How to make engine rev happy ?

[TSF]

A friend of mine suggested to change to shorter conrod. it will make the engine shorter stroke and lower compression .. making it possible to turbocharged later on ..

currently my car is a 1.6 high compression (modded).. i wanted to have a more rev happy engine ..and maybe turbo upgrade in the future.

 

[HDi fun]

You'll also have to finely balance all the internal components to minimise vibration. Stiffer valve springs to resist bounce will also help.

 

[TSF]

so his idea might work ? will it add the rev range or just lighter ?

ok .. will add engine balancing in the list as well ..

 

[HDi fun]

Lowering compression isn't really going to contribute all that much to revability. Free flowing intake and exhaust will help but balancing is crucial.

 

[MasterAuron]

What do you mean by rev happy? Balacing won't in practice make it rev any more freely, but will allow the engine to rev higher mroe safely due to less vibration.

Lightening will though. For something easy to do without ripping the engine apart, have the flywheel lightened and balanced. How much you have taken off will depend on it's strength and how much smoothness you want to compromise. Very cheap too if you remove and refit yourself.

 

[HDi fun]

The lightened flywheel won't make it rev to higher RPMs ,it'll just have less inertia and get there quicker. Smoothness is also key to a high revving engine. Vibration can destroy an engine very quickly.

 

[MasterAuron]

I said lightening will make it more free-revving. Erm...thanks for backing me up though :love:

 

[HDi fun]

Sorry - I got tangled up there.

Getting rid of excess weight is good - just do it evenly and keep things balanced as you go along.

Cheers,

P.

 

[pgarner]

think we need more info on what hes wanting
a free revving engine that will rev from 800 - 7000 easy
or rev up to 9000

 

[TSF]

Lowering compression isn't really going to contribute all that much to revability. Free flowing intake and exhaust will help but balancing is crucial.

ahaha . sorry about the confusion everybody ...my goal is :

1. Faster response
2. Higher Rev
3. Lower compression so i can fit a turbocharger later on

engine balancing will be my priority ..

What do you mean by rev happy? Balacing won't in practice make it rev any more freely, but will allow the engine to rev higher mroe safely due to less vibration.

rev more ...

think we need more info on what hes wanting
a free revving engine that will rev from 800 - 7000 easy
or rev up to 9000

the 2nd one ..... ahaha .. current redline is at 7000. peak torque at 6300. is it possible to increase the maximum rpm ranges ?

before this, i was thinking to dump my gsxr1100 (14K max rpm) engine into the car but cost and upon some research, the bike torque is not enough to provide quick accelaration ..

after that a friend of mine keep telling me to convert the current engine into a turbocharged high revving engine instead ..

 

[pgarner]

from what your coming up with it sounds like you need to
free up the intake / exhaust - to make it more free to rev
lighten - to make the engine rev more free
balance - to allow it to rev higher.
and lower the compression to allow the foced induction. this wont as such make it rev higher but more torque lower down which will get it to rev free

 

[MasterAuron]

There you go! Summed up nicely pgarner :bigsmile:

 

[TSF]

thanks pgarner ! ...

on the lowering the compression , i have another block from the same model but different version. it has the same specs except it has longer stroke .. would that suffice or i still need to install low compression pistons ? and i might have those in my store as well.

 

[pgarner]

MA;s the man for this. i would have thought the conrod would only have increased the CC not really had much to do with compression.

 

[MasterAuron]

See here for what you need to know about lowering the compression:

http://www.torquecars.com/forums/f8/best-ways-lower-engine-compression-ratio-7953/

Try a search first mate, just saves people having to type the same things out over and over again.

 

[TSF]

i know how to lower compression ratio .. just im concern i will lower it too low or still need other thing to lower it down more ..

i have a similar block with longer stroke . fitting it will reduce the the compression already . i also have brand new low comp semi forged pistons from my previous turbocharged engine (same exact bore size and made). my question is, is just fitting the block will be good enough or i still need lower it more .

current compression is 10.5:1 .. turbocharged engine usually have around 8-9:1 right ?

 

[MasterAuron]

That's correct. Just fitting the block will be good enough imo. To be sure you need to calculate your comp ratio.

 

[Munday]

Ok as said inducting and exhaust modification, lightning the flywheel etc will help it rev up quicker

You might want to fit some cams with higher lift and duration to give you more power and shift the power band higher in the rev range, its pointless revving higher on stock cams IMO because you wont be making any extra power.

The benefit of having shorter rods reduces the distance the piston has to travel in one rotation of the engine, reducing the speed of the pistons. This means you can run a higher rev limit.

Dont bother reducing compression ration until you fit the turbo though

 

[obi_waynne]

Good points Munday. Just lowering the compression ratio will sacrifice performance so it makes sense to do this at the same time you put the turbo on it.

 

[Sid447]

A friend of mine suggested to change to shorter conrod. it will make the engine shorter stroke and lower compression .. making it possible to turbocharged later on ..

Yes it does lower static CR. But it would completely mess up Dynamic CR.
It's better to fit lower CR pistons for forced induction.
Changing the crankshaft to one with shorter throws is what changes an engines stroke.

Using shorter rods won't do anything to effective stroke.
If a rod is shortened then the piston deck height needs to be altered by the same amount to correct for TDC position in the block. It's difficult to get good combustion efficiency having the piston @ TDC 10 or 20mm down the cylinder.

Making an engine rev-happy has more to do with cylinder head (and intake) breathing ability and what camshaft is used.
(The camshaft does more to give an engine it's "personality" than any other engine part).

Both Honda and BMW use over-square engines (numerically longer stroke than bore size) that are not only rev-happy but have validated rpm limits at over 7,000rpm

 

[TSF]

i see .. maybe just changing the block, low comp pistons will do .. maybe some port&polish , bigger throttle body and better air filter with heat shield will do the job ..

 

[Sid447]

Be careful about fitting,

bigger throttle bodies. Many of them make the car more difficult to drive at low and middle rpm. Most of the time they will lose you hp lower down and only give you a few hp above 6,000rpm. Bigger T's can also can upset the airflow into the engine and cause the engine check light to come on.

Not worth it IMO. Unless it is a proven and well-known restriction in the intake.

It would be much easier to find a better camshaft from the same range of engines and fit that along with a new set of valve-springs.
e.g. maybe a more powerful version of the same type of 1.6 engine uses a camshaft that has higher lift. This would be what to look for.