RB26/3 factory valve timing

[ALF750]

Hi all, new here, first tech post,  be gentle!   Been lurking a bit reading of late, hope someone can help.

My 'problem' car is a 1994 Maserati Ghibli II 2.8 V6 biturbo.   Similar vintage to the R32/33 and similar numbers - 287bhp@6000rpm/305ftlb@3500 with 0.9bar (~13.2psi)  boost.   Limited support and tuning help for them here, as you can imagine, plus I'm in the bush.   4-valve bucket and shim belt driven DOHC, 94 bore x 67 stroke, 24deg valve angle - much oversquare cf. the RB series.   Two IHI RHB5 turbos, GFB electronic boost controller, hi-flow cats, engine internals standard.

My cams per factory have 8.6mm lift, 245Ex, 236In duration (at 0.5mm) set at 12-68-72-12 timing (as best I can find, no VCT).   Last year I reset valve clearances and timing when I installed new performance 'chips' (don't laugh! yes it still has the original un-flashable ECUs - yes two, for double the fun.....).  Thes chips are mapped to be good for 1.1bar/350hp supposedly.  Car runs Ok, slight leanness at low power/boost, boost comes on and it smooths out 4k and up.   Torque has moved up from ~3000-3500 before mod and probably revs better.   I don't have access to a dyno so no figures or data, just after info to make an 'educated guess' before I decide to change anything.

To that end, I was after the standard factory RB valve timing,  if anyone has it, to compare please?    I have a thick skin so pile on!  Some pics below.

TIA

 

[Ben C34]

https://www.tomeiusa.com/_2003web-catalogue/e090_camshaft-specs.html

 

 

 

To be honest I can't see how knowing a different engine, especially an inline VS vee engines cam specs will help, but above link has what you are after. No mention of at what lift, so please guess!

[ALF750]

Yes, all info must be assessed, but engine config. probably less important than valve sizing and bore/stroke ratio I think.   That link looks like it has it all Ben, thanks!   Interesting, lift and duration are very similar to what I have, though the lobe centreline angle looks wider.   I also found Ferrari F40 data - same management system and vintage, not as overdsquare again - and it looks almost the same 244 deg duration and 12-52-54-10 timing.  More to chew one, thanks.

[Ben C34]

I'd be measuring up for an engine swap!, BUT that's taking the easy way out

 

I wonder what info you could get emailing some cam grinders, Kelfords etc

[GTSBoy]

Keep in mind that both 25 and 25Neo have VCT which swings the cams ~20°. On the Neo, the cam profiles were changed from the vanilla 25 to further improve emissions and fuel consumption, as part of the whole ELEV thing that drove the Neo programme in the first place.

[ALF750]

swap an LS....everyone's doing it!  or 2JZ?   Just teasing.

I'll stick with the V6 - probably the best bit of the car - smooth, compact and nicely engineered with Cosworth Coscast designed and manufactured heads.    Best value would be to install a modern single ECU and sensor set/loom, but I've invested/learned so much to get this far - old school monitoring software, changing the .bin with TunerPro and burning my own chips!

Chassis is very E30-like, gearbox is even a Getrag and currently has a 635CSi clutch plate in it.   And XR6 Turbo radiator and fan set,  stiffer King springs, rebuilt turbos and ceramic coating.

Does the VCT change only the inlet cam +/-20, or both?   I'm looking at the RB26DETT solid lifter data - no VCT on these?   Exhaust info looks funny, unless it gets moved 20.   Assuming the '113' and '120' figures are LCA.

[GTSBoy]

51 minutes ago, ALF750 said:

Does the VCT change only the inlet cam +/-20, or both?   I'm looking at the RB26DETT solid lifter data - no VCT on these?   Exhaust info looks funny, unless it gets moved 20.   Assuming the '113' and '120' figures are LCA.

VCT is inlet only on R33 onwards RBs (no RBs prior to that had VCT).

RB26 does not have VCT. There are aftermarket kits (HKS VCAM) to add it.

It's not +/-20°. Only 20° total. It's activated by throttle % and across an RPM band ending at about 4500-4700 depending on which engine.

Those figures are lobe centres, at rest.

[ALF750]

OK thx.   Duration and lift are similar but RB cams are set with almost no overlap (using the stated LCA) whereas the Italian cars use 21-26 deg.   Obviously a different philosophy going on there?   Also, the valve clearances are odd to me - less on exhaust and more on intake (.38E cf. .45mmI) - pretty much the reverse of the Ghibli??  I think my exh valves are also sodium filled. Interesting.