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Throttle response

Discussion in '308/328' started by Sigmacars, Apr 3, 2019.

  1. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
    7,091
    Agreed. It's CSI, not injection in general. The Op asked about throttle response on injected cars below 3k. I stand by what I said. There is none to speak of. There is no power, no torque below 3k and the result is the motor is slow to respond. But why would anyone drive a 3x8 in that rpm range? No point in musing about carbureted cars. I personally have no interest in them or dry sump cars. For 35 years I get in my car, turn the key and it starts and run as it should, no matter how long it's been since I last drove it.
     
  2. Martin308GTB

    Martin308GTB F1 Rookie
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    plus poor design according to smg's explanations.

    I want. Since it works great with carbs. While my Alfa with its long stroke engine just masters great torque in the low rpms with sharp throttle response, but hates high revs, the 308 masters both. Torque at low rpms, throttle response and revs.

    Same here. Though if it has been very long since the last drive, it is necessary to wait a few secons on ignition 'on' till the float chambers are again filled.

    Best from Germany
    Martin
     
  3. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
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    Rifledriver likes this.
  4. Sigmacars

    Sigmacars Formula Junior
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    There is nothing wrong with the car it runs very nice,I was just asking if there is something I can do in the lower RPM.the Car runs now exactly the same as when it was new,just stay above 3000rpm and there is no problem.
     
  5. dave80gtsi

    dave80gtsi Formula 3
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    Well, since this thread is seemingly bouncing around from here to there, why not introduce another variable?

    Old thread: https://www.ferrarichat.com/forum/threads/enlarged-throttle-body-a-diy-product-review.353881/

    Yes, my reactions to the work which I outlined above are all subjective - I have no way to measure the performance otherwise. But suffice to say that I was very impressed by the gains in throttle response thru the enlarged throttle body and complimentary smoothing of the air path into the plenum.

    If you do not wish to read the entire thread in the link above, my final post on Page 2 was where I tried to summarize what I thought was going on.

    DM
     
  6. Rifledriver

    Rifledriver Two Time F1 World Champ

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    Some like to believe it can be done by ear. Thats hilarious.
     
  7. Rifledriver

    Rifledriver Two Time F1 World Champ

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    Nothing wrong with liking museum pieces. Just as long as you understand there are many better ways to perform the job.
     
  8. Saabguy

    Saabguy Formula 3
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    Tell me more about the gauge please.

    Lester

     
  9. Hinecker

    Hinecker Formula Junior

    Mar 14, 2011
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    If you have no measuring instruments, at least you keep it running:)
     
  10. Rifledriver

    Rifledriver Two Time F1 World Champ

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    A massive compression change can help that a lot. My 11:1 328 has very good low end torque. The stroke increase helped too I am sure. Ferrari was very timid about compression historically.
     
  11. Aircon

    Aircon Seven Time F1 World Champ

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  12. ginoBBi512

    ginoBBi512 Karting

    Oct 9, 2016
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    These 328s really wake up with a Tubi and a Test pipe, K & N , its that simple, as long as the car is tuned correctly, air fuel, its the best your going to get without major motor work, My mechanic has an 86 328 with 6 k miles in his shop , and he says my cars runs 100 % better and my car has 100 k miles Tubi / Test Pipe / K & N I also just replaced the alternator, with all that I had done to this car, I never changed it out, and at 101 k miles it froze !! I took the car out last night, I have to say I can not believe how insanely fantastic it still runs !! And the new suspension is breaking in very nicely.
     
  13. Aircon

    Aircon Seven Time F1 World Champ

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    I owned a non cat 328GTB UK spec....the throttle response was still rubbish.

    I've seen a 328 with throttle bodies and injection which revved like a motor bike. CIS is terrible,relatively speaking, but it was necessary for emissions.
     
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  14. mike996

    mike996 F1 Veteran

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    One of the things that impressed me most about the 328 is the fact that it can literally drive away in 5th gear at 1500 RPM - no drama, no bucking and spitting, just drive away with no difficulty or protest at all. It's one of my favorite things about the car!

    However, with a US 328, you can increase the low end a bit by changing the timing on the microplex to duplicate the Euro timing by simply grounding one connection on the microplex. I did this years ago and now I can't remember what specific connection it is though for some reason #17 comes to mind but DO NOT trust that recollection!

    The Euro timing adds a considerable bit of advance from idle compared to the US timing.

    I did some informal testing back when I made the change and posted my impressions on this site. It may be available if you search. But basically what I did for test purposes was make up a toggle switch that grounded/ungrounded the connection and ran that up to where I could switch it while driving. So I was able to alternate between US and Euro timing by flipping the switch.

    I was in the parking lot our marina - where the car lived at the time - and found some shallow puddles. I would approach the puddle in 1st gear, idling along and nail the throttle when the back wheels were in the water. With the US timing, the car would just gather speed; with the Euro timing, the tires would almost immediately break loose/instant burnout! It was clearly producing more power at that RPM range.

    At higher RPM - accelerating above 3k RPM, I could hear a slight difference in engine sound when flipping the switch but I can't say I could feel any noticeable difference in actual acceleration. I didn't have a helper who could do some stopwatch checks for a 50-80MPH test using the two different timing curves.

    After doing the "puddle tests" I disconnected my temporary switch and permanently grounded the connection in question. So my '89 has been operating with euro timing since then...at least 8-9 years - I think I did it in '09 or '10.

    The only downside to doing this is that the car will not pass an emissions test. However, if that's an issue, you could rig up the toggle switch in the cavity where the microplex is located and just revert to "US" on test day.

    This will not turn your 328 into a Challenger Hellcat beater but it made a noticeable improvement in low RPM acceleration on my '89 328. I ASSUME that all 328's had the same Microplex system so I ASSUME the ability to change timing curves exists for any 328, regardless of year.
     
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  15. kiwiokie

    kiwiokie Formula Junior

    Aug 19, 2013
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    Tulsa, OK
    Read a lot of comments about throttle response of CIS over the years but honestly never had a problem with my 911SC. Engine revs fast and clean and runs like a scalded cat (and have never touched the mixture screw). When you read up about it, CIS really was a pretty clever design given the technology of the time and if properly adjusted should dump more fuel even with small adjustments in throttle.
     
  16. Martin308GTB

    Martin308GTB F1 Rookie
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    Like 'smg' explained further above, it plays a significant role, how the system was implemented. Maybe the design cooperation between Bosch and Porsche was better, given the fact, that the headquarters are just a few minutes distant from each other :)

    Best from Germany
    Martin
     
  17. Aircon

    Aircon Seven Time F1 World Champ

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    The Porsche isn't as good as he thinks, incidentally, but it's all relative. The Ferrari system made a very lively engine very lazy.
     
  18. Martin308GTB

    Martin308GTB F1 Rookie
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    #43 Martin308GTB, Apr 7, 2019
    Last edited: Apr 7, 2019
    The most lively engine with a Bosch K-Jetronic I experienced, was the VW Golf GTI MkI (1.6ltr.). What a shame.
    With Porsche I am not familiar. I only remember our family F-model 911S 2.4 with its mechanical FI, when dad broke down in the middle of nowhere because of a failed drive belt :)

    Best Regards
    Martin
     
  19. Ferraridoc

    Ferraridoc F1 Veteran
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    I'd be interested to see how it all fitted on the manifolds. Did it use the ones made by Frank?
     
  20. Aircon

    Aircon Seven Time F1 World Champ

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    No idea where that car is now...I haven't seen it for many years. Geez it was good though.
     
  21. Ferraridoc

    Ferraridoc F1 Veteran
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    I know your local man made the 328 manifolds for a carbie conversion, so I thought they may have been the basis, with ITBs on top
     
  22. Aircon

    Aircon Seven Time F1 World Champ

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    Who's my local man?
     
  23. mike996

    mike996 F1 Veteran

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    Larger throttle body alone will not improve low end power. It will have the opposite effect. If folks are truly unhappy with the 328's low end, it's going to take more than a typical bolt-on to improve it.

    As far as muffler/Cat changes - ASSUMING the present cats/muffs are in good mechanical condition, there's no noticeable power to be gained by changing/eliminating them. We did so many dyno tests on such stuff that I was sick of "geez, not ANOTHER muffler test." They never made more than a few percent change. Some of the aftermarket "high performance" mufflers REDUCED HP over stock mufflers but they made up for it by being loud! :)

    One of my favorite dyno tests on mufflers/cats was performed/published by John Lingenfelter some years back. They found that on a built-up 700HP chevy motor, adding/eliminating the Cats made a HP difference that was within the tolerance of the error on the dyno. They ended up concluding that the difference in HP with/without the Cats was 7-8 HP...so, at best, removing the cats increased HP by 1%. The general rule of thumb is that it takes around 30% HP increase to make an easily noticeable difference in power.
     
  24. Brian A

    Brian A Formula 3

    Dec 21, 2012
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    Since this thread is mostly peoples' opinions, I will express mine.

    I am in the carburetors-belong-in-museums camp and love Bosch K-Jet. K-Jet, aside from some of the hydraulic complexities of Control Pressure, is a simple system that my little brain can visualize how it works: no electrons needed; all mechanical/hydraulic.

    Like mike996, I love how it is drama-free at low rpm. Its an engine that likes higher rpm range and I am more than good with that. I have never had an issue with low end torque. Thats for the muscle car people.
     
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  25. Brian A

    Brian A Formula 3

    Dec 21, 2012
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    I am sceptical that it was the fuel injection system. Those old VWs had huge flywheels which stored a lot of momentum. They had great acceleration for 10 metres.
     

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