Rebuilt 4.0 vs 4.0 S engine

[olliete]

Hi all,

I'm not too familiar with the difference between the 4.0 and 4.0S engine on the Tuscan.

My Tamora has a 4.0Ltr Tuscan engine but it had a full rebuild by TVR Power a few years back - does anyone know how different this would be to a standard 4.0S engine? It feels plenty quick so I'm just wondering really...

Thanks,

Ollie.

[dvs_dave]

S spec engine has bigger injectors, different valve timing (same cams, just timed to have more overlap), larger bore exhaust system and a different ECU tune.

Unless those changes were done by Power during the rebuild then you have a standard 4.0L, albeit now a properly built and durable one!

[borat52]

From reading around it seems that a lot of sources place the biggest difference on a thinner head gasket raising the compression. Bigger injectors would do nothing unless the stock ones are already maxed out (which they will be if you increased displacement like powers 4.3). Not hugely convinced on the cam changes either as that would make the engine behave significantly different at lower RPM if it resulted in a significant improvement at higher RPM.

[olliete]

Yes, I ran a Lotus with racing cams and that was nearly undriveable under 3500rpm, it would jerk and stutter constantly!

I need to get mine on a dyno; it has a red cam cover too so it looks like an S!

[dvs_dave]

borat52 said:

From reading around it seems that a lot of sources place the biggest difference on a thinner head gasket raising the compression. Bigger injectors would do nothing unless the stock ones are already maxed out (which they will be if you increased displacement like powers 4.3). Not hugely convinced on the cam changes either as that would make the engine behave significantly different at lower RPM if it resulted in a significant improvement at higher RPM.

The same cams, just timed for more overlap is one of the well known differences. TVR didn't have the cash to spend on two different cam profiles.

Regards the injectors, the standard ones are renowned for tapping out at higher rpm. AFR reading goes very lean at high rpm when on a dyno with AFR probe.

[Tonymg]

Ok for what it worth my two pence worth your TVR been done by Tvrpower so its sorted and time to Enjoy.... like I did just take your time and drive safe...


Tony...

I got two tuscans that have had rebuilds by Str8six and they sorted as well...

[olliete]

Wise words mate!

Cheers