heads
 

hey all,

how do the heads work on the flat 4. the car i have is a '95 wrx uk spec.

does it have rockers or just lifters?
are the lifters hydraulic?
are the cams 4 lobe?

if a remap moved the rev limiter up, how far is it safe to go on the scooby engine?
would it suffer from valve bounce if the springs were not uprated?

is the head an interfearance design?

and lastly, is there an easy way to chage the spark plugs. they look really hard to get at.

thanks

L.

bump,


anyone?

L.

not 100% on the valve actuating mechanism on that model year but i think it may be shim on top of buckets. someone will confirm.

a remap wont increase the revs. unless your engine is in a very high state of tune and running higher lift cams you wont have any of them kind of problems. a standard engine will be running well out of puff before the rev limiter anyway so there is no point reving it that hard as you wont be going any faster.

by interference i presume yoiu mean with a machined portion that locates in the bores as on a few bike engines. no its not, its a flat fire face against a flat block face, obviously with a gasket in between.

the left side plugs are easy, on the right side remove the washer bottle and battery and you can get in.

thanks for the reply!

by interfearance i meant, do the valves hit the pistons if the belt timing is out?

on the remap idea. i have had custom mapped systems on a few cars now and in each case i raised the rev limiter up a bit if it was safe on that engine.

i'm intending on changing the cams for higher lift ones and adding ARP bolts to the bottom end and wondered if i would be able to get a few more revs out of it with the better cams and a better turbo, while not having to do many more mods.

maybe i should have asked:
how many more revs than standard, can the stock engine take without problems?


cheers

L.

yes, the engine is interference.

thing is the standard cams and valve train are good for over 400 bhp, which you will get with the right turbo and suporting mods. At that point you are a lot safer with diferent pistons and rods anyway so you are looking at a built bottom end. so 'not having to do many more mods' is not really applicable.

its not really on the list of first things to do, particularly cos its not cheap. there are sti's on here running close to 500 bhp with standard cams.

why raise the rev limit if you dont need too. if your mod package means that you are still producing good power at your existing limit then depending on your managment system i would think your mapper can sort the job.

ive no idea whats considered safe for revs. its gonna depend on other things like what boost you are running etc.