I have an 84 Spyder. I know the stock horsepwer ratings are pitiful, so I'd like to get more and still have reliability. It has a full ANSA exhaust and cone air filter, aftermarket spark supply. For a project in the Fall, I'd like to take it up a notch or two,, 10:1 pistons, cams, bigger valve/better flow heads, underdrive alloy crank pulley and lighten the flywheel. Is that it? This seems to be the most I can do and still have the fuel injection keep up... from what I've read, anyway. Who's done this stuff to their car and what kind of additional power did you really feel? Do I need to go to a pair pf PMO's for more fuel, but then how is the reliability? Please, comments about your experience,,,
Thanks!
-Karl
Street Horsepower: FI or Carbs?
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narfire
- Posts: 3959
- Joined: Sat Dec 27, 2008 2:14 am
- Your car is a: 1980 124 spider
- Location: Naramata B.C.
Re: Street Horsepower: FI or Carbs?
Karl, I have a 80 FI. What you are wanting to do is exactly what I have done to my engine other than the spark supply.
I put a 1800 head on with big valves. 84.4 Mahle pistons , header and shaved flywheel The whole lot was balanced as well. I think there is a difference,big or not I don't care but the car really has a noticable difference in the mid range pull. Your right in the limited upgrades one can do without changing the fuel delivery, I had asked the same question to several people and most if not all said one would have to upgrade the fuel delivery if you want even more. That skill set is beyond me as was the wallet capacity. I left the cams the same, but Mark Allison is offering a set that would work with the FI system.
One could also dial in the cams with a set of adjustable cam wheels. I might go that route this fall as well
Good luck
Chris
I put a 1800 head on with big valves. 84.4 Mahle pistons , header and shaved flywheel The whole lot was balanced as well. I think there is a difference,big or not I don't care but the car really has a noticable difference in the mid range pull. Your right in the limited upgrades one can do without changing the fuel delivery, I had asked the same question to several people and most if not all said one would have to upgrade the fuel delivery if you want even more. That skill set is beyond me as was the wallet capacity. I left the cams the same, but Mark Allison is offering a set that would work with the FI system.
One could also dial in the cams with a set of adjustable cam wheels. I might go that route this fall as well
Good luck
Chris
80 FI spider
72 work in progress
2017 Golf R ( APR Stg. 1)
2018 F350 crew long box
72 work in progress
2017 Golf R ( APR Stg. 1)
2018 F350 crew long box
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BEEK
- Posts: 1833
- Joined: Wed Mar 24, 2010 10:45 pm
- Your car is a: 1975 Spider
- Location: clermont fl
Re: Street Horsepower: FI or Carbs?
DIFFERENT INJECTORS, oops caps, find injectors with the lbs/hr rating of your needs, there are many to choose from.
i would also try and find a larger throttle body, 60mm. that adaptation will be a challlange, but not insurmountable. a air flow meter from a larger displacement motor will also be needed. will take some research. but i feel it can be done, i have not yet built any performance efi motors. other than high compression big valves, aftermarket cams, chassis dyno at 125-135hp. in dyno testing we determined than stock early fiat cams made almost the same power, more when properly degreed, for the street, the big cams use a rpm range that most dont see in daily driving. but i understand the concept. i have built hundreds of performance fiat motors, carburated. you are definatly going in the right direction. it is amazing how much stock fiat parts will take before failure.
i would also try and find a larger throttle body, 60mm. that adaptation will be a challlange, but not insurmountable. a air flow meter from a larger displacement motor will also be needed. will take some research. but i feel it can be done, i have not yet built any performance efi motors. other than high compression big valves, aftermarket cams, chassis dyno at 125-135hp. in dyno testing we determined than stock early fiat cams made almost the same power, more when properly degreed, for the street, the big cams use a rpm range that most dont see in daily driving. but i understand the concept. i have built hundreds of performance fiat motors, carburated. you are definatly going in the right direction. it is amazing how much stock fiat parts will take before failure.
Automotive Service Technology Instructor (34 year Fiat mechanic)
75 spider , 6 Lancia Scorpions, 2018 Abarth Spider, 500X wifes, 500L 3 82 Zagatos. 82 spider 34k original miles, 83 pininfarina, 8 fiat spider parts cars
son has 78 spider
75 spider , 6 Lancia Scorpions, 2018 Abarth Spider, 500X wifes, 500L 3 82 Zagatos. 82 spider 34k original miles, 83 pininfarina, 8 fiat spider parts cars
son has 78 spider
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So Cal Mark
Re: Street Horsepower: FI or Carbs?
there are a couple of cars that use injectors with higher flow rates that are a direct replacement for the Fiat injectors. That will help the top end, but not the low rpm driveability if you use a very radical cam. Unless you add compression ( and that's not a cure-all) stay with a short-duration cam. Adjustable pulleys will help if you choose cams too radical, but then you're just trying to mitigate the effects of the having the wrong cams. A free-flow header and exhaust is mandatory with a cam upgrade.
The problem is that the L-Jet injection system relies on air flow, and lots of overlap at low rpms causes effects the L-Jet can't compensate for. You'll have a difficult time trying to get a fuel mixture that is proper all throughout the rpm range. If you want high-rpm cams, you need a stand-alone ecm that can be mapped.
If you're willing to use an rpm range similar to a stock motor, you can make gobs of torque and have a street car that is a blast to drive with good driveability
The problem is that the L-Jet injection system relies on air flow, and lots of overlap at low rpms causes effects the L-Jet can't compensate for. You'll have a difficult time trying to get a fuel mixture that is proper all throughout the rpm range. If you want high-rpm cams, you need a stand-alone ecm that can be mapped.
If you're willing to use an rpm range similar to a stock motor, you can make gobs of torque and have a street car that is a blast to drive with good driveability
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turbokh
Re: Street Horsepower: FI or Carbs?
Thanks for all the quick replies.
My experience is with the flat-6 911 engines and a few VW 4 cyl turbos. We used megasquirt to replace the ECU on one of the VWs and it was great once dialed in. My fear with bigger injectors on the Fiat is like Mark said, more fuel but the Bosch FI won't know how to compensate. I see 10:1 pistons, big valve heads.. cams, of course.
I wouldn't expect 150hp that's still daily driveable, but more than stock for sure. I can see it'll take a lot of research since the Fiat community is relatively small. I've got til Fall to have a plan. Here's a question: does anyone build a killer long block for street use with FI? Racing grooup? If someone has already done the research and I can just fling it in there I would do that.
I know.. I should leave it alone and drive it for the fun car that it is. I have another car with 5 times the power when I need the thrill. But it's a sickness! You guys understand, I'm sure.
-Karl
ps Mark.. I didn't realize you ARE Allisons automotive. You must have seen this question a million times!
My experience is with the flat-6 911 engines and a few VW 4 cyl turbos. We used megasquirt to replace the ECU on one of the VWs and it was great once dialed in. My fear with bigger injectors on the Fiat is like Mark said, more fuel but the Bosch FI won't know how to compensate. I see 10:1 pistons, big valve heads.. cams, of course.
I wouldn't expect 150hp that's still daily driveable, but more than stock for sure. I can see it'll take a lot of research since the Fiat community is relatively small. I've got til Fall to have a plan. Here's a question: does anyone build a killer long block for street use with FI? Racing grooup? If someone has already done the research and I can just fling it in there I would do that.
I know.. I should leave it alone and drive it for the fun car that it is. I have another car with 5 times the power when I need the thrill. But it's a sickness! You guys understand, I'm sure.
-Karl
ps Mark.. I didn't realize you ARE Allisons automotive. You must have seen this question a million times!