[Caroni]

I have Mr. Kartalamakis' DOHC Engine High performance Manual 2nd edition and I am planning on building up an 84 or 86 motor, have both on hand, but using some of the plumbing (intake, perhaps throttle bodies) from a Spica injected car. Is there anything in the 1st edition that I really need that is not included in the 2nd edition? 1st editions are going for about $65 and up so I hate to spend the cash of it is not necessary.

Thanks for any advice, and commentary.

David

 

[Jim K.]

You don't need both books David, the second one will do just fine, although there's very little about Spica performance mods. If you're going to use the throttle bodies, it may be a good idea to enlarge them to at least 40mm ID all the way.
Jim K.

 

[Caroni]

Me and my big mouth, or is it dreams?

You don't need both books David, the second one will do just fine, although there's very little about Spica performance mods. If you're going to use the throttle bodies, it may be a good idea to enlarge them to at least 40mm ID all the way.
Jim K.

Thank you... I was going to ask a "stupid" question and inquire as to what to do about the Butterflies, but after some measurements, I realized that 40mm is the inside diameter at, and after, the butterflies.

On page 23, (2nd edition) it shows the desired cross sections of the head and intake manifold dimensions for a 2L. At cross section "A" it shows the manifold opened up to a diameter of 46mm. It would seem to me that if I am only going to be able to open up the throttle bodies to 40mm then 40mm would be the limiting dimension using the Spica throttle bodies and manifold. There would seem to be no reason to open up the manifold to anything greater than the 40mm of the throttles, in fact it seems as though this would actually be detrimental to a smooth flow. So rather than the 46-41.5-40mm the manifold is going to be a straight 40mm all the way through. Is this a correct assessment?

I suppose one has to wonder why use a Spica manifold and Throttle bodies on an 84 or 86 engine? To be frank my intention is to adapt a Bosch CIS injection; the Bosch Constant Idle Circuitry and the Lambda Sond system to the Spica manifold in order to turbo charge the car. I have the parts at hand and I feel that it avoids the need to mess with computer MAPs that are currently beyond my budget and expertice.

My first goal is to get a functioning engine, Most likely the 86 with a change to the 84 VVT system, since it has the least miles on it by half and then rebuild the original 84 engine to more exacting specifications.

(All other issues and lunacy aside) I realize that I may have 2 intake/throttle body options. 1) To adapt or use an existing plenum with a single throttle body, probably the least complicated; or 2) to adapt the ITB set up from the Spica, the more "sexy" option in my current opinion. (After I deal with leaky throttle shafts and such I'll probably go to a single TB but first I need to go for the multiple TBs.)

A couple of reasons I was wondering about the 1st ed. was that the dimensions for porting of the heads and manifold might have been different for the Spica based motor and I was hoping that it might have had some information regarding the probability of turbo-charging the DOHC. Anyhow, I appreciate any thoughts you may have and/or any paths you may have to point me towards.

Although I have not yet pulled the manifolds off of the car to see what the actual component fit will be like, I’m hopeful that I will be able to satisfactorily create this little project. I have been collecting components and thinking through some of the more obvious details of such an endeavor. As I start machining parts and mating the systems together I will post a thread to the BB. I hope that I don’t offend those Alfisti that are more pure at heart amongst the BB but I do enjoy many aspects of my Spider including its classic beauty and the unique and mechanically attractive design but…. After years of driving more horse-ridden carriages I miss the umph.

Sincerely David

 

[Jim K.]

I intentionally did not deal with Spica ITB mods, because as you saw, diameter is 40 at the throttles. When they are wide open you have something to the effect of 38mm or so (do the math and subtract the shaft profile area from the 40mm circle. Head porting dimensions must naturally be proportionately reduced with these ITB's and manifold. If you go this way I wouldn't even bother with bigger valves. CIS is a nice simple system, but how will you 'tailor' the cone shape of the AFM to your particular engine needs like different cams, CR etc?? You may want to think about this before you spend any money on the project.
Jim K.

 

[genericwood]

Jim, I'm curious, is the 40mm throttle body of the Spica really a limitation? On a performance Weber engine, most don't go over 36mm chokes, at least not for a street car. If the carb is breathing through a 36mm hole, why is the effective 38mm hole of the Spica TB a limitation? I'm not challenging you on this, just trying to learn!

Erik

 

[Jim K.]

Key word in your post: street car. You can live with these dimensions for up to about 140-150hp max. but any higher than that and you'll have to go bigger. Weber says that 40mm carbs are only good for up to about 5400rpm (!!) but 38mm venturis in proper size carbs (45-48mm) are good for about 7100!! With Spica ITB's and manifold you have something resembling 40mm carbs, therefore high power capability is just not there as the engine can't breathe efficiently.
Jim K.

 

[slyalfa]

I cut my Spica ITB to 42mm
And am runing a moded spica pump controled by a VEMS ECU
And hot cams.

I might want to try a turbo with this set up. but with the CR I have I would have to keep the boost very low.

 

[180OUT]

]I cut my Spica ITB to 42mm
And am runing a moded spica pump controled by a VEMS ECU
And hot cams.

Did you lose anything on the bottom end when you enlarged the ITB? While I like the looks of the Weber style ITB's it'll take about $1k to put a pair on an Alfa. That seems like a lot of money to spend when the Spica ITB can be made to do the exact same thing. Even better they're dead cheap and were designed for the motor so the linkage, air box, etc. hooks right up. I'm surprised there isn't more interest in using Spica ITB on modified Alfas in other parts of the world.

I wonder if a Spica ITB could be made to work on a TS motor?

 

[Caroni]

CIS is a nice simple system, but how will you 'tailor' the cone shape of the AFM to your particular engine needs like different cams, CR etc??
Jim K.

Jim, Pardon my ignorance but what is the AFM.... OHHHH Air flow Meter. Duhhh.

To be perfectly honest what I'm trying to do is to build a bit more power for the street and have an interesting project to boot. My assumption, and it may be incorrect, is that by using an AFM that is from a previously turbocharged 2.0 L (or so) engine I should be somewhere in the ball park as to overall flow/fuel metering proportions.

I believe the AFM that I have will adequately flow sufficient air and if anything it may run a little rich. Coming off of a 2.1L turbo motor. My hope is that it will still be within the range that the Lambda Sond system and frequency valve will be able to compensate and keep the mixture within an appropriate range. If that turns out not to be the case, I guess I'll have to play with the components in some other more, as of yet not yet determined or clearly thought through, sophisticated fashion.

As to spending money.... well it's to late for that. I already disassembled my 240GLT and gutted it for the parts I want. I have also assembled a collection of used ALFA, VW and SAAB components through ebay. Fortunately, the overall cost so far has been reasonable and I'm looking forward to the challenge. Right now I'm having fun designing, or attempting to divine, how to build a stout and adequate exhaust head to turbo manifold. (Taking some of "Corky Bell's" suggestions there.)

My initial goal is to see if I can do it and then see how close to truly functional it is. If it does work reasonably well then I may look into a complete rebuild of the motor with the turbo set up as the ultimate goal of the rebuild. As i have 2 motors my intention is to craft the parts for the turbo conversion and bolt/test them on one motor as is. I'll probably use the newer 86. If it works and I like it HURRAY! If I can't get it to work or it just isn't what I imagined then I can always bolt the original intake and exhaust components back on and rebuild the 84 motor in a more traditional fashion following the concepts of your book. Either way the 84 motor will eventually be rebuilt and the 86 will serve to keep the car drivable during the driving season in one guise or the other.

Your comment about the 38mm overall dimension of the ports is a good one. It is certainly one argument in favor of using a single throttle body plenum instead of the ITBs. That would allow for more aggressive porting and larger valves if the turbo works and I decide to rebuild for that purpose. Frankly before it is all done I will probably build and try both set ups. Who knows. I still have that darn Mustang to finish.

Thank you for the reply and the continuing food for thought. It is highly appreciated and I hope that the quantity of detail I'm providing is not overly annoying.

David

 

[Caroni]

Bigger butterflies? or are they just in my stomach

I cut my Spica ITB to 42mm

I'm curious when you say that you cut the ITB's to 42mm did you do that all the way through or did you enlarge the passages but retain the same butterflies? If you changed the butterflies tell me more please...... Did you make them yourself or did you find a source for 42mm butterflies and adapt them to the larger bore sizes?

Thanks, David

 

[Jim K.]

Ahhhh...you're building a turbo engine..! I wouldn't worry about using the ITB's then, I'd go right ahead and use the single throttle intake job.
As for David and the 42mm butterflies, you can make any butterfly you want in any half-decent machine shop. What is done, is to cut an iron or even aluminum rod (approx. 2-3"long)in the lathe to the required butterfly diameter, 40, 42, 45 etc. This rod is then angle cut (milled) on one end at an angle of 78* and two 3.5-4mm holes are drilled and tapped in the middle of this slant cut. You will now need some 0.060" brass sheet stock which is roughly cut (hacksaw or shears)to about 2-3mm larger size than the finished article. Drill two 4mm holes in the middle and bolt onto the angle-cut stub. You can now use the lathe to make perfect butterflies! I've done this exact thing many times, especially when converting 40DCOE carbs to 45DCOE (butterflies is only a negligible part of this job!). For a machinist, the above process is very simple. I neglected to mention the two holes drilled in the middle will have the same center-to-center distance as the holes on the ITB shafts.
Your last job is to lengthen the slots in the shafts to fit the larger throttle plates. This you have to do by hand using a small file taking care to keep cutting in a straight line! Don't make the slots any wider than you have to.
Jim K.

 

[slyalfa]

" 42mm did you do that all the way through"
Yes
I made a new post showing how I did it. but the bb changed so the images show up 2 times
I also made one new rod so it would have the right D shape to fit a TPS pot I grabed off a BMW at the junk yard.
I got new ball bearings from ebay and new seals from wes.

 

[la_strega_nera]

I've done this exact thing many times, especially when converting 40DCOE carbs to 45DCOE (butterflies is only a negligible part of this job!).

You what now? wouldn't be easier to put 40DCOE jet covers on 45s?

 

[Jim K.]

Geeez, Ben, if we had enough 45's back then to go around I wouldn't have to go through all this trouble!
What you propose though, was a cheap (**** cheap!) trick for cheating on superficial tech inspections (probably still is)
Jim K.

 

[la_strega_nera]

So what *was* involved in converting 40s to 45s then? you've piqued my interest!

 

[Jim K.]

Ok Ben, just for the sake of curiosity: First I'd buy 45mm chokes and aux. vents, all other parts being the same. Then, using the bore dimensions of a 45, I enlarged the bores of the 40 but wait!! Not concentrically because that would break into the progression hole chamber! New bore centers had to be ~1mm below and closer together than the std 40mm carb. This was carefully done on a mill at first, but later on I made a special offset base and did it on the lathe. The only additional job was to lengthen the shaft slots for the bigger plates. You can see that the shaft was not centered any more but that was of no consequence at all. It was important to select the proper plate angle (78, 79.5* or what) in order to have proper progression characteristics. This choice depended roughly on engine size. I now wish I'd kept a set of those modded carbs, who knows what junkyard they're resting at! I used to do this back in about 1981-83, long time ago in a far away galaxy...
Jim K.

 

[la_strega_nera]

Thanks Jim, interesting stuff! Necessity is the mother...