Long duration cams both suck and blow - hence carbs.

Always found the F.I. to be pretty easy to work on myself. Armed with a voltmeter and a Bosch manual, troubleshooting the F.I. system is almost gratifying.

Carbs scare me. I like methodically running through a list of F.I. components until the voltmeter tells me something's out of whack. Then you buy a new part, install it and off ya go. Then again, I have a voltmeter. Don't own a sychronizer or flow meter or float vial.

Most guys I know "think" they know what they're doing with carbs, when in actuality they have little to no understanding of the priciples of it's inner workings. I've seen too many fools...er...fellas have a problem totally unrelated to the carb and correct it by "adjusting the idle". Or the famous, "It was running rich, so I re-jetted it".

On the 914, carbs are the easy way out because you can take off the unfunctioning F.I. system that's not allowing the car to start and replace it with a "carb kit" that will. To those guys the thought must be, the car now runs, so it must be fixed. I don't agree.

Just me, but I wouldn't do it. Wouldn't buy one with a carb on it either.

Rob-O

Sigh. I know I shouldn't, but the beer if flowing and I just GOTTA put in my 2 cents worth :)

I ran my 73 VW bus (1.7 type IV motor) on dual 40 IDF's (yeah, I know - WAY too much carb for the motor) for 7 years. I learned a LOT about those carbs. After a bit, I finally got it dialed in pretty good. Got 15/17 mpg (slightly low for a 73-79 bus with 17/19 being average). But my bus would push into the 90mph arena which, if you've ever driven or riden in a bus is pretty impressive!

Also ran dual 40's on my 74 914 2.0 for the first 3 years I had it. Good performance, cool to look at, and under full throttle sounded absolutely wonderful!

Then, at the PCA Porsche Parade in San Antonio a few years back (1997??), a few guys that had come over from CA were talking about how they got 35-40 mpg on the trip. I thought they were full of sh#t!! I was also pissed that the dual carbs on my otherwise bone-stock 2.0 put me in improved class. So I got busy and tested & cleaned my FI setup that had come with the car (in boxes). Once installed, I never looked back!!

Performance was about the same (slightly slower at WOT, but made up for it in crispness and transition). MPG increased from something like 18/21 to 20/30. And on the FEW times I was able to keep my foot out of it on trips, I've actually seen 35 mpg!

The other great thing about the FI is the car (and my clothes) don't stink of gasoline all the time. In fact, I like it so much I installed a 74 914 2.0 complete with FI (and 5-speed tranny) into my 73 bus 3 years ago. And I LOVE it.

Is FI better than carbs? Are carbs better than FI? Can't say - everyone's got their thing. My 914 FI has been going without a single glitch (other than an injector connection coming loose and scaring hell out of me) for about 5 years/20k miles now. And my bus's 914 FI motor has 3yrs/20k miles on it with nary a glitch. Me personally? I wouldn't go back to carbs.

Does everyone with carbs experience your clothes and interior smelling like gas?

There are three reasons that carbs are better at WOT for the application you described. First, and most trivial, they sound great :D . Second is that you have less air restriction with dual IDF's in comparison to the single throttle body of the FI application. Lastly is that many FI cars don't have sufficient full-load enrichment to reach 12.7:1 A/F. It's adjustable, however :)

I'm curious as to whether anyone has used any of the aftermarket FI systems with a big bore motor? Can you use a higher performing cam with them? I'm still trying to sort out the carb vs FI issue for myself and had been leaning (pretty strongly) toward carbs. Anybody?...

D-Jet works with displacements up to 2.4L. "Higher performing cam" to me means high-lift and/or high duration - you may get a higher HP peak with such a cam, but at the expense of low-end torque and idle stability. Not a concern for a track car, but not preferable for a street car. YMMV.

It's unlikely that you're going to find an aftermarket FI system that is pre-tuned for your specific engine application. This means that after going through all the trouble of fitting it to your motor (e.g. TPS, crank sensor, possibly different injectors, etc.) you then will have to spend dyno time tuning the motor to get the FI system parameters correct for your application. You can try the "seat of the pants" method of tuning, but only people with a lot of experience with doing this are usually successful.

I got a lot of help in this here a while back, Search on posts by DDS and aftermarket or something like that and you'll find some great help given to me on this topic. I elected to go with Carbs for cost (good aftermarket FI total cost is expensive) and convenience reasons. (to pbanders point about setup)

Dave - thanks for the suggestion. I searched the archives and my head has now stopped spinning long enough for me to at least see the keyboard again :eek:
Brad - yes, lift duration, and overlap were what I was thinking when I mentioned a better performing cam. I have an extremely limited knowledge of FI, but my understanding is that D-Jet and CIS work on the same principle, and that the basic design limits what can be done in terms of using a "hotter" cam.
As I said earlier, I had been leaning strongly toward carbs, but I'm not so sure now. I participated in my first auto-x last Sunday. I'm told that there is one thing in life that is actually better, but I'm not sure I believe that, and in any event, I don't remember what it is ;) . I'm now beginning to get a better grip on how I want the car to respond, and why. I'm also not a hard-core tinkerer so the thought of spending a lot of time experimenting by mixing and matching FI parts isn't appealing to me. Maybe it's time to talk with CB (or other knowledgeable FI guys - Brad, DD?).
This entire train of thought has also got me to wondering how much useful gain - the application of mid-range torque - could be had by some combination of bore & stroke increases, transmission gearing, and wheels & tires, as opposed to just getting myself fixed on induction. (And, yes, I learned - the hard way, of course - that the driver is really the first area needing improvement!).
Time for some more research...

GregS, Congrats to your first Autox. How is your car set up? 1.7 or 2.0L?
Maintaining the speed thru the course is what is important for autox. Most courses are run in 2nd gear so torque does play a part but I think supension and tires is very important too.

Geoff

In the last year, I have negotiated this choice for myself, I am not sold on the choice I made either. My car came with a stock 1.7 FI motor. After reading and tinkering, I realized that fuel injection is pretty simple. You can test every component and know for sure if it works. The motor grenaded before I could get it running very well. So, I bought a 2.0 motor with carbs and ended up going with that. Once it is warmed up, it runs great. I have a cam and a high compression motor with 40IDFs and it is very fast and has a spirited tone when wound up. Also, it is very hard to start when it is cold and needs significant warm up time. My friend has a stock 2.0 with a perfectly functioning FI system. His car is nearly as fast and starts on the first touch of the key, everytime. So, I have gained some power, at the expense of absolute reliability. To make my FI system function perfectly would have cost about the same as it did to rebuild my carbs, so the cost was a wash.

My car was built mostly for auto crossing and some road use.

These cars are so fun to drive:D

Geoff, thanks! As usual, there's a long and short version, but what the heck - I've got some time if you do!
The car is a '73, with a bus 2.0. I just received 2 sets of 914 2.0 heads for it. All 4 are good (no cracks), although one has a dropped seat. They were courtesy (yes, gratis) of the guy (who has become a friend of mine) I purchased the car from last year. The car suffered an engine compartment fire (from a broken gas line) before I bought it. It is a "project" car, so other than WANTING to get it running, there's nothing sort of forcing me to. Since buying it, I've purchased a 911 suspension (Koni struts), early 911 rear hubs, S-calipers, etc. I'm getting ready to drop the engine (finally) so that I can get into the engine compartment, clean it up, repaint it, fix the rust under the battery tray, and so on. I had planned on taking a few years to modify, build, fix-up, and on and on and on, but that first taste of auto-x probably deep sixed that idea forever. All of a sudden, I can see how to fix it, drive it, and auto-x it all at the same time!! Funny how that works.
So, what about the auto-x?
The friend I bought the car from called and asked if I wanted to drive his 914 at the region's auto-x last Sunday, and I said absolutely. So I get there Sunday morning and can't find him or his car. Turned out he broke a clutch cable while he was leaving his home, so he parked the 914, jumped into his 944 and showed up in that. I'd never even sat in a 944, never mind driven one, but we had a great time (I finished 4th). They are pretty amazing (is it OK to say that on this board?) but I really want to get the 914 going now. So, the engine is a big question, of course, along with all the other stuff you guys are already aware of. We'll see how it goes. I'll keep you guys posted, and, I'm sure, be back here to the well for lots of help as we go down the road. Greg.

OK, here is my answer to the situation.

I just got through building a "big" 2.0 with a street cam, stroker crank, and 44s. I want the HP and the attitude. My stock FI was fine and now is in one of those nice plastic bins from Home Depot along with the fuel pump and all associated wiring. I will eventually pick up another rebuildable 2.0L and build a hi-quality stock replacement with FI so when I eventually blow-up my carbed engine .......

Maybe I will get tired of the hard starts first or ?
I still want to try a bigger engine.

Next on the list - a 6?

With time on my hands,

RJ

thats true, i hate the stinky gas smelling interrior.

there is alot of valid points made here.

Does anyone have experience w/ an aftermarket FI system...like the simple carb-looking system that CB sells? I was wondering if this one was any good...not like I'm going to change mine anytime soon or anything like that. Just wondering for imformation's sake.

Nathan

I do not have any personal experience with the CB system you mention. I do know that others who have fitted aftermarket systems to their stock motors have not noted any increase in power or driveability over the stock D-Jetronic system. I would wager that you could collect all of the parts for a D-Jetronic system for your car for less money than buying a CB system.

If your goal is to do extensive mods to your motor (e.g. cam, intake, displacement, compression, forced induction, etc.), then an aftermarket FI system or carbs may be the best way to go.

That CB system is covered somwhere in the archives, IIRC it si referred to as a 'competition' system a bit rough off idle and good for WOT operation. I think this was because it was solely TPS-based - not very sophisticated, can't compensate for load. I ruled it out early and the memory is very hazy and I could be wrong.

.

I think the Haltec system is more advanced.