VVT Cam profiles

[StanTheMan]

VVT cams. Are they different?

theoretically, in my mind at least ( rightly or wrongly) you could just run any agressive cam that fits the head and adjust it accordingly.

or do they profile them differently? I understand that profiles for the solid lifters are slightly different for solid lifters to the HLA lifters.

Mahura cams are ridiculously expensive & need the lifers adjusted but only really add a little to the overall lift and duration.

[NitroDann]

You could just run a race cam and use vvt to dial in the candy is as though they were vernier cam gears or move them around a little if it makes better power.

[plohl]

The exhaust cam is just a different profile and can be run in the other BP heads. I'm running on in my BP at the movement.
The vvt cam is well different. Has the trigger lugs at the back, and is longer at the front. You could make it work in a non-vvt head... I don't know why would though.
What are you trying to achieve? Did you want to use the vvt cams? Or replace them with large cams, less the vvt gear?

[NitroDann]

I think he is asking what happens if you put big regrinds in a vvt head.

That's how I answered it.

Dann

[plohl]

If that's the case, you'll have to check clearances with adjustment, and the bigger cams you go, the less vvt range you can use.
I know on some of the vvt race engines, the vvt cam wheel is mechanically limited so instead of having 40* advance, it'll have to be limited to 20* etc. Relying on the the vvt mechanism and ecu to control the range of the cam is risky business under track/race conditions, especially when another few degrees could result broken bits.

[StanTheMan]

I think he is asking what happens if you put big regrinds in a vvt head.

That's how I answered it.

Dann

thats totally what I was asking. Thank you Dann

without having read a huge amount on VVT tuning I figured with more aggressive cams you could then adjust low RPM for better low power & then move it as it gets to the high rpm to make use of the scavenging effect.

If I do end up with a VVT.....I'll be looking at something a little more aggressive than what I currently have in my 1.6. somewhere around the 230 @ 0.050" not necessarily big lift. Probably something that fits without having to modify the lifter guides. But that's unlikely with a regrind.
The only way to achieve it is a regrind as Mazda blanks are currently in short supply. Yes I do get the lifter adjustments requirements. But I then need to understand more about VVT adjustment phol talks about. Which then may have to be a custom grind. If the advance and retard is limited
The current cam I'm considering are a grind for HLA. Not solid lifters. That needs to be addressed as well.



Ultimately Id like a aggressive N/A street engine with a bit of drama that's just going to sing at 5000-7000 rpm.

all show no go ha, ha

[Magpie]

Ultimately Id like a aggressive N/A street engine with a bit of drama that's just going to sing at 5000-7000 rpm.

Ditch the MX5 and find something with a K Motor in it!

[hks_kansei]

The mention of a HLA grind made me think.

I know you can easily put solids in a B6/P that originally had hydros, but is the opposite true? Or did the NB heads no longer have the appropriate oil feeds to pump up a hydro if fitted?

[StanTheMan]

Ultimately Id like a aggressive N/A street engine with a bit of drama that's just going to sing at 5000-7000 rpm.

Ditch the MX5 and find something with a K Motor in it!

LOL

[StanTheMan]

The mention of a HLA grind made me think.

I know you can easily put solids in a B6/P that originally had hydros, but is the opposite true? Or did the NB heads no longer have the appropriate oil feeds to pump up a hydro if fitted?

I guess it all depends on what type of lifters the VVT comes with . I was under the impression it was solids. Might just be easier to change the lifters if that is possible as i wouldn't be looking at revving way past 7000 anyway.
My current B6 motor is toast. Upgrade is on the agenda, although a 1.6 replacement isn't totally off the cards

If I end up with a BP4W.....well....that changes everything....

[plohl]

I really liked the vvt engine when I had it in my car. It pulled so well... Unfortunately it was short lived. If you didn't want to build an engine, I would definitely recommend swapping one in.

I would say the std vvt engine is better than the bp I have now with the 805c on the intake and vvt exhaust cam. I have the cams dialed to 2mm @tdc for the intake and 1.70mm @tdc exhaust... bit more overlap, makes it a dog to putt around under 2k... and yeah, the vvt engine had the same power, drove nicer at low rpm and had lots more torque through the mid range.

The vvt head doesn't have the feed ports for HLAs iirc.

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[StanTheMan]

Just re read your post

thinking of the 935C profile if I end up with a BP4W.....which looks like is most likely the case now.

cant afford the VVT I was looking at & got a price today.

[NitroDann]

Plohl is right, the VVT motor works well. Lachlans NA with VVT setup makes 135whp with bolt ons only and heaps of torque.

Dann

[plohl]

yeah, they aren't cheap, which is super sh*t. Best thing would be to find a wrecked NB8B if you could for the right price. Or find a vvt head and just build a bottom end.
Seriously, you can get a second hand k24 from an accord euro cheaper than a BPZ3... makes as many kilowatts as the BP does horsepower... pity the engine is about the cheapest thing about a k swap :'(

[StanTheMan]

k swap is beyond my skills. Doesnt interest or appeal to me