Just another damned project thread, 914-6 3.2 conversion in GT dress-up Options

[McMark]

Thanks Randal (and everyone else). I'm happy with how it's turning out, and can't wait to finish up all the little bits to get cleaned up.

That's one of the glorious things about the bell-crank linkage. Takes about 10 minutes to get a perfect sync. :drool:

[Randal]

Thanks Randal (and everyone else). I'm happy with how it's turning out, and can't wait to finish up all the little bits to get cleaned up.

That's one of the glorious things about the bell-crank linkage. Takes about 10 minutes to get a perfect sync. :drool:

Wasn't around when we put my engine together. So drool it is.

Off and on it took about two hours to do mine.

[McMark]

https://www.youtube.com/watch?v=S-Riud_GI-0

[McMark]

https://www.youtube.com/watch?v=JI_OyO5KIMc

[rick 918-S]

Just like a proud papa! (IMG:style_emoticons/default/beerchug.gif)

[BigDBass]

(IMG:style_emoticons/default/beer.gif) (IMG:style_emoticons/default/aktion035.gif)

[jmill]

Very nice. Revs smooth and has a bunch of pep. Great work. Now we need an in car cam of you opening that thing up (IMG:style_emoticons/default/beerchug.gif)

[jcd914]

What you wait to start it until right after I left?

Sounds good, can't wait to see it live.

Jim

[McMark]

Well we made some good progress tuning today. If we hadn't gotten sidetracked a couple times we could have gotten farther, but we worked out some 'bugs' and got a pretty nice tune on our last run.

Here is a video from earlier in the day where we encountered what everyone said we would see. Serious oscillation in the MAP sensor readings. After this run we installed a welding wire tip in the line and things got really nice. I expected to have to do this (it's been mentioned by most people who've done EFI Type IVs) but I wanted to see the effects before jumping ahead. I like to see a problem before I fix it. (IMG:style_emoticons/default/wink.gif)


https://www.youtube.com/watch?v=LYRpM2lKYck

[rwilner]

Here is a video from earlier in the day where we encountered what everyone said we would see. Serious oscillation in the MAP sensor readings. After this run we installed a welding wire tip in the line and things got really nice. I expected to have to do this (it's been mentioned by most people who've done EFI Type IVs)

Mark
Do you expect I'll have to do the same on my stock EFI conversion? Do you have a pic of this?

[JStroud]

Sounds great Rob, excellent job Mark. Was hoping to make it over to see the start up, but my son came by Saturday and was racing at prairie city on Sunday, so ended up going and watching him race.

Good luck with the new motor on the 19th
Jeff

[rick 918-S]

That engine sounds like a torque monster! Clear clean pull! Nice!

[ConeDodger]

Just home after 155 mile trip from Mark's shop... Still really pretty charged up about this!

A couple of notes. The guys who have been suggesting dyno tuning have a very good point. For the first tuning run on the road we went out to a loop just in to Napa County (Mark is in Sonoma County) and did several laps of the loop. I didn't think we were going that fast but the exhaust is a bit loud as you can hear in the video. We decided to head back to the shop apparently just in time. As I turned the corner by Mark's shop a CHP cruiser was turning to head out to that 'loop' (IMG:style_emoticons/default/sad.gif)

That first run with MAP tuning was probably an exercise in pure frustration for Mark as it was lean or rich - lean or rich... Even though it seemed to run fine, the wide band O2 gauge was pretty lean on tip in and rich in a lot of other places.

The last run of the day, after using Dave Hunt's suggestion and putting a welding tip in line between the common plenum and the MAP was VERY NICE and we are pretty encouraged that this will be a good starting point for tuning with MAP.

Thanks to Mark for a great couple of days!

[ConeDodger]

Here is a video from earlier in the day where we encountered what everyone said we would see. Serious oscillation in the MAP sensor readings. After this run we installed a welding wire tip in the line and things got really nice. I expected to have to do this (it's been mentioned by most people who've done EFI Type IVs)

Mark
Do you expect I'll have to do the same on my stock EFI conversion? Do you have a pic of this?

I'm not Mark of course, but if I recall your thread correctly you will still be using the stock plenum and throttle body? If so, I wouldn't think you would have huge vacuum fluctuations. I wonder though how much vacuum you'll be making. The problems with using MAP if I understand it come from the Individual Runner manifolds and the multiple throttle plates opening at the same time while the cam is opening and closing valves at different times for each of the individual throttle plates. The vacuum at tip-in is all over the place. Again, if I recall correctly you will have only one throttle plate and a common plenum.
You are also using a system Mark has come up with. I am still getting a grasp on the SDS but it seems I can run MAP or TPS but not a blend of each. I think your system probably runs a blend.
Mark is a good sport. I don't think he is SDS's biggest fan. I am having my doubts too though. I would love to run a blend of TPS, MAP, and closed loop. I guess if it could do that they would call is CDS instead for Complex Digital Systems. (IMG:style_emoticons/default/dry.gif)

[McMark]

Rich, you probably won't have to. Rob's got it right. With individual throttle bodies, Rob has what equates to a 160mm/6.25" throttle body. With four throttle plates, he's got a huge change in air flow by even the smallest throttle movement. Couple that with a cam that's built for power and not vacuum signal and you've got a recipe for a MAP signal that is pulsing like crazy.

You've got a ~45mm/1.75" throttle body and a cam that's designed to have decent performance while giving great vacuum signal to the FI (so the normal people who buy those 914s new actually enjoy them). That smaller throttle body means less air flow at WOT, but also means great low speed modulation. Think how much more air is flowing a 5 degrees of opening in 160mm vs 45mm, and you'll see why the smaller throttle body makes great sense for a 'street engine' where you're throttle position spends more time <50% of throttle opening.

For reference, this is what a MIG welding tip looks like. It's simply an obstruction with a small hole in to modulate changes in vacuum, and anything could be used (aluminum rod with a drilled hole, a carb jet, a drilled plastic BB, etc). In a way, it introduces a 'lag' or slowdown of changes in vacuum, so you get a sort of averaging effect. Much better than having the MAP sensor report every peak and valley in the signal, and having the FI trying to keep up with that.

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.alltoolsdirect.co.uk-419-1320767173.1.jpg)

[McMark]

Here's an out-of-order update. The last part of the custom wiring harness was building our own relay board harness which would be compatible with the new coil location. That yellow wire needs some help, but I didn't have large gauge yellow wire here at the shop, so we made due for now.

[DNHunt]

The last run of the day, after using Dave Hunt's suggestion and putting a welding tip in line between the common plenum and the MAP was VERY NICE and we are pretty encouraged that this will be a good starting point for tuning with MAP.

I suggested this but it was Jake's idea in the first place.

Dave

[jmill]

Love this thread. Great progress and in car cam. If it were me I'd be wearing an Enzyte smile for weeks.

[ConeDodger]

The last run of the day, after using Dave Hunt's suggestion and putting a welding tip in line between the common plenum and the MAP was VERY NICE and we are pretty encouraged that this will be a good starting point for tuning with MAP.

I suggested this but it was Jake's idea in the first place.

Dave

We were just citing our source. Thanks for citing yours. That welding tip and the integration of the stock AAR were very appreciated and I want you to know your input has been very valuable. Thanks Dave... (IMG:style_emoticons/default/biggrin.gif)

[rwilner]

it introduces a 'lag' or slowdown of changes in vacuum, so you get a sort of averaging effect.

Interesting. Other ways to do this:

1) Place a capacitor (or a proper RC filter in low-pass filter configuration) on the output of the MAP signal to the ECU. If you did build an RC filter, you could use a potentiometer for the "r" and tune it till you got it where you like it.

2) MegaSquirt / MicroSquirt has a configurable "averaging / lag" factor on all analog inputs. This parameter will average the number of digital samples of the analog signal you specify, and output this average to the controller. It will repeat this averaging function every fixed cycle, so you can tell it to send the average of every 5 or 50 samples. The effect is exactly the same as the RC filter or welding tip trick -- it filters out the high frequency stuff. Not sure if SDS has this also, might be something else to try.