I'm pretty sure Matt's above plot shows full advance and full retard, with no gain in between at 50%.

 

Exactly, so it should be very easy to do? I would be weary of running at both extremes too, but the dyno plot doesn't lie...I'm not sure about daily driving or part throttle abruptness though. Matt?

 

ben, look at the teenie tiny area where the purple line is higher than BOTH the red and blue line (3750-4700). how much power you think that is? 10 hp/ft-lb? 5%? on top of a 35 ft-lb gain already? I say do it the cheap and easy way.

another thing: you may not be able to go to "half way" or some other value than full advance or full retard without constant feedback from the CAS.

 

oh um i have no idea what switching it over from -12.5 to +6 (or +12.5 if that's what it is) would do for driveability. probably not noticable if done at the crossover point.

 

Can I have your engine Matt?

 

So just to clarify said "cheap and easy" way would be to remap my EBC table for 0% from 0-4499 rpm and 100% from 4500-redline. Then run power to one end of the vvt solenoid and ground from vvt to the ms?

 

that's how i'd try it. and if not the ebc circuit, a simple ground circuit like the NOS or WI. to trigger ground at a certain rpm. but the EBc could do a better job controlling DC% for a smooth transition.

 

well you might want to check what causes advance and what causes retard (voltage or gnd) and then what voltage to supply (5 or 12).

But... yeah.

Tim: I plan to keep it as a "spare" when I get the new one built. sry!

 

If I'm reading what you and others have wrote in this thread correctly and seeing as I will be setting this up using a 1.6 harness anything running to the VVT will have to be custom. Based on that statement I can assume that leaving it unhooked will give me full retard which gives nice torque up till about 4500, at which I would want to send voltage to the vvt solenoid sending the cam full advance giving me a nice boost in hp. So it looks like I will try and use a water injection output which is a simple switch ground/power circuit. I'm assuming that at any amount of throttle I still want the cam crossover. Seems simple and way better than the exintake cam mod I was going to try and monkey with.

 

Before anyone gets all carried away with illusions of grandeur(as MikeRiv has started to do on our local Miata forum) I would just like to make some observations. Correct me if I'm wrong.

We are talking about the performance of a VVT head with the VVT operational vs. it being disabled. Not a VVT head vs a non VVT 99/00 head. It only makes sense that an engine with a cam designed for VVT would perform a hell of a lot different with the VVT on/off. So unless it's the same profile cam that is found in the 99/00 we can call it a shitty all around cam when not used with VVT.

So whats the deal with the VVT intake cam vs. the 99/00 cam? Ben?

Does anyone have any dyno charts of the same turbo kit on a 99/00 vs 01+ that shows the VVT setup to be superior by any margin that cannot be attributed to the higher compression ratio?

Mazdaspeed chose to go without the VVT head for the MSM. I was under the impression that it was because they could not make considerable gains on a turbo'd car to justify it. Anyone know more about this?

 

they could have done without VVT on the mazdaspeed to cut cost too.

 

I found a very crude way of operating the VVT. Here is a pic from a page in the service manual. Basically if i under stand it correctly no power for full retard and nice torque then add 12v for full advance and top end Vtekz.

 

I have been reading over at M.net not saying they are gods of the miata creed but many can be quoted saying that you may not see much gain NA but with a turbo the way the VVT works you can note awesome gains. Has something to do with what was touched on in my exintake cam thread. Again the exintake on an NA gives some gain but it makes an ideal scenario for a turbo with the overlap.

 

True, they did do a good job of keeping the price down compared to the non MSM version.

 

Yeah, are you talking about y8s's threads? again that is about a VVT head using and not using the VVT. or link to said threads

 

LOL

As stated on our "local forum". I want to try something different. Not many people have done a 94-97 block, 01+ Head with semi-working VVT, and a Greddy kit using the ETD 1.8L Greddy Manifold. Im excited to see the results are as apposed to going with a begi/FM kit and knowing exactly what the outcome will be. Main reason why I abandoned 240's almost everything had been done over a dozen times.

 

I'm referring specifically to the claims of 270-300 rwhp you projected.

ps, you quoted the wrong post.

 

If i had any idea what cam profile was ideal for a turbo vs. NA application maybe we could dissect the 99-00 head in stock form VS the 01+ Head with VVT at full advance above 4500 rpm. The way I'm comprehending this whole thing is that the 99-00 head with stock cam setup is good for NA and good for turbo. (As you have proven with your 300whp.) Now back to exintake thread. The 94-97 stock good NA and turbo. 94-97 exintake modded good NA and ideal for turbo. 01+ VVT head Good NA and ideal for turbo. Now the question is then, Is the 01+ VVT Head's "Ideal for turbo" better performing then the 99-00 Head with stock cam setup? If nobody can answer that then we are pissing in the wind about what makes more power and can get back to figuring out how to make it work in my 1.6L chassis.

*Also this ideal for turbo that others are referring to I'm assuming has something to do with faster spool and not blowing unused **** out the exhaust before the valves close.

No i didn't. I was Laughing at your sarcasm to that guy about the MSM...

 

1. VVT controls the intake cam only.
2. i was serious in saying Mazda did a good job on the price of the MSM.

 

If I close the intake valve at a more optimal point it WILL stop the turbo from blowing out as much from the exhaust valves as apposed to just plain suction from the pressure differential inside the cylinder during the intake stroke and inside the exhaust manifold which in a turbo shouldn't be that great. You know with the exhaust being jammed up having to spin a turbine and all.

Well then i just got



Oh I also have a question. All this talk of cam timing has me wondering, how does that affect my ignition timing? Can i just run the semi tuned timing map that many of the locals are using or is the cam timing going to run the risk of detonation?