Eric,
I don't think Harvey came up with this by accident. These 8.5" wheels fit like a glove. Last I talked to Harvey, he said he could take my fronts and add an inch to the inside to make them 8"...
I had little time to fool with pressures at the event on Sunday so I just told Mark where to start. He must have done some reading because he told me after his first three runs that the car was pushing. I said to either add air to the rear or take air out of the front and he already had! That burger boy learns Mcquick!

Did a bunch of tuning today. When I got it back here to Reno after WCR and the Sacramento Valley event, it was running way lean! That's weird because Mark had it tuned pretty much perfectly when it was at Sea-level in Sacramento and Marina.
I added bunches of fuel at 3500rpm through 7250rpm and gave both the low and high rpm accelerator pump function +10 increases. My stock temperature gauge which is oil temp was sitting on the 'P' but CHT was 200 and EGT was fluctuating between 1200 and 1400 under load. These values are way better than a stock 2.0. Not necessarily EGT but CHT for sure...

We were baffled as to what could have happened to the tune... I think it may be that MAP is more sensitive to fluctuations at altitude. Everything was still plugged in and appears to be functioning. Either that or the ECU lost its mind from having the car bounced around on the trailer on the way back from WCR...

How frustrating. Sell it...

These are the kind of problems we all should have. Enjoy this beast Rob!

I had the same problem with SDS too driving up to Tahoe. I kept adding fuel with the tuning knob. I'm not sure what gives since they use it on small planes. Maybe, pilots are used to adjusting mixture and don't mind.

Dave

We don't have the mixture knob wired in to the custom harness. Not that I want to use that as a crutch...

I don't have the tuning down the way Mark does. He looks more like he is texting his wife than tuning with his fingers dancing around on the tuning interface. I would say that is why it is at 90%. That and he could tune while I drove and I have to drive, look at the AFM and the tach, go back to the house and add to the areas where it was lean. Go out and do it again and so forth...

Rob, you can buy the engine. It is priced around the same price you are asking for the Pirate Ship

I wonder if these planes are using TP tuning?

I agree, you really need a tuner riding along. I'd give SDS a call. I talked to them a couple of times and they were very helpful.

Dave

I will Dave. I just need to print that page from the manual where you write down all of the tuning so they have an idea of what you are doing.
I wonder if they need all the other stuff as well? O2 logs and such as well as temperatures...

BTW, I'm building an engine for the 240Z soon. I have debated a turbo or a NA 2.8 block with a 280Z intake plenum and a big throttle body. I will go with microsquirt this time.

I just asked Yopu if she wanted to go for a ride in the 914. She got this look like "why the 914" and then said it... I said, let me rephrase that, "let's take a ride over to the Apple Store in the 914". Big smile and "Ok". Her birthday is Wednesday and she wants the new iPad... (I get her old one)

Come on up and run Cascade Lakes hill climb Rob. You can take the back way through Lassen Park and make a holiday out of the trip.

I suppose it never hurts to be prepared.

When I had that happen I was really surprised and I finally thought it was a problem with their code because I ended up taking fuel out as I came down the hill and my tune was fine on I-5 again.

Dave

When is it Randal?

Dave,
I assume you were tuning with MAP? If so, you were experiencing the same thing as me. I just didn't see it because the car climbed and descended on the trailer... But I am at 4500' here and Mark was tuning at a bit above sea-level.
Sorry for messing with your tune Mark It was pretty much nuts-on!

No problem.

I dropped by a local Porsche shop today. The owner is a PCA member and we are working on an event together. He had an interesting thought... Every once in a while, the car will backfire on start-up. When it does, it usually blows off one of the lines to the common plenum and the idle goes through the roof. He said maybe it damaged the MAP???

Dave? Mark? What do you guys thing of that? I will still be calling SDS when I get the values all written down though...

I'd say that is a possibility.

He mentioned installing a blow off valve! Really? Can I do that?

Interesting. Maybe you need a blow off valve like the 911's were running... Something to cushion the force.

Question: I know nothing about SDS but does it have an 02 sensor to read the emissions and a knock sensor? How come the system doesn't self adjust like the factory EFI cars?

I understand the need to read the engine and tune it out of the gate but then what happens?

I'm still figuring SDS out Rick. I think it seeks Stoichiometric when you use the closed loop mode but that isn't conducive to performance, and having tried it, it didn't seem to adjust very well either. It still went lean under loaded acceleration. They recommend against a knock sensor on VW type engines because they sound like they are knocking all the time apparently.

Pete Stout was critical of aftermarket EFI in a conversation we had a few years back. He said that factory EFI samples many more times per second than aftermarket programmable EFI. SDS allows a setting change every 250rpm. This conversation was back in the Kit Carlson EFI days so it was a while ago... This was back when McMark had a running 914. Demeaning look shades on Go ahead Mark. Give it your best shot!

There is a start-fuel setting, and I have a feeling that richening that up may stop the occasional cranking-backfire.

Get one of these. set the spring to pressure. dial it to 2psi and screw to your vacuum manifold.
http://www.mcmaster.com/#brass-relief-valves/=hmysok

With the air cooled element in the equation it makes sense that the thinking and reacting portion of the management would have to be fast, fast, fast. The engine doesn't have the added benifit of stable coolant slowing the change of the environment in the cylinders.

"Every once in a while, the car will backfire on start-up. "

Mine will backfire on hot startups, too. Maybe once out of five or ten times, but it'll give a good bang out the tailpipe--I'm figuring it's maybe cranking one or two revolutions before the ignition part of SDS starts firing but fuel/air left in the cylinders is now in the tailpipe & goes off. Interesting that yours is banging back in the induction end of things....can't quite figure that out unless it's perfectly timed during overlap. You've got a good header system, with no restriction right?
Mine has never blown off the rubber hoses to the MAP 4to1 block--they're really a tight fit & a bear to get off by hand, so that may be why.
I'm sticking with TP sensing--lucky to be on Eastern seaboard & don't get much elevation change between home & event venues....I also see the lean AFR's on light to moderate acceleration when in closed loop but it goes pleasingly rich when I boot it. I use closed loop most of the time in street driving unless I'm thrashing it. It homes in on 14.1:1 pretty reliably but seems to like being rich (like 12:1) if rpm's are below the 2750 notch. (And yes, my CL low limit is set at 1750.)
I'm still blown away by the fact that the car cruises at 60 with the TPS still in the "5" notch and accelerates at the "6" value--meaning that the throttle plates are just barely cracked (the TPS values start at 5 with throttle closed and span up to 50 at WOT). These engines are truly muscular for the car they're in...

Got some props today. I took the 914 for a drive, top off, stereo blaring. I noticed a green Cayman in my rear view mirror. Followed me for about 2 and a half miles through my neighborhood. When I pulled up to a stop light the Cayman pulled along side in the right turn lane. A woman was driving and she looked over, gave me a thumbs up and said "that car is so cool"... I wanted to tell her it was the faux painted flares but the light turned green and she was gone.

Does the setup you have use a seperate map sensor for atmo correction?
Just about all the aftermarket ecu's I looked at use the second one to adjust fuel for altitude change which could account for your changes.
time to cut the sds plug off and put a megasquirt into this?
What sort of timing values are you using for starting and running?
I had lots of issues with a startup backfire and have changed to some really far out timing and it starts better and no backfire.
When do the seats arrive?
Loving this thread
Edwin

Remember, this is a batch fired wasted spark system so there is fuel sitting in the intake and there is a spark every rotation instead of every other rotation. It can fire on the exhaust at the end of the exhaust stroke and during overlap under the right conditions. It is even possible under the right conditions to get it to run backwards. Ask how I know.



This system uses a single MAP reading at startup. The expectation is it should richen as you climb. Restarting the engine at altitude should correct that but his experience is the opposite and so was mine.

Dave

You need 2 map sensors so it will auto correct on the fly. Not sure if SDS can do this. My Haltech can.

Hope this shows what you want Eric... The fender wheel arch flange was too close for Mark's comfort and I am sure mine (I wasn't there to see it). I guess there is much more flange on these reproduction flares than on the factory original flares. As you can see here, Mark has done some very nice trimming to make wheel rub a non-issue...

Another... Looks like plenty of room but as we know, the car gains negative camber under acceleration and suspension squat. I will pull one of the rears and see if there has been any rub...

I would say that Harvey knows exactly what he is doing. I had thought 8.5 was all he could do with the 2 - 16X6 wheels he used to make these wheels. Now I believe he knew that it was the limit without extending the flares.

and another with Andy's old camera apparently

Another tiny little project today: Protecting the elbows from blowing off under intake pops...

Oh, that reminds me. I have doubts that the MAP sensor was damaged because of the hoses popping off. Pressure relief.

I agree, I don't think it is damaged. But besides the elbows blowing off, where is the pressure relief?

No, I meant the elbows blowing off.


It was a design feature...

LMAO!!!

Here's a shot of mine....tight fit rubber on barb fittings--I do get the backfire, but not blown any of these off.....smaller diameter than yours...maybe 1/8".

Well the nylon ties are working. Since I made the mixture richer throughout all the 'usable' rpm set-points it has run better. In fact I suspect I am a bit too rich.

One thing I would suggest to SDS would be to write there manual with a tuning sequence. They really don't give you a 'do-this-first-then-do-this' approach in the manual.

Need to find spacers for these front wheels though... Maybe 3/4"?

A bit of PMB goodness peeking through the wheels! Love these brakes!!! I can't wait for some matching rear calipers!

Aren't the 944 spacers 21mm? I bought a set for $25.

Nice. Yeah, the 8.5 thing simply plays out. I experimented with an inside 9 and it rubbed inside. The inside 8.5 would pull a little off the flare and just clear inside (as your pictures show).

I have another full set ready to send his way I guess. I'll keep the 7's and 8's I have and use those for street tires. Then, as the 911 develops I'll probably move those over there and send those off for 8.5" treatment as well. Seems like the magic number. Actually, I'll have to check the offset on the 911. It might like a set of 8.5's as well.

I'm glad that picture worked for you. I was just about to take another with a ruler for a reference...

Harvey is doing a full polish on a set of 7X16 for the street. His wife Susan is hand painting the crests so it will be full-blown sexy!

Actually Eric, Harvey said he can add an inch to the fronts too. I suspect he puts together some kind of offset that brings it out so it is perfect both inside and outside. That guy has forgotten more 914 tricks than I will ever know. Got to be different than just an 8X16 or he would have just told me to source some and he would RSR them.

Chasing down gremlins. I found my idle was high and getting higher so I quit driving it a bit ago. I had a ton of things to do with the 240Z anyway and it was good to work on that for a bit as I am down to just a few things for that to be complete.

What I found was that my entire throttle body tower on the passenger side was wobbling. Well, duh! There's the leak!

I tightened up the nuts that hold the manifold to the head and no bueno... I guess that means the seal to the head has been compromised.

So off it must come... Boo

Bummer...

Dropped off the car at Original Customs today... A little McMagic and it should be just fine!

And now it is... just fine I mean!

Paper gaskets around the phenolic spacer were blown away and tattered!

So does that mean the large displacement Raby engines creates such a high volumetric flow that gaskets cannot withstand it?

Inquiring minds wanna know..

So for today's fun, I did what you might call an educated butt dyno tune. In general butt dyno tuning is inaccurate and can even be dangerous to the engine as you have no data and you can easily go in the wrong direction.

But I have EGT, CHT, and A:F ratio to look at if I want. That's not what I did though. The SDS EM4-F that I control the engine with has a data log feature that records the average A:F ratio in each RPM range that you spent time in during the last running engine session. So, I took a ride... Three actually.

I knew I was running rich as my gauge reads in the 11:1 to 13:1 range everywhere. Given that the car is dual use, street and track/autocross I want to target a 13:1 range with unleaded premium fuel. I am much closer to that now. The engine is clearly happier and I also discovered that I needed to lean out the ACCPUMP feature at both low and high RPM. I also increased the sensitivity and the result is a better throttle response and less fuel gargling on tip in...

A productive day and a ride in the 914!

They do if your manifold fasteners back off.