Jump to content
SAU Community

Recommended Posts

It was retarded not advanced . The idea being the exhaust valves open and close 2 degrees earlier so the cylinders blow down fractionally earlier in their cycles and the overlap timing is a little shorter .  So instead of the valve timing being 8-68 63-13 it would be 8-68 65-11 and the overlap duration 19 rather than 21 degrees . 

I imagine they set the cam where they wanted it with the crank at TDC , then moved the crank with the modified pulley so the cam would be in the normal position but with the crank 2 degrees after TDC . Tighten the four bolts and cam timings finished .

A .

4 hours ago, Dose Postman STFUU said:

brap brap brap bro :)

 

Edited by discopotato03

Presuming you've had something done with the head?  Pretty economical with the detail Adrian.:10_wink:

Do a bench test and see for yourself what happens to injector spray patterns with bigger base pressure.

Takes the guesswork out of whether you need to listen to what "people" say.

Probably going to be hard to beat a Walbro 460 if you need a new pump.  Contact Mafia for some comments/experience on what works well and how to control the pump to best effect on a road car with Link/Vipec ecu tricks.

I think the buckets were fine , just a few RS exhaust valve guides . If they don't line up with the seat they don't seal too well . Was ported first time round and had Ferrea (sp) over sized exhaust valves fitted . Head was O ringed to make the OE gasket reliable with extra heat and pressure . Std springs shimmed for a few extra pounds .

A .

  • 2 weeks later...

ok so cams are in, fitted to standard positions, no adj. gears...due to other work also being done to car over last few weekends, haven't done heaps of driving as yet or fully retuned, but impressions so far - idle is a little bit rougher but nothing overly noticeable. If you're giving it low throttle, standard cams win as there's a slight loss in pickup. If you're giving it medium or more throttle, the 256's are noticeably better although haven't even given it full throttle yet.  Looking forward to retuning and seeing the end result.

^^ Andy the truth is for most cases there's far more gain in having optimised inlet, exhaust, and cooler piping than there is cams.  Comments from Stao in his Hypergear thread bears this out.

But changing to these baby upgrade cams sure isn't going to hurt.  Going to be interested to see your results.

The best explanation I have is that aftermarket cams in a street car get you the last 50 Hp , not the first (over standard) . I think there are many better mods to make initially than cams in either flavour RB25DET . Better easier bang for buck .

I just happened to go that way since I opted for a second head to modify , saved downtime , and had it all done together . I also opted to have that head decked to get the highest practical compression ratio without making it unreliable , supposed to be around 9.2 - 9.3 to 1 . Not really a relevant comparison but I was told at the time that the GMS GTRs ran about 9.6 to one esp after CAMS forced them to reduce boost to make it "fairer" for the iron ox taxis .

I now think that lack of exhaust valve sealing and fuel pressure issues were ganging up on me , first issue fixed and a new pump shortly (no time atm) .

A .

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • It is a kunfine Android screen . Does anyone know the wirering diagram of the fuga ??
    • just an update to this, poor man pays twice  Tried sanding down the pulleys but it didnt do the trick. Chucked another second hand alternator in the na car which I got for free off my mate and its fixed the squelling. Must have been unlucky with the bearings.    As for my turbo car, I managed to pick up a cwc rb alternator conversion bracket + LS alternator for 250 off marketplace, looked to be in really good nick. Installed it , started the car and its not charging the battery.... ( Im not good with auto elec stuff so im not sure if this was all I needed to do but I verified such by using a multimeter on the battery when the engine was running and I was only getting 12.2v )   I had to modify the earth strap for the new LS alternator , factory earth strap was a 10mm bolt which did not fit the bolt on the LS alternator which was double the size so I cut it off , went to repco bought some ring terminals that fit, crimped it onto the old earth strap and bolted it up to the alternator , started the car and same issue. Ran like shit and was reading 12.2 at the battery.  For a "plug and play" advertised kit thats not very plug and play but alas.  My question is , am I missing something ? Ive been reading that some people recommend upgrading the stock 80 amp alternator fuse to a 140 amp but I dont see how that would stop the alternator charging especially at idle not under load.  Regardless ive pulled it out and am going to get it bench tested by an auto elec tomorrow but it would be handy to know if ive missed something silly or have done something wrong.   
    • My wild guess is that you have popped off an intake pipe....check all of the hoses between the turbo and the throttle for splits or loose clamps.
    • Awesome, thanks for sharing!
    • To provide more specific help, more information is needed. What Android screen? What is its wiring diagram? Does the car's wiring have power at any required BAT and ACC wires, and is the loom's earth good?
×
×
  • Create New...