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Hey All,
Was wondering if anyone have done this to their SU's. I was thinking of boring the openning out a little. I would probably make it the same diameter on the inside of the openning but tapper it outward towards the outside, shape it like an air horn. Then fab an airhorn the same diameter as the outter and bolt it on.

Just trying to see if I could get more air through the carbs that way. Let me know what you all think.

Thanks,
 

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i was curious about running the airhorn type additions also, but im not sure if they actually have air filters that come with them?

i have K&N filters on each carb now and i think they flow like crap as they dont even go edge to edge on the chrome housings.
 

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ZsDown-I don't think that's going to entirely work, but I think your on the right track. ZTherapy offers bored out Su carbs I believe, they are on the web you can look them up. I am thinking they go up to like 55mm, I may be wrong on the size though.

brian510- If your not running a velocity stack on your carbs, you really ought to be doing so. The reason is that it'll offer more torque to the engine and it helps to straighten out the airflow as it enters the carb. Not sure why the K&N's don't fit. Were they purchased as a set? By the way, good looking Z! I had a set of those wheels on the back in a 15x10 size! Man were they heavy!

Dave
 

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z240:

here is a picture link below of my engine with view of the filters and a link of video of the car. the filters themselves do not go to the edges of the chrome top/bottoms, but maybe thats the way they are.

ill be ordering a pair of stacks today...


my rims are 14x6.5 i think and the tires hit with it lowered. the previous owner put 225/60's on and should have gone with 215's or he got the wrong offset which is what i suspect.

thanks

1973 240Z video

Engine picture



Post Edited (Oct 12, 6:55am)
 

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actually the only "smog" stuff that is on there is the throttle vacuum dashpot which only slows the throttle from closing too fast when letting off the gas suddenly. there is no EGR or smog pump.

wait.. you were joking about he smog stuff right? LOL

that dashpot doesnt affect performance at all, and when we took it off last week it sounded like crap everytime we downshifted gurgling and popping out the tailpipe.



Post Edited (Oct 12, 5:43am)
 

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my Z Therapy carbs already run so rich i wouldnt want those pistons moving any faster than they are now with 10-30 in there.
 

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well go figure i had my thinking backwards!

well now i guess i really need to figure if under full throttle if i am just right or too rich or too lean...

and to get the old oil out? syringe and suction tube?
 

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Take the Dashpot cover off and just dump the old oil and spray carb cleaner and clean it up. Another way is slow but works, just paper towels rolled up and just soak the old oil out.

Rob
 

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ok, i thought i missed some smog crap so i started looking at what you might have seen in the picture...LOL

we just put 2.5 inch exhaust on this afternoon and a flowmaster 40 series delta flow muffler. man does it sound good now!
 

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The stock AF housing is MUCH better than these K&N type setups. It has dual velocity stacks built into it, routes the float bowl vent tubes to the filtered side of the AF etc.. People hear the noise from the open element AF and think it faster.
 

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Absolutely...

When tested by Z-Therapy on the dyno, EVERY aftermarket system bolted onto the SU's of a Datsun 240Z LOST power when compared to the STOCK air cleaner element.

For a vast majority of people with engines not revving much past 7K, the stock filter housing with a low-restriction K&N element is all you will ever need for the vehicle.

But that doesn't cost a buttload of money, doesn't look particularly trick, nor have any marketing genius behind it telling you lies, so they usually get tossed for the "first improvement" when making power on a car.

I could go on, but I won't...
;^)
 

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I'm not so sure the K&N filter element when oiled works as well as a good regular paper one will. Until I see proof with a manometer that they do have less restriction, even that seems like mostly hype. I know when I was racing 2 stokes, the K&N filters were slower than oiled foam filters even when the K&N was 2X as big!
 

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Interesting...

I have a Dywer Manometer, as well as a Magnahelic, but the fluid tube is a pain to get to read right under heavy load unless you are at the very top of the rpm band in top gear going very fast....

But the K&N replacement filter did show about 4" W.C. less than a new Stock Filter at speed by the Dwyer, and more than that by the Magnahelic, though I tend to believe the Dwyer since it's an actual technical instrument.

For a turbo, 4" W.C. is considerable regarding discharge temperature, for an N/A I suppose midrange is better if the Magnahelic is correct... (was showing like 10" less at top end)

Anyway, the filtering efficiency is not in dispute. Paper filters are more efficient in removal in particulates. Unless you massively increase the paper filters surface area, there is no way it will have the reduced inlet restriction.

BTW,the reason the K&N replacement filters have such a great increase in size is to decrease the speed of the air across the element---increasing the particulate removal properties approaching the paper element.

OEM's use Paper because you can pleat the **** out of it, get a lot of surface area for loading, and it's cheap. They are very efficient at particulate removal...
 
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