Technical Thread
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You are currently reading a thread in /o/ - Auto
Sick of all the benchracing, memes, and shitposting which make up 95% of this board. This thread is for discussing automotive technicalities and maintenance.
Anything mechanical or electrical goes.
So, benchracing.
How do they fit so many horses in the engine?
>>15128050
why would you put a wheel in the engine that looks really uncomfortable
>>15128050
Right then, Well I'll start I guess.
If you're looking to upgrade internals on an engine what is the first thing you should upgrade?
My thought is camshaft, timing chain, probably better springs, camshaft bearings maybe.
I haven't actually read into upgrading internals but going off the top of my head of what I'd try to upgrade besides boring and stroking.
>>15128085
Sleeves, pistons, connecting rods. You're upgrading things that actually take the force of the combustion.
>>15128072
vapourise them
>>15128050
Sometimes my car will not crank. I don't know if it's the starter itself or something else. I just sanded and cleaned the terminals on the battery and the connections really good, made them look nice and shiny for maximum contact area. I also disconnected the wire that goes to the starter and cleaned the contact points on it as well, then I tightened everything up and tested it and finally applied a light coat of dielectric grease on the terminals for corrosion protection and whatnot.
I still have the issue of no crank sometimes. The thing is when I pop the hood and try again it starts normally. Could it be the heat from the engine bay that could be messing things up? I have noticed it does that when the engine is hot, like I'll pull up to the store and when I get back in to my car in won't crank, but then I pop the hood open and it starts fine.
>>15128101
>/o/ working on cars
Usually you'll do a hot cam and the usual bolt ons before you tear the motor apart.
can i ask advice on how to build a car for a sport here or what
>>15128141
>>>/QTDDTOT/
>>15128191
no fuck off
>>15128204
oh sorry i guess you guys just want more benchracing and misinformation as if this board doesn't have enough of that
>>15128191
What car and what disciprine. Or, more usefully, what car and what is it failing to do that you require of it?
>>15128085
>>15128186
Why would you want a different cam? The only thing it does is increase horsepower at RPMs that you rarely touch on the street, kill lower end torque and give you crappy driveability with a shitty sounding idle.
>>15128050
I love cutaway illustrations!
>>15128231
3/10
>>15128244
Is he wrong though?
>>15128193
>Mechanical thread.
I mean, it's not like he created his own thread. So.
Alright, /o/, how bad of an idea is it to swap in higher compression cylinder heads into my engine?
>>15128252
What for?
>>15128248
2/10 and falling
>>15128252
What is the deficiency you're trying to counter? Have you tried skimming the head?
>>15128252
it's not a bad idea unless you're planning on turboing it too or some other retardation.
if you do it right it will be fine
>>15128186
Well, yeah, but he asked about internals.
>>15128231
Because some cars, especially smog era V8s, came with garbage cams.
>>15128285
No I want to stay n/a, so I was thinking it'd be a good way to get some more horsepower since I'm only making about 170 right now since I resurfaced my heads
>>15128298
garbage how?
>>15128313
Not that great at anything besides cutting emissions. They have crap heads, crap exhaust, and crap intake manifolds as well.
>>15128319
Yeah but that's pretty much every eco production car.
You can do a lot to an eco car just by changing that type of stuff too. I'm pretty sure if you make the exhaust pipes a little bigger that helps too but I'm not sure.
>>15128224
FF in drift
>>15128313
There was a lot of valve overlap to control emissions.
>>15128416
If you're buying a car with a V8, it's not like you care about gas mileage or emissions.
>>15128446
I meant in general even with non v8 production cars. This V8 eats gas meme needs to go away, I drove a 95 GT that got 25-31 mpg as long as I didn't put my foot down at every light. When you talk older classic V8's then yeah, you're pretty much just stuck with shit mileage.
>>15128478
It just happens as you modify the car. More power means more fuel consumption.
>>15128141
Cables conduct less electricity when they're warm/hot. How long do you leave the hood open before it will start?
>>15128141
You probably have a bad engine ground run a wire from the negative battery to the engine and see if it's better
>>15128236
>>15128050
Requesting cut away of a Lancia Stratos please.
>>15128518
About the time it takes me to open the hood, get back in the car and start the engine. So, maybe 15 seconds?
>>15128503
Yeah, thought you meant in just a general V8.
I also like the people who add chips and etc to make a car run quicker/faster and then complain when their I4 Camry explodes with 215k miles.
It's weird, for me I cant imagine adding mods without touching the internals to handle my added mods and people do it everyday, but then again a lot of those same people are running cheap engines.
>>15128231
A good cam shouldn't lose that much bottom end in a b18 with decent cams and a tune you will lose 15 ft-lbs at low rpm but gain 50HP and get a fatter power band
If you are not running forced induction cams and tune make all the power
>>15128549
Try changing you air filter. Your air flow may be too restricted with your hood closed.
>>15128552
It depends on the engine. You won't kill a car with heads/cam/intake/exhaust unless it has really, really shit internals. That's just improving flow, not like you're cramming boost into it.
>>15128580
How is air flow to the engine related to the starter not turning?
The filter is clean by the way.
>>15128595
right sorry. woke up 20 minutes ago. have someone slowly lift up the hood while you keep the key in the start position. another thing to do is the tedious work of searching for continuity with a voltmeter.
>>15128647
Continuity between where?
>>15128545
Everything on google is low-res or tiny but here
![MTM1MTQyNTc5OTUxMDgwNzIy[1].jpg](https://i.imgur.com/BBK1gRM.jpg "MTM1MTQyNTc5OTUxMDgwNzIy[1].jpg")
[sand people noises]
For the Group C fans ITT
>>15128252
>>15128302
if the final compression ratio is 9:1, there isn't a problem. Increassing the compression beyond that can restrict the torque, and thus the power, because if it starts detonating you'll have to advance the spark more than ideal to compensate. If it's forced induction, then there's no point whatsoever.
High compression N/A engines need exhaust manifolds that flow really well to be able to eliminate as much exhaust as possible from the combustion chamber, and tend to work better at higher revs because the fuel has less time to ignite.
The best to start with modyfing your car is to change the intake tract. And I don't mean to change the air filter (which makes practically no difference), i mean checking the entire piping.
http://www.autospeed.com/cms/article.html?&A=111369
The article above puts it better than I could. You can modify it further by doing the same to the exhaust (keeping the manifolds stock), although the results might not be as noticeable (and no, putting huge exhaust silencers/fart cans in the back actually makes it worse from a power perspective).
To go beyond that means spending a lot more money because then you start into modifying the intake and exhaust manifolds themselves, but by that point you'd be better off porting the heads as well to be able to take full advantage of them, so then you also need to change the camsaft and the valve springs... But being N/A the results probably won't be drastic as you'd hope, and the cost would be getting pretty close to what you'd pay for a brand new engine.
>>15128141
The hood thing is bizarre, but probably a red herring. I'd check relays and fuses, a very rough guess is your relay is getting stuck open somehow, and opening and closing the hood may jostle it enough to free it up again.
>>15128663
battery to starter solenoid. check the resistance with hood open, and below the hood level where the starter won't turn. what car is this?
>>15128141
No crank? That means you probably have a bad ground. Usually there's a ground directly from the starter, sand it down a bit and hopefully you'll be better.
>>15128427
e-mail these guys:
https://www.youtube.com/watch?v=S3g-mvFihdA
>>15128141
...strange, a lot of starter issues are due to cold, not heat.
When it doesn't start, is the starter doing its job and is it making any noises?
>>15128669
Thank you very much.
>>15128695
I'm not sure exactly what compression I'm at right now, but it seems like there's plenty of reason to keep my cylinder heads as they are. I'll have to look for some other means before I tear open that whole pandora's box of compression
>>15128669
This is an improvement from the same frame.
>>15128811
There's a tool to check how much compression your cilinders are actually making though, it's also pretty useful to check if you have some sort of headgasket or piston segment failure.
>>15128718
>>15128719
>>15128731
01 Jetta VR6
When it does crank it starts just fine, when it doesn't, all I hear is a click, no turning of starter or engine.
the black wire on the left is the one that goes to the starter motor, both ends were cleaned.
step aside plebs
>>15128545
close but no cigar
variable compression ratio rod
inboard brakes
where is your god now?
OHV vs OHC
in case you were confused
some historical context
>>15128695
Probably a typo, but you retard spark to stop detonation.
>>15128982
Needs more Rover P6 with De Dion tube rear suspension and inboard discs
>tfw Rover SD1 was a downgrade from the previous model but with a better gearbox
new cars and suvs have horrible blind spots
>>15129013
It was definitely a typo you generally advance ignition timing for a longer burn and more power
>>15129041
>bullet
>clearly still in its casing
>>15128835
Well I already know my head gaskets are fine now (it's an EJ-family engine so I kinda had to change them), but yeah I'm sure a buddy of mine has a tool like that, I'll ask him sometime
nubs should all do this, cross-threading spark plugs is very expensive
>>15129049
Was gonna shitpost and accuse you of ignorance but I make the same mistakes myself, type undersquare instead of oversquare etc.
>>15128982
Because 90s jaguars weren't already shitty enough
all tapped out
>>15128894
A click....just to make sure, did you check the cogs on the starter?
>>15129087
I have not.
>>15128894
bad solenoid or bad contacts somewhere
>>15128141
>Sometimes my car will not crank.
Crank? First, is there a clicking noise when you turn the ignition key? It can be a clicking noise from the relay, but there is typically a lounder one from the starter solenoid that engages with the engine in order to have the physical connection to turn (i.e. crank) the shaft.
>>15128141
>>15128894
>When it does crank it starts just fine, when it doesn't, all I hear is a click, no turning of starter or engine.
That sounds like a bad solenoid. I had a similar problem with an old car. It would start sometimes, but sometimes all I get is a loud click. The non-starting got worse and finally nothing but clicks one day. That car was an old one so it wasn't called "solenoid" which is the modern term but a "Bendix". In those days, people would say "oh, your bendix is bad" if you got a loud click but no cranking when you turned the ignition key.
Try googling this:
what does the solenoid in a starter do?
>>15129035
>new cars and suvs have horrible blind spots
It doesn't matter how tall/short I am, I can even go to my back seat and try to look back and cannot see. The interior rear dash is so high for styling purposes and the rear trunk lid is so high that I cannot see a lot of things to the rear now. And the rear pillars block so much that the traditional blind spot is really large.
These body styling changes are not good for safety purposes. Or they are there under the assumption that customers are FORCED to purchase rear view backup cameras and computer-aided parallel parking features.
And before you say I cannot parallel park, I can do so the very first drive in. But what I cannot do is NOT hit the car behind me as I back up because I genuinely cannot see anything but the rearmost part of its roof as my rear bumper approaches within 10 feet of that car. I tested and got out to check. My loss of visibility begins approx 10 feet away! So without a rear view camera, it is genuinely impossible to tell how far I can go back. I estimate from looking at landmarks on the curb but estimates are only guesses.
>>15128050
is this stupid questions thread? if yes:
what difference would 195mm make vs 205mm tires on 7" rims?
>>15129869
next to none, might be slightly more confortable. The aspect ratio of the tire is much more important.
>>15129066
They got rid of inboard brakes in the 90s.
Inboard brakes were pre 90s
The wankel rotor is at it's most efficient in the 4000-6000 rpm range
suspension tuning isn't a black art.
>>15130468
although with the tire pressure, I must point out that both increasing and decreasing the tire pressure beyond it's optimum will make it slide, and the chart assumes your tire pressure is above optimal.
>>15128050
>This thread is for discussing automotive technicalities and maintenance.
>implying the thread won't degenerate into some OHV vs OHC baiting or some other such turd-flinging shitfest like every other thread.
>>15130468
i learned this shit from /ovg/
>>15130468
>no mention of KPI, scrub radius, anti squat/dive geometry, suspension arm lengths, roll centre
there is a car cutaway specific thread on /o/
>>15130761
KPI and castor angle relate to camber gain or loss under steering effects, scrub radius and trail has to do with steering feel, which is why you have to reduce both on fwd cars to decrease or eliminate torque steer.
>>15130761
>>15133453
Suspension roll arm lenghts and roll center are both concepts that get thrown around a lot but actually just confuse something that is straighforward: that if the tire does not moving perfectly vertically, then the application of a lateral force will induce a vertical component through a ramp effect. In other words, jacking down or up the car.
if the inclination of the tire's path is towards the direction of travel, then we're talking about anti squat and anti dive. If the inclination of the tire's path is trasverse to direction of travel, then we're talking about a roll center height above or below ground.
Suspension arm lenght and geometry essentially describes how the inclination varies throughout the entire range of travel.
>>15128894
I had a similar issue on my Subaru. I thought the starter was bad. Went to take it off and nut that held the ground wire on was finger loose. Worked fine after that.
>>15128982
If you were to make the rotors like four times as thick as necessary and made the brake pads easily accessible from a pit I'd probably prefer inboard brakes to regular ones.
Toyota being naughty
>>15133570
I have some more pics of these
>>15133579
Yeah see, that's retarded. When the disks are the same thickness as easily accessible regular brake disks mounted on the outside, but are mounted on the inside so deep that you have to disassemble the drivetrain to get at them, then your engineers fucked up or were held at gunpoint by cost cutting measures.
>>15133579
>>15133591
>>15133579
Jaguar
>>15133591
Citroen (SM in the picture)
>>15133594
Alfa
Also hydrolastic/hydragas suspension is better than conventional suspension (except at actually lasting).
https://www.youtube.com/watch?v=5TwOc62YXJc
>>15130181
Picture neglects to mention what one might call aggressive cornering wear, it is sort of opposite camber wear. It shows why race cars have more camber than street cars. Many of us may have had to replace tires early due to that wear type.
>>15136248
...That's because it IS camber wear. The optimum camber for a cornering tire is having it leaning towards the inside of the corner, due to deformation of the tire itself. For technical reasons, the outside tires on a cornering road car are either leaning towards the outside of the corner, or at best paralel to the ground. Ultimately even racing cars have to optimize wear rather than simply maximize the lateral acceleration.
And no, the car in the pic isn't stanced, note how it has actual road clearance and thin tires.
>>15136716
suspension wise, it's a straightforward double A arm arrangement, using the upper triangle to support and the lower triangle and steering arm for full adjustability.
>>15136741
forgot pic
