4A-GE: Bigport with smallport fuel injection

[nyberrg]

Hello, my Carina currently has a smallport 4A-GE. I recently came across a newly renovated bigport engine that I want to fit to it instead. Would there be any issue using the fuel injection from the smallport on the bigport engine? I would be using the smallport ECU, fuelrail, injectors and such.

[Bean]

smallport and bigport have different injector spacing so the fuelrail isn't interchangeable. ECU, fuelrail and head should be from the same model ideally. you could switch the head onto the bigport block and retain ecu etc. there's many other mix and match options but it really depends what your goals are and how much work you want to put in to it.

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[nyberrg]

The bigport engine, was part of my fathers AE86 purchase, it has HKS cams and higher comp. Pistons. Plan was to just swap everything onto that engine and get more power without tinkering with the electrics, vut that might be some more work then.

Whats the difference between the fuelrails more than spacing, should i not be able to just swap fuelrails and have smallport ECU?

[Uzelac]

It should work ok, just mix and match parts so everything fits

[jondee86]

Use the bigport rail and smallport injectors.

To use the smallport intake on the bigport head you will need
an adapter plate.

If the compression has been bumped on the bigport, then it will
probably run OK on the smallport ECU. Give it a try

Cheers... jondee86

[fax0815]

Yeah mix and match till it fits, should be no problem. Like Jondee said, only thing you´ll need is the adapter to run the Smallport intake on the bigport head, or get a normal bigport intake and run it without the TVIS plate.

[ZDoman]

I have a friend who is running an engine: smallport bottom end (10,3:1 pistons) with bigport head, bigport intake manifold and smallport MAP (italian spec) electronics, injectors, etc. Stock cams, stock exhaust. We have never tested it with wideband O2 sensor, nor knock detecting, but it runs great for 1 year now. Fuel consumption is relative low, I think he were able to get under 7l / 100km on country roads. Runs like a healthy bigport, nothing special.

[nyberrg]

Thanks for the help, not sure what i will do yet but I have all the parts for putting it together, so if I do I'll be sure to update my project thread