'74 Spider conversion to FI

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prodigalson
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Joined: Wed May 03, 2017 8:03 am
Your car is a: 1974 Fiat 124 Spider

'74 Spider conversion to FI

Postby prodigalson » Fri May 19, 2017 10:47 am

I’d like to convert my ’74 Spider to fuel injection for multiple reasons, not the least of which is that I work for Bosch, but also I'm much more familiar with FI and it makes good powa!

I have a few questions:

-Does the Euro version of the fuel injection system differ from the North American version? (a friend from work is giving me a compete FI system from a Euro Spider. I'm asking because he said that the engine that the FI system came from was 122hp. Maybe because it was 9.8:1 CR and tuned for it?).

-Can the conversion be done with a 1756cc engine block/heads?
-Assuming that it can be done with a 1756cc block/heads, how much HP would I be giving up?
-Any other undesirable consequences of using the 1756cc block/heads?

-Sounds like the Bosch ECU cannot be easily be tuned to accept HP modifications (CR increase, bigger valves, bigger cams, etc). If I went with an aftermarket ECU like Megasquirt I should be able to dial in the necessary fueling, correct?

If the original air flow meter is removed, how does the ECU (Megasquirt) calculate air flow? Air density tuning? Modern MAF?
Last edited by prodigalson on Fri May 19, 2017 1:12 pm, edited 2 times in total.
1974 Fiat 124 Spider- Restoration in progress
1974 Fiat 124 Spider- (Mostly) complete parts car
2012 Mazdaspeed 3
2007 Kawasaki Mean Streak Special Edition (Currently up for sale to fund the Fiat project)

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RRoller123
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Your car is a: 1980 FI SPIDER 2000
Location: SAGAMORE BEACH, MA USA

Re: '74 Spider conversion to FI

Postby RRoller123 » Fri May 19, 2017 11:53 am

TTBOMK, the only real tuning that you can do easily with the stock system is air flow: by fiddling with the bypasses (AAV, Idle Screw, AFM Bypass) or fiddling with the fuel mixture a little bit by playing around with the tension on the AFM flap. Some folks have changed injectors to change fuel flow for AFR mixture and top end power reasons as well. I am no expert, but I would think that the stock FI system would have one heck of a time working well on one of the older motors with smaller displacement, as so many parameters are fixed. There is no customer accessible tuning on the ECU, you would literally have to start changing resistors, etc.
'80 FI Spider 2000
'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/STD BED
2002 Edgewater 175CC 80HP 4-Stroke Yamaha
2003 Jaguar XK8
2003 Jaguar XKR
2021 Jayco 22RB
2019 Bianchi Torino Bicycle

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AndyVAS
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Your car is a: 1980 Fiat 124 Spider

Re: '74 Spider conversion to FI

Postby AndyVAS » Sat May 20, 2017 2:30 pm

The stock system doesn't adjust very much. There isn't any reprogramming. Conversion to MAP hasn't been done on this Bosch system that I'm aware of.

As for putting it on the smaller motors, it's great. The stock systems run a bit on the lean side at higher RPMs and WOT but when you drop the demand the system keeps up. Having put the system on both a 1756 and 1608, I highly recommend it.

You should make more power with Bosch EFI than a single carb. Dual carbs make about equal peek power but not as much average power.
Andy Phillips
Vick Auto - Technician, Performance Engine Builder & PFI Developer (with ITBs)
http://www.vickauto.com
Stock parts or Performance parts we've got what you need.

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kmead
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Your car is a: 1969 850 SC 1970 124 SC 85 X19
Location: Grand Rapids, MI

Re: '74 Spider conversion to FI

Postby kmead » Sat May 20, 2017 2:42 pm

Actually I believe it would likely work just fine.

Basically the system is reading the amount of air going in and then releasing a given amount of fuel as a percentage of the amount of air. Given this even though an early engine may not pump the maximum amount of air the system is capable of applying fuel to, it will still provide the right amount of fuel in ratio to the actual air pulled into the engine.

What the stock injection system doesn't deal well with is cams with signficant overlap as they push some of the air back into the intake, particularly at idle. This causes the system to not meter the air properly causing fuel issues.

The system does rely on certain parts to be in the right places, particularly the coolant temperature sensor, so you will need the late style neck from the head to the two coolant hoses.

Getting the entire wiring harness, which is completely separate from the rest of the engine compartment and the rest of the car, is critical to you being successful in your install. You will need to make good use of the Fuel Injection Troubleshooting Guide after you complete your install as you will likely find a few errors in your work or in some of the old parts you are transferring.

The engine will make good power and most importantly will be much more consistent when running. It won't make as much power as a well tuned set of IDFs but it will surpass the standard carb and manifold. You will want to go to the later header with two outlets and two into one downpipe if you don't already have one.

Good luck and please let us know how it goes.
Karl

1969 Fiat 850 Sports Coupe
1970 Fiat 124 Sports Coupe
1985 Bertone X1/9

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RRoller123
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Your car is a: 1980 FI SPIDER 2000
Location: SAGAMORE BEACH, MA USA

Re: '74 Spider conversion to FI

Postby RRoller123 » Sun May 21, 2017 5:12 am

This will be fun to watch, I am looking forward to it!
'80 FI Spider 2000
'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/STD BED
2002 Edgewater 175CC 80HP 4-Stroke Yamaha
2003 Jaguar XK8
2003 Jaguar XKR
2021 Jayco 22RB
2019 Bianchi Torino Bicycle

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FiatMac
Posts: 290
Joined: Sat Aug 01, 2009 1:14 pm
Your car is a: 1982 2000 Spider
Location: Salisbury, North Carolina

Re: '74 Spider conversion to FI

Postby FiatMac » Sun May 21, 2017 9:43 am

kmead wrote:Actually I believe it would likely work just fine.

Basically the system is reading the amount of air going in and then releasing a given amount of fuel as a percentage of the amount of air. Given this even though an early engine may not pump the maximum amount of air the system is capable of applying fuel to, it will still provide the right amount of fuel in ratio to the actual air pulled into the engine.


Agreed. Where the stock fuel injection runs into trouble is when the air flow exceeds the the capacity of the air flow meter(AFM).
Stan McConnell
Retired Mechanical Engineer
Salisbury, North Carolina
82 2000 Spider (driving)
78 124 Spider on the rotisserie
76 124 Spider parts car or possible Lemons racer
83 parts car

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So Cal Mark
Posts: 13839
Joined: Wed Jan 25, 2006 3:45 pm
Your car is a: Fiat
Location: upland, ca.

Re: '74 Spider conversion to FI

Postby So Cal Mark » Sun May 21, 2017 9:46 am

we've done several conversions on 1800 motors and the system works fine, even with mild performance cams.
Mark Allison
allisonsautomotive.com Fiat and Alfa Romeo parts and service. Performance parts our specialty!
Headers, ignitions, wheels, cams, flywheels
starsmark@hotmail.com 909-981-3566

prodigalson
Posts: 17
Joined: Wed May 03, 2017 8:03 am
Your car is a: 1974 Fiat 124 Spider

Re: '74 Spider conversion to FI

Postby prodigalson » Wed May 24, 2017 5:14 pm

Thanks for the feedback fellas! I'm sure I'll have plenty of questions as I move forward with this!
1974 Fiat 124 Spider- Restoration in progress
1974 Fiat 124 Spider- (Mostly) complete parts car
2012 Mazdaspeed 3
2007 Kawasaki Mean Streak Special Edition (Currently up for sale to fund the Fiat project)

85redpini
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Your car is a: 1985 pininfarina spider

Re: '74 Spider conversion to FI

Postby 85redpini » Thu May 25, 2017 2:10 pm

if would be cheaper to buy a fi spider considering what they are selling for on ebay. usa version had no where that horsepower. it would be simple enough to check a European bosch catalog versus a usa bosch cat to see if the bosch part numbers were different.

prodigalson wrote:I’d like to convert my ’74 Spider to fuel injection for multiple reasons, not the least of which is that I work for Bosch, but also I'm much more familiar with FI and it makes good powa!

I have a few questions:

-Does the Euro version of the fuel injection system differ from the North American version? (a friend from work is giving me a compete FI system from a Euro Spider. I'm asking because he said that the engine that the FI system came from was 122hp. Maybe because it was 9.8:1 CR and tuned for it?).

-Can the conversion be done with a 1756cc engine block/heads?
-Assuming that it can be done with a 1756cc block/heads, how much HP would I be giving up?
-Any other undesirable consequences of using the 1756cc block/heads?

-Sounds like the Bosch ECU cannot be easily be tuned to accept HP modifications (CR increase, bigger valves, bigger cams, etc). If I went with an aftermarket ECU like Megasquirt I should be able to dial in the necessary fueling, correct?

If the original air flow meter is removed, how does the ECU (Megasquirt) calculate air flow? Air density tuning? Modern MAF?


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