Rev higher

I did. But I don't read good.

Depends.

>lightened rotating assembly
>reworked valvetrain
>more aggressive camshafts that make power high in the rev range
>new ECU and tune to give enough fuel for new power and reset rev limiter

If you just raise the rev limiter you won't do anything except run the risk of breaking things most likely.

thank

Really depends on the car , I bumped my rev limiter from 7500 to 8200 with a billet oil pump and fuel system, the valve train was strong enough to handle it. It's a boosted 370z and the engine really only needed better oil delivery.

So the only limit is every possible thing that could be a limit.

Thanks for the help, stupid.

>forgetting retainers
It's like you want the valve springs to shoot out the hood

first of all
HEAD GASKETS ARE TRAITOROUS SUNS OF BITCHES

keep an eye on cooling and lubrication
stock water pumps and radiators are not very good
you'll want a pump that avoids impeller cavitation while also having sufficient flow

and if your really nuts get something like evans waterless coolant (reduces boiling and pitting of water jacket)
on the high end of this is things like swirl pots and catch cans
for pretty much every kind of fluid just to get bubbles out

so much as half of an engines cooling can be done by oil you need flow there too and possibly an oil cooler
also as rpm go up you may get into oil starvation in the valve train
and worse some problems with the crank shaft bearings

part of avoiding oil starvation is having the oil at the right temperature
the temperature of the oil changes its thickness and how much distance it will cover from the pressure applied to it (same goes for water)
to this end some cars have oil to water heat exchanger for quick warm up

or in the case of air they have a port that goes from the exhaust manifold heat shield to the air intake (hot air intake)
but that's more to do with winter starting same with radiator muffs

If the engine were to operate primarily under 5,000 rpm,favouring a longer stroke helps get piston speed up.
However, beyond 6,500 rpm, a large-bore engine simply breathes better compared to an equivalent-displacement but longer-stroke engine.
there is a bunch of stuff about air intake .eg volume vs flow

>more aggressive camshafts that make power high in the rev range
at lest with old engines that don't have vtec or what ever
a lumpy cam sort of moves the torque curve further up
and at higher rpm crank geometry becomes more important

Great info, but fuck what's punctuation for 400 Alex

apologies
I never learnt to touch type punctuation
one line return for apostrophes two for full stops

also that post was pushing close to 2000 characters as it is

So, one think that I have not yet seen touched upon is piston speed.

During a stroke (one recriprication of the piston) the piston goes from a stopped point (Top dead center) accelerates to some velocity, and then must be slowed down to a stopped state once more (bottom dead center) So, there is a practical limit to how fast that piston can reach, as there is a mechanical limit on the tensile strength of the engine's rod (ie, if the piston speed is too great, the rotating assy will just tear itself to pieces)

So lets say you have two engines, a 2.3 liter 4cyl with a bore of (x) and a stroke of (y) and another 4cyl with the same bore (x) but a stroke of 0.783(x). At 7 grand, the first engine has a max piston speed of (z) but the second engine will have that same piston speed at 7000/0.783 = 8940rpm(!)

My point is, you need to look at the bore and stroke ratio of your engine and it's geometry to determine how well the rotating assy can handle higher engine speeds.

Then there's the matter of how your heads are designed, how your camshaft is cut to handle flow at high rpm, if you can upgrade your internals to lighter ones to reduce rotating inertia, valve springs to keep lifters in contact with the cams at high rpm, and cooling the engine/keeping it oiled at higher RPM/outputs. All of which could be dissertations of their very own, but I'm lazy

TL:DR Depending on your engine's basic geometry and how robust it is, you might not need to do anything, or you might need to do everything.

Just buy a fucking Honda. No need to mess with anything

Oh yeah, I forgot. Everything connected to your engine needs to be able to speed faster too. So:

Alternator
AC Compressor
Transmission
Water Pump (cavitation can be a HUGE issue when you start to over-speed your water pump)
Oil Pump
etc.
Now, underdrive pulleys can solve some of these issues, but you need to strike a balance between running the accessory too slow at low RPM and keeping it from grenading at high rpm.

There's a great deal that you have to consider when trying to increase an engine's max speed by any significant margin. Not saying it's not possible or even reasonable, just that you need to consider a lot of stuff before diving in.

also rpm may be of little help to you
want you want is more CFM for hp or more static pressure for more torque

some ideal rounded numbers
1/10 at 6000 rpm draws in one atmosphere to make 100 hp per liter
every 14.5 lbft is one Atmosphere
8.7 lbft adds 50% power
17.4 lbft adds 100% power
1 lb/min for every 10 hp

divide cfm by 14.27 to get lb/min
twerk multiplied by rpm then divided by 5252

as with diminishing returns you may only get a few extra horse power
at the cost of smoothness of operation and to have power that is not useable within the range of your gear ratios

Smaller diameter pulleys/pinions for the water pump, alternator and valves.

Piston speed is important is terms of duration of the piston rings and combustion velocity, but the hard limit to revs is more piston acceleration which is the square of the rotation velocity.

lmao just press the gas pedal nigga

cam shaft rotates at 1/4 speed of the crank shaft
at lest that's how it is on muh shit box
>chain driven camshaft also drives the oil pump and runs the distributor

Rip off the bonnet and replace the inlet manifold with a tunnel ram

should last at least a couple pulls with just extra fuel and a raised rev limiter

the camshaft operates at half speed on a 4-stroke engine

Have a look at their builds for some ideas:

boba-motoring.de/

>piston, rod and crank lighter than stock yet forged to increase strength
>knife edged crank leading surfaces to slice through the sump of oil
>titanium beehive valve springs and retainers
>lighter valves
>more injection capacity to support the increased intake of air
>velocity stacks and individual throttle bodies to minimize the resistance to air intake
>high capacity coils and cooler spark plugs
>ecu tuning, most likely a standalone ecu to let the engine rev higher and supplant fueling etc
>underdrive pulleys so your accessories dont explode. will compromise DD though

or maybe your engine can handle a little above the stock limiter

tuning will unlock the extra revs. a standalone

>to slice through the sump of oil

Should not be happening even with a stock engine.

yeah, at most there is some oil splashing going on but that would only justify using a dry sump instead (and it is only really needed if it's meant for high cornering forces).

Correct, but I didn't want to get into crank offset or eccentricity of loading or anything like that, so I kept it (kinda simple) but you're correct, it's really the max acceleration (maybe even max jerk? I need to do more research) that's really the determining factor for the rotating assy.

The absolute cheapest way to get a high revving engine is to buy a motorcycle.

Don't kid yourself. It's what you can actually afford.

All the shit in this thread is expensive and if you do it right you will be taking the entire fucking engine to a machine shop.

yeah, if you need to do more than camshaft + springs + pulleys/pinions + reprograming you're probably better off buying an engine made for high revs. It's rare that a car can rev high with just a raised rev limiter, but some have literal motorcycle engines:

youtube.com/watch?v=x4yLqyiM0hQ

You need to do more than that to actually rev higher for the vast majority of engines anyways.

IIRC there was a ford engine that had a safe redline of over 8k when tuned, but came detuned and limited from the factory because it would overdrive the accessories they wanted to use if ever revved that high.