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3.2 w/ Webers - dyno #3

Discussion in 'Technical Q&A' started by snj5, Jan 14, 2004.

  1. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Russ Turner
    Hot off the Dynojet drum:

    Ferrari 3.2qv, 9.2CR, Weber 40DCNF, Stock Microplex ignition
    New dyno data with the 36mm venturis, 145/F24/190/.55, stock cams:

    SAE Rear Wheel HP: 235.9 @6600
    SAE Rear Wheel Torque: 202.7 @5600

    Flywheel SAE hp (18% driveline loss): 287.6 @6600
    Flywheel SAE torque (18% driveline loss): 247.2 @5600

    Max uncorrected (actual today) hp: 296.3

    idle A/F: starts off quite lean, but comes down to 15
    A/F during 4th gear pull 13 - 14

    (Ferrari Factory specs, US Mondial 3.2 with Kjet: 260 SAE hp @7000, 213 ft-lb @5500)

    140 and 145 mains, while producing basically parallel A/F curves a point apart, differed in hp figures only about 1 hp.

    I think I have maxed out these stock emissions oriented K-jetronic cams and Microplex ignition advance with these carbs. I'm done for a while with the Webers, will now drive a bit and look at the ignition later to finish off the winter project.

    Super thanks to all the great folks on this board who helped, especially Mark and Philip. This has been a hoot and great fun, and I've learned a lot.
    best to all
    rt
    'fuel injection is for kids' :)
     
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  3. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
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    Russ
    Great stuff. Would love to see the plots (torque, HP, AF) if and when you have the chance. It looks like your adventures to date have delivered another 35 ft lbs or torque over stock. Pretty cool to see your hard work in creating a set of well tuned Webers and the power increase they've delivered. Be very curious how your results would vary with a 150 main jet

    Now, another 20 or 30 horses from a set of cams and you'll really be cooking...http://www.ferrarichat.com/forum/images/icons/icon12.gif
     
  4. Newman

    Newman F1 World Champ
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    Dec 26, 2001
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    Im glad to see you basically hit the 300 mark Russ, thats what I was hoping for. Just imagine if you had 10:1 comp and custom cams, maybe another 50HP waiting for you? It certianly gets the gears turing in my head about fitting a 3.2 in my 79. Thanks for the info.
    Paul.
     
  5. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    Very nice, it looks like you've got it about perfect. You'll probably need to do some more jet work when you get the cams installed, but it looks like you've got the hang of it.
     
  6. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
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    BTW Russ, who's in the pic? Dyno op?
     
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  8. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    That's 'Wheat', the dyno op and a great guy whose specialty is superchargers. Next to my car they were putting a big belted supercharger on an H2. While we roughly do look similar, I don't think the AF would go for the ponytail down my back.

    Will try to get the graphs today.
    best
    rt
     
  9. Mike328

    Mike328 F1 Rookie
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    And here I thought Russ had a pony tail! :)

    Paul (Newman), if you get a 3.2 I've got "dibs" on your engine! j/k

    Russ you've really gained a lot of knowledge on the carbs that's applicable to all of us carb guys (and gals). Thanks for sharing so much.

    Next month I plan to do my own set of dyno runs on my freshly Pierce-Manifolds rebuilt carbs, once I get the electromotive HPX installed. Like Russ has, I'll post all the results with the various jets!
     
  10. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Mike
    Thanks. I have been holding out a bit as some painfully technical emails on jetting have passed between Mark, Philip and myself as to the jetting strategy. Currently they are ganging up on me saying I need to go to a richer idle, although the dyno tech advises that idles in the A/F 15 range are common. By going to a .6 idle, I would then go down to a 140 main as the richness is additive. The increased idle jet size would also cover a small lean spot I get with rapid full throttle opening before the accell jet fires. On an even more detailed point, may go down sl. on the accell jet to lessen a rich peak (A/F 11) I get after it fires.

    Then again, I may not mess with the accell jet - we are down to the really fine points as the response is WAY BETTER than the Kjet. On my first 36mm venturi test (36/140/190/.5) for drivability and flat spots (none), when I punched it above 4000 it slams you in the seat RIGHT NOW with a 'woom-woom', and hang on!! Pretty amazing for a Mondial, and very reminiscent of a 911 I had, except instant response. I'm expecting a bit more low end torque with the earlier full advance from the new distributor I'll be adding later.
    And hopeflly, I will add a little reliability.

    best to all
    rt
     
  11. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Emulsion tube selection in the carb'd Ferrari V-6 and V-8

    Since these emulsion tubes are stock in most V-6 and V-8 Ferraris, here is a brief amateur explanation as given to me on Ferrari 40 DCNF emulsion tubes. Early V-6 and V-8 Dinos had F24 emulsion tubes which were replaced in the later versions by F36s. While the main jet runs the overall mixture, these ET's fine tune the midrange air/fuel mixture much as the air correction jets provides fine control the top end A/F

    The diameter of an F36 has more holes toward the top than the F24 making the F36 somewhat leaner, and was probably used to lean the mixture as Ferrari worked on emissions by leaning mixtures. These tubes are different diameters as well with the F36 having a larger air space. Ergo, the F36 will lean the midrange a little compared to an F24

    My A/F in the 3000 - 6000 range is about 12 using the 145 main jet. One way I am looking at leaning a little bit is to replace the F24 with an F36. Since I am also going up in idle jet size, the midrange will need a bit of leaning from the additive effect as well. The target is an A/F of about 13 - 13.8. I have also found that a main jet size difference of 5 (like between 140 and 145) will have the effect of changing the fuel ratio about 1 point.

    Would love to hear anyone else's experience.
    I know hundreds of you have been wondering about this.
    best
    rt
     
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  13. Mike328

    Mike328 F1 Rookie
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    Any thoughts on running F24s in a standard stock carbed 308?

    Obviously, this was not chosen casually by Ferrari engineers. Was the choice, though, for purely emissions reasons? Streetability?

    I wonder if a higher-performing but streetable config could be found by varying the emusion tubes in addition to main, idle, and air corrector jets... On 78/79 stock 308 cams.
     
  14. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Mike (and other carb 308 owners)

    I would love to see a stock 308 (carb or injected) dyno pull with AF ratios to best answer that question.... :)

    That being said, the Carobu 308 tuning Forza (#48, Oct 03) article mentioned better hp results by better jetting, although it was not a lot. They used stock cams and increased the venturi size to 34mm. The article did not reveal their magic jetting, but I'm inclined to believe it had to be close to 140/F24/200. That would take about an hour or less to do for everything. If you pre-built the jets and had them ready to drop in, 20 minutes. All the jets (main, et, a/c) should run under $100 I *think*.
    I also happen to disagree with their assessment that the K&N does not help. It's been my dyno experience that it does. Sheer speculation here, although based on my dyno experience so far, I think the K&N reduced resistance to flow leaned their mixture enough to where they lost a couple of hp. That suggests to me they are running a bit lean for their max hp. Just my nutty ideas, but I've got graphs, too. :)

    Hope this helps, and I'm wide open for discussion as I am an amateur and very new to all this.
    best
    rt
     
  15. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
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    Russ
    My gut is the 34mm venturis would be an interesting and cheap mod for stock carb'd 308s too.

    In the realm of "probably going too far" (or proving that there is a fine line between inspiration and insanity), given I am going to use my 308 almost exclusively on the track next year, after a dialog with the race crowd at QV London, I am going to try 44 DCNFs with 36mm chokes in '04.

    Keep you posted
    Philip
     
  16. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Philip,
    Just to whet your appetite, there is a guy on the Superformance board with one of their 308 2v hop - ups with 10:1 CR, 44DCNFs and 302 cams who says he dynos 270 HP AT THE WHEELS! You do the math.

    best
    rt
     
  17. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
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    With 17 - 18% DT loss, that says he's pulling 325 - 330 flywheel. Quite impressive. As another reference, LFSC indicated they were getting 340 BHP from their 2V 308 in full race trim.

    If pistons are worth 10 - 20 BHP (?), the P6 plus 44s should pull 300FW/250RW with the carbs, however, the mid range (below about 4500) will be in the tank so I think it'll be OK on the track (although gear ratios for different tracks are going to start to become more important) and pretty difficult on the street.

    From the other (vintage) thread, interesting that the 12 cyl cars like the GTO (which had the TR motor) are so "over carburetted" and "over cammed" in comparison even to this spec.
    Philip
     
  18. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    Philip,
    I have a harley XR750 motorcyle that is a 2v with bore and stroke almost exactly the same as a 308. It runs 12.25 CR (on pump gas), cams with 270 duration at .050", and carbs with 38mm venturis. Idles at 1000 rpm, 95rwhp at 8500, over 90rwhp from 7800-9000, 65 ft-lbs torque at 6000, with over 40 by 2500 rpm. Adding 6 more cylinders, like a 308, you'd have 260 ft-lbs torque and 380 rwhp. I also had a 2.7 liter 911 that made almost 300 rwhp at 8000 rpm using carb with 37mm venturis and 11 cr on pump gas. I don't know if 308 heads can be worked to flow enough for those kind of numbers because I cheated this time around and went with pressure. The porsche heads took me over 200 hrs, but the numbers are possible without loosing drivability if all the parts are matched well. Your P6 cams with bigger carb should be fine on the track, but unless you increase your CR, I think you'll find it flat below about 4000 on the street.
     
  19. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
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    Interesting analog. I assume pistons would do more for low down torque than peak HP.

    I think you are right on the CR/drivability issues with the stock CR. Right now I am looking at options to give me more flow and HP without rebuilding the engine. That may come down stream. I have been offered a set of factory competition liners and pistons... so...well, who knows.

    I'll post info when I have the 44mm carbs rebuilt, tuned and on the car.

    Thanks for the thoughts.

    Philip
     
  20. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Philip
    another interesting note from the Superformance UK 308 guy - he said one of the most important factors to getting more power out of his engine he discovered was the ignition advance - made a special point about it as I recall.

    Don't know if I'd roll in 38-40 mechanical degrees @5K empirically, but.....

    What are folks running now? My stock Marelli is about 32.5 @ 5K at WOT. Off power is vacuum advanced by the ECU of course.

    All advice and experience welcome.
    best
    rt
     
  21. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
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    Re: You were wondering about 'stock' A/F ratios. My 1975 GT4 is stock except for a K&N, and aftermarket ANSA. At WOT, A/F at 3500 was 13:1 and gradually and evenly leaned out to 14:1 at 7200 rpm. This is with .55 idle, 135 main, 220 A/C, and F36 tubes. I switched to 210 A/C for a touch more fuel up top, but haven't re-tested.
     
  22. mk e

    mk e F1 World Champ

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    "I assume pistons would do more for low down torque than peak HP."

    Yes, I believe that is true. Big cams cause blow-down at low rpm resulting in very low effective compression ratio and very low output.
     
  23. vincer77

    vincer77 Karting

    Dec 12, 2003
    71
    Please note that the Carobu Forza article test was on a 2v 308 motor. From your profile you have a 3.2 Mondial. Were your tests on the 4v 3.2 motor from the Mondial or a 2v 308? If on the 3.2, since these are two different motors (2v vs 4 v and 3.2l vs 3.0l) the air requirements are different. Whereas the stock air box appears to be well designed on the 308 tested by Carobu, it may be restrictive for the 3.2.

    Your thoughts?
     
  24. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Yes, I think while the stock 308 airbox was designed for a 255 hp 2v with a paper element, I may getting a bit outside the design margin since I am pushing 280 - 290 with a K&N. There is also the issue of bonnet height - I do not wish to cut my bonnet lid. The stock 308 box is the biggest, tallest I can get in without bonnet modification.
    As to the relative restrictions of paper vs the K&N at issue, I've found effect on mixture which may explain Carobu's power loss if not compensated for - the K&N definitely flows more air though. I owe Tate a call, and will discuss this with him then as he is far more expert than me.
    I like the stock box for the cold ram air (not reflected in dyno), and have just recieved the drawings for the 308 LM airbox and other options which I'll be looking at. Will be interesting to see effect of the new cams next month.

    Anyone know the stock CFM ratings?

    Superformance and Pierce both sell a nice set of 40DCNF trumpets with open wire mesh, but a bit impractical for day-to day. :) Also must keep remnding myself the main reasons I went to carbs were reliability, sound and throttle response.....

    All suggestions appreciated.
    Thanks for the interest, as we have not discussed the airbox issues!
    rt
     

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