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ic932
Joined: 11 Feb 2005
Posts: 1104
Location: UK
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 Posted: Sun Mar 01, 2009 8:57 pm Post subject: |
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| Raceboy wrote: | I didn't say EFI isn't improvement over K-Jet, I said that when adding turbo to existing EFI engine, you will get worse MPG.
And obviously if you add turbo to K-Jet, same story.
After my efi and turbocharger install to white 924, MPG is roughly the same as it was with NA form and old K-Jet, maybe a little bit worse (better on the highway, around 7-8l/100 km/h and worse in the city due to lots of acceleration). |
Cheers, thats a very important insight... |
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SXX360
Joined: 07 Mar 2009
Posts: 36
Location: Adams, NY
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| Posted: Tue Mar 17, 2009 4:52 am Post subject: MY thoughts |
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Just putting a turbo on an engine will not get better gas mileage, everyone else has already stated that.
What gets the better mileage is because of the increase in power you can then run a transmission with lower gear ratios.
My mom owns 2 daytona's..dont get me started..
her summer car an 88 turbo 5 speed
her winter car a 90 or 91 efi 5 speed
usually gets better with the turbo because its got way smaller ratios
its also alot more fun to drive.. |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Tue Mar 17, 2009 8:57 am Post subject: |
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If those daytona's are both 4-cylinders, the increase in efficiency is likely also due to the change from multipoint EFI to singlepoint EFI (Throttlebody injection) Also, in 89, the Daytona's cme with a 2.5L SOHC turbo (non-intercooled) or a 2.2L SOHC turbo (intercooled) and the TBI versions in 90/91 are 2.5L SOHC's. Otherwise it is a 3.0L V6, which is another matter altogether.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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SXX360
Joined: 07 Mar 2009
Posts: 36
Location: Adams, NY
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| Posted: Tue Mar 17, 2009 10:22 pm Post subject: |
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yes they are both 4 cylinders.
the turbo is currently not intercooled but thats going to change
I dont remember what size either of them are but back to the mileage thing
its the gear ratios that get you the better mileage to the point where the engine is actually bogged down which then you will get worse mileage.
my mom has a trip computer in the turbo car and you can drive at 35mph in 5th gear and it will say maybe 20mpg, if you then go to 4th and drive at 35mph it will say maybe 27mpg.
Im sure someone else can describe it better but...
Because your trying to push so much fuel into the engine but because of the low gear ratio at the low rpm it just bogs down the engine |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Tue Mar 17, 2009 11:43 pm Post subject: |
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Just as a data point, the 87 daytona shelby I had would get 30mpg at 90mph in 5th gear
It really is about the point in the power curve that the engine is most efficient. On batch fired cars of small size that point is a bit higher in the power band. Also the turbo does help provided you are at it's most efficient point as well. At 90, the turbo had the intake at zero inches of vacuum/zero pounds of pressure.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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Nobbi
Joined: 24 Aug 2006
Posts: 1396
Location: Germany
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| Posted: Fri Mar 20, 2009 12:26 am Post subject: |
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I think ive heard that opel puts a turbocharged LPG car onto the market,probably you could gather some info there....... 
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NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1967 |
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924 FAQ (Technical)
