So it's widely known, thanks to the ECU disassebly gurus, that the ECU clips the MIVEC values from the timing table to a max of 28.8* and a minimum of 0*. Since the limit tables have been discovered, I'm wondering if there would be any advantage to raising the limit and running more than 28.8* for torque and lowering the minimum to roll the cam back beyond 0* at higher RPMs.

I'm thinking of doing some dyno testing with this, but wanted to get your input first.

I assume there's a mechanical limit to the MIVEC rotation, but does anyone know what the physical limits are in terms of degrees?

If this physical limit keeps the valves from hitting the pistons with stock cams, is there enough separation to keep high-lift cams like the Cosworth's from valve interference? Mr. Bradley, perhaps your handy-dandy modeling software can be of assistance with this?

Discuss.

 

Depending on boost and octane I have found the Cossies like a little advance. I can give it a shot though and see. The max retard is -1.2* But you might be able to get a little with the cars that run less octane (cali, new mexico, etc.)

It definitely helps the idle though running -1.2* on some of the larger cam cars.

JB

 

Are you saying that there's a physical limit to the MIVEC at -1.2* and that you've reached it by adjusting the ROM's MIVEC Min value and set the MIVEC timing map to -1.2*?

 

Yes, it's physically limited. You would need to modify the gear itself to allow for more adjustment.

 

There's a physical limit to what the gear mechanism travel range is, you'll be lucky to get 31 deg travel max.

 

and the limit is to prevent piston - valve contact

 

Does it still prevent interference with 11mm lift cams like the Cosworth's while the gear is maxed out?

 

The diagram that mrfred supplied awhile ago shows that there is substantial range in the mechanism if the stopper were modified or removed. The mechanism is listed at 30* range by mitsu and it has been logged that 28.8 is the furthest advance ( with the -1.2 makes 30 total). I mean if you really wanted to you could also setup your cam gear a tooth off and advance it back (what is it 7* per tooth?) but I dont see any advantages. On the the Cossie M3s they like 3.6* advance and it made 8hp more than 0* with no other changes to the tune on a stock turbo.

 

3.6* advance after 6000rpm? Care to show the map?

 

A 130 deg intake lobe center isn't going to help power until you are WAY up in the RPM range.

 

I know most of the IX cams are ground on the 130* center like the stockers, but I have been wondering when and if a company might step up to the plate and offer something a little more "practical".

 

We put some extra advance in the 9 cams, low and midrange benefits. Don't know about anyone else.