheive a higher grams/second perhaps I could set an 'outlet' as vaccum or whatever at different strengths until it shows 170 grams/second as the mass flow rate with an approximation of my current intake there. It will be easier that way to see changes as mass flow rate seems a lot less like reading tea leaves than pressure drop which seems less sensitive(which I guess is why they use MAF in modern cars so much) and also obviously increasing the mass flow rate is the end goal which gives an engine more power. I've been thinking about whether a big bathtub looking scoop thing in front of the front radiator panel could build positive pressure past the filter at 100+ kph.... Making the intake tract up to that point 'free'. I would probably need to model a reasonable amount of the front of the car but thats fine because the point of this exercise is to learn how to use solidworks more than anything else / cbf actually working on my car haha.

The only problem I can see with this is that if all four wheels are spinning, it's going to interpret this as though you're travelling at a higher speed, and so increase the boost and then your wheel spin increases more. Or if just front or rear wheels are spinning... How does it know which ones are or arent? (Is this for Sentras car you're talking about?) Limiting per gear is probably a better option? If you can look at the datalog and figure out the first rpm/load combination that the wheel spins at. Figure out how much HP this is. Then apply the horsepower formula to the rpm etc of the wheel to figure out how much horsepower the wheel can put to the ground at various speeds then limit your boost to acheive approximately that amount of horsepower at each speed.