VVC Manifold

Wacky Racer · Post by **Wacky Racer** » Tue Jul 31, 2007 7:33 pm

Is there any performance benifit in fitting a VVC alloy inlet manifold and injectors to a standard S2 rover engine?

robin · Post by **robin** » Tue Jul 31, 2007 8:11 pm

Not really; you may gain 1% at the top end but will probably lose the same 1% over the low-to-mid range.

Cheers,
Robin

Rich H · Post by **Rich H** » Wed Aug 01, 2007 8:09 am

I would say the gains are masked by the losses. Mid range just disappears. In hindsight I wish I hadn't fitted one, I had to fit a 4-2-1 to regain torque at sensible revs but I port matched it to the head so I couldn't go back.

Daveb · Post by **Daveb** » Wed Aug 01, 2007 9:22 am

I put one on the Caterham and it was night and day.

It did loose a little mid range but up the top was very impressive.

Brunty · Post by **Brunty** » Wed Aug 01, 2007 3:45 pm

Has anyone got RR graphs to show before/after?

I'd suspect that a lot of the loss/gain may be psychological.

Post by **Shug** » Wed Aug 01, 2007 3:49 pm

Brunty wrote:Has anyone got RR graphs to show before/after?

I'd suspect that a lot of the loss/gain may be psychological.

Depends on the state of the head, I'd say. On a standard engine it'll do feck all, but I'll bet it helps a ported head gain a few hp further up the rev range.

Post by **Shug** » Wed Aug 01, 2007 3:51 pm

RICHARDHUMBLE wrote:I would say the gains are masked by the losses. Mid range just disappears. In hindsight I wish I hadn't fitted one, I had to fit a 4-2-1 to regain torque at sensible revs but I port matched it to the head so I couldn't go back.

Yeah, you omit to mention it was fitted with 270 cams and a head port at the same time dude - I'll bet that killed more torque than the VVC plenum

robin · Post by **robin** » Wed Aug 01, 2007 4:17 pm

I'm not sure how else you would account for the 135's early dip in torque (it uses the same cams).

The type of porting they do the head itself is unlikely to be harmful to torque. Sure, there is more that can be done, even while keeping the standard valves, but there is nothing "bad" in there, when compared to say the head that got fitted to Campbell's car or the RLC.

If properly port matched, I suspect that the torque loss due to lower air speed in the manifold will be negligible.

But, there are plenty of engines out there making 160 on plastic plenums so I am not sure what the calling for the (heavier) alloy inlet plenum really is, other than to make the engines look different!

Cheers,
Robin

Rich H · Post by **Rich H** » Wed Aug 01, 2007 5:41 pm

Shug wrote:
RICHARDHUMBLE wrote:I would say the gains are masked by the losses. Mid range just disappears. In hindsight I wish I hadn't fitted one, I had to fit a 4-2-1 to regain torque at sensible revs but I port matched it to the head so I couldn't go back.
Yeah, you omit to mention it was fitted with 270 cams and a head port at the same time dude - I'll bet that killed more torque than the VVC plenum

True enough. RR would be good to see.