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The X-pipe WILL make it smoother sounding, and therefore quieter.. Leave it out, and it will sound rougher. Plus, the X-pipe or a H-pipe will gain some power too.
And in the pics above, the X-pipe is not the lowest point. That is in front of the X-pipe.
My plan is quite unlike anything I have ever seen on any car. It is very different in layout and truthfully you need to think outside the box every once in awhile. Let me tell you a tale of quiet exhaust. Years ago I was involved with a program to make observation aircraft much quieter. So quiet that you could not hear them pass over at 300 feet! Three main things make noise on an aircraft, airframe drag, the propeller, and finally the engine and exhaust system. We had slick airframes to work with, they were strutless (Helio H295s) and had a pretty quiet airframe. The prop is a real culprit in plane noise. The faster it goes, the louder it is. The more blades the prop has, the quieter it is. The Lycoming engines used .67 to 1 gear boxes to slow the three blade props. Example engine RPM 2000, prop about 1300 or so. The entire muffler/pipe system was replaced with some good old hot rod thinking and completely turned around to quiet the motor more than you can believe. BTW one of the requirements was to lower the IR signature to aid in evading detection. Basically the exhaust was routed through a very special system and then out the top of the plane to suppress sound detection from the ground and to improve IR exposure.
Jarhead
PS I agree H and X pipes do quiet exhaust, and I did not say I would not use an X pipe, I said no X pipe would be visible under the tranny.
The dyno graph is a 6 liter LS testing Hooker long tube headers vs Hooker LS swap manifolds. No doubt about it, the long tubes outperform the manifolds everywhere. Especially down low in the 3-4K range, the long tubes add over 50 pounds feet which you can really feel. However, past 4k the spread is not too bad. I originally was going to run the Hooker cast manifolds (which I already have) but the lure of that extra power is hard to ignore. The more that I think about it, I realize that the manifolds are the way to go for me. I want the car super quiet more than I want that extra power.
I have had some very fast rides in my life, the four NHRA rocket cars much faster than most of you will ever experience. My best in the 1/8th mile of 2.79et at 301mph still cannot be topped by any vehicle running anywhere on earth today. (That was in my rocket dragster The Texas Starship. Fred Goeske's dragster probably would have gone quicker than my car in the 1/8 mile but I never drove it on anything but full quarters.) I did that when I was 29-34 years old. Hopefully I will turn 71 later this month. I love acceleration but I think the Cutlass will be fast enough for me and quiet enough for my wife. Happy wife, happy life.
Jarhead
There is also a hint in these pictures of coming things for the Cutlass.
"Stomp the go pedal of a rocket car, squash your *** flat it will." Yoda
Last edited by jarheadl34; 09-30-2018 at 11:48 PM.
I chatted with Rick at the shop this morning, it is pouring rain in central Texas and they needed it badly. They are in the process of removing the body from the frame.
The frame will be slicked up a bit and new poly body mounts installed. When finished (and is any project ever really finished?) my goal is for a Cutlass with slightly over sized tires and stock looking right down to hubcaps. Quiet as a stocker but much faster. Some chrome removed and a few other minor custom mods. Stock interior except for the gauge panel (thanks Rocky Topper). Should be a fun ride for an old fart like me. Pictures to follow of the body off frame and frame cleanup.
Jarhead
PS It also has to beat my 1967 Motion Camaro's best time of 11.54 with me driving. It went quicker with a driver that could power shift.
A picture I found of some frame braces and some strengthening of the lower control arm mounts. All of the GM A cars(and G cars too) used flimsy frames, although some boxed frames were under droptops and el Caminos. I am having some frame bracing and a few other things like this done to my frame while it is out from under the car. It is amazing how much better these frames can be made with just a few pounds of tubing here and there. I saved over 100 pounds by using an aluminum block, I do not mind adding a few pounds back where they will do the most good. More to come.
Jarhead
PS There will also be bracing between the upper rear shock mounts to help tie the car together better. I just did not have any pictures of that.
Three pictures of frame stiffeners. All GM A and G cars have frames as flimsy as a noodle, even the factory boxed frames are weak for optimal performance. I have decided to go ahead and really stiffen the chassis while it is out. I plan something very similar but with a few twists thrown in. For sure the main stiffening rails will be square tubing as opposed to round pictured here. I plan to not only stiffen the car but the new tubing will carry the tranny mount, additional body mounts and the exhaust will use this system too.
Jarhead
Last edited by jarheadl34; 09-30-2018 at 10:55 PM.
Some pictures of the Cutlass taken yesterday. Cleanup on the frame has started, the bracing will be welded in soon and more pictures to follow. I am hoping that when finished the chassis and body will be as rigid as when the full cage was installed. A two door post like this has a really strong body shell, much better than a hardtop and of course worlds better than a convertible. As mentioned the bracing will add several more body mounts and the exhaust is going to be incorporated into the structure to add even more strength.
Jarhead
Last edited by jarheadl34; 09-18-2018 at 06:14 PM.
I talked with the guys at the shop yesterday, and this is an update. The frame cleanup and bracing is progressing. The material for the PWTBs (pressure wave termination boxes) has not arrived yet so they cannot finish the chassis just yet, I think you will find the entire exhaust system for the Cutlass is unique and we will see how it works out. After talking with the guys at the shop, looking into what it costs to end up with brakes and suspension to work best with stock looking 15 inch wheels and hubcaps, I have decided to bring the Cutlass more into todays ride technology. The new plan is for Global west tubular a arms and C5 brakes and tall spindle up front. 18 inch wheels and a just slightly lower than stock stance. 15s are no match for modern 18s, even my Rav 4 has them. 15 inch tires are getting expensive and only allow a maximum of 12 inch brakes. Pictures of current work to follow.
Pictured are three of my favorite cars, all are blue with white trim. One is in Garlits museum in Florida, one is here in Sonoma and the Cutlass is in central Texas getting redone. I turned 71 yesterday, life has been good so far.
Jarhead
Last edited by jarheadl34; 09-30-2018 at 10:50 PM.
More bracing pictures. Those GM a car frames are weak but this one I think will hook well and turn well. Lots more tubing going in and I was notified that the material for the PWTBs has arrived. It is all 304 stainless and it will be welded in soon as the chassis continues to take shape.
Jarhead
I want you to notice the work in the first picture. Those lower control arm mounts are weak in stock form and flex when the chassis is pushed hard. Note how it is now plated on the top and how the cross brace ties in to strengthen the mounts and tie them together. The factory uses cheesy pressed tin braces on the HP models to stiffen up the rear. Also note the tig welding, wish I could lay a bead like that. That shock mount brace is going to have more tubing added too.
Jarhead
09-08-2018, 03:00 PM
