I am running an L28 with early SU,s and Weiand Long-Flo air filters. Would there be any performance benefit to adding the MSA Air Horns to the setup? How about the Air Horns with the K&N filters? Do Air Horns really do that much?
I was thinking you needed air horns on carbs. I just searched through the archives to find out more info before I commented and was a bit surprised that alot of people are not running air horns. I thought they helped w/ the venturi effect or something along those lines. If the price is right on the MSA air horns I would go ahead and try them. You could always return them if they don't make a difference.
I did a little research a while back (in the archives) and the conclusion I came to was that air horns WILL help your power compared to not having them. The thing is, most people say that the air horns built into the stock air cleaner assembly are just as good as the aftermarket ones sold by MSA and others.
Air horns are generally a cosmetic application, but on the SU's I believe they act like venturi's to speed up the air charge. If your filters are made to run without air horns I would trust them to work properly. If you want more power, then a new set-up with air horns will help, however I don't believe that "20+ horsepower, with a K&N filtercharger!" Bull-$h!+. They make good stuff but c'mon an airfilter won't get 20 extra horsepower out of a blown big-block.
Well according to Norm who did dyno testing on this subject the air horns do not either benefit or hinder HP.. From what I remember he said there was no difference from having them on or off and I dont think he runs them either.....Which works for me because when I do a new induction system I wont have to stress over whether or not I need to mod them in ....
The above posts are right. You should be running Air horns. The best bang for the buck is really the stock Air filter box, because it does have air horns built into it. They are really pretty much the same as the aftermarket ones MSA sells. So I would recommend maybe looking for one for sale.
If all else fails I recommend you try contacting Ztherapy
www.Ztherapy.com they might have a cheaper alternative to air horns. But the thing you need to remeber is you can't just run air horns by themselves. I really recommend having Filters over them, whether it be K and N chrome fitlers which can be had at
My track times were slower at the track with the stock air horns cut out and installed under my dual K&N airfilters as well as without the filters installed.
My buddy dynoed his Z with some MSA airhorns and saw no improvement.
David Vizard's carb book covers air horns on SU's and has documented HP losses with improperly flared airhorns.
The key is to have an airhorn designed as below but with a rolled 270 degree lip
However,the stock airhorns are designed more like the illusration below with a 90 degree lip with a sharp edges which is bad for airflow.
David Vizard showed that a short stub stack about 3/4 of an inchin length would increase power 6% on an SU powered motor which is amazing, but this guy aint a bullshitter, so if he says it increase it 6% then it does do it.
I am going to try and find a similiar stub stack or design one and test it out on my 240.