Duel carbs VS. Fuel injection, Whats the real deal Options

[Jaymann]

So whats the real story.What are the pro's and con's,I am working on a 1975 porsche 914 1.8L 4cyl. I am currentley using the stock fuel injection.I decided to start this project, by getting the car running back to stock.This car had been in storage since 1992.The gas tank was bone dry, and in perfect shape inside and out.I replaced all the fuel lines,filter,fuel pump.All the vacuum hoses,a bunch of gaskets and o-rings and stuff,chaged the oil,fiters etc,and did a complete tune up.
Now she runs ,and starts real nice.The car has very little rust at all anywhere,the motor runs very strong.This car has always been stored in a heated garage,and never driven in bad weather.My end goal is to have a car that is still street legal,but I can run at the track.So if I rebuild my motor and go from 76 h.p. to like 150 or 185hp can you still use the f.i. or do you need duel cabs at this point?I am not a mechanic, and this is my first 914.So please forgive me, if I ask any stupid questions.I am planning to run this engine for a while,she still has plenty of life left in her.I am just trying to figure out, what I want to do in the future.Jaymann

[zymurgist]

I'll let the experts field this... but you're definitely not going to get 150 hp out of a stock 1.8. You'd be looking at a rebuild (cams, heads, etc.) with carbs or Megasquirt fuel injection. Don't waste any time thinking about a single carb in the middle.

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[ME733]

(IMG:style_emoticons/default/popcorn[1].gif) Sounds like you have a "keeper "car. why not just do what your doing ,drive it, and enjoy what you have, in its original form. you can purchase a less well cared for car to modify and go racing with, or do some "rent a racer" programs...to find out if it,s what you really want to do and want afford . (IMG:style_emoticons/default/popcorn[1].gif)

[VaccaRabite]

The short answer is no.

To get 150+ HP from your 1.8, you need to do a full rebuild - and NOT a stock one. 150 is 2270cc land, or a hot and probably short lived 2056. You could bring a 1.8 there with a turbo, but you would still need to rebuild it with the turbo in mind.

PM Racer Chris. he races a 1.8 - and wins. But his car is a dedicated race car, and he races within his class.

our FI is limited unless you really know what you are doing. Modern FI like SDDS or MS is a better option. Or go to dual carbs with an engine that was made for dual carbs - a stock engine will make LESS power with duals.

Zach

[Drums66]

Like said above.....drive it until it goes down
on it's elbow's and think big in the mean time!! (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/popcorn[1].gif)
don't even think about carb's.........just for health, LOL

[Todd Enlund]

My understanding is that L-Jet has more potential than D-Jet, but you are still going to max out at ~110-120 HP no matter what you do. To go further, you must switch to carbs or aftermarket FI.

[ClayPerrine]

The L-jet systems is capable of high horsepower, but you can't use a radical cam with it. The air flap starts to flutter at idle if you do, and that really screws things up.

But you won't get there with a stock 914 intake system, the throttle body on a 1.8L is way to small for any serious performance improvement. If you want to do anything with the injection, then you have to bore the throttle body.


The rest of the system is seriously reliable when treated right. I suggest you drive your car the way it is, and plan a new motor if you want more ponies... That way you can keep driving it,and build the new motor over time.

[davesprinkle]

The 914 fuel injection systems (either ljet which you've got, or djet) are extremely well-engineered. The Bosch engineers are some of the best in the world and I don't say that lightly. The people who advocate ditching the FI in favor of carbs do so only because they don't understand the FI system.

If in the future you decide to go for a high HP rebuild that exceeds the authority of the stock FI, then you should consider other options.

But right now, keep the FI, take the top off, drive the car.

[Drums66]

The Bosch engineers are some of the best in the world and I don't say that lightly. The people who advocate ditching the FI in favor of carbs do so only because they don't understand the FI system.

But right now, keep the FI, take the top off, drive the car.

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[SLITS]

If you have Duel carbs ... which one won the fight?

Now with Dual carbs that's a different story. Personally, I'll stick with injection and will learn how to fix it and keep it running.

[tat2dphreak]

I think Jake can get 150+ hp from a 1.8 race engine, but I don't think it's a daily driver engine, and would probably cost north of 20k for the build. you are talking about DOUBLING the HP, but not changing the displacement... that's a huge feat!


imo figure out what you really want out of the car, and what kind of budget you can afford, and go from there... 5k for a 2056 will get you a strong daily driver in the 125hp range. and you can still do occasional fun races... if you want a dedicated SCCA racer, then more rules about displacement and such apply, read the rules closely, and find a mechanic that is used to building race engines...(JAKE)

if it was me, I'd drive it as it is for a good while, you said yourself it's running good... just drive it (IMG:style_emoticons/default/smile.gif) a 914 on the road is already moving faster than all of the ones on jackstands (IMG:style_emoticons/default/smile.gif)

[aircooledtechguy]

Your '75 sounds to be in really good shape; Congrats!!

I too have a '75 w/ a 1.8. . .Fine running machine, but lacking in the power department. Here's my plan:

Bought a core 1.7L that I can use for parts, case heads & rockers. I will rebuild this to either a 1.8 turbo, or a 2270 n/a and run MS EFI w/ a custom induction system. All the while, driving and enjoying the car w/ the stock 1.8L L-jet motor. Once I have the replacement built and run out of the car, I will simply swap motors over a couple weeks in the winter and save the stock motor w/ L-jet in the corner of the shop.

No harm, no foul. . .

'Course, that's the P-L-A-N; plans being subject to reality and all, who knows what I'll end up with. (IMG:style_emoticons/default/smile.gif)

[ghuff]

L-jet and d-jet suck if you want to go forced induction.


You can probably squeak 150hp out of them. I'm not sure what the injectors duty cycle is and where they max.

If you want to make serious power, go megasquirt or Tec III electromotive.

[KELTY360]

Take your time. You've got a nice running 914 at the moment, savor that. There are guys on this board who have had their 914 for years and still have never driven it. You can do a lot of stuff before you ever get to added horsepower. Learn to exploit the light weight and responsive handling to best advantage. Learn to appreciate the the subtle attributes that make these cars so much fun to drive...even in their stock form. There is plenty of time to read, research and in your case, drive, before you need to make decisions about more power. We've seen time and again that a stock 914 in skilled hands can embarrass more powerful rides.

Congrats on finding a low rust car on the East coast! Drive it like you stole it! (IMG:style_emoticons/default/driving.gif)

Oh yeah, (IMG:style_emoticons/default/welcome.png) and (IMG:style_emoticons/default/thisthreadisworthlesswithoutpics.gif)

[zymurgist]

a 914 on the road is already moving faster than all of the ones on jackstands (IMG:style_emoticons/default/smile.gif)

QFT