Superformance Exhaust

[wanab5150]

Update Saturday...

I went up to Reno and fitted the pipes to the car and tacked everything in place. My stock turnouts actually pointed up slightly rather than being 90 degrees to the ground. I turned the new turnouts down just slightly....I mean just a touch, but not enough to ever be considered leaf blowers. I've seen some that are almost 45 degrees and they make a friggin mess especially with any dirt around.

I've done exhausts for Harley's and noted the sharpness of the exhaust note decreased more than you would think when you turn them down just a degree or two. It kind of takes the bite out of them. They will still be louder, but it does help.

I fired it up and "what a difference". It doesn't sound like an air compressor anymore. Such a "deep throat" sound.....I meant to say "Deep and Throaty"? I didn't get to drive it because it had to be removed and Tig welded, and will be sent off to Fresno for Jet Coating. I will have them on the car Aug 6th. and be back with a sound and performance update. It will be a seat-of-the-pants performance update because I'm not so inclined to spend an extra $500 for a couple of "before and after" dyno pulls. My performance rating will be listed as .....Pretty Good..... Wow, what a difference..... or, Holy Sh#@! I'm hoping for Holy Sh#@!

[Bxx1]

Congrats on the exhaust... can't wait to hear it!

[wanab5150]

Remember Ron....Your car will have to start first to here them if you put them on YOUR car.

[Bxx1]

Originally Posted by wanab5150

Remember Ron....Your car will have to start first to here them if you put them on YOUR car.

Well, if I can just crank the darn thing over I would like to 'hear' your car. AND since I put in new spark plugs last nite I have at least A 50% chance!

[jhv48]

We're waiting here!

If it works, I will want a set too. If the cost isn't prohibitive!

As an aside, why can't we use the Finishline or FFR sidepipes and bolt them up to the header pipes of the SPF. Won't they bolt right up?

[wanab5150]

WELL, HALF THE VIRDICT IS IN……

The mufflers came back and they looked like jewels. Steven let me use his rack at "Full Throttle" in Reno to do the install and I put them on Thursday morning. I burned up several sets of gaskets doing all the fitting before he sent them off so the final cost was $1350, and I did the install myself. Steven added a finger or two when needed.....OK, maybe a little more. It's easier with another set of hands. They fit right up and the coating looks very chrome-like compared to the stock Superformance pipes which turned sort of flat silver over the first 2000 miles. Time will tell if these stay this nice looking.

When I fired it up, I couldn’t believe my car could sound so F…ing mean. It sounded like what I think it should have sounded like when I bought it. The pop from the cam is unbelievable. It sounds like a Nascar. And yes, it is loud! The sound reverbs off buildings on a 4 lane street. On a two lane street.. …Holy Sh&%!

Hot August nights was all last week until Sunday (today). Honest to God, I have had only a handful of comment about how cool the car sounds in the last year and a half. I do get a lot of “how nice it looks” and how much people love Cobras. But during Hot August Nights, the comments were over the top about how bad (good) it sounded, and I completely concur!

Remember, I turned the internal louvers toward the engine for a little more sound deadening. Chambered Exhaust told me about 4 Db less. These are also packed. I parked at the /Full Throttle booth at Hot August nights and had the opportunity to fire up another 427R Roush (just like mine) right next to my car. He has the louvers pointing away from the motor so they virtually absorb nothing, and they were unpacked. I had Mike from Full Throttle fire up both cars as I stood about 20 feet from them and I couldn’t hear any real difference. Mike and Steven both say my car is just a touch quieter…I didn’t hear the difference.

As I said, these suckers are loud. If you take it easy it’s pretty easy to deal with. When you jump on it, I swear, people 2 blocks away turned around to see what-the-hell! I wouldn’t trade those looks for the world now. The looks I will now get from my neighbors will also be what-the-hell, but in a different way…Screw’em! I hope none of them read this.

Something I didn’t expect was the lack of the drone as in the stock mufflers. The Superformance had a sound that seemed to drone in your head under cruising conditions. I never thought about it until the switch. Although these are substantially louder, they don’t seem to annoy me as much and I drove the car 120 miles home today without a headache and no earplugs. I will probably get some anyway as I’m sure the noise isn’t that good for my virgin ears. Cruise is actually quieter at freeway speeds than the stock mufflers. It was the damn drone that was so irritating. Push the pedal a touch at cruise and it comes back to life until you’re back to cruise speed.

I was unable to do a performance evaluation as I was concerned about my jetting. Reno is at 4000 ft. and my car is jetted for sea level. It ran really good there compared to the stock mufflers and did not seem to be as rich, but that would make sense because the pipes would lean it out and help at that 4000 ft altitude.

I babied it when I got down to 1500 ft. altitude coming home. I did however do some brief acceleration tests in 3rd, 4th, and 5th looking for a lean pop or any other signs of leanness, but it ran flawless. No overheating, bogs, flat spots, ping, detonation ….not a single hitch. When I got home I was dog tired, but I pulled the plugs to check the color…..I just couldn’t wait for tomorrow. They actually looked perfect. They have 6000 miles on them, but I thought they might show signs of leanness anyway, but they didn’t.

I am going to put some new plugs in it tomorrow and run it pretty hard and read the new plugs. I have a feeling they will look real good. Almost all Holly’s are pretty rich from the factory and it may be real close, if not right on now. I will update the jetting tests and performance feel as soon as I get a chance. The performance test will be seat of the pants compared to before the muffler swap, but I should feel something. Regardless, it was more than worth the time and effort. It's like being at the track every time I fire it up! ……Be back soon with the final eval. Tom

[Bxx1]

Great that you are sooo satisfied!

[Rare Iron]

Originally Posted by Bxx1

Great that you are sooo satisfied!

Me too - that's music to MY ears! Glad you like 'em.

-Eric S.
President - Classic Chambered Exhaust

[decooney]

If you like your neighbors, or want to keep it that way, now you get to perform the whole "push the car in/out out routine before you actually start it before you leave" practice; especially on those early weekend meetups. The funnest part is sneaking up on a pack of Harleys and give 'em a dose, payback time!

"New mufflers, what mufflers" %^&*() ????

[wanab5150]

I changed the plugs this morning and ran it about 50 miles, mostly at 3000 RPM cruising. I jumped on it in 3rd, 4th, and 5th and it ran great. No issues at all. It has perfect throttle response with no bogs, hick ups, stutters.....nothing. I drove west toward Sacramento to maintain seal level as much as possible. The temp was 80 degrees.
I drove home and checked the plugs, and they looked like they have never been run. I wasn't expecting brown or even a medium tan, but I mean clean! There weren’t any signs of lean either. They were clean to the point it scared me. Fifty miles isn’t much, but I expected some coloring.

I called Holly and discussed the 770 Street Avenger which is the carb I have. They said that no re-jetting would be required as Holly's are flow tested and a pipe change would make no difference. The more you put your boot into it the more air enters and takes the metered fuel with it....regardless of RPM or exhaust.

Well, jetting Harley’s and race bikes always required going up a few jets, but it also entailed changing either the air cleaner or air box. In this case only the pipe diameter was changed. Since I was not reassured by Holly’s response (too simple) I called Roush and told them my tale. John, the tech guy, said that the Holly 770 CFM was a really good match for the 427R and they switched to that carb and dropped the 750CFM a while back. He said they test a variety of Holly’s and this one was the best all around carb for torque and HP. I asked him what a good replacement would be if I wanted one and the phone went silent for a few uncomfortable seconds, and then he said “I would keep the 770”! OK, I said. It was clear that I Sh%* in his Cheerios at that point.

I stumbled into my exhaust story before he hung up on me, and asked about the jetting issue. John said the same as the Holly guy. He said these Roush engines are set up with a straight header when their dyno’ed and are sold to thousands of customers with a variety of systems, and the exhaust size has no bearing on the jetting unless you change to an odd-ball carb , manifold , or head. They said it was set up for that motor and if it’s been running good for the last 6000 miles, it should remain in the correct jet range.

Now that I have listened to two complete professionals in their field, and been told to leave it the hell alone, it was time to completely disregard what they said and venture into uncharted territory. I pulled the 70 primary jets and replaced them with 71’s and changed the secondaries from 73’s to 74’s…….what’s the worst thing that could happen.
I took the car out and ran it through the gears like this morning. Performance was not much different except for a slight surge when I hammered the throttle through 3rd gear and 4th gear. It didn’t do that earlier with the stock jets. There was also a touch of a stumble at 2500RPM hammering the throttle, also NOT THERE EARLIER! It was 90 degrees at that time but I can’t believe 10 deg. would make a difference…….But!

I should mention that the car is downright scary in 3rd. and 4th. Red line is there instantly. 1st and 2nd are out of control anyway as they were before. But after it straightens out it hits hard. I can’t say that I gained a hundred HP, but it is substantially faster through the gears. It seems that up to 3000RPM is the same (no loss at all) but above 3000RPM it’s nuts. I’ve run it up to 120 before and I would say it does feel 15-20% quicker. That’s the only way I can describe it. I did this for the exhaust sound in the beginning so I’m completely satisfied. The HP gain is a side benefit, and I need a hundred HP like I need an extra ass! But, I’ll take it.

I changed back to the stock jetting this evening and will test tomorrow when the sun is high and the CHP are having coffee! I think I’m done. Tom

[jhv48]

Anybody have a phone number for Full Throttle in Reno?

[Got the Bug]

Originally Posted by jhv48

Anybody have a phone number for Full Throttle in Reno?

Here you go. Stephen Bramlitt is the owner.

http://fullthrottlereno.com/

[jhv48]

Thanks. Will check it out soon.

[wanab5150]

I got the carb back together with the jets it came with. Just for kix, I looked up the carb on the Holly site, and the Holly index calls for 72 Primary’s and 75 secondary’s. I have 70 Primary’s and 73 secondary’s……. Sh#@, here we go again.

I did not relate the jet info to Holly yesterday because I just didn’t think of it. I tried to call them today but no response after holding for 28 minutes. I’ll try again tomorrow.
It’s possible, Roush jets the carbs before adding them to the engine and have worked out this alternate jetting spec beforehand. If so, the guy I pissed off at Roush did not mention it and I would have thought he would have since my questions revolved around jetting.

I’ll run it this way (#70/#73) for the weekend and see how it goes. I think I’ll put a couple of hundred miles on it then check the plugs again. If it seizes up or burns a hole in a piston I will have a clear cut answer to my question….”Is it too lean?” Tom

IF ANYONE HAS A COMMENT OR SUGGESTION I'M OPEN TO IT!

[wanab5150]

I ran my sled up and down Highway 80 this afternoon in 95 degree weather. I cannot distinguish any difference between the #70 and #73 Roush jetting and the #71/ #74 jetting I tried yesterday. I’m thinking the very, very, slight surge I described might have just been the crappy pavement on 80. Bumping along on 17 inch donuts combined with the aerodynamics of a brick at speed with even a slight breeze could produce the feeling of a light surge. So, I’ll chalk it up to that that theory.

For now I’ll drive it this way for a couple of hundred miles and report back. I think I’m very close if not right on. Tom

CONTINUE IF YOU ARE NOT BORED.

I drove to Smeding Engines in Rancho Cordova and talked to Unki Kim, manager and assistant engine Guru. Still searching for the universal knowledge of carburetors and jetting, I ended up getting the full tour of the shop including the dyno room, build room, and storage area where six engines sat ready for shipping. I was there for about an hour and was treated like a diplomat. For what reason, I don’t know. Was he just a nice guy? Was he was bored? Does he just love his work? ……I think it was the latter. Well, very nice guy too!

Unki pulled three different carb brands from the back room and described the differences in each, eventually stating my Holly 770 should still be jetted correctly and if it runs flawless and doesn’t overheat then he would not recommend changing to any of the cool iron sitting on the counter. Now I have a trifecta of answers from Roush, Holly, and now Smeding stating the jetting should not have changed with the addition of larger exhausts.

The three trick carbs he showed me were a Holly 4500 series 750cfm HP, the second was a Speed Demon 750cfm and the third was a Quick Fuel Technologies 750cfm double Pumper with red anodized metering blocks and base plate all made out of some special high grade “un-obtanium”. All 3 of the carbs sell for about $500 to $600.

The Quick Fuel carb looked like “MAN JEWELRY”, and I wanted one. If I could just get him to say it produced more HP than my 770 it was a done deal. He wouldn’t! I tried the direct approach….”Could I get another 10 HP out of it?” “Possibly, but maybe not, he said “. My Visa card was burning a hole in my hand. Christ, what do I have to say to get him to take my money?

Unki said if my Holly 770 was working correctly with no issues it may not be worth the money or set up time to switch. The performance difference would probably be negligible and at $500 for MABEY five HP it just wasn’t worth it. He said come back and see him if I had an issue with my Holly and he would help me out. But, from what I was describing, my Holly was set up better than most.

The myth of any major HP gains were also dispelled when we discussed the Holly’s (and others) air horns where the choke butterfly’s are located. I’ve heard rumors these deflect air as it enters the carb throat and because the Demons and 4500 HP Holly’s have a smooth bore entry with no air horn or other obstruction, more Horse power will be on tap. Unki said if you don’t run an air cleaner you may gain a few if any, because the air cleaner already re-directs the air downward in most cases and therefore changes the airflow before it even enters the carb. If no air cleaner is used or a velocity stack is used instead, then maybe it would matter, but not enough to be concerned about.

Most of the high performance /race carbs allow for easy air bleed adjustments and changes where street carbs usually have fixed air bleeds. There are also usually less vacuum ports and lack of the choke horn I discussed above. Generally, Unki said, it’s adjustability that differentiates between high performance carbs and street performance carbs. At wide open throttle, a 750cfm hole is a 750cfm hole! What matters is the fuel /air ratio, which is the jetting.

I asked about going to an 870cfm or maybe a 1000 cfm carb as I have read some Cobra guys are running them, and swearing by them. He said in a drag race scenario the Roush 427 could handle the carb but on the street you’re going to lose all the “drivability” and furthermore all the torque will drop as a result of the huge intake. He said you have to choose WHAT KIND of power you want as opposed to how much power you want. If I wanted 600 HP and 400 lbs of torque go with the 1000cfm and live with the crappy street manners. If I stay with the Holly 770 I might have ONLY the 550 HP but I gain the torque back and the good manners for the street. ….It seems the carb Rouse put on the motor is a good choice!

I was impressed with Unki’s knowledge and the shop itself. The Smeding engines are remarkably similar to Roush engines in Cubic inches and off the shelf parts. As strange as it may seem, the Roush 427R engines are made from Dart Sportsman blocks, “H” beam rods, 10 to 10.5 compression ratios, AFR 205 heads, 1.6 Rollers, Edelbrock, and Holly carbs. Roush parts? Smeding uses mostly the same components with their own cam spec, Quick Fuel or your choice of carbs, and choice of ignitions. The biggest differences are price …..Roush $15,995 (mine) and Smeding $9,995. The Smeding engine posts 560HP and 560TQ. It’s no surprise that their 427 is called a “Smeding 427 Cobra”.

I am happy as a pig in Sh@! with my Roush, but I think I may be swayed if I decide to build another sled. For $6000 I think I could find an engraver to scratch “Roush” onto the look alike valve covers.
Smeding is in Rancho Cordova, Ca. 1(916)638-0899

[Danny Fong]

Tom, [b]FUEL INJECTION[b]..... then you wouldn't have to deal with this. Then again, you'll be bored, and have to spend more time Debbie.....

I love carbs and actually miss not haven't it. I'm running out of things to tinker with.

[greg schroeder]

Originally Posted by wanab5150

I ran my sled up and down Highway 80 this afternoon in 95 degree weather. I cannot distinguish any difference between the #70 and #73 Roush jetting and the #71/ #74 jetting I tried yesterday. I’m thinking the very, very, slight surge I described might have just been the crappy pavement on 80. Bumping along on 17 inch donuts combined with the aerodynamics of a brick at speed with even a slight breeze could produce the feeling of a light surge. So, I’ll chalk it up to that that theory.

For now I’ll drive it this way for a couple of hundred miles and report back. I think I’m very close if not right on. Tom

CONTINUE IF YOU ARE NOT BORED.

I drove to Smeding Engines in Rancho Cordova and talked to Unki Kim, manager and assistant engine Guru. Still searching for the universal knowledge of carburetors and jetting, I ended up getting the full tour of the shop including the dyno room, build room, and storage area where six engines sat ready for shipping. I was there for about an hour and was treated like a diplomat. For what reason, I don’t know. Was he just a nice guy? Was he was bored? Does he just love his work? ……I think it was the latter. Well, very nice guy too!

Unki pulled three different carb brands from the back room and described the differences in each, eventually stating my Holly 770 should still be jetted correctly and if it runs flawless and doesn’t overheat then he would not recommend changing to any of the cool iron sitting on the counter. Now I have a trifecta of answers from Roush, Holly, and now Smeding stating the jetting should not have changed with the addition of larger exhausts.

The three trick carbs he showed me were a Holly 4500 series 750cfm HP, the second was a Speed Demon 750cfm and the third was a Quick Fuel Technologies 750cfm double Pumper with red anodized metering blocks and base plate all made out of some special high grade “un-obtanium”. All 3 of the carbs sell for about $500 to $600.

The Quick Fuel carb looked like “MAN JEWELRY”, and I wanted one. If I could just get him to say it produced more HP than my 770 it was a done deal. He wouldn’t! I tried the direct approach….”Could I get another 10 HP out of it?” “Possibly, but maybe not, he said “. My Visa card was burning a hole in my hand. Christ, what do I have to say to get him to take my money?

Unki said if my Holly 770 was working correctly with no issues it may not be worth the money or set up time to switch. The performance difference would probably be negligible and at $500 for MABEY five HP it just wasn’t worth it. He said come back and see him if I had an issue with my Holly and he would help me out. But, from what I was describing, my Holly was set up better than most.

The myth of any major HP gains were also dispelled when we discussed the Holly’s (and others) air horns where the choke butterfly’s are located. I’ve heard rumors these deflect air as it enters the carb throat and because the Demons and 4500 HP Holly’s have a smooth bore entry with no air horn or other obstruction, more Horse power will be on tap. Unki said if you don’t run an air cleaner you may gain a few if any, because the air cleaner already re-directs the air downward in most cases and therefore changes the airflow before it even enters the carb. If no air cleaner is used or a velocity stack is used instead, then maybe it would matter, but not enough to be concerned about.

Most of the high performance /race carbs allow for easy air bleed adjustments and changes where street carbs usually have fixed air bleeds. There are also usually less vacuum ports and lack of the choke horn I discussed above. Generally, Unki said, it’s adjustability that differentiates between high performance carbs and street performance carbs. At wide open throttle, a 750cfm hole is a 750cfm hole! What matters is the fuel /air ratio, which is the jetting.

I asked about going to an 870cfm or maybe a 1000 cfm carb as I have read some Cobra guys are running them, and swearing by them. He said in a drag race scenario the Roush 427 could handle the carb but on the street you’re going to lose all the “drivability” and furthermore all the torque will drop as a result of the huge intake. He said you have to choose WHAT KIND of power you want as opposed to how much power you want. If I wanted 600 HP and 400 lbs of torque go with the 1000cfm and live with the crappy street manners. If I stay with the Holly 770 I might have ONLY the 550 HP but I gain the torque back and the good manners for the street. ….It seems the carb Rouse put on the motor is a good choice!

I was impressed with Unki’s knowledge and the shop itself. The Smeding engines are remarkably similar to Roush engines in Cubic inches and off the shelf parts. As strange as it may seem, the Roush 427R engines are made from Dart Sportsman blocks, “H” beam rods, 10 to 10.5 compression ratios, AFR 205 heads, 1.6 Rollers, Edelbrock, and Holly carbs. Roush parts? Smeding uses mostly the same components with their own cam spec, Quick Fuel or your choice of carbs, and choice of ignitions. The biggest differences are price …..Roush $15,995 (mine) and Smeding $9,995. The Smeding engine posts 560HP and 560TQ. It’s no surprise that their 427 is called a “Smeding 427 Cobra”.

I am happy as a pig in Sh@! with my Roush, but I think I may be swayed if I decide to build another sled. For $6000 I think I could find an engraver to scratch “Roush” onto the look alike valve covers.
Smeding is in Rancho Cordova, Ca. 1(916)638-0899

In my opinion you're getting some misguided information.

On my Roush 427R single plane intake the side pipe change from Superformance to 3 inch internal louvered mufflers, louvers forward, the mechanical secondary carb from Pro-Systems took 3 jet sizes higher for winter months. The carb had no saccrifice for street or strip driving and was a little over 1000 cfm. The thing is the cars are so much like a brick at higher speeds there really isn't one perfect jet configuration for 1st through 4th on hard acceleration. You don't want to be lean in 4th or particularly in 5th. At the strip you don't quite hit top RPM in 4th by the end of the 1/4 so that's nice. I tried the 870 vacuum secondary from Holley. It sucks on this application for sure and it made about 30 wheel HP less than the Pro-Systems carb. The Pro-Systems is instant power, linear at any throtle position and makes the most power.

Here's the wheel dyno, 4th gear pull Dynojet with air fuel displayed.

[wanab5150]

Since Holly, Roush, and Smeding state the 770 is the best combo for the Roush 427, I guess I have a couple of questions.

Why, out of all these professional sources do they recommend the 770 or 750 instead of being able to advertise that a Roush puts out 600 horse power, rather than holding back to 550 HP If they added the 1000cfm carb, considering it was perfectly streetable. Why would they not use it? I talked to a Roush tech about the fact you run the 1000cfm and he said it's way too much carb for the street. He (no name) said they use 1000cfm's on 500+cu.in. motors because they can handle them and they are primarily racing engines.

Also Smeding runs 750's on their 427 Dart motors and they would surely like to advertise higher HP ratings for sales if for nothing else. I'm trying to make sense of what you are saying but everyone else says it will not be streetable. I virtually tried to talk these guys into selling me some more horse power (that I really don't need), I would surely spend the money for a carb to gain another 30 hp. I'm assuming you're using their 1040cfm carb.


I've read your other comments and it's obvious you are a knowledgeable guy and know how to find HP. Pro-systems website is all about Drag Racing. Maybe your idea of streetable is different than that of the masses.

[209]

Hello wanab5150,
To begin this: I'm on your side. I have nearly the same engine and horses as you, but why did you settle for 550? Sure I can see trying to up the power with pipes and what not but geez give me a break. If you wanted 750hp to begin with you should've went with it. After spending what you did, what was 2k more? Jerk out the Roush and put a Kraft in and be done with it. Hey, I'm really on your side, really. I see you live in Roseville. My mother-in-law lives in Roseville and when I come up to visit her, I'll look you up and buy you a beer. Peace. 209

[wanab5150]

Things may be taken out of context a little. I'm looking for max potential with what I have. If I wanted 630 HP the Roush 588R which is exactly the same money as my polished 427R. I want maximum driveability with whatever carb will give me that.

The answers are so all-over-the-board, it's confusing. And, going all the way back to the beginning of the thread, I mostly wanted a better sounding Cobra.
The extra HP was just a bonus. Now,I just want the carb to match the exhaust. If it does now, I'm happy.

I enjoy the multitude of answers from these threads. I've learned a lot about things I didn't even have questions about. It was Schroeder that got me started on the header and carb thing...."It' all his fault!" LOL. I may come off nit-picky and anal because I am. I've been called anal retentive, over the top, obsessive compulsive and more....but I like it.