The V8 Owners Forum -

Building a GT40 kitcar.

Came with a P6 3.5 with dropped liners.
Found myself an SD1 3.5 engine but that needs a rebore.
With the SD1 engine I now have the frontcover with better oilpump then P6 and better heads.

Can buy refurbished shortblock 4.0 & 4.6 for about £2500.
Or rebore my 3.5 to 0.20 with pistons for about £900

Whats the better engine for a GT40 kitcar that will see 6000rpm.

Offenhauser JWR dual port intake with Holley 390.
Comp Cams speial grind Extreme Energy cam with Rhoads lifters, Duration: 224 IN 230 EX, Cut at 5-degrees advanced ( as recomended by Comp for my 3.5 )

The dual port is very restrictive, it will not all any of the 'larger' RV8 engines to rev very well. AJMHO!

The dual port is what it came with. Its low deck so it fits under the GT40 rear window with a small phenolic spacer under the carb.

So basicaly you're saying 4.0 max. or better rebore the 3.5

My Capri had the Edelbrock Perfomer before it recieved the Offy 360 based Blower intake ( UKblowers) which it still runs.

I think that the 4.0 engines suffered with the drop liners quite badly, more so than the 3.5 engines. You could look at a 3.5 but you need to check main bearing registers because they fret. The later 3.5 (stiff block) engines would be a good one to go for. The SD1 heads are better than the P6 heads so if your SD1 has heads then that's good news!