My first day of Aussieheaddom...

C

CobraSix

2K+
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Well, picked up the car from the exhaust shop yesterday. Drove it to work today.

Comments:

1) Holy Shit...
2) Did you replace the 6?
3) If I didn't know better, sounds kinda like a V-10

My observations>
1) Holy Shit...
2) Did I replace teh 6?

I was fairly easy on it until I got to the highway on ramp. I was able to wind the motor up to 50MPH in 2nd gear without a care in teh world and the engine still felt like it had more to go. Shift into 3rd and boom...take off. I have some fun, and really start noticing my fuel gauge. Which brings me to a question...I'm pretty sure I'm running rich right now since I haven't dyno tuned the Holley 390, but what are you guys with aussie heads gettting for mileage (highway). I was getting around 17 today...which seems pretty bad since mild V-8s get better then that. My mileage dropped around 5-8 MPG. But like I said...that have been because I was having fun.

My second observation, beside my car finally having some guts, was the exhaust. Quiet as can be at highway speeds, really annoying at cruise speeds of 35 and 45. I'm tempted to pull the Flowmaster 50s, but I'm going to try putting sound deadening material in the trunk and between the trunk and interior. Worse come to worse, I'm going to put some turbo mufflers on.

Overall, have some minor tuning issues to work out...but I am very happy. Hope to get to the dyno this weekend (provided they finish setting it up) and get the carb tuned up and get some numbers.

Slade
 
The droning sound at secondary road speeds is because of the design of the Flowmaster. They rely on pulse cancellation and if I remember correctly there is no absorption material included in the housing. It all depends on the frequency of the exhaust pulses in the pipe. Try a different gear at the same speed or even install an absorption type resonator at the tip to change the frequency of the overall system.

Better yet just keep your foot in it. It may cost more but it sounds like your having fun.

Ric.
 
I can't help wonder if a lot of these heads are ending up over-exhausted. That would explain the fuel consumption pretty well.
 
66200i6":1zfudk8m said:
I can't help wonder if a lot of these heads are ending up over-exhausted.
Click to expand...

What??!
Click to expand...

I agree...I'm not following, not questioning...just don't understand. I'm only running 2" duals. Also, my mileage was down before.

The Flowmasters are going. Too loud and annoying for daily driving in stop and go traffic like it will be this summer. Going to Turbo mufflers...

The old head...that has been spoken for since September. Hopefully will be shipping it out in a few weeks to a member in Colorado.

Slade
 
The droning sound at secondary road speeds is because of the design of the Flowmaster. They rely on pulse cancellation and if I remember correctly there is no absorption material included in the housing. It all depends on the frequency of the exhaust pulses in the pipe. Try a different gear at the same speed or even install an absorption type resonator at the tip to change the frequency of the overall system.

Better yet just keep your foot in it. It may cost more but it sounds like your having fun.

Ric.
 
I put on a Borla Pro XS last week. When the guy called to tell me it was ready he said he did not think I would like it, that I should put a 50 Flowmaster on instead. I was surprised at how quiet it was, you can see straight throught the muffler so I was expecting it to be louder. Anyway I am not disapponted, the turbo was too loud for me. Drove the car to Daytona, came back yesterday. It has a very pleasant buzz, particurlarly @ 75 mph. Only problem is now I can hear all the air leaks.
 
I'll post a sound clip when my brother gets back from Cleveland.

It's not much louder than stock at idle. Accelerating hard as I normally do kinda reminds me of a motorcycle. A little raspy buzzing sound. I found myself on and off the accelerator between 70 and 75 just to hear it. At no time does it drone.

Mine is a 2" single, I think the dual would enhance the sound.

Don
 
so...not neccesarily quieter...just different? Sound clips are great, but I've found relative sound comparison between mufflers are the best besides actual trial and error. I just can't afford to keep replacing my mufflers.

I think turbos are supposed to be louder at idle, and quieter on idle due to the way they are baffled usually.

Slade
 
The turbo is way louder, mine was a "generic" sounded good at idle but had a terrible drone at crusing speed. My car is a daily driver and I wanted something I could enjoy but still listen to music without having to turn it up wide open.
 
my car is daily too, so sound quality from the exhaust is key. I want it to have a nice low hum at idle...quiet when cruising at part throttle. Maybe I'll give another look at borla's before I go Turbos...

Slade
 
Guess what I"m trying to figure out about Borla's is why every exhaust shop I've gone too (and these are performance ones) they tell me Borla's are louder...

I talked to the shop, he said we can try the Turbos, if I don't like them, he'll pull them off and take them back without charging me for the mufflers. So, I'm going to try that.

Slade
 
I was referring to the fuel consumption. Between the choking inlet/exhaust of a stocker and the freer flowing 2V headers/manifold is a world of difference. I still believe a lot of the small six cams are ground to optimise a less than perfect exhaust situation.

The exhaust side may be open a little too long, too late or too high compared to what is now needed for the intake "effort". It can overefficiently scavenge.

Typical issues found with an overexhausted engine (otherwise in fine fettle): Poor fuel consumption, sooty/fouled plugs and exhaust pipe. It won't affect power output really, but changing the cam timing or grind can reduce the effect (and save you a few MPG).

Adam.
 
Interesting that the 2V was re-designed only on the inlet side and the exhaust remained mostly unchanged. All that Ford thought was necessary was to supply headers as fitted from the factory to even things up. Just this alone would have accounted for some of the HP difference between the 2V and the log head (as some headers can give about 15 HP).
I cant help thinking that even with the exhaust fitted with headers on the 2V that not totally re-desigining the exhaust by Ford may have been a compromise to save money. Apparently a head with a good inlet to exhaust ratio can easly be over-exhausted with headers and exhaust system, makes me think the 2v with headers maybe about perfect, or near to it. Who knows, its too much guess work for me? A lot of Fords do like more exhaust on the cam.
I be prepared to take a pun at it and say the 2V likes more, even at the risk of loosing a bit of efficiency. It would be nice to know for certain.
Cheers
 
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