Stock type 4 fi.i. with megasquirt

[scottdownsouth]

I have a 912e that has webbers on it right now. Stock 2.0 motor. I have the stock fuel injection parts but I want to use megasquirt to control it . I'd like to keep it stock looking but maybe go with cop. Anyone ever done this type of thing that could help me out?

[dawie]

http://www.shoptalkforums.com/viewforum.php?f=66

[Piledriver]

Welcome to the STF!

The stock manifolding works very well, and you can easily adapt modern injectors if you are inclined.
The stock Djet TB can be refitted with a Volvo tps easily, but some folks just use a MAP based accel enrichment.
The TPS's major function (for me) is in the fuel cut and idle logic, can be replaced with a switch with few limitations.
(is useful for triggering ac cutout and some other events if equipped with ac etc)
Due to the excellent injector location, very little compensation is needed, even for warm up.

The std Bosch djet pressure regulator is my first choice, one with a vacuum reference is also available from MSD through Summit/Jegs et al.

Porsche got the manifold design right on the 2L motors, and will work well unless you have a wild cam.

cops are neat (i'm running fully sequential w/ls2 coils, T4 in a squareback) but on 99%of motors a logic controlled waste spark setup using something like a 2000 era VW coil pack for ~$35 is just fine, and saves two I/Os, on ms2extra I/O (esp analog input) is in short supply.
If you go MS3 you'll have more I/O lines than you know what to do with.(initially...at least)

I do miss they music Webers made, but I do not miss the headaches that go with running them in a true daily driver.

[scottdownsouth]

Thanks Pile, got any links or info on the injectors and tps? I did a search but am overwhelmed with the results.

[Piledriver]

Mid-80s-mid 90s Volvos, but you can buy tps off the shelf, many are designed to work with the half circle shaft.
They can also provide a bit more modern high Z injector that bolts in, although they are still ~20 years old.

Digifant VWs are possible donors as well.

[raygreenwood]

They got the manifold right on the 2.0...sizing and runners wise....but the TB entry angle is not as clean as the 1.7/1.8....but the 1.7/1.8 manifold volume is only really sized correctly for the 1.7.

The 2.0 bus plenum and TB location may be useful Here. Ray

[supaninja]

I ran the stock FI on my type 4 motor with mega squirt, ran good but I wanted better throttle response and more power so I made my own ITB's from a gixxer throttle body...haven't looked back since.

[Piledriver]

I run a widened Vanagon plenum and 2L 914 runners/heads.
(same as 2L bus save for mounts and larger TB hole, is backwards and fwd compatible for 45mm bus or 50mm Vanagon TB)

[raygreenwood]

I run a widened Vanagon plenum and 2L 914 runners/heads.
(same as 2L bus save for mounts and larger TB hole, is backwards and fwd compatible for 45mm bus or 50mm Vanagon TB)

As I m tuning out my hot 1.7L engine build this summer I am splitting one of the original 1.7L plenums up the middle at the seam to weld in a spacer for about 15% more volume....and a few half dowel airfoils to facilitate quick airflow turn into runners.

I may pick your brain about how well it went together or not. Also...I found a really smooth muffler/tailpipe expander that did a factory looking jog widening the TB hole to allow a 2.0 bus TB to be used a long time back. That alone makes for better throttle response on the 1.7. Ray

[Piledriver]

Shorter runners are also a huge tuning knob... I basically widened it to fit between the shorter 2L Porsche runners.
I have considered cutting the runners down more and going bigger on the plenum, or better with a split plenum using larger tubing (going across, so 180 degree) with slot feeds off a center log.
This should be easy to boost as well.

The slot feeds can have a LOT of area, and the feed/slots becomes the "TB" area and length in the eyes of the plenum, mostly decoupling the actual TB size from that part of the equation, the main reason Lehman-style manifolds work as they do IMHO. (See: Virtually any Audi race car from the mid 80s to date, including the all conquering diesels at Lemans...)

(Ray will think about that for a few seconds and develop an Evil Grin, as he will know exactly where I'm going )

I suspect I can move the primary peak up where everything can sing in harmony at ~5-6K while not really hurting the bottom end.

[raygreenwood]

Shorter runners are also a huge tuning knob... I basically widened it to fit between the shorter 2L Porsche runners.
I have considered cutting the runners down more and going bigger on the plenum, or better with a split plenum using larger tubing (going across, so 180 degree) with slot feeds off a center log.
This should be easy to boost as well.

The slot feeds can have a LOT of area, and the feed/slots becomes the "TB" area and length in the eyes of the plenum, mostly decoupling the actual TB size from that part of the equation, the main reason Lehman-style manifolds work as they do IMHO. (See: Virtually any Audi race car from the mid 80s to date, including the all conquering diesels at Lemans...)

(Ray will think about that for a few seconds and develop an Evil Grin, as he will know exactly where I'm going )

I suspect I can move the primary peak up where everything can sing in harmony at ~5-6K while not really hurting the bottom end.

Yes.....there is an, evil grin!......and yes I agree that tuning runner length is abig knob. And you widened the plenum for the same reasons I have been thinking.....more of a reach issue.

The 1.7 plenum as it is.....is almost perfect in volume for a 1.7. About all it can handle I think in upsizing is about 10-15%.....which I am hoping will get me to shorter runners.

But what I am really thinking of doing is leaving the actual runner length alone....technically......and in widening the plenum.....actually extend the runners into the plenum. The ends of the runners would then be reshaped to be bellshaped around the back and open faced (kind of donkey eared andalternated upward and downward slightly.....splayed out) facing directly at the TB.
The half dowl turn bars I am speaking of would be right behind the TB and keep some of the airflow bounce off the wall opposite the TB and recenter it quickly.....going through an air straightener grid right before the runner inlets.
The turn bars and the grid will probably take the 10-15% volume increase almost back to normal. My weldink skills through primative are finally getting to the point where I can accomplish this. Ray

[Clatter]

Reading, tipping my head to the left, re-reading, Googling, and basically understanding...

Still,
Re: your mods,
Got a pic?

Now feeling the need to go and cut open a plenum...

[Piledriver]

The split plenum setup currently only exists in the amusement park of my mind* and in some simulations...
... but I do have the required tubing etc.

Workin 6 days a week is nice for the paycheck, but it really cramps your style for projects, esp when it seems to rain ~every weekend I have Evil Plans...

I even have that whacked out under the trans does-it-actually-work-like-a-tri-Y header 90% done, just needs some flanges welded on two tubes so it can actually be separated and installed over studs.
(The mock up had exhaust bolts... come to think of it so does the square... Hmmm. Still going to need a snorkel for the next few days to work under the car, it either really RAINS here or it doesn't at all, so I can't complain. Much.)


*Thank you, George Clinton.

[raygreenwood]

Clatter...I will see if I can sketch it out this week. There are lots of similar ideas and partial ideas in other intake manifolds over the years.

The biggest problem in plenums that people do not realize (because they dont think like the air going through the plenum)....is turbulence from the single flow of inlet air trying to change directions...and split in four different directions....virtually simultaneously.

And....too add to that the air is trying to make a 90 degree turn into each runner.

VW did some pretty smart things with the 1.7/1.8...and somewhat the 2.0 bus plenums (smarter than the 2.0 914 plenum to be sure).

The first of which is that strange offset TB...and that engineered curve in the wall of the plenum directly opposite. It causes the inlet air to "bounce" and recenter itself somewhat in the plenum.

2nd..The valve open events moving air through the runners... and the subsequent runner stack-ups upon closing (reversion) are not actually the issue everyone "surmises" on these systems because...and you can measure this with math alone....a runner reversion wave on any of at least the VW type 4 based systems...because of long runner length....when it reaches the plenum (if it reaches the plenum...as the faster the engine runs the less time there is) .....there will already be another intake valve open on one of the other three cylinders....so any back pressure into the plenum pushes to that direction and not to the TB. Its virtually impossible to get/see or measure any reversion at the TB of these plenums.

The issue with reversion is though...that its adding yet another direction of turbulence into the plenum....where the centered intake plume from the TB after its bounced off the wall opposite (which has its own "rope" of turbulence due to the throttle plate itself).....is creating a rapid harmonic fluctuation s its ripped apart in four different directions.

What I am planning to do is:.......lets say if you could stick your head into the plenum through the TB ...and look to your left, as it is from the factory ....if you imagine your point of view as the airflow....you would not be able the runner ports. They are flat along the walls.
Now.....if they had slight scoops or elbows facing toward the TB......and since they are one behind the other....the rear on one side might angle slightly up the rear on the other might angle slightly down........and the whole plenum would have a horizontal divider plate partially splitting airflow into different planes. This plate would probably have perforations or slots in it. You dont want to subdivide the plenum permanently. The cylinders need to be able to draw on the whole volume or the vacuum spikes and the signature becomes unstable.

The object of the plate/plane is to subdivide the airflow into upper and lower planes. Whether a particular runner goes to upper or lower plane will depend on firing and drawing order. This along with the slots in the plate will/should help homogenize the turbulence a bit. That along with the scoops should make for easier entry to the runners with less velocity loss.

The turn bar idea....I already know works. I have used it on other machines and types of plumbing.

You know how a wing works right? So visualize.....air coming in from the TB at high speed. In front of it...on end....you have a bar with a half moon profile. Its straight on to the airflow in the most aerodynamic method possible....the flat side facing the runners...the curved side facing the front of thee car (this is a 1.7L plenum). When the air hits this bar....just like a wing.....because the curved side has longer surface area than the flat bottom....as the air comes off the back side....it will make a left had turn just like off the back of a wing.

By angling this bar in the other axes you can literally steer the air plume. In fact...these could probably be used to actually cause the air to make 90* turns into the plenum without scoops.

A lot of this I played with back in the mid to late 90's when one of the shops I worked in in Dallas had everything from regenerative blowers, smoke generator and anemometers and lots of other toys...and we had the run of the shop at night. At one point I had some black and white scope shots inside of a 1.7: plenum with on a running engine....with smoke coming in the intake.
I can still see the picture of that "knot" of turbulence in the plenum in my head.

Before I do any of this again...I need to finis my current build and recreate the tools to test with. Ray

[scottdownsouth]

Tried to get the shop cleaned out and such but the rains came down and put a damper on my progress.
Figure I'd make a need list of the things I'll need.
Fuel pump.
New injectors
TPS
Fuel Pressure regulator
Figure out how I'm going to wire all this up and make it work.
Am I missing anything?