2.8 REBUILD UPGRADES

granca69

New Member
Messages
10
Hi guys And Girls,
So my timing belt broke on my 2.8 24v ghibli non abs engine, currently sourcing parts to rebuild it. been plenty of discussion online but havent found anything definitive, whilst im rebuilding this motor looking for any upgrades that other people have performed. currently looking to upgrade the pistons and rods to forged units, has anyone had these supplied or will i be forced to get them custom made. has anyone upgraded capacity in one of these. anyone know of some upgrades while the heads are off and ive got a few valves to replace. any help or advice welcome. Thanks Rob
 
Messages
388
What's the mileage? If it hasn't already been done recently I'd get the timing chains and sprockets replaced while you're there and the engine is out. Think of it as 'future-proofing'.

Any ideas why the belt broke?
 

alpa

Member
Messages
169
Great, someone trying to do more than just a rebuild :) .
Please read the discussion referenced earlier.
Ghibli stock pistons are forged. Crank and conrods too.

The first question is: what do you want ? More power, just improve, repair ?
If you want more power/torque then how much more ? What usage: street, racing, mixed ? What about the management (ECU mapping) ?

I'd suggest to check clearance of all valve guides, it's usually too large.
Check valve springs, they are of poor quality so they get weaker.

Valves: your non ABS ghibli must have one groove valves. Later Maserati switched to 3 groove valves. Try to find used 1 groove valves, I don't think you'll find them new.

Here is my list of mechanical aspects to improve in a 2.8 24v, off the top of my head:
  • conrods too short, piston pin too large (22-23 is enough)
  • pistons too tall (because conrods too short) and heavy, old style thick rings
  • standard new big end bearings have too much clearance
  • CR too low, should be at least 8:1
  • you may have a bi-mass flywheel, replace it with a simple one
  • because of the Getrag pulled clutch: possibly the miserable modern thrust bearings
  • for more power: small valves and tight intake ports
To me the cheapest decent rebuild would be:
  • use 2.0/2.5 18v conrods: they have 22mm piston pins, same length
  • custom made pistons: avoid CPS in Italy
  • custom made big end bearings to get proper clearances, but you should first check dimensions of your conrods and the crank
  • custom made or original (not available today) wider thrust bearings. Or reuse the push side old ones (if they are the original ones) on the pull side.
  • aftermarket stiffer valve springs, should be at least 30kg closed and 70kg open. Catcams or any other brand.
  • custom made valve guides to have proper 0.02mm intake and 0.03mm exhaust clearances, shorter intake guides. So called "Bronze", actually a copper-nickel alloy (CuNixSi)
Budget for the above: 3000 euros
All the rest standard (in the engine).

I think I've already mentioned elsewhere the companies I use for custom made parts, we can discuss. I'd be happy to discover new companies.
 
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Motorsport3

Member
Messages
869