Non-restricted exhaust

Make it go fast! Kick it up a notch. Post tips in here.
User avatar
So Cal Mark
Posts: 13841
Joined: Wed Jan 25, 2006 3:45 pm
Your car is a: lots and lots of Fiats
Location: upland, ca.
Contact:

Re: Non-restricted exhaust

Postby So Cal Mark » Tue Mar 14, 2017 10:25 pm

I really like the Hushpower H2 muffs. If you go to the Hushpower website you can listen to the exhaust note on several different cars so that you can approximate what yours will sound like
Mark Allison
allisonsautomotive.com Fiat and Alfa Romeo parts and service. Performance parts our specialty!
Headers, ignitions, wheels, cams, flywheels
starsmark@hotmail.com 909-981-3566

grrrdot
Posts: 142
Joined: Mon Jan 02, 2012 11:14 pm
Your car is a: 1967 124

Re: Non-restricted exhaust

Postby grrrdot » Tue Mar 14, 2017 11:26 pm

I'll just chime in for the environment and mention that honeycomb catalytic converters have a negligible impact on performance and reduce pollution that cause smog, acid rain all kinds of other stuff.
Unless you have an older bed type converter or your cat is broken/melted focusing on the exhaust manifold, muffler and/or pipe diameter will get you more power gains.

-G

P.S. Plenty of info out there on this stuff..
These guys have a bunch of videos where they test different things like headers vs manifolds, dented headers etc. This one they show how HP changes with exhaust diameter: https://www.youtube.com/watch?v=_PVXvHkr-Vs

User avatar
So Cal Mark
Posts: 13841
Joined: Wed Jan 25, 2006 3:45 pm
Your car is a: lots and lots of Fiats
Location: upland, ca.
Contact:

Re: Non-restricted exhaust

Postby So Cal Mark » Wed Mar 15, 2017 12:42 am

our dyno testing using our header and complete exhaust system show no difference with or without catalyst. We use compact, high flow honeycomb catalysts. In fact, our X1/9 testing showed 1hp more at peak with the cat compared to the non-cat system.
The two big differences are cost of course, and heat from the catalyst
Mark Allison
allisonsautomotive.com Fiat and Alfa Romeo parts and service. Performance parts our specialty!
Headers, ignitions, wheels, cams, flywheels
starsmark@hotmail.com 909-981-3566

brackie1
Posts: 502
Joined: Sat Dec 14, 2013 1:24 pm
Your car is a: 1978 124 spider
Location: Winston-Salem, NC

Re: Non-restricted exhaust

Postby brackie1 » Wed Mar 15, 2017 10:29 pm

I hate beating a dead horse but don't want to make costly mistakes. I am looking at the hushpower hp-2 as mark suggested. There seems to be two kinds an 18" I guess replaces the muffler, and one they call a shortie and seems to be a resonator. So the question is, in order to boast performance would you replace current resonator with the shortie or replace the current muffler with the hp-2 muffler?
Gene
North Carolina

brackie1
Posts: 502
Joined: Sat Dec 14, 2013 1:24 pm
Your car is a: 1978 124 spider
Location: Winston-Salem, NC

Re: Non-restricted exhaust

Postby brackie1 » Fri Mar 17, 2017 12:48 pm

Mark
so as you recommended I ordered a Hushpower HP-2 muffler. The question now becomes how to hang it. First of all, the smallest inlet size is 2"id which is what I ordered. Since it is 2" id that would mean it is probably 2 1/8" od, but my current exhaust is 1 3/8" od. What do you uses as a connector piece? secondly, since there is no flanges on the sides of the HP-2 how do you mount it? I am thinking of a wrap around hanger of some sort. Any suggestions would be great.
Gene
North Carolina

User avatar
So Cal Mark
Posts: 13841
Joined: Wed Jan 25, 2006 3:45 pm
Your car is a: lots and lots of Fiats
Location: upland, ca.
Contact:

Re: Non-restricted exhaust

Postby So Cal Mark » Fri Mar 17, 2017 11:09 pm

if you intend to use the Hushpower with a stock exhaust you'll need to make a connector that is expanded to fit the muff. We usually weld tabs on the side and use the stock hangers
Mark Allison
allisonsautomotive.com Fiat and Alfa Romeo parts and service. Performance parts our specialty!
Headers, ignitions, wheels, cams, flywheels
starsmark@hotmail.com 909-981-3566

User avatar
aevansgatech
Posts: 342
Joined: Mon Jul 27, 2015 2:51 pm
Your car is a: 1982 Spider 2000

Re: Non-restricted exhaust

Postby aevansgatech » Mon Mar 27, 2017 2:50 pm

So Cal Mark wrote:free-flow exhausts are important for power increases, I can't imagine why in your opinion they aren't worthwhile? Exhaust systems with back pressure cause reversion to enter the cylinder during overlap, sapping hp.
Would you care to offer some proof to back up your opinion?


My point was just that it depends on the individual owner's goals for the car. Based on the rest of the thread it's clearly a worthwhile mod for him, but I wouldn't take an all original car and modify the exhaust just for the mild performance upgrade. To each their own! :D
1979 Spider 2000 (gone)
1984 Pininfarina Azzurra (for sale)
1982 Spider 2000 (here to stay)

carl
Posts: 244
Joined: Mon Oct 06, 2008 9:56 am
Your car is a: 1971 128

Re: Non-restricted exhaust

Postby carl » Sat Apr 01, 2017 4:01 pm

You do realize the stock spider exhausts for a spider is a free flow exhaust in that the muffler and resonator are straight through with no baffles. I think the issue is whether the pipe and muffler core diameters are big enough. I have to say, I am fabulously happy with the two sport exhausts I got from Auto Ricambi. They are made just like the stock system (apparently they are the European spider exhausts). Bolt right on with no hassle and have a 2" diameter core. No silly polished stainless steel or 8" diameter tail pipe and after more than 30 years of playing with spiders I'm done with Ansa mufflers which are too small in core size, weigh a ton and always break where the pipe goes into the muffler. Both systems are on spiders with carbed 2 liter motors using an early 4-2-1 manifold and 1800 stock down pipe.


Return to “Performance”

Who is online

Users browsing this forum: No registered users and 4 guests