the flyin' scotsman

The intake manifold on the '90 GT is stamped with 928 110 546 4R.

Is this the correct part # for this model and year? PET cant confirm.

Rob Edwards

My 90GT, 91GT and '93 GTS intakes are all .4R castings.

the flyin' scotsman

Thx Rob...............would you know the differences with S4s for example?

Rob Edwards

Good discussion here:

https://rennlist.com/forums/928-foru...s4-intake.html

Cliff note: Factory had to port-match by hand some '89 GT intakes to make claimed HP, then modified the casting so all 90+ cars should have mildly larger diameter intake runners. I have seen a '2R' intake at Greg's shop that I'm pretty sure came from an '88. Not sure if a '3R' exists, or whether the '4R' denotes the modified casting mentioned in the above link.

Perhaps Erkka can set me/us straight.

the flyin' scotsman

Good discussion for the first page then it kinda went of the rails

thx for the cliff notes..............thats an enormous commit by Porsche of $50k for one casting.

Here's a pic of the GT casting numbers:

Hilton

For reference, my '89 S4 engine's intake is 928 110 546 2R (engine no. 81 K 00352).

Vilhuer

...4R is large casting.