Performance 1800 build - RESULTS!!!

[ebrown0104]

Over the winter I decided to perform my first ever car engine rebuild on the Spider. I also decided that while I was rebuilding, I was going to try my hand at a performance build. So after 4 months of tearing apart and rebuilding and another month or so of troubleshooting (hint: a clean gas tank will fix 99% of your problems!!!), I finally got to the dyno to get the car tuned in perfectly. Here are the results...

First, a list of what I have done:

1977 Spider (California spec model)
1800cc
European 84.4mm pistons 9.8:1 compression
Vick's 40-80/80-40 cams with Allison adjustable gears and Iskenderian valve springs
Mildly ported head with Vick's 43mm/37.5mm oversize valves
Weber 32/36 DFEV carb on stock single-plane intake
Lightened stock flywheel (~12lbs)
Auto Ricambi aluminum crank pulley
Balanced rotating assembly
Marelliplex electronic ignition
Vick's stainless header and full 2.25" exhaust
Removal of all emissions-related equipment
+ some other stuff I'm probably forgetting

My estimate was 130-140 horsepower at the crank, or 110-120 at the wheels. I based this on nothing in particular, other than the Euro models were rated at 120 and my build was going above their specs by a little. So how did I do?



The blue chart was the first run of the day, and the red is the final run. I had the carb tuned way rich initially (you can see the AF reading is never even on the graph because it's so rich), and ended up with jet sizes fairly close to the originals that come in the DFEV (145/150 main, 165/170 air corrector, 55/65 idle). Does that mean a DFEV on a stock engine runs really rich? Probably.

The runs were done in third gear from 2000-7500 RPMs.

We went plus 3 degrees and minus 3 degrees with the cam gears and lost a fair amount of power either way, so they're set at 0.

The only thing I'm sort of stumped by is the dip in torque from 3500-4000. The AF ratio also dips in the same region, which says to me that it's getting too much fuel temporarily (or maybe not enough air). Also, coincidentally, at this same RPM range my exhaust note gains a buzzy, raspy noise that doesn't exist before 3500 or after 4000 RPMs. Any ideas of how to lessen that drop?

Anyway, my prediction was pretty close. I think switching from GL-1 to Redline MT85 in the tranny could pick me up another few ponies and get me right at the magical 110WHP mark. I plan on going to IDF's next winter, so that should add a little more, also.





VIDEOS!

Dyno run:
https://youtu.be/k__n-JIUeww

Idle/walk-around:
https://youtu.be/nt0dweedyag

The car is really fun to drive now. It revs with authority, idles like a V8 (I've had people ask me what the engine is, and when I tell them it's a 1.8 4 cylinder they don't believe me), and while I wouldn't call it fast, it moves quickly with very little effort. It still gets 20MPG and cruises in traffic much like a stock Spider. It does all of this without overheating and without pinging. All in all, I'm very satisfied with the outcome. I think once I add the IDFs and a 3.90 rear end it'll be just about perfect.

Thanks for looking, let me know what you think!

[joelittel]

Nice job! Just in time for summer too.

Which muffler did you go with?

[RRoller123]

"The only thing I'm sort of stumped by is the dip in torque from 3500-4000. The AF ratio also dips in the same region, which says to me that it's getting too much fuel temporarily (or maybe not enough air). Also, coincidentally, at this same RPM range my exhaust note gains a buzzy, raspy noise that doesn't exist before 3500 or after 4000 RPMs. Any ideas of how to lessen that drop?"


Porting of the head mismatched to the headers? Seem to remember reading in GC Manual that this is a particular problem and the porting angles on the exhaust side have to be paid attention to. Splaying out to match the header can actually be bad and a step is actually good as it causes reflection pulse back down the exhaust into the proper direction.

Just adding to the conversation, not at all sure about this, but I think this was the gist of what I read in his workshop manual.

[CajunMike]

Great job! Looks and sounds great!

[vandor]

Great results! Nice, clean engine bay!

What jets did your DFEV come with? I was under the impression that the stock jetting for the mains is 137/140.

The loss of torque could be unfavorable exhaust resonance.

[RRoller123]

"unfavorable exhaust resonance". Csaba gets it in 3 words, that took me 2 paragraphs to describe.

[ebrown0104]

Thanks for all of the comments everyone. I'll try to answer all questions:

The muffler is from Vick's - http://www.vickauto.com/newstore/index. ... ts_id=4208. I also have their center section and header. It's a tad on the loud side when accelerating (especially in the 3500-4000 range where it buzzes), but I have a resonator to add in sometime.

The machine shop that did my work said they didn't do anything to the actual ports themselves because on a street-driven car it almost always runs worse. The work they did was cutting in the oversized valves and blending them into the bowls, along with some minor porting of the bowls. As far as I know, the exhaust port openings are original size.

The guy running the dyno did mention adding a taller carb spacer or some kind of velocity stack to maybe lessen the dip.

My DFEV did have 137/140 main jets installed originally. I'm currently running 145/150.

[vandor]

> The machine shop that did my work said they didn't do anything to the actual ports themselves because on a street-driven car it almost always runs worse.

This is sort-of true. Ideal port work can only be done with a lot of trial-and-error and a lot of flow bench testing. So your machine shop that does not specialize in Fiats would likely make the flow worse if they just enlarged the ports. Fiat specialists who have been doing this for a while have invested the time and money to come upwith porting that actually works and will add HP even to a street car (assuming it is a high performance engine with cams, larger carb/carbs, etc).

[baltobernie]

Thanks for looking, let me know what you think!

Looks and sounds great! I have almost the same motor, with approximately the same results. At what RPMs did peak HP and torque occur?

[ebrown0104]

Thanks for looking, let me know what you think!

Looks and sounds great! I have almost the same motor, with approximately the same results. At what RPMs did peak HP and torque occur?

Not certain on torque RPMs, for some reason my printed dyno chart got all messed up on the scales (showed runs from 1500-6200 which is off by a lot), but max horsepower is about 7000 RPMs exactly. The dyno operator said that shifting at 7100-7200 would be ideal for max acceleration.

[Dawgme85]

When I picked my car up, after having the head rebuilt and port-matched, and a 4-2-1 manifold installed, I was told that the flat spot at around 4000 RPM should now be gone. Sure enough, it pulls all the way up to redline, with no hesitation or flat spot at any point in the range. I had to call back 2 days later to ask, "what the f#$k did you do to my car?". The change was jaw-dropping, even with a stock bottom end and cams!
My next engine mods will probably be to build a nice, streetable 2 liter that runs on pump gas, with a bit more compression, a performance intake cam, stock exhaust cam and 40IDF's. That's the recommendation I've gotten, although I'll need to talk it over some more before finalizing my build details.

LeRoy