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Topic Review (Newest First)
05-14-2013 01:15 PM
F-BIRD'88 Re: open headers. For max performance with open exhaust You would want to add a 12" to 20" collector extension to the end of the open headers.
This builds low end torque right where you need it, to launch hard @ 3500 rpm (your stall speed)
as compared to just open headers. If you uncork it and remove the tiny air cleaners from the blower scoop, you may then need to again adjust the carb jetting a bit.

This collector extensions will also help your AFR gauge to read correctly, with open exhaust. But again leaks at any gasket joints effect the O2 sensor accuracy.


Re: street exhaust system. I prefer to use a Tri-flow high performance "Turbo" style muffler. I build my own unique custom design modified version of this muffler design, for my car. But many of the off the shelf stuff is good. (Walker Industries)
Next is a straight thru perforated pipe design like Dynomax and or Magnaflow.

Use a full exhaust system with the exhaust going over the rear axle, exiting at the back of the car.
The mufflers should be mounted as far rearward as practical. A transverse mounted 2 in 2 out muffler is another option
mounted behind the exle.
2- 1/2" diameter exhaust pipe gives the best flow/power/exhaust sound volume level mix on the street. The most sound level reduction with the least power penalty. (If any at all)
{The 2-1/2" dual exhaust system on my 11 second ET car does not reduce power or performance at all. It's a matter of good design}

Larger diameter exhaust pipes like 3" are naturally louder, regardless of muffler design.

You need to get the car up in the air so you can plan out the best routing of the custom exhaust system.
Look at the modern muffler designs used on the new Corvette and Viper and new Camaro or Mustang for inspiration on your design that is quiet but powerfull.
You will enjoy driving your car a lot more and tend to drive it more, if the exhaust system is well designed.
05-14-2013 12:51 PM
AutoGear -grumble- sissies! lol
to quote my best friend "bang-shift the wee out of it!"
Its cool though; any Gasser tribute on the street that sees track time is aces in my book.
05-14-2013 09:58 AM
Fang16
Quote:
Originally Posted by AutoGear View Post
YEE HAW! feels good don't it
To say that I was pleasantly surprised would be an understatement! Did the 1/8 mile conversion to 1/4 mile. Didn't think I'd ever break 12's with this setup.
BTW, looked at a bunch of the gassers (for ur pix) and we're almost all running auto's. Bunch of lazy old guys in the group. LOL
05-14-2013 09:52 AM
Fang16
Quote:
Originally Posted by F-BIRD'88 View Post
The flow master mufflers are not your best bet.
Every car I have worked on that had flowmasters picked up significant performance by removing them or replacing them with a different high performance muffler design.
Louder than they need to be. There are better design mufflers that are both quieter and more powerfull.

Any exhaust leak 25" to 30" fore or aft of the O2 sensor on the pipe will throw off the O2 sensor reading.
Next I'll be trying open headers. lol What mufflers do you like? Could quite it down a little to keep piece with the neighbors. lol
Here's the same Thank You I posted to 1Gary.
Went to Tulsa last Saturday, ran 1/8 mile (didn't know they were only doing 1/8 mile) Not geared for that but using your advice and F-bird's, looking at the big picture, jetted the carbs to what I thought was needed, knocked over a second off 60' and ET, turned a 7.37@89+ n a 7.39@89+. Wanted to thank you and F-bird big time for all the help!! Came out of the hole at idle and just put the peddle to floor, no bog, just go like he**!!!! Still some tunning to do but well on my way now.
05-14-2013 09:47 AM
AutoGear YEE HAW! feels good don't it
05-14-2013 09:45 AM
Fang16
Quote:
Originally Posted by 1Gary View Post
Yeah.We have had a number of 9.90 cars over the yrs.I do think we are sharp tuners.Some of the cars did have tunnel rams.Talk about learning,what we found is they where not as consistent and where more susceptible to minor climate changes.We have been using weather stations for yrs.We did get a data log on them and somewhat had a handle on it,but at the end of the day the raiser single 4 worked overall better.So we left that chapter behind us and never returned.
The tune on these is not static where you are going to be making adjustments on it long term.One thought I always have is where I see a car at a car show that is outlandish just setting there,well really two,that guy really knows his sh**t and most of the crowd passing by don't know the back story to the car to get there(maybe the week before of prep work)not like the articles in a fan car magazines.
Went to Tulsa last Saturday, ran 1/8 mile (didn't know they were only doing 1/8 mile) Not geared for that but using your advice and F-bird's, looking at the big picture, jetted the carbs to what I thought was needed, knocked over a second off 60' and ET, turned a 7.37@89+ n a 7.39@89+. Wanted to thank you and F-bird big time for all the help!! Came out of the hole at idle and just put the peddle to floor, no bog, just go like he**!!!! Still some tunning to do but well on my way now.
05-09-2013 03:56 PM
F-BIRD'88 The flow master mufflers are not your best bet.
Every car I have worked on that had flowmasters picked up significant performance by removing them or replacing them with a different high performance muffler design.
Louder than they need to be. There are better design mufflers that are both quieter and more powerfull.

Any exhaust leak 25" to 30" fore or aft of the O2 sensor on the pipe will throw off the O2 sensor reading.
05-09-2013 02:50 PM
Fang16
Quote:
Originally Posted by spinn View Post
A exhaust leak can be found by listening . Stuff a shop rag in the tailpipe with the engine running. Follow the exhaust piping. It will increase the backpressure sos that you hear the leak better.
You haven't heard my car. (loud) lol Headers, 20" pipe, flowmaster 10's. HUH? Will try the shop rag trick though. With them in the exhaust should be a lot quieter.
05-09-2013 12:04 PM
F-BIRD'88
Quote:
Originally Posted by AutoGear View Post
One of the fastest hot rods I ever saw was a 56 chevy with twin turbos mounted underneath the car. This thing was absolutely quiet at idle...like Targetmaster crate motor quiet. Blow through carbs on it...TONS of time on the dyno to tune it. And MAN would that thing come on after about 150ft....just freight train people. He had 3.08s and an automatic.

If you go unconventional, there will be some give-and-take. But for some people, the theme, or just taking the road less traveled is worth it. In the end thats what makes this hobby great.
If you want the tunnel ram; keep it, just know that on the street a guy with a purpose built dual plane single 4bbl is going to probably beat you.
Theres always more compression and E85 LOL
This is not true.

The tunnel ram takes a bit more advanced tuning skill to get it dialed in but will make MORE STREET POWER than any other intake manifold design.

The 750's will work the best. You ahve barely started the tuning process. Just stick to it and get the carbs dialed in.

Based on your info it is very liekly the exhaust system is leaking somewhere
This throws off the AFR gauge, especial at idle.
05-09-2013 11:17 AM
AutoGear One of the fastest hot rods I ever saw was a 56 chevy with twin turbos mounted underneath the car. This thing was absolutely quiet at idle...like Targetmaster crate motor quiet. Blow through carbs on it...TONS of time on the dyno to tune it. And MAN would that thing come on after about 150ft....just freight train people. He had 3.08s and an automatic.

If you go unconventional, there will be some give-and-take. But for some people, the theme, or just taking the road less traveled is worth it. In the end thats what makes this hobby great.
If you want the tunnel ram; keep it, just know that on the street a guy with a purpose built dual plane single 4bbl is going to probably beat you.
Theres always more compression and E85 LOL
05-09-2013 11:04 AM
1Gary
Quote:
Originally Posted by Fang16 View Post
Thanks Gary! Seems I lost site of the big picture. Hit the track 6-8 times a year and was just concentrating on that. We lives and we learn. Thanks again!!
Yeah.We have had a number of 9.90 cars over the yrs.I do think we are sharp tuners.Some of the cars did have tunnel rams.Talk about learning,what we found is they where not as consistent and where more susceptible to minor climate changes.We have been using weather stations for yrs.We did get a data log on them and somewhat had a handle on it,but at the end of the day the raiser single 4 worked overall better.So we left that chapter behind us and never returned.
The tune on these is not static where you are going to be making adjustments on it long term.One thought I always have is where I see a car at a car show that is outlandish just setting there,well really two,that guy really knows his sh**t and most of the crowd passing by don't know the back story to the car to get there(maybe the week before of prep work)not like the articles in a fan car magazines.
05-09-2013 10:31 AM
spinn A exhaust leak can be found by listening . Stuff a shop rag in the tailpipe with the engine running. Follow the exhaust piping. It will increase the backpressure sos that you hear the leak better.
05-09-2013 08:57 AM
Fang16
Quote:
Originally Posted by 1Gary View Post
Fang.I get it.You like figuring out this.Yep-I get that.My question to you knowing this manifold was never designed to run at part throttle and no matter what there are trade-offs,is it really worth it??.

I mean how often are you going to buzz this from 5,500 to 7 grand where this tunnel ram comes alive??.

Do take a third party look and think long and hard about that.Guys respect you for the car alone.Ya know.Nothing like a long pleasurable cruise too.

Just think about it some.
Thanks Gary! Seems I lost site of the big picture. Hit the track 6-8 times a year and was just concentrating on that. We lives and we learn. Thanks again!!
05-09-2013 08:53 AM
Fang16
Quote:
Originally Posted by F-BIRD'88 View Post
You cannot do that.... you have to calc the area of the jet and area of the rod.
Subtract rod area from jet area.... not diameter.
AREA..

set the idle for best vacuum and idle quality ... should be 12.5:1 to 13.5:1 ish... you got it too lean at idle.

area of a circle is Pi x (radius squared) Pi='s 3.1416 radius is diameter /2

You cannot find an exhaust leak by dumping junk down the carb and looking for smoke.
Get a grip.
How do you find an exhaust leak if there are no visable signs of one?
05-08-2013 11:55 PM
1Gary Fang.I get it.You like figuring out this.Yep-I get that.My question to you knowing this manifold was never designed to run at part throttle and no matter what there are trade-offs,is it really worth it??.

I mean how often are you going to buzz this from 5,500 to 7 grand where this tunnel ram comes alive??.

Do take a third party look and think long and hard about that.Guys respect you for the car alone.Ya know.Nothing like a long pleasurable cruise too.

Just think about it some.
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