Skyline Revs And Exhaust Problem

[homedog56]

Hey guys just wanting some advice on a couple of things. I have a R33 series 1 fitted with jasma/jasm/jasmo (one of them cant read the last letter on the label) extractors which seem to do the job fairly well and came with the car. Now there are 2 problems, i have read about the rasping sound that Rb25's commonly make but it says that it is usually between 2800-3500 rpm, my exhaust sounds perfect at these revs and has a really nice note until about 4000-5000rpm wen a horrible rasping sound erupts from the exhaust any ideas on how to fix this. I was told another muffler would probably completely fix this but i dont want to lose any power from reduced flow or would a muffler do nothing like that?. My 2nd problem is tonight i was driving along and decided to give it a push around in 2nd gear and as i hit about 6500rpm the revs dropped and then regained but no more than a 500rpm drop as if something was slipping and then recatching i then did the same in 3rd and the exact same thing happened any ideas on what this could be? I have already had the fan belt and air con belt replaced as they were a mess wen i got the car so i doubt it would have something to do with that.

Thx for any help.

[Eug]

JASMA isn't a brand, it stands for Japanese Automotive Sports Muffler Association. It's basically a group which approves exhaust components to a standard.

my raspy sound comes on around 4000, but only under full throttle. mufflers have been found to work, depends on which/brand/etc.

slipping clutch? revs would 'free rev' in that case though.

could also be electronic related, injectors, sparkies, coil packs, etc. trouble shoot it and eliminate it one by one.

[homedog56]

Thx for all the info its all gettin checked out tomorow another quick question. What number should the oil gauge be sitting on.

[H@ME]

i'd say a muffler would help alot in your cases!

[homedog56]

thx guys found out it was my clutch

still have time b4 i buy one so any reccomendations would be appreciated

[GTS4WD]

Without a doubt its a slipping clutch.. especially at those rpm

And about the nasty zorst noise at 6K.. by then your pretty close to redline.. NVCS has well and truely kicked in.. cams are screaming off their chops.. its just a characteristic.. you will hear high comp NA's (like Hondas) screaming HARD and VERY raspy.. its just the sound it makes.. if you want to change the note.. a new muffler will solve your not problem without adding any more restrictions..

Edited December 24, 2007 by GTS4WD

[Asphalt Jet]

Was running a GTR exaust set up and got that raspy sound a lot when I was taching out. Scored a three inch titanium cat back For 40,000 yen and the raspy sound disappeared and was replaced gobs of power and and a very nice note which got really racy as the RPM's increased. As for the over lap you are experience my theory is possible bog from the lack of an LSD. possibly overlap is the wrong term, I experience the loss of power at 4000R's lose about 500R's then it comes back.

Edited January 13, 2008 by Asphalt Jet