The online racing simulator
The most beautiful engine.
(222 posts, started )
Didn't see the 1 series part. :rolleyes:

Im sure the majority of cars don't have this though.
the majority of cars didn't have abs (now it is mandatory) airbags (now it is mandatory) crash testing (you get the idea) auto-choke

already you can't do much to damage the engine except for downshifting from 4th to 2nd going 90 or something funky like that

all cars now have a rev limiter. that alone is very limiting to how much you can mistreat the engine.

go bouncing off the limiter in 1st during july from stone cold (don't know how you would do that in mid july... underground garage i guess)

if you manage to do that for a while (that is, if you are such a cold hearted bastard or astronomicaly ignorant) you will still be left with a running engine.

if you do that with a wankel, think it will start the next time? the next next time?

anyway it's getting late, i hope you get the idea
Quote from G!NhO :Nope haven't gotten my drivers license yet, but that doesn't prevent me from telling you my opinion about your car.

I will be getting a bmw e30 next year if everything goes to plan...

dont buy an e30, as you will start by buying the nice spiderweb BBS's, then the leather interior, before you know it your broke.
Quote from G!NhO :Nope haven't gotten my drivers license yet, but that doesn't prevent me from telling you my opinion about your car.

I will be getting a bmw e30 next year if everything goes to plan...

So...what?


You're 18.
You call my first car, that i paid for by myself, a rusted shitbox.
You don't have your license.





....yeah, you're doing SO much better than me.
Talk to me when you atleast have your license, lol.
I have done 2 driving lessons, lol.

Atleast the e30 i will buy won't be a rusty shitbox.
Quote from G!NhO :I have done 2 driving lessons, lol.

Atleast the e30 i will buy won't be a rusty shitbox.

wont it? not sure where your from but you exactly get E30's in primo condition anymore without big bucks!

2 driving lessons... and your already deciding what car to get.. get used too your mums soccer coach first
Is it strange that i already thought about what car to get, or isn't that just smart?...
Listen, if i buy a 25 year old E30 i will only be paying 50 euro a year for insurance, hey i already thought about that!

Btw in germany you can find some great E30's in great condition.
Quote from G!NhO :I have done 2 driving lessons, lol.

Atleast the e30 i will buy won't be a rusty shitbox.

Even my e36 is a rusty shitbox.. let alone that 1920 e30 model
Just wait!!!!

/off topic
They are right though
Good conditioned E30 will start from 1-2k (good not great!).
Maybe i got more to spend? :rolleyes:
Quote from G!NhO :Maybe i got more to spend? :rolleyes:

Oh, well we all assumed that if you had more to spend, you'd go for a Jeep
Quote from morpha :Oh, well we all assumed that if you had more to spend, you'd go for a Jeep

Then i'd need alot more for all the repairing costs.
Quote from G!NhO :I have done 2 driving lessons, lol.

By that you mean driving in daddy's car with daddy next to you giving you instructions?
We've all done that, pumpkin. I wouldn't call that a driving lesson.

O well, atleast you're being honest about Jeeps.
No replacement for displacement
Quote from GrIp DrIvEr :Whoop! Game over!

Niet Comrade.

This is the ASC McLaren Viper.



All 8.3 liters of it.
i believe tristan still owes me a discussion on moemnts of area
It requires time, and an ability to express myself clearly without getting myself in a muddle and without confusing you or being ambiguous - skills I don't have!!!

I'll start again, if I may. 'Cheap' rods use an H section. I suggest that I section rods are what you want. This is with the neutral axis horizonatally through the middle of the section, because the rod is free to rotate around the journals, and hence has no bending on it, whereas in the other direction there can be bending loads (and of course there is the compressive/tensile loading). Therefore the axis of the journals is vertical, and this applies to both the H and I examples.

So, in an ideal (simplified ) world we want enough material to manage the tensile loadings and material distribution to best manage to bending/compressive loads.

I can't be bothered to draw stuff, or scan something, so bear with me with the explainations.

I section - The horizontal width of the top/bottom 'webs' is B. The length of the web to the middle is b. The length of the middle is a and the total height of the I is A. Does that make sense? I shall say that A and B are 10 and the material thickness at any point is 1, so that makes b = 4.5 and a = 8

I = 1/12 * (BA^3 -2ba^3) = 450

H section - B is the height of the H, T is the thickness of the materal and a is the length of the inner horizontal (which would be A-2T). Hope that makes sense. We'll stick with the same material dimensions for simplicities sake - thus 10 tall, 1 thick and (10-2*1) = 8 wide across the middle of the H.

I = 1/12 * (aT^3 + 2TB^3) = 167

For a given weight (it just so happens that my dimensions give a cross sectional area of 28 each, so would weigh the same) the I section is vastly stronger in bending in the direction that matters.


Obviously extremes of use might change what you're after. Very low revving, high BMEP engines might actually benefit from a different cross section (many ships use round section for instance), and that will vary with load, stroke, journal sizes, rpm etc, but for 'car engines' which operate over a broadly similar rpm range and power range then the I section conrod is much, much better.

It's not explained very clearly, and I think I might have actually contradicted what I said earlier - not on purpose, but because I found the I/H section thing very confusing, trying to visualise the bending axis, the journal axis, the Ixx diagrams and the name. Apologies for that; I've literally had to sit here for 5 minutes sketching things to try and get my head around it. But the jist is that the one on the right (the I beam by my terminology) below is the one that resists bending better in the direction bending is likely to occur.


To make is easier, the overall width of the bits you can see are (on the left) is dimension A and (the one on the right) is dimension B. The depth (into the picture) is B and A respectively. Maybe that doesn't clear it up... Maybe there will be no hope but to draw a picture.
Quote from tristancliffe :I'll start again, if I may. 'Cheap' rods use an H section. I suggest that I section rods are what you want. This is with the neutral axis horizonatally through the middle of the section, because the rod is free to rotate around the journals, and hence has no bending on it, whereas in the other direction there can be bending loads (and of course there is the compressive/tensile loading).

this is where youre wro i mean where we disagree

if i understood you correctly the direction your propsing the rod bends in will be restricted through the width of the bearings on both the piston and the crank
the bearings wont allow the rod to tilt away from its intended position by a lot so both ends are essentially fixed in the direction you think the rod would bend
the direction i think the rod is most likely to bend is the one where the bearings by their very function allow the rod to rotate into the bending

essentially what youre thinking of is euler buckling case 4 (beta = 0.5) and im thinking of euler buckling case 2 (beta = 1)
if you look up what beta means youll see that your rod bends in a 4 times less likely direction than mine
I actually destroyed my brain whilst reading those two posts.

The most beautiful engine.
(222 posts, started )
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