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Thoughts on going from PMO carbs to PMO ITBs/EFI
Anyone have experience with that switch? My car has a 3.3 short stroke with 40MM PMO carbs currently. Also has Georges Euro header/m and K muffler. It feels a bit sluggish to me and I am considering PMO ITBs/EFI. I'm being told that the EFI/ITBs and sequential ignition will really liven up the engine. Any thoughts? This is the motor in the car now. Should I just stop playing around and go 3.6/3.8.
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16 Boxster Spyder (sold), 82 911 Wide body/Miami blue/Mike Bruns built 3.6 (sold), 80 911SC Black/tan (sold), 87 930 Turbo 505 slant GP white/black (sold), 95 993 C2 GP white/tan (sold), 82 911SC Hot Rod lightweight Black/black (sold) Last edited by nippy; 09-03-2017 at 04:38 PM.. |
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09-03-2017, 04:34 PM
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let me know if you take the pmo carbs off. looking for a used set right now... also a 3.3 SS twin plug race motor... need asap.. thanks
frank rauscher@wistar.org |
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09-03-2017, 04:59 PM
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Quote:
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16 Boxster Spyder (sold), 82 911 Wide body/Miami blue/Mike Bruns built 3.6 (sold), 80 911SC Black/tan (sold), 87 930 Turbo 505 slant GP white/black (sold), 95 993 C2 GP white/tan (sold), 82 911SC Hot Rod lightweight Black/black (sold) |
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09-03-2017, 05:01 PM
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I think that carbs can also provide good throttle response but I wonder if the 40s are too small for your engine. I would have thought 46 PMOs would be better. What kind of cam are you running?
EFI is slso good but will require a lot more tuning but you may get more power under the curve (and better mileage) when it is dialed in. A 3.3 short stroke is a great motor that can rev High if built right. A 3.6/3.8 would have more low end torque but probably won't rev as high. |
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09-03-2017, 05:47 PM
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83 911 Production Cab #10
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Talk to Richard @ Clewett Engineering, The complete solution for ignition & fuel injection
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Who Will Live... Will See  83 911 Production Cab #10, Slightly Modified: Unslanted, 3.2, PMO EFI, TECgt, CE 911 CAM Sync / Pulley / Wires, SSI, Dansk Sport 2/2, 17" Euromeister, CKO GT3 Seats, Going SOK Super Charger |
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09-04-2017, 02:40 AM
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Join Date: Jul 2000
Location: So. Calif.
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A short stroke 3.3 feels "sluggish"? Maybe down on power? Timing off? Is that seat of the pants or firm numbers (e.g. 0-60mph)? Sure, maybe 46mm Webers/PMOs are more ideal, but hp, torque and butt feel is relative. Maybe check the compression and optimize your setup before springing for that 3.6.
Sherwood |
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09-04-2017, 11:16 AM
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Location: Brisbane
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i don't think you'll regret going EFI/ITB's.
peak hp won't change much from the carb's but it will just run better everywhere else. |
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09-04-2017, 02:46 PM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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Are your carbs jetted correctly? Don't make the change until you have them running properly.
That being said... I went from carbs to ITBs/EFI and found a significant increase in perceived power. Overall, the difference was that the EFI can be tuned to run right everywhere in the load/rpm space. This is sometimes difficult to do on carbs but is also highly dependent on engine build spec.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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09-04-2017, 03:34 PM
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nippy my engine builder says 40mm simply too small for my build... so thanks anyway glws frnk
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09-04-2017, 03:45 PM
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Das Babe
Das Babe Metalberiech
