# Motronic 2.9 on a full jh- economy build



## blown020 (Jan 9, 2009)

Lately I've had this horrible idea of shooting for a solid 40 mpg out of my rabbit and I've entertained multiple ideas. First I almost picked up a full 1.6td but wasn't willing to spend upwards of 900 for all the motor and necessary tune up parts. Second was swapping in a full aba with a "O" grind cam but then decided against, since my JH has a fresh rebuild. 
So here's the plan. 
OBD1 Motronic 2.9 on the jh, using obd1 engine harness and all necessary electronics. The distributor guts will be swapped over to the "short block" distributor housing.
I'll be using a 60-2 trigger wheel from 034 most likely. Maybe crespo, still undecided. 
I'm going to be speaking with TT to see if they can burn me a chip for the motor since I'll be running a "K" grind since the goal is to make a gas sipping torque setup and 8v's chug down gas when you're revving them past 7200 rpm when running a big cam










So yes, I'm finally decided on the direction for EFI on my motor. 
In addition to the fuel management change, I will be figuring out a simple belly pan, but at the moment the switch to REAL EFI is the first priority. 
I'll be posting updates as they come. Sourcing parts at the moment. 
The car:








And the last dyno with the 288 and stg.3 scientific rabbit manifold while I was having major, major fueling woes with CIS
http://www.youtube.com/watch?v...lated



_Modified by blown020 at 3:45 AM 6-25-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*

Interesting... I likey... 
my goals on my little gas sipper (on CIS-Lambda







) is 40 City / 50 Highway... I'm already hitting 30 / 43.. and thats on Colorado roads, where NOTHING is flat


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## blown020 (Jan 9, 2009)

*Re: FV-QR (Southcross)*

I'm seeing 41mpg on the highway when Cruising, and that's with a 288, but I want to see more than that. We'll see what happens.


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## ziddey (Apr 16, 2006)

*Re: FV-QR (blown020)*

if i could do 41mpg while raping it on the highway, i'd have a field day. tell me to go 55 and practice hypermiling? f that


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *ziddey* »_if i could do 41mpg while raping it on the highway, i'd have a field day. tell me to go 55 and practice hypermiling? f that

then buy a TDI


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## ziddey (Apr 16, 2006)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_then buy a TDI








I know, right? With diesel here being 20 cents cheaper than 87e10, not to mention there being a "biofuel oasis" here


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## blown020 (Jan 9, 2009)

*Re: FV-QR (ziddey)*

There is no way in hell I'm buying a TDI. Sorry, let me correct myself. There is no way in hell I can afford a TDI









Again, this is a project thread to see how much mileage I can get while not spending more than 350 to 400 dollars. http://****************.com/smile/emthup.gif 

Get this diesel talk outta here, for now.


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## Southcross (Jul 2, 2004)

*FV-QR*

I'm perfectly happy hypermiling my bunny... if I wanted a car to romp on, I choose my GTI or my Dasher that reason


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## Prof315 (Jan 5, 2009)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*


_Quote, originally posted by *blown020* »_Lately I've had this horrible idea of shooting for a solid 40 mpg out of my rabbit and I've entertained multiple ideas. First I almost picked up a full 1.6td but wasn't willing to spend upwards of 900 for all the motor and necessary tune up parts. Second was swapping in a full aba with a "O" grind cam but then decided against, since my JH has a fresh rebuild. 
So here's the plan. 
OBD1 Motronic 2.9 on the jh, using obd1 engine harness and all necessary electronics. The distributor guts will be swapped over to the "short block" distributor housing.
I'll be using a 60-2 trigger wheel from 034 most likely. Maybe crespo, still undecided. 
I'm going to be speaking with TT to see if they can burn me a chip for the motor since I'll be running a "K" grind since the goal is to make a gas sipping torque setup and 8v's chug down gas when you're revving them past 7200 rpm when running a big cam









So yes, I'm finally decided on the direction for EFI on my motor. 
In addition to the fuel management change, I will be figuring out a simple belly pan, but at the moment the switch to REAL EFI is the first priority. 
I'll be posting updates as they come. Sourcing parts at the moment. 
The car:








And the last dyno with the 288 and stg.3 scientific rabbit manifold while I was having major, major fueling woes with CIS
http://www.youtube.com/watch?v...lated

_Modified by blown020 at 3:45 AM 6-25-2009_

Your mileage will still be in the crapper when you press the loud pedal. OBD1 Motronic (or is it moronic?







) goes pig fat (11 to 1 or worse afr) at 70% tps and up. And you can't chip it out, been there done that. A Megasquirt 2 will cost less and be far more flexible. We had a customer who spent $900 on chips trying to get around the wide open enrichment before we megasquirted him


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## Southcross (Jul 2, 2004)

*FV-QR*

could always block the TB from achieving more than 65%


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## blown020 (Jan 9, 2009)

*Re: FV-QR (Southcross)*

At this point, after talking to t3bunny, it looks like I may be going with megasquirt. It's an option I've thought about, and chip tuning can get pricy, so who knows. 

Either way we'll be seeing 40mpg, hopefully more.


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## Southcross (Jul 2, 2004)

*FV-QR*

Do it on *CIS!!!!*








I need someone else to bounce ideas/plans against... someone with a similar car and FI method








Then again... we could still bounce ideas for improving MPGs outside of engine/FI mods


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## blown020 (Jan 9, 2009)

*Re: FV-QR (Southcross)*

I'm down to bounce around ideas. 

Have you seen the use of widebands on cis?


_Modified by blown020 at 3:05 PM 6-25-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*

I've talked a few people through doing it







unfortunately, the only wideband setup I have is on my Turbo'd Dasher. I haven't set aside the funds for the daily to get one yet


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## blown020 (Jan 9, 2009)

*Re: FV-QR (blown020)*

Well holy ****. Things are looking up. 










Dropping the motronic 2.9 plan, but it seems like the goal has changed to 50mpg now and looks feasible.


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## blown020 (Jan 9, 2009)

*Re: FV-QR (blown020)*

Parts are piling up. Waiting on some parts from T3Brunny. 

Decided to keep the 288 in the car and go for 40mpg and hoping for more.


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## blown020 (Jan 9, 2009)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*

Stash of goodies. The ecu is in the possession of T3bunny since he's going through it just to make sure all is good. 
The lc1 is in the garage and all that's left for me to buy is some soft fuel line and some clamps. Can't wait to get this all in.


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## wantacad (Apr 4, 2003)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*

ooooooooooh pretty... http://****************.com/smile/emthup.gif


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## MaxVW (Nov 4, 2004)

wouldent using a 1.6 help out further?


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *MaxVW* »_wouldent using a 1.6 help out further?

small displacement + compression http://****************.com/smile/emthup.gif
why i love my little 1.7


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## blown020 (Jan 9, 2009)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*


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## blown020 (Jan 9, 2009)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*


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## ny_fam (Apr 3, 2004)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*

I'm interested in how those dyno runs were, and some feedback on how the combo 288 cam and stage 3 intake went.- recommendations for others running that combo?
I think the clipper kit from a cabby would add some aerodynamics to that brick. Greg Raven's VW performance book says something about them reducing the cars overall drag.


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## blown020 (Jan 9, 2009)

*Re: Motronic 2.9 on a full jh- economy build (ny_fam)*

The dyno went meh. I had some major fueling issues with CIS. One run went super lean, hovering around 15:1 and the other runs were pig rich around 11:1. 
As far as the manifold goes, I loved it. Would be awesome to see what it would be like with upped compression, but it really isn't what you want if you daily drive the car. Bottom end and midrange suffer quite a bit, but holy balls does the motor feel so much smoother and sound smoother too. I guess that's what happens when you port it out and equalize runner flow. Anyways, with my 288 and major fueling issues on 8.5:1 CR I made peak hp @ 6400 and then it flattened out, but you don't hit a wall. Just stays there. Torque was good,as well, but when I put a stock intake that's ported for a big tb (welded up on the back side too) the throttle responsive at the low end is much nicer. 
Either way, that stage 3 manifold was the ****. I freaking loved it but wasn't logical for a daily driven car, and neither is the 288, so that's why it's coming out. 
Plans are as follow. Swap in the stock cam sometime this week and just continue datalogging and tuning At some point I'll up the compression and keep the stock cam. Just want a nice torquey motor that idles well. I'll enjoy the more relaxed power band and still haul ass in the backroads


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## ny_fam (Apr 3, 2004)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*

Thanks for the info - Think the 288 is to much cam for 8.5:1 CR, could be part of the issue. I've only noticed below 2k power loss, but I was running higher compression at that time.


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## vwpat (Oct 25, 2000)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_small displacement + compression http://****************.com/smile/emthup.gif
why i love my little 1.7









 bore and compression are same on 1,6 and 1,7. The 1,7s longer stroke should get better mileage. I want to run my 1,7 Heron (Heron head, 9,5:1, G grind cam) on Digi I and see how it does.


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## snowfox (Apr 4, 2002)

*Re: Motronic 2.9 on a full jh- economy build (blown020)*


_Quote, originally posted by *blown020* »_The dyno went meh. 

Charts please.


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *vwpat* »_ bore and compression are same on 1,6 and 1,7. The 1,7s longer stroke should get better mileage. I want to run my 1,7 Heron (Heron head, 9,5:1, G grind cam) on Digi I and see how it does.


compression is 2 tenths higher on the 1.7 because of the longer stroke







but otherwise, same pistons/block/head/etc... a 1.7 Heron would be over 10:1, as compared to the "stock" 1.6 Heron


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## vwpat (Oct 25, 2000)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_
compression is 2 tenths higher on the 1.7 because of the longer stroke







but otherwise, same pistons/block/head/etc... a 1.7 Heron would be over 10:1, as compared to the "stock" 1.6 Heron
1,6s come in 8 or 8,2:1 (hard to believe there are actually two pistons though), the 1.7 is 8,2:1 not from the longer stroke but maybe from the increased cylinder displacement. The 1,7 pistons have a 3,2 mm less compression height to compensate for the 6,4 mm longer stroke. If you stuck 1,6 pistons on a 1,7 crank you gain quite a bit more than 0,2 points.







I have. I have the correct compression height pistons for a 1,7 crank so I still have 9,5:1. 1,7 block does have more clearancing inside but for all practical purposes they will interchange.


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## secondgen (Jan 9, 2004)

*Re: FV-QR (vwpat)*

FWIW, the last iteration of my coupe motor with a TT276 and Scientici rabit manifodl on Megasquirt, with nothing other than street tune on it, got 39MPG doing 85mph the whole way back from H20i last year...
I won't even rub in what my diesel gets for mpg...lol


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## secondgen (Jan 9, 2004)

*Re: FV-QR (blown020)*

I've got 16V bunny that's going to get similar treatment....


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## wantacad (Apr 4, 2003)

*Re: FV-QR (secondgen)*


_Quote, originally posted by *secondgen* »_FWIW, the last iteration of my coupe motor with a TT276 and Scientici rabit manifodl on Megasquirt, with nothing other than street tune on it, got 39MPG doing 85mph the whole way back from H20i last year...


intresting....


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## blown020 (Jan 9, 2009)

*Re: FV-QR (wantacad)*


_Quote, originally posted by *wantacad* »_
intresting....

Long 5th gear and mk2 aerodynamics will do that


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## secondgen (Jan 9, 2004)

*Re: FV-QR (blown020)*


_Quote, originally posted by *blown020* »_
Long 5th gear and mk2 aerodynamics will do that

No low 5th on that trip. Had a 2Y tranny in it. Was spinning in the 4k RPM range.


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## wantacad (Apr 4, 2003)

*Re: FV-QR (secondgen)*


_Quote, originally posted by *secondgen* »_
No low 5th on that trip. Had a 2Y tranny in it. Was spinning in the 4k RPM range.









That's even more interesting. http://****************.com/smile/emthup.gif 
My winter goal is pretty close I guess. 2.0 ABA, TT 276, megasquirt and a 7a tranny. (.71 5th.)







in a MKI. 

Figured it would yield decent power and good MPG's. Seeing your results give me hope.


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## secondgen (Jan 9, 2004)

*Re: FV-QR (wantacad)*


_Quote, originally posted by *wantacad* »_
That's even more interesting. http://****************.com/smile/emthup.gif 
My winter goal is pretty close I guess. 2.0 ABA, TT 276, megasquirt and a 7a tranny. (.71 5th.)







in a MKI. 

Figured it would yield decent power and good MPG's. Seeing your results give me hope. 


I should mention, it was leaned WAY out. 17.8-18.2:1 AFR no knock or pinging ~10:1 CR very light throttle only, as soon as you went in the throttle more, , it richened up. Love Megasquirt.


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## blown020 (Jan 9, 2009)

*Re: FV-QR (secondgen)*

That's the nice thing about stock gearing. With the longer fifth, it gets very finicky since part throttle at 3000 rpm in the city is also your cruising speed with a long fifth. 
I got it runnng last week and still tuning, but almost got it worked out so there's no lean surges or flat spots.


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## secondgen (Jan 9, 2004)

*Re: FV-QR (blown020)*

http://****************.com/smile/emthup.gif


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## BladesNet (Mar 29, 2001)

*Re: FV-QR (secondgen)*


_Quote, originally posted by *secondgen* »_FWIW, the last iteration of my coupe motor with a TT276 and Scientici rabit manifodl on Megasquirt, with nothing other than street tune on it, got 39MPG doing 85mph the whole way back from H20i last year...
I won't even rub in what my diesel gets for mpg...lol

Those 8v can handle some massive timing advance








92 Cabby, --> top down <-- , 65mph all day, stock 1.8 8v 2H engine, AUG transmission (65mph @ 3100rpm), usually did 38mpg ! I had the timing pretty advanced on it. Hoping to do even better with an ABA engine on digi-2. If it doesn't, going back the old 1.8 (rebuild !)


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## secondgen (Jan 9, 2004)

*FV-QR*


_Quote, originally posted by *BladesNet* »_
Those 8v can handle some massive timing advance








92 Cabby, --> top down <-- , 65mph all day, stock 1.8 8v 2H engine, AUG transmission (65mph @ 3100rpm), usually did 38mpg ! I had the timing pretty advanced on it. Hoping to do even better with an ABA engine on digi-2. If it doesn't, going back the old 1.8 (rebuild !)


Sad part was, I wasn't even running that much timing. Was maybe 28-32* advanced. I'd have to pull the map up and look....


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## blown020 (Jan 9, 2009)

*Re: FV-QR (secondgen)*

woopsies, I just threw my stock cam in the recycling. I guess that leaves me with only the 288


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## ny_fam (Apr 3, 2004)

*Re: FV-QR (BladesNet)*

How is your engine temps with all that timing? and leaner fuel mix.


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## BladesNet (Mar 29, 2001)

*Re: FV-QR (ny_fam)*


_Quote, originally posted by *ny_fam* »_How is your engine temps with all that timing? and leaner fuel mix.

With digifant-2, how about .... bad ! Fan often kicked in on the highway and stayed on in the city. Oil temps close to 120 C on the gauge in the Cabriolet (gauges are in Celcius and bars in Canada)
Maybe I helped kill that 1.8










_Modified by BladesNet at 10:37 AM 8-8-2009_


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## secondgen (Jan 9, 2004)

*Re: FV-QR (BladesNet)*

My setup ran fine with the rocco 1 radiator, and stock tstat, 180* fan switch. Rarely got over 200*F


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## blown020 (Jan 9, 2009)

*Re: FV-QR (secondgen)*

So here's an update for everyone. 
Still waiting on the air dam to come in. Filed a dispute to see if they get off their ass and ship the part. Filing a claim tomorrow if i haven't recieved a tracking number by then. 
Now the important stuff. The car is running well. Still tinkering a bit with fueling, but the rest is pretty good. Having some pinging at low rpm, high load 5th gear nonsense so I'll pull some timing from that area but then it'll be almost set. 
I picked up some brake duct hose from a local race shop in hopes of bringing air temps down. For the time being I'm not running a scoop for it, but it's already working astonishingly well. Comparing the data logs from previous drives, I've been able to drop the air temps around 15 degrees when the car is moving. eek: That's a huge drop and hopefully it'll drop a bit more once I get the duct set up behind the grille. Instead of pulling air from behind the radiator like the stock setup, I'm now pulling it directly from the grille. :
I'll get better pictures of the setup in the daytime, but for now these'll do. 
Here you see the hose meeting the factory scirocco lower box








Here you see how it comes up and reaches the grille









Nex part to the project is setting up Viatrack's KnockSenseMS setup. It's something that I've been wanting to get ever since I started thinking of megasquirt, and after yesterdays little pinging nonsense, I need it. 
An official before and after (mind you I still need to finish the wiring harness, once the knocksense goes in)
Then








Now








:tip:


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## wantacad (Apr 4, 2003)

*Re: FV-QR (blown020)*

Any thoughts of switching to a mk2 intake mani so you can put your airbox on that side and not have to run your fresh air hose across?
or are you just going to reroute the hose when the air dam comes in?

or should I just keep my trap shut and go to bed since it is 5 am.


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## blown020 (Jan 9, 2009)

*Re: FV-QR (wantacad)*

I'm planning on keeping the air hose where it's at for now. It's not in the way of anything and it runs across the core support, so it's fine.
I'm going to keep the rabbit intake setup. The mk1 cis manifolds flow better than the mk2 manifolds. 
I may just cut a hole on the duckbill and have the hose pull air from there and then cut another hole with a dual outlet scoop for the brakes, but this is only if the airdam ends up being a scam. 

Time for bed for me as well. 3am out here.








edited for not being able to spell right now. 


_Modified by blown020 at 3:24 AM 8-15-2009_


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## blown020 (Jan 9, 2009)

*Re: FV-QR (secondgen)*

Quick update. Switched back to stock cam (w grind) and wow, I missed the torque. Still doing some tweeking on the fuel maps every so often, but the car is running really well. Haven't really checked what mileage I'm getting since I haven't driven the car that much lately cause of school, but if my calculations from the other day are right, I'm getting roughly 45mpg on the highway driving about 75 mph. I drove 100 miles on the freeway and another 15 of city and only used a quarter tank according to the fuel gauge (it's probably lying though). So, best case scenario, I'm getting mid 40's right now not driving like a grandma. Worst case, I'm around 38 ish. 

Mounted the vestatec airdam. The wind noise dropped dramatically after mounting the airdam. It's also feels like it cuts through headwinds much better now. Very nice addition. 








Picked this up. Brand new for 75 shipped







I just mounted them today so I'm very interested in what change they will bring. I heard they cut down on wind noise and help with the aero package.
















Thinking about cleaning the car later and taking some better pictures.


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## wantacad (Apr 4, 2003)

*Re: FV-QR (blown020)*

nice... http://****************.com/smile/emthup.gif


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## ziddey (Apr 16, 2006)

*Re: FV-QR (blown020)*

45mpg.. dang. you got me hurtin for a squirtin


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## blown020 (Jan 9, 2009)

*Re: FV-QR (ziddey)*

45 mpg if the fuel gauge isn't lying. 

Check out this thread as well. It's one that I started on the mk1 forums and there's a lot of good info in there as well. Definitely worth a read. 
Regarding the a pillar fairings. wow. That's all I can say. The combination of the air dam and the a pillar fairings have helped dramatically with controlling wind noise inside the cabin, which in turn means better aero package









I tested them up to 80mph on the highway and the reduction in noise is amazing. Oh, and they're on a non rope in windshield with no extra adhesives and they didn't fly off. Thanks to which ever one of the previous owners that replaced the windshield and had them put on the thicker rubber trim around the window. 

Keep in mind that even though I'm tuning for mileage, it doesn't mean I don't want to enjoy my car. The car feels faster than when it was on cis and gets better mileage. The 'downgrade' to the stock cam was actually a great upgrade. The car feels more powerful. I think the combination of a big cam and the low compression of the jh makes a combination that isn't all that great. The Dynamic Compression drops substantially and makes it not so fun to drive. Definitely learned a lesson on that one. 



_Modified by blown020 at 3:51 PM 9-6-2009_


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## wantacad (Apr 4, 2003)

*Re: FV-QR (blown020)*

you had a 288 in right? wonder if there is a happy medium with like a G, N, or K grind or 268?








Really wish it was springtime then i could be doing the same *sigh*


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## blown020 (Jan 9, 2009)

*Re: FV-QR (wantacad)*

I've gone from w grind (stock gti) to tt 272 to a 288. All on cis. Out of all those, if you're low compression, I would stick to a w grind. 
From the ones you listed, I think G grind or 268 at the most. 272 is a happy medium, but you still do lose a lot of that low end torque. 
My personal opinion from cams that I have used.


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