Carb 8 valve head, can it run EFI?

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missioner
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Carb 8 valve head, can it run EFI?

Post by missioner »

Here's a question for the customisers on the forum and anybody else who might know.

As per the topic of the thread I am curious to know if anybody has converted a carb u flow head to run fuel injection and if it was successful how did they do it and so on.

I am aware that there is some science behind port injection to do with the position of the injectors in relation to the valves. So therefore I am not asking why a EFI head is better, I know that already. I am simply lookin at another angle regarding the next phase of my build and want to satisfy my curiosity regarding the topic in question

Thanks in advance.
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Re: Carb 8 valve head, can it run EFI?

Post by Torker »

Sarel's done it, he machined a 25mm thick alu adaptor that sat between the FI intake and the head, basically morphing from the keyhole port shape to the oval port shape. Wasn't done for performance, more due to budget restrains on the owners side. Ran well enough at the end of the day. I did a bit of research when I fitted a Rowland manifold on my solid lifter head, I had a choice of using the injector holes in the manifold or in the head. The closer the injectors are to the valve the better the throttle response, if the injectors are further away you get a slight power advantage at higher rpm's due to better atomisation.
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Re: Carb 8 valve head, can it run EFI?

Post by panic-mechanic »

Many years ago also due to budget we also basically used an mp9 manifold on a carb head and machined the head a bit to have that hollow section. It worked ok enough.
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Re: Carb 8 valve head, can it run EFI?

Post by missioner »

Thanks for the replies, I'm glad to know at least its possible.

One more thing the carb head has a water port that feeds coolant to the manifold. I am assuming this was blocked or welded closed for the conversion. Correct?
Last edited by missioner on Thu Oct 08, 2015 10:14 am, edited 1 time in total.
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Re: Carb 8 valve head, can it run EFI?

Post by zain_c »

another q, sorry to OP for the hijack.

I've got a CLX MK2 Jetta, 1800 carb, would there be any issues on fitting an MP9 head with the rest of the MP9 ancillaries (intake/throttle/loom/ecu etc) to my current sub and having everything run smoothly?

Would anything need to be changed on the sub?

Thanks
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Re: Carb 8 valve head, can it run EFI?

Post by panic-mechanic »

No issues. Straight boltmover.
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Re: Carb 8 valve head, can it run EFI?

Post by zain_c »

thanks Panic!

I've heard that I might need to change pistons to up compression a bit?
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Re: Carb 8 valve head, can it run EFI?

Post by zain_c »

IIRC guy mentioned 82.5mm
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Re: Carb 8 valve head, can it run EFI?

Post by missioner »

cap'ncook wrote:thanks Panic!

I've heard that I might need to change pistons to up compression a bit?
Not neccesary 81mm stock pistons work fine there.
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Re: Carb 8 valve head, can it run EFI?

Post by zain_c »

missioner wrote:
cap'ncook wrote:thanks Panic!

I've heard that I might need to change pistons to up compression a bit?
Not neccesary 81mm stock pistons work fine there.
great! Thanks missioner!
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Re: Carb 8 valve head, can it run EFI?

Post by panic-mechanic »

The head cc's are the same inside carb to FI. no ned to change anything.
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Re: Carb 8 valve head, can it run EFI?

Post by graham savage »

Just ensure you are getting a 1.6/1.8 Mpnaai head, the 1.4 one won't work
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Re: Carb 8 valve head, can it run EFI?

Post by Pieter94 »

I want to find out can i use a 1.4l Injector head on a 2e Long block MK1 Engine ?
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Re: Carb 8 valve head, can it run EFI?

Post by missioner »

Pieter94 wrote:I want to find out can i use a 1.4l Injector head on a 2e Long block MK1 Engine ?
Check valve diameter. Otherwise it will bolt on.
Compression ratio will be very high. Would probably ping it's tits off.


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Re: Carb 8 valve head, can it run EFI?

Post by Dayknight-VW »

Ive got a setup like this but the opposite way. Using a fuel injection head with a carb. Car feels normal but it has a bit of a flat spot on low rpm
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