Will 2.4 L engine work with stock FI, Will stock FI work with a larger bore engine Options

[reharvey]

I'm getting ready to build a 2.0 engine for my latest 914 project. I've put together several of these motors in the past but have always used the Euro type Mahle 94mm pistons. How big of a piston can I use and still retain the FI. I can make minor modification to the FI if need be. I've done this in the past. Has anyone out there try this?

[realred914]

I'm getting ready to build a 2.0 engine for my latest 914 project. I've put together several of these motors in the past but have always used the Euro type Mahle 94mm pistons. How big of a piston can I use and still retain the FI. I can make minor modification to the FI if need be. I've done this in the past. Has anyone out there try this?

ive been told that thebig bore 2056 cc motor (96 mm pistons, stock strck
) is about thelimit for stock 2.0liter d-jet tweeks of the pressure sendor will be required to run the 96mm pistons.

[orange914]

NOOOOOOOOOO

[orange914]

oh (IMG:style_emoticons/default/welcome.png)

2056 with MPS modification is about the limit to a 2.0 d-jet

[Chris Pincetich]

Maybe Andy will chime in. He has a very nice red 914 with 2.3 TIV and a tweaked D-Jet FI system. I know he did not build it himself. He uses it for cruising and AX racin and was always happy w it when I saw him (IMG:style_emoticons/default/beerchug.gif)

[reharvey]

Maybe Andy will chime in. He has a very nice red 914 with 2.3 TIV and a tweaked D-Jet FI system. I know he did not build it himself. He uses it for cruising and AX racin and was always happy w it when I saw him (IMG:style_emoticons/default/beerchug.gif)

I would like to hear from Andy or anyone that has tried this mod. Thanks, Ray

[r_towle]

Yes it works.
Keep the stroke the same, 71mm and put in the 103mm jugs.
Keep the camshaft the same...
You can change the heads to 46/38mm valves for a bit more flow.
You will need to tune the MPS.

It works.

Rich

[reharvey]

Yes it works.
Keep the stroke the same, 71mm and put in the 103mm jugs.
Keep the camshaft the same...
You can change the heads to 46/38mm valves for a bit more flow.
You will need to tune the MPS.

It works.

Rich

Thanks for the info Rich. I was sure someone has done this. Just wanted as much input as possible from other 914 owners before going ahead with this rebuild. Thanks, Ray

[VaccaRabite]

since you are increasing displacement by nearly 1/2 a liter, don't you need bigger injectors?

Zach

[reharvey]

since you are increasing displacement by nearly 1/2 a liter, don't you need bigger injectors?

Zach

Will increasing the fuel pressure provide the extra gas that would be needed?

[r_towle]

You cant change the type of manifold pressure (short stroke and stock overlap) but you can change the volume.

You will need a way to tune your mps when you are ready.

Rich

[reharvey]

You cant change the type of manifold pressure (short stroke and stock overlap) but you can change the volume.

You will need a way to tune your mps when you are ready.

Rich

I've tuned the MPS on several of my other cars so that's not a problem. Just hoping that the end result will give more go power without any major glitchs with the FI. Some people would just put on carbs but I've kept the FI on all of my 914s because it works so well.

[johannes]

Then Jake Raby will come in and tell you 2056 is the limit ...

Welcome in the arena ...

The french guy ...

[r_towle]

You cant change the type of manifold pressure (short stroke and stock overlap) but you can change the volume.

You will need a way to tune your mps when you are ready.

Rich

I've tuned the MPS on several of my other cars so that's not a problem. Just hoping that the end result will give more go power without any major glitchs with the FI. Some people would just put on carbs but I've kept the FI on all of my 914s because it works so well.

150-165 hp is the max D-jet really....and that would be with a 9.5:1 CR....
If you do that, its gonna get hot, so plan for the heat.

Manfold pressure is how drag racers use fuel injection, so there really is not an upper limit....but with our Djet you are dealing with fixed air/fuel maps that are hard coded.

You can use aftemarket FI and get alot better results, but you can also restrict the build to use Djet and that can be fun.

Same cam is the key. And that really sucks, but thems is the facts.
Same stroke is the key.

This leaves alot on the table for potential HP. but its still a fun car to drive
Get a header also...

Rich

[reharvey]

You cant change the type of manifold pressure (short stroke and stock overlap) but you can change the volume.

You will need a way to tune your mps when you are ready.

Rich

I've tuned the MPS on several of my other cars so that's not a problem. Just hoping that the end result will give more go power without any major glitchs with the FI. Some people would just put on carbs but I've kept the FI on all of my 914s because it works so well.

150-165 hp is the max D-jet really....and that would be with a 9.5:1 CR....
If you do that, its gonna get hot, so plan for the heat.

Manfold pressure is how drag racers use fuel injection, so there really is not an upper limit....but with our Djet you are dealing with fixed air/fuel maps that are hard coded.

You can use aftemarket FI and get alot better results, but you can also restrict the build to use Djet and that can be fun.

Same cam is the key. And that really sucks, but thems is the facts.
Same stroke is the key.

This leaves alot on the table for potential HP. but its still a fun car to drive
Get a header also...

Rich

Speaking of camshafts-------------------------I've used Web-Cam grind #73 on two of my fuel injected cars with good results and plan to use one on this motor. Hoping to keep the CR at 8.5:1. And yes----I've read that it'll run a little hot.

[Brett W]

Why would you handicap the motor? I realize it is a little more money, but in the grand scheme of things, a more modern FI unit will make the car that much more enjoyable.

[Jake Raby]

There are really no limits in engine maniplation. The difference is what can SAFELY be done without losing the entire investment or creating an engine that does nothing well except idle. Been there..

Smart people won't try to build an efficient D jet engine above 2056cc, beyond that the compromises are great.
Projects that begin with compromise, end in demise.

[Krieger]

My engine is a 78 x 96 with a mild webcam for FI engines. It has been together and running extremely well for 10 years. I've been driving very hard at autocrosses for 8 years and it doesn't even leak a drop. And yes I built it! It does not run lean anywhere. No it does not make as much horsepower as Jakes, but it is a torqy SOB and it was probably less than 1/3 of the cost of his. I built this engine to pass smog and it did...barely. The compression is around 8.1:1 The fuel pressure is around 36 psi. Early 2.0 manifold pressure sensor/injectors (supposedly flow more gas and cheaper at the time). Stock rev limiter, larger or bored out throttle body. The big deal is to trick the brain into thinking its cold outside, so put a resistor inline with the head sensor. Mine took about 400 ohms resistance to accomplish this. I determined this with an O2 sensor in the exhaust and later it was checked on a chassis dyno. Do a search it has been discussed here before.

[reharvey]

My engine is a 78 x 96 with a mild webcam for FI engines. It has been together and running extremely well for 10 years. I've been driving very hard at autocrosses for 8 years and it doesn't even leak a drop. And yes I built it! It does not run lean anywhere. No it does not make as much horsepower as Jakes, but it is a torqy SOB and it was probably less than 1/3 of the cost of his. I built this engine to pass smog and it did...barely. The compression is around 8.1:1 The fuel pressure is around 36 psi. Early 2.0 manifold pressure sensor/injectors (supposedly flow more gas and cheaper at the time). Stock rev limiter, larger or bored out throttle body. The big deal is to trick the brain into thinking its cold outside, so put a resistor inline with the head sensor. Mine took about 400 ohms resistance to accomplish this. I determined this with an O2 sensor in the exhaust and later it was checked on a chassis dyno. Do a search it has been discussed here before.

Thanks for the info Andy. Everyone has been very helpful. Think I'll go with the 96mm pistons and use the Web-Cam grind # 73 that I've use in my other engine rebuilds. Nice to hear from someone who has put one of these together himself. Ray

[Chris Pincetich]

Of course Andy built it himself! (IMG:style_emoticons/default/headbang.gif)
One day, I will build one too. Just waiting for the 1.7 to kick the bucket. If I get from the AX track to Sears Pt big track this year, that should speed things up (IMG:style_emoticons/default/biggrin.gif)
(IMG:style_emoticons/default/driving.gif)