[Curby]

When I bought my 72, it had the 2 1/4" Hooker header/side pipes on it. The Hooker inserts sounded good to me, but I felt that they were too restrictive for the big block. I read a few articles about dyno results and decided to find something less restrictive.

I saw a lot of discussion about the baffles and decided to pull the trigger on a set last winter. They have been sitting in the garage in my pile of "Stuff I want to get on the car before the Hot Rod Power Tour" but I never got a round tuit.

Well, this Saturday, I started out with the intentions of replacing my header gaskets and inserts. I got the side pipes off after beating on them. I opened the box and was impressed with the build quality of the baffles. There were very good instructions (even though I didn't read them until I was done). I measured twice and drilled the holes for the STS baffle mounts. The drill walked a bit on me, so I had to re-position the mounting plate with my 5# precision instrument. I got the baffles installed and could not wait to replace the gaskets, so I just snugged up the bolts and fired up the monster.

The first thing I noticed, was that the exhaust was much quieter in the car at idle (950 RPM). There was no longer any low frequency resonance. The first thing Terry noticed, was that the car was much louder and raspier.

I took her to the cruise-in, and found myself making a lot more noise in traffic and getting more attention than before.

After the cruise-in, I made the hour-long trip home. The interior noise at cruise (2200 RPM) is a little lower volume, but a higher pitch. No more resonance, but I do hear the bark a little more.

Before, if I drove the car onto grass, the engine sound would almost disappear, but now the engine still has that raspy bark to it.

I like some aspects of the sound, and need to get used to the other aspects of it.

The car does feel peppier, and I think I have freed up a bit more HP.

 

[ajrothm1]

I like the looks of sidepipes on early C3s but after I learned about the restriction they can cause, I never gave them much thought. Hopefully you will gain some power with your new baffles...

My dad recently had a 69' 427/390 coupe with Hedman headers and modded piping to work with stock 69' side pipes. It looked and sounded great but damn....that engine just made no power after 4500....it had the stock aluminum intake and q jet so that hurt it some but...the engine had a nice solid roller cam in it but was just choked....I figured it was the factory sidepipes killing it....he sold the car before I got to play with it.:down:



So you gonna try your luck at the strip again?

 

[GS81vett]

Very cool! I have the glass packs in my side pipes now and would love to put in the baffles! Guess I will do so now..:laughing:

 

[D_B]

I love Hooker chrome side mount headers and side pipes. I have had two sets on my current Vette, one set on a previous Vette, and two sets on my friend's '74.

I juts bought my new set that I installed with the roller 405 I put in this Spring. I of course got the glass packed Hooker mufflers that come with the set.

I've heard how they sound with half of the inserts cut off and the fiberglass blown out. Awesome, if not a little bit too loud.

What I have thought of doing was to cut my new inserts down by half, but instead of removing the glass inside, I'm going to re-cap them so the glass stays.

In effect it'll be a half glass insert.

It'll be less restrictive and retain some of the muffling characteristics.

 

[Curby]

I am sure that the side pipes hurt my top HP, while the large 2 1/4" primaries hurt my low end torque. I also believe that I need better valve springs because it sounded like the valves started to float at the last dyno pull, but I just stay away from 6.000 RPM for now.

The car is my toy, and she goes to the drag strip with me as often as she can. I only run her 2 or 3 times each time I go.

She also gets a lot of highway miles, as she has been on 2 Hot Rod Power Tours and been to the NCM 3 times, been on Talladega Superspeedway twice, and will be going to the beach in a couple weeks for the first time.

I have a base line at the dyno (I don't recall the numbers, but they are on file there). and I should see some improvement from the better tuning on the EFI and the baffles. I hope to have a programmable MSD box installed before my next trip as well.

I will sell my old inserts if anyone is interested, shoot me a PM. I can't go back as I have drilled holes in the side pipes now. I think I will grow to love the sound of the STS inserts.

 

[blckslvr79]

I love my STS baffles. :thumbsup:

 

[Mako72]

Jeff, I picked up almost 4 mph in the quarter mile when I made the switch from the Hooker inserts to the STS baffles. I was one of his earliest customers. Been trouble free for many years now. I think you'll like them. :thumbsup:

 

[ajrothm1]

Jeff, I am not familar with your engine (other then its a 454) but maybe a quick valve spring swap will be in order. I just did a spring swap myself as I thought I may have hurt the springs from floating the valves a couple times.....I just put the same ones in that were in there and it runs fine.....just make sure you set them up to the correct installed height...


Its awesome you race your car and drive it all over....I will be doing the same....My sh*t aint scared of long trips or rain.....The fuel bills on the other hand....:thud:

 

[baxsom]

I have seen a few posts on here talking about the sidepipes hurting power. I honestly dont think thats true. There are quite a few posts over on a few other corvette related sites where the person picked up power with open pipes over even headers. In one case he lost like 5 when going from open pipes to the sts baffles. I havent seen anything yet on low end torque being lost. (of course I also suscribe to the scientific explanation saying that backpressure is a myth too) so I may have overlooked it.

 

[Fred Mann]

I haven't done any research to back this up at all, but an engine builder recently told me that the bigger the displacement, the less the effect of the long sidepipe primaries. My new 468 is still a work in progress, but the builder loves my Hooker side-mounts and STS Baffles.

Curby, I'm surprised you didn't say anything about any power increase until the last line of your post. When I took my glas-pak inserts out and replaced them, the word "peppier" would have been a gross understatement. The engine seemed choked by the Hooker inserts. I would expect less mixture dilution with the lower backpressure with the baffles. Does your EFI automatically lean the mixture?

 

[Curby]

I haven't done any research to back this up at all, but an engine builder recently told me that the bigger the displacement, the less the effect of the long sidepipe primaries. My new 468 is still a work in progress, but the builder loves my Hooker side-mounts and STS Baffles.

Curby, I'm surprised you didn't say anything about any power increase until the last line of your post. When I took my glas-pak inserts out and replaced them, the word "peppier" would have been a gross understatement. The engine seemed choked by the Hooker inserts. I would expect less mixture dilution with the lower backpressure with the baffles. Does your EFI automatically lean the mixture?

I agree that the engine felt "choked" before and I hoped that the inserts were the culprits. I need more seat time to be certain. I have only idled around town in the car for a couple hours, and then drove about 50 miles on the interstate home.

The FAST EZ-EFI is an auto-learning controller and it stays in "learning" mode almost all the time, so it responds to changes rather quickly. I leaned out the AF ratios a bit on the way home, too. I did a couple WOT runs through 4th gear on the trip home, and it was running much better when I arrived.

I will post more opinions as I spend more time behind the wheel. Now that it has cooled off some, I plan to visit the drag strip some more.

 

[GS81vett]

Hey Curby do you like the EZ Fast system? I was thinking of converting my carb to EFI and like the looks of the FAST system do you like it? Good investment?

 

[Curby]

Yes, I really like it, but I was never that good at tuning a carburetor. My engine always ran too rich at idle, didn't want to start cold without flooding, and ran too lean at WOT.

The EFI system is the same height as the Holley, but the fuel rails interfere with my vent tube on the L88 air cleaner so I had to use a 3/4" spacer and turn it about 30 degrees.

I re-used the main fuel supply line as my new return line and added a new -6 line for the supply. i mounted the fuel pump and filter on the rear cross brace where the rear sway bar mounts. The EFI computer is mounted behind the driver's side egg crate and my O2 sensor is installed right after the collector, before the side pipes with the STS baffles. I ran the wiring harness over the brake booster with the vacuum lines and used the switched power wire for the MSD box to power the EFI computer.

I don't think the EFI is any more powerful than the carb, but it idles better, starts instantly, and gets about 25% better fuel efficiency over the Holley 850. I went from 15 MPG on the 2009 HRPT with a 3.36 rear end to 18.6 on the 2010 HRPT with the 3.73 rear end.

 

[Marks76ray]

Hey Curby, just wanted to know if you are still running the STS baffles. If so, do you like them as far as noise in the cabin. I know you drive your car on trips and thats what i'm going to do and don't want excessive noise. I do plan on well insulating the cabin so the STS might work for me. What do yo think:cheers:Mark

 

[Curby]

Hey Mark, yes I really like the STS baffles better than the mufflers that Hooker put in them originally. They are raspy and loud at idle but I can talk on the phone while driving at cruise speed, and they are quieter than the glass packs. At wide open throttle, they scream.

I have lizardskin and reflectix under my carpet.

 

[Marks76ray]

Thanks Curby, I have bought lizzard skin and Eastwoods sound deadener and will do the inside of the doores as well as the floor. Also I saw where a member installed a cone insert before the STS and said it made a difference in the tone.

 

[rtj]

Thanks Curby, I have bought lizzard skin and Eastwoods sound deadener and will do the inside of the doores as well as the floor. Also I saw where a member installed a cone insert before the STS and said it made a difference in the tone.

I was getting pulled over about once per month. I put the vortex cones ahead of the sts's and they left me alone.

The side pipes run hotter, before the cones they weren't very hot.