Ok Motorheads,

Senerio:
New 2056, Slightly more aggressive than stock Isky VP-228 cam, ported 5pt heads with '74 2.0 D-Jetronics. Crane xr700 009 dizzy. Burch exhaust through SSI HX'ers

Question:
What would be some tricks and tips to make this engine more efficient.

I thought of having the MPS adjusted for a 2056, read that somewhere. Would like to put an oil cooler in most likely.

What else would be things to concider. The engine is in boxes ready to assemble.

Please chime in

Joe D

Lets start here.

Go with a Jake cam. PERIOD.
Reason: You will absolutely know you have a cam AND A MATCHING SET OF LIFTERS THAT WON'T GO FLAT. This is also a proven cam/lifter combo for the factory FI.

Balance the entire reciprocating assembly.

Get your heads checked and machined by a Type IV pro.

Get your block, cylinders, pistons, pins, rings (end gap), machined and checked out by a Type IV pro.

Use Jakes double thrust cam bearing.

You probably wont need and oil cooler. But it never hurts to add one.

I could go on forever.....

OR: Buy a Jake kit and be done with it.

Whats your budget????

Clayton

Budget? That's funny. I have a 2563 78.4mm CC chevy journaled x 102mm nicacil cans, short skirt pistons, A re formed combustion chambered highly modified 2.0 heads with nailhead valves, custom Isky valvetrainan"ACT turnkey SDS FI system. Parts will be cryoed and coated. MDS/Jacobs ignition engine in the works. Tell me about a budget.

The 2056 will be balanced locally, the stock 2.0 heads were done by Rimco.

If there is something in this little beater engine as far as low grade mods I'd still like to know.

Really like to get rid of both of them and by an electric motor kit from http://www.electroauto.com/catalog/kits.shtml#voltsporsche

Get the 9550 cam/lifter set from Jake and then you can run the Djet plus have 115hp.

Yep the MPS needs to be adjusted, someone on this BBS does it.

Dunno how the Djet works with a 009 dizzy since it doesn't have trigger points.

Isnt the 914 dizzy a 009? It has tpts

I had no idea you knew about engines... YEA...!!!!!!!

I am guessing at this point.... You know more about Type IVs than most of the fellas here. You have been there done that....

So give me some help here.

What data do you need that you don't already have?





AND:

How does your stroker motor run? Who built it? And how big is the grin on your face when you stab the throttle?

If ya ever sell it... Keep me in mind.....

Cheers,

Clayton

Well djet is not really adventageous to use for ultimate performance but in this case its all its gunna get. I was amazed that you could teak the MPS so I was wondering what other tweaks there could be.

Factory D-Jet dizzy for 2.0 ends in 009 to add to the confusion. It cannot be mistaken though, it does have the trigger points.

Hey Joe! So is that my distributor?

I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season.

The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well......

I have no regrets in going with Isky.

Good luck with the engine... Jim

Ha ha no yours is sitting near Kevins MPS in the garage. Are you still in the Denver area? LOL

Bump the fuel pressure up. My 2270 with djet and a mild web-cam runs 37 psi with stock regulator adjusted. Leave the MPS alone. Put a resistor in line with the head sensor to trick the brain into thinking its colder than it is. I put an 02 sensor in my exhaust with a monitor that I built off Pelican parts to dial it in on the road. I ended somewhere about 425 ohms to get right mixture. Dyno test showed go A/F mixture throughout the rpm band.

Oh, check the throttle position sensor for your miss. It is posible the tracks may be worn as the arm sweeps across them as the throttle opens.

Wow Jim, Your the man. I've got to study up on all you said. It's over my head right now, but I'm gunna learn that stuff. Mind if I pick your brain in time? Joe

Trying to learn about engines, as I might be doing a 2056 myself. What does MPS mean??

Thanks


-Peter

If you'd come out once in a while you'd know!

Come to the swap next Saturday and bring it with you.
Dart Auto 9am-1pm, 3/24/2007
Google Maps to Dart Auto, Commerce City
www.dartauto.com

I have to work on TLB next Sat/Sunday finally, The place is off I70 on Brighton, but I can meet before 10am............

Manifold Pressure Sensor

Hey Joe
have you been hibernating?

You might say that Greg. Acually hibernating would have been better. But the sun started shining again.

Sure, but it'll be a two-way exchange. I'm still putting some of this together in my own head, so I'll look forward to learning from what you're doing.

You see, I'm just a humble 914 hobbiest. I don't have all the answers, but I'm a fast learner, a pretty good engineer, and I'm not stupid. I'll warn you though- some of my ideas go against the accepted conventions around here! Makes it fun!

[/quote]
Sure, but it'll be a two-way exchange. I'm still putting some of this together in my own head, so I'll look forward to learning from what you're doing.

You see, I'm just a humble 914 hobbiest. I don't have all the answers, but I'm a fast learner, a pretty good engineer, and I'm not stupid. I'll warn you though- some of my ideas go against the accepted conventions around here! Makes it fun!
[/quote]

Now thats the good OLD American way. My pleasure.

Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doeable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's.

[quote name='Bleyseng' date='Mar 19 2007, 12:18 AM' post='876619']
[quote name='jk76.914' post='876526' date='Mar 18 2007, 09:04 PM']
I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season.

The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well......

I have no regrets in going with Isky.

Good luck with the engine... Jim
[/quote]
Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doeable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's.
[/quote]
[/quote]
Its much easier to adjust the MPS for the correct AFR using the inner, outer screw and the WOT end plug. The stock injectors have plenty of fuel flow to handle it. The 2270 might be tough be still doable depending on the cam. I have never used the Isky cams, I just know how much research was done by Raby to perfect his cam and lifter face grinds to stop the excessive wear and early death caused by the changing of the oil formula's.
[/quote]

I thought I saw a post somewhere that you have to put constant WC pressure on it turn on screw than a nut. I'll have to find that again. Sounds like lots of tool bench preparation. But worth it, if I don't fkit it up. Nice to know the adventurous geniuses out there already figured these things out.

Thanx Geoff




Do we posses the 914 or does the 914 posses us????????....LOL

Jim

Actually, this is exactly one of the adjustments you can make to the MPS. The stock MPS has the diaphragm come off of the part-load stop at about 6 inHg. That adjustment is set with the so-called outer screw. You can set this to a larger value to get it to start the enrichment sooner. With my 2056, I experimented with this and ended up adjusting my MPS to come off of the part-load stop at 9 inHg for earlier enrichment just like you are talking about.

Here are some posts that you might find interesting:

part 1

part 2

Demick

I have a 2056 with D-Jet. I know nothing about it, but am trying to be a sponge so I can get the most out of the setup.

I was just going to comment the same thing that Demick posted, that you can adjust the transition point from 6 inHg to a lower level to get the transition to full-load to come in earlier.

BTW, many of you are using the figures from my articles on the MPS, be aware that from recent testing I've done on several NOS OEM (non-rebuilt) MPS's of the same part number, that there are significant differences in the full-load mixture and transition point even within the same part number. Bosch didn't do the greatest job of calibrating these units precisely, so these numbers aren't etched in stone.

It's too bad that Porsche or Bosch never published the model-by-model calibration settings for D-Jet. I've tried to get this info from Bosch in the past to no avail....

Hey, Demick, your vacuum chart in the postings you reference is great, I haven't seen that before. I'm going to be doing the same on my freshly-rebuilt motor in the near future.

Demick did you do all your adjustments with the MPS on the bench..?

did you do some fine tuning on the car?

I will need to do this soon.

Demick, I read those postings of your tuning efforts on your 2056, you've done some good tuning. I think you'd get it better if you looked at the situation differently. Remember that D-Jet is a speed-density type of FI system. The "density" part is what the MPS is responsible for, that is, measuring the intake air density (i.e. manifold vacuum level). The "speed" part is what the trigger contact points do, which is to determine the engine speed so that the mixture can be corrected for the pumping efficiency curve (the "volumetric efficiency", or VE curve) of the particular engine.

By changing the cam and the displacement of the engine, you've changed the VE curve, and you're trying to use the "density" component, the MPS, to compensate. What you really need to do is to modify the VE circuit in the ECU to accomodate the new cam's effect. This is easier said than done - the ECU does this compensation by "OR'ing" four or five waveform generators together to achieve an overall compensation characteristic. You'd need to experiment with changing the components (resistors and capacitors) to get the desired effect - AND - you'd need to know what the effect of your new cam and displacement were on the stock VE curve to know which waveform generators to modify. The discussion on this circuit is in my ECU page.

Brad

I'm sure you are correct in your assessment. But modifying the ECU (or even understanding it) is wayyyyyy beyond my abilities. I am a mechanical engineer - so the MPS being a (mostly) mechanical device is something I can handle and understand.

But my motor runs beautifully with the modifications that I made, plus I get 20% better fuel economy as well. So I have no complaints.

Demick

Dan

I wrote this to you in another post awhile back, but I guess you didn't see it:

Hey, if you're happy with how it runs, that's really all that matters! And I haven't taken on the task of modifying the speed control circuit, either. I need to look at the Megasquirt manual some time and learn more about tuning a speed-density FI system, perhaps there are some good techniques we could apply to D-Jet to cover both the MPS and speed correction tuning.