Engine modding

[Steviec]

What should I do?
Ive been told that my car has a road/race cam, but I have no proof of this other than it runs a bit rough. I also have no knowledge of what cam it is and therefor stuffs me up on chipping it ect.
Should I just get a normal cam put back in and then chip it so that I know what my car is running and is running right or should I leave it as it is and hope for the best?

[Steviec]

Having thought about it, when I have the spare time, Im going to take it back to normal and re do it from there.

[M5pilot]

You may have a very good cam in there. Remove the cam cover and see what you can find in terms of markings. Cams work very well on 325i's especially once youve had a remap done.

If its a Schrick 284/272 you should be laughing as its on the wish list of many.

Find out before you go back to the standard cam.

[Steviec]

I havnt got a clue what im looking for as im really just getting to know engines.
But with the trusy haynes manual, I will set to work when we have some decent weather!

[oze30]

if it does have a cam, would it make it idle a bit lumpy?

[MikeF]

Hi if your interested I worked out the lobes on my cam using a vernier and the duration chart, (I have a schrick book,) I think a 284 cam gives around 10 - 11mm extra lift on the valves than a standard cam, also if it a 284/272 the lobes should measure different in lift between the inlet and exhaust the 284 being the inlet, let me know have a look and see how big the lobe is in diameter on the inlet side.

[Demlotcrew]

The 284 gives 10-11mm extra lift???

Andrew

[Andy335Touring]

That's total valve lift not additional lift surely ?

[Dan318-is]

thats total lift

ifts thats additional il eat my hat

[chief]

i heard stories about cams like this before but not sure what they actually do.
from reading this interesting thread it seems a sporty cam lets the valves open further. is the 11mm extra each valve or total of all 12.
sorry for this question but i am learning all the time
thanks and sorry to but in

[Demlotcrew]

Its for the Inlet, and the numbers is the degrees of the lobes, further appart more overlap and more power at top end! (with very very poor town MPG)

Andrew

[Andy335Touring]

Cam's are a fairly big subject to cover here, but the gist of it is that it's a balancing act between duration, valve lift and over lap. These factors are developed by the manufacturer and a lot will depend on what sort of power delivery they want to achieve for a certain type of engine.

A stock cam has a duration(ammount of time the valves are held open measured by degrees of rotation) of about 250-255, sporty cams have a higher duration and tend to give the engine more top end power, really high duration cams circa 290+ will give more high end power but will sacrfice some of the low down power.

For the M20 Schrick do four differant profile cam's that go from mild to wild.

272/272(mild cam)
284/272(good all round cam)
288/288(a bit to peaky for road use ?)
304/304(track use)

[Andy335Touring]

sorry, i was a long time writing that

[Demlotcrew]

LOL NP.



Same thing really.

Andrew

[Dan318-is]

304!! that shit must be off the hook!

[Demlotcrew]

Mapped correctly the 304 can work in a road car!

Andrew

[Andy335Touring]

I think you would need TB's and a stand alone ECU to get a 304 streetable and ticking over ?

I can't imagine it would make a good every day car, more a Sunday blast/week end car ?

[Demlotcrew]

I think you would need TB's and a stand alone ECU to get a 304 streetable and ticking over ?

Without a doubt!

Andrew

[chief]

fantastic
thanks a lot to andy335touring & demoltcrew
now i am beginning to understand a broader picture about engine tuning. thanks a lot.
when you fit a track use cam ie the awesome sounding 304. is this a big job. ( i mean is it as simple as taking off the rocker cover and replacing old with new or ???)
am i correct in assuming this would give a powerband at for example 4500rpm like on a motorbike.
thanks a lot fellas

[Andy335Touring]

Which engine Chief ?

[chief]

i'm an m20 325se
stripped it out and stiffened done the brakes
engine next and i reckon i can keep with those evos

[Andy335Touring]

Whats it's main use ? Road or track day car ?

BTW it is a fairly big job to change the cam as the cylinder head needs to come off to do it.

[chief]

its an everyday car but i am more interested in track performance than road, for example the ride is quite stiff and as i live on an unadopted road it takes your teeth out, but i don't care. when you get to the track it all makes sense, and hats what counts for me

[Andy335Touring]

I'd say stick a 288/288 in it, your not going to get the full benefit of the 304 if the rest of the engine is fairly standard ?

[Andy335Touring]

To add....

A cam like that is going to need a remap or a suitable chip to get it to work well.

There are other way's to get your power fix but that depends on your plans for the car and budget.

[chief]

thanks for that andy

[Steviec]

Its for the Inlet, and the numbers is the degrees of the lobes, further appart more overlap and more power at top end! (with very very poor town MPG)

Andrew

That would explain my petrol bill then!

[chief]

That would explain my petrol bill then!

what mpg is that then steviec

[Steviec]

That would explain my petrol bill then!

what mpg is that then steviec

Im not sure, I just know that im spending alot more on petrol since getting the E30. I think I get about 250miles to Ԛ£40 at 92.9p per litre, but ill see how far I can go on my current tank of fuel.

[chief]

i think thats no too bad m8.
reckon i do the same , my problem is not my engine mod its my right foot- its got lead in it , if you know what i mean