Nissan 200SX Club - South Africa

if a car doesn't have a dumpvalve on we will get pedgeoning right or wrong???
if that's the case. why don't volvo or golfs even a stock 200sx have that sound? is it because there isn't enough boost by factory spec?
or am I missing something here completely?

When Phinx ripped out his stock airbox and put in a cone you could hear it, the stock airbox and plumbing has alot of sound deadening, then he changed all his intake pipes to steel it was even louder.

On my car when I put the cone on I started hearing my recirc valve, one big woosh when changing gears, subtle yet potent

the vw's and audi's have recirculating bov's. when pressure builds up in the manifold, and the bov lets go, all of that air gets redirected back into the intake.

the loud bov's that you hear quite clearly are usually atmospheric bov's, meaning that they "dump" compressed air straight out of the induction piping into the engine bay, making a loud sound.

the stock airboxes and piping and things usually disguise this sound well, but mods like airfilters can make these sounds more prominent!!!

[quote="veecee"]the vw's and audi's have recirculating bov's. quote]

ai. i keep inbarasing myself. 4got about that

ye, they've always had those ugly plastic ones if I remember correctly.

correct - saw one lying on the ground at a junkyard the other day.

picked it up, and it didnt look very good.

no wonder the guys upgrade to ali ones!

now that your question has an answer you wont mind me hijacking this thread

this also falls under the silly question category
does a N/A car have more power/torque than a turbo car before it boosts? or does it just feel that way coz youre waiting for boost? or is it just a gear ratio question? i havent had much experience in other types of turbo cars

now the running and screaming can start

widowmaker wrote:now that your question has an answer you wont mind me hijacking this thread

this also falls under the silly question category
does a N/A car have more power/torque than a turbo car before it boosts? or does it just feel that way coz youre waiting for boost? or is it just a gear ratio question? i havent had much experience in other types of turbo cars

now the running and screaming can start

I'll take a stab at using my theory and say yes, you have less power under boost than a 1300 N/a has at same RPM. I think its the compression ratio, the lower you go the less power you have under boost; the reverse is also true you can increase your compression and if the dumbass SNS article is anything to go by you get 5% for every .5 compression step up. But 5% doesn't sound right, you wouldn't loose "5%" by dropping compression .5, there must be some science based formula that is more exact.

I know the initial craze with turbos in the 80's (when even f1 V6 3.0's where turbo'd) and maybe even earlier in some places said that the lower your engine compression is the more you can boost.

Personally it seems like you can add as much boost + compression as your internals can take, but short of welding on bits of metal to your pistons or grinding grooves in them to drop compression, only the latter I have personally heard of, you can't change it as easily as using a boost controller. I think I have seen a formula that calculates your "true" compression under boost. I'm sure google will know but isn't this more fun?

I will be posing my idea of raising my compression somewhat with thecalibrator when I have saved up enough for a SR20DET overhaul. That way I should have more power overall and won't have to boost my turbo so high. I know it also may make it sound like a V8, which could be problematic. I would want to boost about .6667 and have the safest compression ratio to match, in the 9's somewhere, 9.5???

I also want to say it seems like you can increase you under-boost performance by doing the same KIND of thing a N/A guy would do and this would actually help in boost as well as before it: lighter rotating parts & balanced internals. I'm not sure what is reliable though/cheap though. Boost is cheap if you don't break something

dont forget about turbo size, and the relative amount of air it can push under certain boost pressures!???!

i'll let you ponder that for a bit!

mmm good points

i suppose the length of piping, heat and intercooler also comes into play

@ Charl
The reason you don't here that wastegate on our cars, is because at the back of the stock air box, is another little box called a resonator, which just absorbs this sound.
If you fit a con filter, you will hear your turbo making all kinds of noises. If you want to stick with the current air box, you can fit a pad filter & pull out the resonator, & will get almost the same effect.

Before I forget, thanks again for taking time out to sort me out with those gaskets. I really appreciate it. Sorry for making you come out all that way.

Only a pleasure Nuren if its for a fellow sx owner.

Since were on Daniel's rings topic, what does gapping them mean?

Charl wrote:Since were on Daniel's rings topic, what does gapping them mean?

Same here. would like to put them in properly

Daniel wrote:

Charl wrote:Since were on Daniel's rings topic, what does gapping them mean?

Same here. would like to put them in properly

you know your ring is not a solid round item right and there is this slit that you use to expand the ring to take it over the piston... well the "gapping" is the size of that gap in the slit when it is in the bore... Hope that made sence

to test it use a feeler guage, you push the ring down the bore ±1cm (i think that is how far Duane pushed it down) make sure it's the same depth all way round, then using the feeler gauge measure that gap...

Then if they are too big, you need to source smaller rings, small you use a tool to "grind" it down to size a little.