Hi Folks.
I'm beginning to think that I may never get this thread up to date with all of the developments of the past six months, so I'll start by bringing you up to date in the present....I got the VVT working!!!! I'm a tad embarrassed to say that it was all my fault. The VVT solenoid was fine, the VVT control valve was fine, even the Adaptronic and my wiring job was all fine. It all came down to an incorrect selection being made in the ECU software. I had chosen the wrong output signal in the drop-down menu. Gah!!!! There were a few VVT-related options to choose from, and I had chosen poorly. "Inlet VVT1 Duty" was the right output signal. It seems obvious now, doesn't it? If I had known then what i know now...
This mighty revelation occurred right before a COVID-Safe sprint meeting at Phillip Island with the legends from the Alfa Romeo Owners Club Aust (AROCA), and the MX-5 Club Vic crew. The sprint meeting was on Sunday, and I had gotten the VVT working on Friday. It rained a bit in the morning, and it rained a bit in the afternoon, but the track dried out in the middle of the day and I got three (?) sessions on a dry track. Well, I have to say, the difference in mid-corner grunt was very surprising. It was obviously pulling harder, presumably thanks to the VVT because nothing much else had changed. It was a cold day, which is usually conducive to fast lap times, but I'm giving some credit to the VVT for my new personal best...
I did a 1:57.5!! That's a full 2.3 seconds faster than my previous best in January. The cold weather and the operational VVT are the biggest factors, I reckon. I had dialled in less oversteer compared to the January setup (damper clickers only - long story, for another day), so that's another relevant factor. Still.... 2.3 seconds faster!! Its nice to finally realise some of the potential of this new engine. It was an absolute hoot!! And now, photos....
2020-06-07 Phillip Island 01.jpg
2020-06-07 Phillip Island 02.jpg
2020-06-07 Phillip Island 03.jpg
2020-06-07 Phillip Island 04.jpg
Thanks for all of the great responses about camshafts and VVT and stuff. I will now attempt to reply, starting with Shane's comments/questions...
Weren't you getting cams from Comp systems? What happened to them? Camshafts were ordered through Competition Systems in Carrum Downs, Vic. They took my money, refused to answer my phone calls, and even hung up on me three times. The camshafts never arrived, and it seemed like Competition Systems had no intention to ever deliver them, so I eventually got a refund after threatening legal action via a carefully worded letter (my buddy is a lawyer). It was a nightmare. By that stage I was out of time to order new "hot" cams due to my Bathurst deadline. Hence, my Bathurst build went ahead using the standard BP-Z3 camshafts.
Do you have flow data from the head guy? Shouldn’t he be telling you what to do cam wise? Let’s be serious, if the heads been made to flow for valve lift above 9mm, and you’ve lost flow below that, you may as well start again.I have no flow data. The guy that did my head had never done a BP before, but he came highly recommended by my engine builder. Therefore I don't believe he can offer useful advice about camshaft selection. My engine builder has given me some advice, which is to aim for a duration of around 270 degrees and around 10mm lift, but until he took on mine he had never built a BP before either, so it's generic advice without experience to back it up. I've looked at maybe getting the head flow tested on a bench, but it's expensive and I don't think I want to. I've spent waaaaaaaay too much on this engine already. I'll choose a cam spec and just go for it. If I go backwards and end up with a horrible engine or less power, then I'll consider getting it tested on a flow bench to figure out what the hell to do next.
I can’t remember, but does it have shim under bucket lifters, or the standard shim on bucket? What are your plans regarding value springs? Are you happy to get rid of the vvt? I have already installed new "shim-under-bucket" valve-train hardware, all in preparation for the cams that never arrived. The specs are as follows:
* CAT CAMS TS100 Lash Caps,
* CAT CAMS CC017 Cam Followers,
* CAT CAMS S90015 Valve Springs,
* The cams that never arrived were CAT CAMS 3702606: 278/278 durations with 9.95mm lift, VVT active.
Regarding VVT... Yeah, I'm pretty keen to keep it at this stage.
Once cams get to a certain size, you need to mechanically limit the VVT. The most lift and duration you can have with the 40* (or 45*?) of the standard system is the standard cams. Another difficulty is you can’t easily adjust the base cam timing. These are some very interesting comments, and I appear to have some conflicting information at this point. My engine builder measured the clearance from piston to valve and I am told that we have around 5mm to play with on the standard camshafts (utilising the full VVT travel range). If what you are saying is correct, then he must have got it wrong. Either way, I will be measuring this clearance again before making a final decision about VVT. A while back I stared at the internals of the VVT actuator for a good hour and I couldn't come up with a way of mechanically limiting the VVT travel that I was happy with. If anyone out there has details of how Gary Stewart did it, I would be keen to chat.
Oh, what are you doing re compression?I've installed the 11:1 Supertech pistons and a Flyin Miata Cometic 0.040" head gasket. The aim was always 11:1 on 98 RON Premium juice. My engine builder has told me that my compression ratio is around 11:1, but I haven't seen it measured/calculated. I'm keen to measure/calculate it. Forgive me folks, I've been busy.
Forgot you have itbs - you'll probably have a faster car without them (standard intake) and those gross air filters.Yeah, there's a lot of work to do on the air intake front. I'm not happy with the current setup for a bunch of reasons. I've come too far with the ITB's to just ditch it all, so I will work on improving it. My plan is to fabricate a plenum to go over the trumpets and bolt up to the ITB's. The filter will go upstream in a box which is pressurised by a duct/scoop at speed. It's been done on BMWs quite a bit, but I've never seen one on a BP. Something like this...
BMW ITBs 3.jpg
Tim_cyc03, thanks for your comments.
I don't have data-logging while I'm on-track, so I don't know when I'm shifting, but my limiter is currently set to 7,200rpm and I generally don't hit it (the power is tapering off a tad before that). I'm very interested to hear more about the cams from Custom Exhaust Systems in Brisbane. They were an absolute joy to deal with, so I'll be giving them a call.
GreenMachine, I totally agree... Billets are the way to go.
Some other comments...
* My engine is 1930cc - just keep that in mind.
* Does anyone know the magical Gary Stewart BP camshaft specs?
* What cam specs would you suggest for this engine?
* I still have electrical noise. I haven't tested for ground loops yet.
* If someone can recommend someone to flow test my head, I may consider it. Anyone?
I've been going around in circles a bit with regard to camshaft choices, but my current preference is to order the CAT CAMS 3702606 camshafts. These cams will allow me to keep the VVT in operation, but still give me plenty of lift and duration to unlock the horsepower that lurks within my heavily modified head. Hopefully it won't be too "peaky". Here's the datasheet...
http://www.catcams.com/products/camshafts/datasheet.aspx?ENGINE_id=351&CAMSETUP_id=2335Regarding VVT... Yep, I want to keep it operational despite the overwhelming majority suggesting that I should ditch it. I expect I may have to limit the travel to prevent expensive internal collisions, and I may eventually get to a point where I realise that the base timing would be better off somewhere else. But until I learn those lessons the hard way I will continue to plan around keeping the VVT. It certainly adds an extra layer to the challenge, and I'm up for that! Thanks everyone for chipping in your 2-cents worth (or your $200 worth Shane!), and please keep the comments and advice coming, even though it seems like maybe I'm not doing as you suggest. If the VVT proves to be folly, I will have proven you all right!