Big Blocks push a lot of air . Has anyone who put their BB on an Engine Dyno later tested HP loss with side exhaust installed ? Small block guys seem to think about 30 HP or so is MIA , probably the exhaust . Club Cobra guys think more is lost . Would like to quiet the car a little but not willing to lose another 15 to 20 HP or so , solution might be to set up a second set of "shorty" pipes for track work and a "quiet set" for general driving . What have we found works well and what does not ? I found the votec cones next to useless . Anyone using the Breeze "quiet" pipes or the Gas&Go stainless pipes. What about Suoer Trap exhaust tips , anyone try that on a big block yet ?
Heres some spirited discussion over at Club Cobra...no easy solution to the noise vs HP loss
With the minimal amount of exhaust system assy. on these cars, if you are going to achieve quiet, you are going to lose major HP. There are 2 effective ways to quiet down relatively short sidepipes: 1. Squeeze the flowpath diameter so small that flow is significantly reduced, & add soft packing material to absorb flow (current stock systems - 1-7/8" +- flowpath approx.). 2. Use a non straight-through muffler core inside the muffler cavity. Walker used to build a muffler that looked like a glasspack externally, yet had two (very small dia.) staggered flow tubes internally. These were called "Royal Scots." Flow on them? Terrible. Noise reduction? Yes.
Bigger the engine Bigger the Loss in HP
To me, all these other turbo baffles, directional louvered units, cones, and every other flim-flam gadget out here inside the sidepipes are just different variations of restriction if you ask me and some are actually louder than a well designed chambered glasspack exhaust setup. I pretty much concluded last year that one could achieve the same results with a $8K 390 FE motor and improved sidepipes as compared to a $20K FE motor with factory sidepipes that come on many of these replicas/kits. This seems to be a repeated oversite with many of these high $$$ cars out there. A few Cobra folks in my neck of the woods with small blocks have picked up 40-60hp rwhp on the dyno with improved sidepipes and others have claimed more but I did not see the before/after
Boston, since no one else here seems interested in your thread, I'll chime-in by simply saying there ARE ways to control sound without killing horsepower. I won't say whose products they are, but flowpath diameter on sidepipe setups is the vital element. Putting "obstructions" in the flowpath (like on Flowmaster mufflers) HURT the scfm flow.
BTW, YOU are on the correct path for your next mufflers.
Ordering "Cobra Packs" from classic chambered this week , I should pick up an easy 30-40 HP at the rear wheels from what I have see on Club Cobra. There is also a "big chat" in the roadster section and a video clip dyno run .
Well I'm very interested in the outcome here. And I've been reading along. I know Ernie (Excalliber) over at CC runs 2 styles of pipes on his ERA with a 427HR. The shorter pipes he states do make more power for the track. Long pipes for the street. It will be really intesting to see the end results....
G.
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68 Cougar GT XR7 S code. 454" FE tunnelport.
Originally posted by BostonBuster: Ordering "Cobra Packs" from classic chambered this week , I should pick up an easy 30-40 HP at the rear wheels from what I have see on Club Cobra. There is also a "big chat" in the roadster section and a video clip dyno run .
Cobra packs installed , painted yesterday , first impressions :
Noticeable performance improvement over 4500 RPM
Sound tone is a lower frequency and seems to be guieter under 4000 RPM , Ears do not hurt.
If you remember what a 66-67 corvette with a 427 sounded like with side exhaust thats the best way to decribe it.
Cost
Flowmaster Exhaust tips $30 a pair
Hooker 3.5 to 3 inch reducer $30 a pair
Cobrapacks 2.5 ID "Packed" 22 inches long / 28 inch o/a length. $140 a pair
2 Lbs of Flux Core weld wire $10
5 Cans of RustOleum Paint
Scotch Brite & Misc Metal Stock $30
So for less than $250 we have a pipe upgrade that lowers noise a little , improves the sound a lot , and improves HP
How much HP , we will find out at the track next spring.
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Just wanted to say you did a fantastic job on the pipes and documentation. And a well deserved "thanks" goes out to you! I think this thread should be archived in the sticky at the top of the page. How about a bigger pic of your car? White looks great on a Cobra. I also like the rounded body cutout shape for the exhaust. I've seen a few originals that use that shape and I like it very much.
G.
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68 Cougar GT XR7 S code. 454" FE tunnelport.
I have a 460 BB. I have had the car dyno tuned with the FFR sidepipes. The car ran a 504 ft lbs at the rear wheels with 425 hp to the rear wheels. I just purchased the Stainless pipes from Gas-N performance. They are far better looking, longer( look like they were made for the car) not short like the FFR pipes. The pipes are quieter and deeper. I have not put my pipes on yet, however there are some sample sounds on the FFCars Disc. Forums. I should have them on this weekend. If I have a chance theis summer, I will be dyno testing it again. I will post the results. I am sure, however, that someone with these pipes will dyno them before I do. The sound they produce is being raved about. I can't wait to hear for myself.
Detrick , those are healthy HP and Torque numbers , you should get an improvement with the new pipes .
Cobra pack update : Had time today to drive the cobra for the second time with the new mufflers . Noticed back in Jan (1st run) it felt a little lean ,(indication the exhaust flow is better) ,so I fattened up the secondaries and added a few gallons of 100 octane AV gas to the pump gas .
Definite seat of the pants HP improvement from 4000 RPM or so on up , the last 1/4 mile run with the FFR mufflers was an 11.85 so whats the HP improvement ? Well if you can feel an improvement in a car that runs in the 11s it would have to be 20 HP or so . Some of the improvement may be due to the smoother transition from header collector to muffler using the Hooker reducers .
Noise and Sound ? I can hear the radio and the solid lifters ticking away at part throttle and steady state cruise , no louder than a pickup truck with flowmasters . Get on the throttle and its loud, a lower frequency loud, but your ears don't hurt like they do with the stock mufflers.
I now have the pipes on and the sound is amazing. It is deeper and sounds bigger. Best of all my ears do not hurt after a ride. I have not had the car back on the dyno , but that will come with time. For now, the car is running lean and I am looking forward to tuning it up. It took me a while getting the pipes on because I ordered the pipes seperate from the flange, I am too picky about the pipes being perfect distance from the body and perdectly parallel to the ground. I'll be back with the update. I am a teacher and the last day of school is tomorrow, so I can get to work and the ride.
BB I'm embarrased to say I didn't see your pics until now. Being this is a sticky and not often updated and I lost track. BUT wanted to say that is a really nice looking car you have there. Nice looking Vette I see peeking out da garage there.
G.
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68 Cougar GT XR7 S code. 454" FE tunnelport.
This is one of the nicest Cobras I've seen.... it has that mean, all business, don't mess with me look and I feel the wheels are a good part of that look, plus the fact that there is very little chrome.
I know there are several manufacturers that make the Torq Thrust, can anyone tell me who makes these particular ones and what width are them ?
These are standard out of the box vintage Torque Thrust Ds , Back wheels are 15 x 8.5s and fronts are 15 x 7s . You need to narrow the standard fox rear end 2 inches a side to make this work , you can also substitute 15 x 10s on the rear if you desire . The rear tires are 275 50 15 Nitto drag radials.
By the way the exhaust sounds like a Nascar stocker the only thing I would do different is go with the 3 -3 1/2 core instead of the 2 1/2 . Expaectations is mid 11s this season.
Another vote for Gasn sidepipes, FFR pipes were to loud when they were new and I did'nt think anything could quiet this monster without loosing hp. I have no dyno results but the car sounds incredible and still scares the crap out of me,I don't feel like I lost anything and now I won't loose my hearing. Engine was dynoed at 630hp at the flywheel with a radical custom grind cam from Comp cams, you could barely hear the cam before, it was just more of a high pitched roar at idle. Now I have a deep, mellow rumble and I love it, I thought it was alot of money, now I think it was worth every penny.
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Without your plumber you would have no place to go...Socrates
x2... on the Gas-N pipes and your great looking roadster!
I have run stock FFR, Lo-baks, and Gas-Ns on my car. Yeah it's no big block, but with the heads, cam, and 4 into 4s it does have a BARK. FFRs, painfully loud.. Lo-baks, not as loud but kinda flat tone, mechanical sounding as opposed to deep.. Gas-N pipes, perfect!!! deep, rich toned and just loud enough to be really enjoyable. My only objection in recommending them for your car is their beautiful stainless finish, it just wouldn't look as right as your current black pipes do.
Boston, Should I assume that you run catalysts to meet the Mass standards?? If so would you consider adding a crossover pipe? I haven't actually seen this done, but was told that it has been (anyone have documentation?). This would address both your needs for power and noise reduction. Search the archives for an excellent thread done by Rod (DV/DT) titled "exhaust shootout"
Peter
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Stella and ibuprofen, the breakfast for aging champions!
Sorry to resurrect an old thread, but I just wanted to ask, as I am about to do a dyno tune on my 521 stroker. From what I understand in this thread, the FFR factory pipes (what I have) are the LOUDEST, but are they they best performing? Least restrictive? I would assume so by the fact that they seem to be the loudest.
I apologize if this has been solved already, but a quick search didn't really give any exact answers.
Loud doesn't guarantee more horsepower. There's a lot to tuning a set of headers. One criteria does seem to be price - cheap headers usually cut the best features because they are the most expensive.
Pipe diameter, radius of curvature, merge angle at collectors, collector shape and length, and what is directly after the collector are just as important as the length of eight pipes at the optimum. You need them all to get the most hp, and it takes a dyno and staff to gain the maximum from an individual setup.
Those who claim that they must match identically in length can't possibly know what that best length is. An inch either way could be better - you have to test them to find out.
Most of us learn as much as we can, and live with the results. It's ironic that dyno operators all use a generic set of four into one headers - their most important criteria seems to be how well they work in the booth, not what's best for the motor.
I don't doubt claims that you might be losing hp, the more important part is quantifying it - some armchair poster insisting on a number can't possibly know. That's why the experts still don't have the specific answer after 55 years of welding them up. There's no guarantee any one method or detail is absolutely necessary. What is necessary is to test them and change them to prove something was as good as it can possibly be.
Then, you change the cam, the intake, port the heads, and start all over again. That's why there are no perfect headers.
As for noise, a kit car performs because the hp to weight ratio is drastically lower compared to a typical auto. A car with horrible headers that weighs 1000 pounds less can still be faster. We sometimes focus too much on the engine. It's the collection of parts as a working machine that counts more.
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Being this is a sticky and not often updated and I lost track. BUT wanted to say that is a really nice looking car you have there. Nice looking Vette I see peeking out da garage there. 
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