355 throttle bodies on 348 project | FerrariChat

355 throttle bodies on 348 project

Discussion in '348/355' started by plugzit, Oct 22, 2006.

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  1. plugzit

    plugzit F1 Veteran
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    Dec 1, 2004
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    Bruce Bogart
    Finally found a good set of throttle bodies off a 355 to put on my 348. I'm thinking that's one of the areas where F increased the hp from the 348. It'll be a couple of weeks til I get them, so I'm trying to be as well prepared as possible to make it a short project. I've been doing strange things to myself while looking at AndyHls's car long enough! Anyway, I'm looking for feedback of a technical nature. First of all, if you've done this already, please post! A few questions to get the ball rolling.
    1. Which injectors-348 or 355-or are they the same?
    2. Are all throttle positions sensors basically the same? (Can I use one that comes on the 355 stuff?)
    3. I really, really wanna use stacks like Andy did. Is it possible to meter the air flow from just one cylinder? If so, any suggestion where to get that meter? I've got the air boxes, so I can easily use the existing 348 meters, but I hate to cover up those beautiful tbs?
    4. I'd like to get started on the adapters-tb to head-is the gasket a good pattern, or do I need to provide for stickey-outs (that's a technical term :)
    5. Anything else I need to be thinking of?
     
  2. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
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    Awesome project, Bruce!

    The 355 FUEL INJECTORs for the F355 2.7 MONTRONIC (BOSCH # 0280155003) are part #149316, but part #130968 for the 348's 2.7.

    The 348 Motronic 2.7 throttle positions sensors Part No. 142434 supercede to part No. 158170 (i.e. they are freely interchangeable), and since 158170 is the 355 Motronic 2.7 TPS, you are good to go.

    Per your #3 above, though, I would just use the TPS for "metering" rather than try to kludge it with just 1 or 2 MAFs that are getting 1/8th the flow each.
     
  3. 348paul

    348paul Formula 3

    Dec 27, 2002
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    Bruce,

    When I made the manifold parts for Andy I ran spares for another car - The lower plates will be OK for the heads but the upper plates are for the jenvey tb's.

    I can take a pic if you want.

    Paul
     
  4. plugzit

    plugzit F1 Veteran
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    Thanks, Chris!
    Paul-a pic would be appreciated-you're a god!
     
  5. ernie

    ernie Two Time F1 World Champ
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    Nov 19, 2001
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    Okay Bruce, you better let me and fatso know when they arrive!
     
  6. Samy

    Samy Formula Junior

    Dec 2, 2005
    603
    1. You need to resetup the ecu anyway so it doesn't metter wich one you choose. Both will flow enough fuel for that change. But better use the 355.
    2. if your running the 2.7 and not 2.5 and the throttle bodys are from a 2.7 if they are of ebay.co.uk they are 5.2 and you have to put the 2.7 sensor to the throttlebodys
    3. Yes but not with the stock ecus. You will need a new ecu for that wich supports speed density, any aftermarket normaly supports that i would use a wolfems it has a very good software and also the ecu itself works good.
    4. To get to the right length of the inlet runners i would cut off some cm of the 355 inlet runners. Laser a aluminium flange from the 348 inlet manifold and create a smooth adapter pipe from the 355 inlet runners to 348 flange in the length of what you cut out.
    5. No i don't think you need anything else except to conntact me if you don't use the airboxes i need one of them.
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  7. plugzit

    plugzit F1 Veteran
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    #7 plugzit, Nov 9, 2006
    Last edited by a moderator: Sep 7, 2017
    The throttle bodies arrived and are as good as I had hoped. I'll have to make an adapter as expected, but it's not going to be complicated for my buddy with a Bridgeport mill with a slab of aluminum. The port configuration is the same and the shape is not dramatically different-see the picture of the gaskets. I think the motor is going to look great with the new tb's on it. I'll have to decide if I want to have them standing straight up like in the pics or canting slightly inward per the direction of the port (only 5 deg. or so). Either way, I'm going to have to slightly modify the bell crank linkage bracket as the ports on the 355 must be farther apart-1/2 inch or so. Also, I'll have to machine off the boss on the water manifold that the little vacuum switch for the plenum equalization valve on the 348 mounts to. I won't need that anymore anyway. The inlet for the 355 air boxes is within 5mm of the same diameter as the MAFs on the 348, so stage 1 using stock wiring and MAFs should be easy. Incidentally, the air boxes on the 355 have beautiful velocity stacks inside canted outward and slightly forward-a very nice piece of work-too bad they aren't visible. I'm doing the work on my spare motor so when the time comes, I can do the swap in a day. The machinist may not be able to get to it for a few weeks, so I've got some time to do more planning. I really want to use a MAP instead of a MAF so I can run exposed stacks like Andy hls yet still have full brain activity. The big question for me now is if the signal from a MAP is nearly the same as a MAF. If so, the wiring is a piece of cake using GM MAPs. Stage 2 will probably involve remapping the brains, but if I'm really lucky the brains will have enough range to compensate for the air. I'll start with the purple 355 injector nozzles. The two motors are within 6 cubic inches-excuse me, .1 liter-of each other, so the mixture should come out about right.
    Positive comments and technical advice are welcome.
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  8. Samy

    Samy Formula Junior

    Dec 2, 2005
    603
    The Mapsensor has the same voltage like the Maf Sensor. 0-5V. But! the Pressure doesn't have anything to do with the mass of air. The fuel calculations in the ecu uses the airmass. So you have to build a system wich picks up enough data to calculate the airmass out of different signals. You need at least the pressure from the map sensor, the air temperature and the engines rpm. Better also messure the throttle position. Because in low rpm when the engine is cold the fuelcalculation is very sensitive and it is very difficult to setup the VE (volumetric efficiency) mapping wich is needed for such a MAF -> Speed Density conversion. Also you should use an engine dyno without it is a lot of work to get the engine running in all conditions. f.e. the engine runs great when its warm but when its cold it won't even start. Because of that i stopped working with such a system and go back to a maf or at least wideband lambda regulation. Speed Density ecspecially a conversion from speed density calculation to a fake simulated maf signal is crap for a street driven car.
     
  9. plugzit

    plugzit F1 Veteran
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    Samy-thanks for your reply! Sounds like you have experience with this. A question. I was hoping to leave the throttle position sensor the same as it is on the 355 tbs and substitute the MAP signal for the MAF signal. Isn't the manifold pressure also a function of temperature? I'm learning here, so please be patient with me. :)
     
  10. gothspeed

    gothspeed F1 World Champ

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    Which gasket is the 355 one??
     
  11. plugzit

    plugzit F1 Veteran
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    the small lighter colored one. There are 8 for the 355 vs 2 for the 348
     
  12. goyal99

    goyal99 Karting

    Mar 5, 2002
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    Nice project!

    Just out of curiousity, how much HP can you gain on a stock 348 engine by doing this TB installation??

    Good luck!

    VK
     
  13. plugzit

    plugzit F1 Veteran
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    Good question. I can't give a straight answer, but when you look at the differences between the motors, the big changes were the 5-valve heads and the throttle bodies. For whatever reason (discussed at length elsewhere), Ferrari decided to discontinue the 5-valve heads but stayed with the 8 throttle bodies on subsequent models. In the same way that we added more or bigger carburetors for more hp back in the old days, I think this will add hp. Maybe 10%???? It's generally agreed that placing the butterflies closer to the valves is better, and a larger overall airflow allows more fuel to be introduced at ideal mixtures, therefore more hp.
     
  14. goyal99

    goyal99 Karting

    Mar 5, 2002
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    Thanks Bruce...

    I have never seen the INSIDE of a F355 throttle body (do you have a photo?) so I wonder how much different is the butterfy setup as opposed to the 348 (which are pretty obvious).

    Thanks - VK
     
  15. plugzit

    plugzit F1 Veteran
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    #15 plugzit, Nov 9, 2006
    Last edited by a moderator: Sep 7, 2017
    Here you go. Note 4 butterflies to replace the 1 for each bank of cylinders. These bolt directly on the head, whereas 348s bolt to the plenum.
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  16. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Well I'll have to come by and see the project. If you mill out the adaptor plates make sure they are wide enough for NOS injectors. I would drill tap and plug for future direct port NON while you are at it. then you can add a piggyback fuel controler for enrichment. I think you need to stay MAF. They work totally different from MAP. If you switch you will need to go to an aftermarket system. I like to go budget so go with a megasquirt. I swear it is no worse than the high dollar motec or EFI systems. Sure they got some features especially in data aquisition but for the a couple hundred bucks you can't beat megasquirt and you laptop computer. I would be surprised if you gain much to any power with 355 parts and oem enginemangement. Perhaps with MS you can. I still have never seen dyno sheets from andy's cool looking intake job. We keep asking but they never come. To me that means no power gain. If you do this bruce make sure you dyno before and after to see if you really get a net gain over the entire rpm range. I bet I could have a turbo on my car before you could have the TBS figured out. Yup a skeptical fat guy.
     
  17. plugzit

    plugzit F1 Veteran
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    " I bet I could have a turbo on my car before you could have the TBS figured out. Yup a skeptical fat guy."

    Challenge accepted!
     
  18. fatbillybob

    fatbillybob Two Time F1 World Champ
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    Well let me rephrase...skeptical that more power will be made with just a part swap. I think you will need to go aftermarket ECU. But IMO the 355TBS are probably just as good as what andy did depending on flow capibility but we all got no data so who knows....

    If you increase flow you got to increase fuel flow too. A larger injector will not do it. ECU feedback will read larger injector and cut back pulse width = about same flow.

    Hey time to change the muffler too. I say ditch the weight and go cats right out to stright pipes and crossover. There you'll dump 25 lbs and sound better too.
     
  19. plugzit

    plugzit F1 Veteran
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    Exhaust in the works. OS reads mixture, more air leans mixture, brain responds with more fuel. Elementary, my dear fat one! More air and fuel equals more horsepower!
     
  20. plugzit

    plugzit F1 Veteran
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    "If you mill out the adaptor plates make sure they are wide enough for NOS injectors."

    This I will do for sure-great idea! Drill, tap & plug for when I'm ready for more horsepower!
     
  21. indytech

    indytech Guest

    May 24, 2006
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    Nice project plug, are you a builder or what. Can't wait so see hear how it runs.
     
  22. plugzit

    plugzit F1 Veteran
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    Nope, just an old hot-rodder shadetree mechanic. Heck, it's just metal with a few electronic gizmos thrown on it to meter the fuel and timing. All the old sh*t still applies. It's mine and if I mess it up, I've got nobody but myself to blame. Been thinkin' about puttin' a flame job on it just to mess with the purists. :)
     
  23. gothspeed

    gothspeed F1 World Champ

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    I think you are doing a good thing Bruce! One question: The 355 port on the throttle bodies are bigger than the ports on the head. Are you going to match them up? Is there enough material available for removal to do this on the 348 head?
     
  24. plugzit

    plugzit F1 Veteran
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    I'm going to build an aluminum adapter about 3/4" thick with the port tapered to fit, bolted to the head, then the tbs bolted to the adapter. Not a perfect solution, it'll leave a few horsepower on the table, but I'll be able to do it bolt-on rather than disassemble the motor. I'll post pix when I'm done with the adapter.
     
  25. group77racing

    group77racing Formula Junior

    Sep 5, 2006
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    What are the bore ID's of the 355 throttle bodies? What is the intake port spacing center to center for 348 heads and 355 heads? What do the 355 purple top bosch 0 280 155 203 injectors flow in cc per minute?
     

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