# 8v on twin carbs with airbox



## thegave (Dec 22, 2008)

Has anyone done this and can anyone walk me through why it would or wouldn't be a good idea?


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## B4S (Apr 16, 2003)

*FV-QR*

I've tried, and given up. On a counterflow head, there just isn't enough room to use one of the (very expensive) commercial airboxes available for twin carbs. This means the box will have to be custom fabricated...and I'm no good at fibreglass work. If a design was made that could emulate the old Ford Lotus Cortina intake plenum/box, then that would work very well...but making it so that the box can be attached to the carbs while in place between the head and the firewall could be tricky. I attempted to make one out of metal, and quickly found myself stuck due to clearances. I was going to attempt one out of plastic, but got some K&N filters/bases instead. I used 3.5" filters so I could fit the horns in them too, and had VERY little space left to bolt the tops down.


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## thegave (Dec 22, 2008)

*Re: FV-QR (B4S)*

Pipercross makes boxes that are supposedly low profile for space-confined areas I think they take up to 45mm trumpets. Still too big?
What size horns did you manage to fit on the carbs?


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## B4S (Apr 16, 2003)

*FV-QR*

The pipercross box would probably fit, it's the outlet that's the issue. It will either hit the strut tower/timing belt cover or the brake booster/master, depending the outlet side you chose







. I have 60-65mm horns on my carbs, with a 3.5"/88.9mm filters. There is just enough room inside the filter unit to allow for proper clearance/airflow to the horn...but that's as big as you could go. If pipercross made a box WITHOUT the filter outlet, and made it so that you could run an intake pipe of a smaller diameter, then it'd work fine. The issue is that all the aftermarket airboxes are so grossly overpriced that it's not worth it to buy one and hack it up. A box can most definitely be made, but it's going to take time/thought. Both of which I was tired of spending on the project







.


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## eurotrashrabbit (Oct 25, 2001)

*Re: 8v on twin carbs with airbox (thegave)*

Here you go this one is carbon fiber and even with the 25mm restrictor it make 140 bhp on a Hydrojet on a 1.6 It does have a drysump and built motor


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## thegave (Dec 22, 2008)

Mine was a second hand plastic Pipercross one I got for $120... I live in the UK, everything's expensive. New would have been over $300. So I might cut it up if I have to, but would like to mount it the other way so the air inlet comes out on the side opposite to the brake servo.
You managed to fit 60mm trumpets on a counter flow head? That's huuuge. What did you do about hot air from the exhaust header?


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## B4S (Apr 16, 2003)

*Re: (thegave)*

Currently I do nothing about the hot air, and it shows







. I am going to try some ducting to direct cooler air towards the carbs now that I have filters. I was running without filters, so I was reluctant to expose them to outside air. The 60mm horns fit great, it was the 89mm filters that were tight







.


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## thegave (Dec 22, 2008)

Did you have to cut the #1 (leftmost) horn to clear the brake servo?


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## secondgen (Jan 9, 2004)

*Re: (thegave)*

I've also been considering/ working on how to get an airbox around mine as well.
The pipercross 600 series box would fit, but as previously stated, even with the small 75mm inlet, the way it's designed it would hit the strut tower or heater core hoses (to those still running one), it also may interfere with the brake booster, but that i'm unsure about, as i'm not running one.
The shortt TWM Induction one would be the next closest to fitting, but it's about .5"-.75" to deep. Weather or not it could be modified to be say, an inch shorter, and still seal properly, i have no idea.
Even with only 1" full radius trumpets, my pipercross 50mm filter socks are really close to the firewall. The shaved raintray helps slightly with clearence on the topside, and at highway speeds, the base of the windshield is a high pressure area, pushing some cooler air down through the vents in the hood. My intake temps that I've logged are still at, or above 100*F. Going as high as 160*F sitting, hood down, in traffic.
My setup:


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## B4S (Apr 16, 2003)

*FV-QR*

I should mention that I'm running a MkI, there seems to be a tad more room in the bay than the above MkII. I didn't have to cut any horns, because on the LHD cars, the booster is on the LHD side of the bay, well clear of the engine, out over the transmission. The manifold I am using is perhaps a shave shorter than most as well, it's an old Weber one with the linkage standoffs cast into it. I've never compared it to any other counterflow manifold, so I don't know if I'm correct or not. All I know is that I fit 89mm filters in there, with about 2-3cm to spare







.


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## thegave (Dec 22, 2008)

Sweet bay there.
So what happens when all this hot air hits the carbs? Does it clear up once you're moving at a good pace?


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## secondgen (Jan 9, 2004)

*Re: FV-QR (B4S)*


_Quote, originally posted by *B4S* »_ The manifold I am using is perhaps a shave shorter than most as well, it's an old Weber one with the linkage standoffs cast into it. I've never compared it to any other counterflow manifold, so I don't know if I'm correct or not. 

I'm running the same manifold, but with the linkage standoffs cut off, so that I can run the fuel rail in the factory location.
I've got another manifold, an old drake model, with linkage, it's shorter, and the approach angle is steeper. It points the throttles up more toward the rain tray. Using it would require me to run the injectors in the ITB's, which would detract from the drive-ability.


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## eurotrashrabbit (Oct 25, 2001)

*Re: (secondgen)*

Are you running the TJ Motorsports dual MC setup I have it on my rabbit and I am very happy with it


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## secondgen (Jan 9, 2004)

*Re: (eurotrashrabbit)*


_Quote, originally posted by *eurotrashrabbit* »_Are you running the TJ Motorsports dual MC setup I have it on my rabbit and I am very happy with it 

Yes, still fiddling with it, pedal seems *really* hard, I think i may have the cylinders backwards. Do you know what size you're running for the front brakes? I recall talking with you about the setup before I bought it. Pretty sure we're running the same size masters. A fellow I know with our similar setup isn't even this firm, which leads me to believe the masters are the wrong size for the application (front or rear or altogether), or I have them backwards.
This box is very similar to the Pipercross one in design, looks a bit thicker though.








Pipercross 600-series 75mm LH inlet:








or








TWM Induction:








Jenvey (pressurized box)








http://****************.com/smile/emthup.gif


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## eurotrashrabbit (Oct 25, 2001)

*Re: (secondgen)*

Manual brakes are not as "soft" as vacuum assisted brakes so it maybe ok. I believe I have a .675 in the front and a .750 in the rear. That is standard for the setup I also bought the cable for adjusting the bias bar from inside the car


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## B4S (Apr 16, 2003)

*Re: FV-QR (secondgen)*


_Quote, originally posted by *secondgen* »_
I'm running the same manifold, but with the linkage standoffs cut off, so that I can run the fuel rail in the factory location.
I've got another manifold, an old drake model, with linkage, it's shorter, and the approach angle is steeper. It points the throttles up more toward the rain tray. Using it would require me to run the injectors in the ITB's, which would detract from the drive-ability.

cool, good to know. The drake manifold might not be great for carbs, if the angle is too steep, but I highly doubt Drake messed with those.
I like that Jenvey box...hmm.


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## darthcabby (Sep 11, 2009)

*Re: (secondgen)*


_Quote »_This box is very similar to the Pipercross one in design, looks a bit thicker though.

the reverie box is identical in width to pipercross 600, the diference(the advantage of the reverie) is that the K&N filter is bigger(more real flow) on the Reverie box.
By the way that´s my set up there.


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## secondgen (Jan 9, 2004)

*Re: (darthcabby)*

Good looking motor setup you have there. Any dyno numbers?
That airbox is far to large in all the wrong places for us counterflow folks.


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## darthcabby (Sep 11, 2009)

*Re: (secondgen)*


_Quote, originally posted by *secondgen* »_Good looking motor setup you have there. Any dyno numbers?
That airbox is far to large in all the wrong places for us counterflow folks.

I dont have any dino numbers yet(engine is breaking in). I will take to the dyno for tune in a couple of months and we will see what is capable of....
About the airbox for counterflow you can try this http://www.reverie.ltd.uk/prod...204CY or
http://www.reverie.ltd.uk/prod...E0434
they make diferent sizes and forms of airboxes just check the web. The only problem is that they are expensive http://****************.com/smile/emthdown.gif


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## Antikrist~86CGT~ (Mar 24, 2009)

*Re: (darthcabby)*

very sweet bay http://****************.com/smile/emthup.gif question though, are you running 2 fuel pumps? looks like you have a facet pump before your carter one. either way, kick ass set-up. http://****************.com/smile/emthup.gif 
Joey


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## darthcabby (Sep 11, 2009)

*Re: (Antikrist~86CGT~)*


_Quote, originally posted by *Antikrist~86CGT~* »_very sweet bay http://****************.com/smile/emthup.gif question though, are you running 2 fuel pumps? looks like you have a facet pump before your carter one. either way, kick ass set-up. http://****************.com/smile/emthup.gif 
Joey

No, i am just running the carter pump without regulator(works great) that thing there, is a fuel filter. thanks for your compliments.


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## Antikrist~86CGT~ (Mar 24, 2009)

*Re: (darthcabby)*

oh ok, kinda threw me for a loop







and no problem man, very awesome set-up http://****************.com/smile/emthup.gif


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## Macho_volks (Jan 2, 2003)

*Re: (darthcabby)*

darthcabby where did you get those blue AN fuel fitting on the carbs?








[/QUOTE]


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## darthcabby (Sep 11, 2009)

*Re: (Macho_volks)*


_Quote, originally posted by *Macho_volks* »_darthcabby where did you get those blue AN fuel fitting on the carbs?

I got them here http://www.demon-tweeks.co.uk/...1-M16


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## Macho_volks (Jan 2, 2003)

*Re: (darthcabby)*


_Quote, originally posted by *darthcabby* »_
I got them here http://www.demon-tweeks.co.uk/...1-M16


thanks


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