Intersting observations on FI vs IDFs

[guycroft]

I'm with Csaba and Jeff all the way on this one.

I have all the time in the world for guys like them who ask for my opinion and advice and then follow it through. I can'tfault Csaba for sticking at it and trying everything in a logical way. Those who do are rarely disappointed (in the end - though the road may be hard..). These folk are the minority. The converse is also true.

There are concerns that one day there won't be anyone who can set up carbs. Well hello.


Carbs v FI - no brainer, sorry.


GC

[BEEK]

Have you people said any of this out loud and listened to yourself?

Carburetors are not as good as electronic fuel injection. Maybe it never worked right for you, but Ford, Honda, GM, Toyota, BMW, Mercedes Benz, and everyone else that employes an engineer, use electronic fuel injection.

I'm sorry to hear that you never made this work, but really, it's not the technology that had the short fall, it's the implementation. Please don't make people gun shy, I want there to be someone to work out proper fuel injection for these cars with better than the OEM system.

As many have already said. I just wanted to put in my .02 worth. I have over 20 years experience working on, building, restoring, racing and doing most everything else that can be done to a fiat twin cam. I am not as learned as guy croft. But I do have many years experience building performance motors. Mostly fiat twin cams, but have built many NASCAR Chevy motors as well. I would like to say that engineers are paid by manufacturers to design efi systems for very mildly cammed, street application motors, where the primary goal is fuel mileage with the trade off of performance. These engineers have the ability to change the design of the hard parts they start with, they can change block or head design, the rod angles, valve size, combustion chamber shape and orientation at will to achieve their goals. This was a modification of an already built motor. All out performance was the goal. Not fuel mileage or streetability. Myself I have built 2.0l fiats that will turn 8000 rpm all day and made 225 at the crank. On a single 40dfi carburetor.

[wmausbach]

Beek,
Do you have the dyno sheets?
Ciao
Wayne

[mdrburchette]

The dyno numbers don't sound out of line since they are from the crank and not the wheels. Racers are getting 185 at the wheel from an 1800.

[BEEK]

unfortunatly no, i dont have the dyno sheets. that was 10 years ago. i do still have the engine on mothballs in my garrage. well most of it. the thing was dissasembled due to a bearing failure. i have the all the parts though. i was thinking about putting this back together and putting it in my spider. will have to install dry sump in the car, but wont be that much trouble. will make some great pictures for the board. unfortunatly right now all of my attention is to a different project. 330hp in a scorpion. im still working out the chassis engineering right now, brakes ect.

[guycroft]

Myself I have built 2.0l fiats that will turn 8000 rpm all day and made 225 at the crank. On a single 40dfi carburetor.

??

GC

[BEEK]

40 dfi is a synchronous opening Weber carburetor from the fiat dino and probably the Ferrari dino as well. It was matched to a single staged manifold from a 74 spider. the head started life as a 2.0 lancia efi casting, before port work, used stainless big valves in bronze guides, billet camshafts with almost 11mm of lift (not regrinds). Arias made me pistons we figured compression to be approximately 13.5-1, even with the big cams and overlap we still had 250lbs of cranking compression.
This went thru special made headers 4-1 with 28" primaries if I remember correctly, 2.5' exhaust exiting from right behind the door. This thing would make your ears bleed it was so loud. Rods were billet from crower. The crankshaft was lightened and balanced. The operating rpm range was from 4500-8000+
i won 52 races and 2 championships driving fiat race cars which i built. 124 coupe's

[sptcoupe]

Sounds like a killer! Nice work!

The coupe's motor is very similar, except compression is 101:1, and we used GC's GC3A billet cams and (now) 44 IDFs on a ported manifold, but the big valves, tapered valve guides, billet Crower rods, the Allsion header with a 3" exhaust from front to rear, balanced and lightened crank, aluminum flywheel, crank pulley and all other pulleys (to inlcude the adjustable cam pulleys) are all there. Did you ever dyno that puppy???

[baltobernie]

... except compression is 101:1,

What kind of starter and battery do you have on that thang (Oh, that's what the compressed air bottle in the trunk is for ...)

[sptcoupe]

Damn! No wonder thjose plugs were always perfectly clean!!!

[ClarkTheShark]

csaba. What are you guys doing with your old ITB's i saw the coupe and intake setup at the freakout and was enamored. i would be interested to see if a change in fuel management would solve some of the problems. send me a pm if you guys are interested in parting ways with them, i doubt you have another manifold but thatd be nice too.

[sptcoupe]

Clark - In the end, the issue was not fuel control. It actually ran pretty damn well and made Ok power (~140 RWHP) up to the 6000 rpm range, except for one version that made 150.5 at 6000 rpms. But that engine would only do that running a very rich mixture that killed the rings after about 1500 miles. It rev'd well to 8000 rpms, but made no more power, no matter what we did to meticulously change out all components, one at a time, over 180 dyno runs. That's not bad power, but with the IDFs it makes power all the way to 7800 rpms, and it made about 144 at 6000 rpms on the very first run with NO tuning and less than optimal jetting. And this 6000 rpm "wall" appears to be a pretty common issue from what I have seen on dyno sheets shared by others doing FI conversions. And unfortunately, you have to put it on a dyno to know what really is gping on.

We have subsequently made jetting changes, and it feels much stronger already, but we will get it back to the dyno to play with ignition/cam timing and check the jetting in another couple of weeks and report out the facts - not conjecture.

I really wanted to have a FI engine this time around, but after this experience I personally can no longer enthusiastically recommend spending the money and time on a FI conversion and building a performance tuned engine that won't make HP beyond 6000 rpms, when I can get more HP and use the entire rpm range with carbs, at half the price. IMHO, that is spending time and money to get a sub-optimal solution. I would rather spend the extra money on things that really do increase performance and reliability, like quality head work, porting, quality components, etc. But that is me, and plenty of people will disagree. And BTW, they run smoothly and there are never any electrical issues (we had to solve a number of those as well).

We still have all the components, but they are spoken for already. If that changes, I'll let you know.

[azruss]

great stuff, guys. wow! talk about a lot of work. glad it drained your wallet and not mine. In all this talk, there is no mention of torque and how that varied with the different setups.

[sptcoupe]

azruss - The torque on the FI motors was consistently in the 140s. I didn't even look at it on the single run on the IDF motor. Will report that out when we get it back on the dyno, but I have always been happy with the torque on my IDF motors.