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914World.com _ 914World Garage _ big engine build
Posted by: 02loftsmoor Dec 23 2012, 04:27 PM
Every one said to keep you orginal engine stock,,So I bought a shortblock, I have a 2.0 crank lined up with rods, an 11lb flywheel and 2.0 heads. I was looking at useing 103mm cylinders. Is the D-tronic able to handle the larger bore???
my D-tronic if from my 1.7
Wes
Posted by: kg6dxn Dec 23 2012, 05:44 PM
Do you want it to run? or run well? I don't think the factory system can compensate for an extra 300cc's. Too many variables (more than extra CC's) for a "dumb" FI system to handle.
In my opinion, you would be better off going to programmable fuel injection.
Posted by: 76-914 Dec 23 2012, 06:02 PM
if you have yellow injectors you'll need to change to green. you will need an A/F gauge installed to adjust (fatten) your MPS.
Posted by: r_towle Dec 23 2012, 06:06 PM
Yes, it works with adjustment to the mps.
Rich
Posted by: Jeff Bowlsby Dec 23 2012, 07:20 PM
I dont know how big that is but I thought there was general consensus that 2056 was the biggest reasonable size for stock Djet?
Posted by: 02loftsmoor Dec 23 2012, 08:14 PM
2366cc
I dont know how big that is but I thought there was general consensus that 2056 was the biggest reasonable size for stock Djet?
Posted by: 02loftsmoor Dec 23 2012, 08:16 PM
help me here,, MPS??
Posted by: messix Dec 23 2012, 08:50 PM
manifold pressure sensor
Posted by: kg6dxn Dec 23 2012, 09:12 PM
2366cc
I dont know how big that is but I thought there was general consensus that 2056 was the biggest reasonable size for stock Djet?
I do not think you can run a 2.36L on the stock injection system. It is just too antiquated for such large displacement.
You might be able to modify a mechanical system from a Rabbit to work but that won't be easy either.
I think carbs or Megasquirt is in your future.
Posted by: messix Dec 23 2012, 09:25 PM
go l-jet
many many aplications out there to build a system that will work
Posted by: 02loftsmoor Dec 23 2012, 09:44 PM
Never heard of I-Jet Mega squirt yes
go l-jet
many many aplications out there to build a system that will work
Posted by: messix Dec 23 2012, 09:46 PM
Never heard of I-Jet Mega squirt yes
go l-jet
many many aplications out there to build a system that will work
l= small L
not i or I
Posted by: ConeDodger Dec 23 2012, 09:47 PM
In my opinion it can be done but the compromises in driveability aren't worth the trouble.
Posted by: kg6dxn Dec 23 2012, 09:52 PM
In my opinion it can be done but the compromises in driveability aren't worth the trouble.
Exactly! Which is why I first asked... "Do you want it to run? or run well?" Two different ways to drive.
There is nothing factory that you can just "bolt on" and go. Even if you can source enough L-Jet parts from various make and models, the money, frustration and time spent won't be worth it.
CB Performance has a programmable system for around $1700. Or McMark can build you a bolt on kit.
Posted by: 02loftsmoor Dec 23 2012, 10:24 PM
I may have to rethink this,, I have been reading up on the Mega squirt, is seems full of bugs, but what what I've been reading they may not fully understand the system,.
Posted by: kg6dxn Dec 23 2012, 11:30 PM
I may have to rethink this,, I have been reading up on the Mega squirt, is seems full of bugs, but what what I've been reading they may not fully understand the system,.
It's not full of bugs but you do need to understand tuning principals. Each engine, even if setup identically will need a slightly different tune. Most newer EFI systems have some sort of self tuning ability. But you need the basic tune to be close for it to work.
Find a tuner in your area and see what EFI system they specialize in. A Dyno and some tuning time is all you need for good running and HP.
Posted by: r_towle Dec 24 2012, 08:27 PM
i will say it again.
it works with djet.
the injectors for the 2.0 liter support the 2.4 motor (71*103)
The mps needs to be tuned while driving, at idle, and under load.
But, the 'consensus' that is does not work is a disproven rumor.
rich
Posted by: Vacca Rabite Dec 24 2012, 08:48 PM
Rich, I don't doubt that it works.
I just doubt that it works well.
There is going to be a lot of heat soak with 103s.
Keeping the heads cool is going to be a challenge.
It might make a great AX engine, where heat is not as much of a concern as the run is only 1 minute or so and you only run 5 or 6 times a day. I was thinking about doing exactly that with the race car Scott and Mike and I were going to build - but that car would not have been street legal. Making the engine drive to the event and back w/o overheating would get expensive I bet.
Zach
Posted by: ConeDodger Dec 25 2012, 12:35 AM
Rich, I don't doubt that it works.
I just doubt that it works well.
There is going to be a lot of heat soak with 103s.
Keeping the heads cool is going to be a challenge.
It might make a great AX engine, where heat is not as much of a concern as the run is only 1 minute or so and you only run 5 or 6 times a day. I was thinking about doing exactly that with the race car Scott and Mike and I were going to build - but that car would not have been street legal. Making the engine drive to the event and back w/o overheating would get expensive I bet.
Zach
My point is that the LJet is much more flexible and in my opinion less fragile than DJet. Before Chris Foley you couldn't pray for a decent MPS. You can easily get a AFM rebuilt...
Posted by: r_towle Dec 25 2012, 04:46 PM
It works fine.
No heat issues, nothing dramatic nor complicated making it work just fine.
Is there more hp to seek out with carbs and a camshaft, sure there is.
Then you have heat issues.
For a very fun, and cheap fast motor, 71 * 103 will put a big smile on your face and with the same stroke, the injection functions just fine.
Have any of you guys with custom motors driven 10k miles yet?
It's really a simple build that has been done for over 30 years.
No complexity nor added stress from a longer stroke...which does add new stress.
Don't believe me, call and ask FAT performance.
Rich
Posted by: r_towle Dec 25 2012, 04:57 PM
Btw, from experience.
48/38 is a high revving track motor, not so great around town.
46/38 is a sweet setup that you can wind up till the valves float
44/38 is a nice tame version that runs nice.
Spend the money on a nice valve job, and port the 44/38 setup and you will love the motor.
This is probably the best setup for all around use, decent port velocity and its cheap fun...no special case work aside from milling out for the jugs.
No need for external oil cooler unless you are on the track only...for street and autos, it's fine with the stock setup.
Again, being a CSOB, I don't think trying to get more than 180 hp out of a type 4 motor makes to much sense to me....it starts to cost a lot more money right about 180 or more.
That is really plenty of reasonably priced fun with a 914
Posted by: CG-914 Dec 28 2012, 07:30 PM
To the over heating topic:
I do agree with rich
Heat is caused by compression not bore!
What I'd like to know is, what cam are you planing to run?
Would the 9550 still work?
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