Let us know how your doing! What size pipes are you hooking up to?

 

Keep us posted, anyone planning a dyno trip after install?

 

I've been taking it slowly as this is a toy, not a daily driver. Besides, the city has all the curbs ripped up so I couldn't get it out if I wanted.
As things sit, I buttoned up the drivers side last night. I got some thermo-tec adhesive back heat blanket and made a couple heat shields to wrap around the two tubes that run past the trans. I also wrapped and tied the flex line going to the clutch slave. I used some .0092" aluminum roof flashing for the blanket to adhere to. At 1st I thought the .0092 was too light, but it worked perfectly. Then I went to Homer Depot's and got some hose clamps to hold it in place.
The header is soooo long that the collector ends at the turn in the floorboard. I can't use the expander sent with the header as it adds too much length. I'm thinking I might have to lose the 3 bolt flanges and go with a 2-1/2" slip fit to the Y. One last thing, on my car there is a small heat shield on each side of the trans tunnel. This is probably for the pre-cats that used to be there. When the header is in place, It is in contact with this shield. I eliminated the mount for this with a chisel to cut thru the alum. rivets. I then used a small section of the alum. backed heat blanket and sandwiched it between the shield and the fiberglass, and screwed it directly to the 'glass. This gave the necessary room and I was also able to position the heat shield clamped on the header tube to help eliminate poss. heat probs.
Also, in our aluminum heads, the FSM says the torque to tighten the header to the head is only 15-24 lb/ft. I set my torque wrench to 16 (192 lb/in) because I'm a chicken at the thought of pulling the threads out of those heads.

That's it for now...

 

I sent Brian an email about this. I wouldn't expect this problem. What's the point in creating a flange and connector -- if they aren't usable!!

(To be honest, I don't think the slip fit option is such a bad idea -- as I probably would have chosen that as the default connector. But, I'm not happy about cutting the Jet-Hot coating. I could void their warranty, induce rust, and/or flaking.

Sounds like you're doing a great job fabbing up connections and heat shielding. I'm glad you're sharing your install with us!

 

You know I'd talked myself out of this until I read your post, now I'm back to riding the fence. When I first looked at the headers they did seem awfully long even without the reducer. If you do slice off the flange what size (O/D) pipe are you going to use? I'm thinking 3", if you do this let me know how long you end up making them.

jeff

 

My set arrived today. They met my expectations.

Glad Corvette Bob is breaking ground. Will save us a load of time.

Thanks Bob. Ever come to Atlanta, let me know. I owe you a beer if nothing else.

 

If gas was cheaper, I'd be there just for the beer!

 

Greg ? Any answer from Brian?

 

Yes, but I don't think we have "resolution" yet.

Part of the problem (from my perspective) is I can't see what the issue is. Because I haven't seen pics, I really don't feel equipped to explore the issue as I'd like.

Corvettebob says the "expander" is not usuable. If things are THAT tight, I'd wonder about putting cats on the system. I also have to wonder if the issue is with the flange. Should it be rotated. Was his set welded differently?

I'd really like to see pics before making any kind of judgement. We haven't seen those yet.

Brian said these were designed for C4 race cars. As such, factory cars may have more installation issues than he's seen (which are basically none according to him). I'm pretty certain the race cars use the flanges from a conversation we had back in March. If so, this issue doesn't sound like it would be unique to factory cars.

He did say it was acceptable to cut the flange off. He said just spray the area with 1200-degree header paint (like from NAPA). But again, that doesn't resolve the issue for me.

With pics, I could figure out if I want to remove the flanges before installation. Otherwise, installation, removal, and re-installtion might be required.

Because CorvetteBob created such an elaborate mounting bracket for the alt support, I have do wonder if he's got some details/goals that might be different that the average installer. (I'm not saying this is true -- just that I have to be open to that possibility).

So, until I see pics or get mine on, I don't feel well-enough informed to address the issue further.



gp

 

Ditto. But............................. I won't cut the headers, period.

The pickle is in the center of a venturi created by the flanged "neck down" , for a reason.

The expansion to the 3" pipe likely completes the body, and I suspect messing with that geometry will affect the velocity, and
that consequence is unacceptable.

Besides, potentially compromising the benefits of these odd ***** contradicts the expense? I mean this is a leap of faith, after all?

Though stepping down to 2-1/2" at some point may make sense,
but I would expect it to be at least 12" past the flange.

Frankly, I am going three inch to the single free flow cat [makes a good X tube and is just as "green" as all get out].

Should begin next weekend, and I'll post any conclusions.

Hope Bob gets the even side on. I'm anxious to here.


TJM

 

I agree that cutting more than just the flange would compromise the design -- by hitting the "pickle". I hadn't thought about the collector "completing the body", but it's a reasonable thought.

I really wanna see pics!

gp

 

Hi,

I also have a set of these. If I have to cut anything I will sell them. When I get these installed (with cats) I will dyno to see if any improvement (now 266 hp 297 tq to the rear wheels). I also will use the track to gauge. I have many laps at LimeRock, Pocono, even a couple of passes down the quarter-mile to compare.

I hope all goes well with the install for everyone!!!

Steven

P.S. my car is a 1992 LT1

 

I assume you got the 1 3/4" version (since the 1 5/8" don't fit LT1's). I look forward to your comments/times/observations!

 

I got under the car today after measuring the new headers. I did not understand what Bob was explaining. When he said the headers came to the floorboard, I assumed he meant the area below the footpedals. But they are much longer than that.

The headers extend to below the seat. It appears the "floorboard" Bob was talking about is the storage compartments behind the seats.

As I measure it, the headers stop 5-6" before the Y-pipe turns back in to the center collector. Since the connector is about 3", most of that room is taken up. If you had 3" pipe (or even with 2 1/2" pipe), I could see where people concerned about maximum HP might be concerned about the immediate turn out of the back of the headers. And, cutting them shorter could allow for a more gradual turn to the center of the car.

For the "average joe", I don't think the problem is bad. But, the average joe doesn't put headers on to maximize exhaust flow and power.

To me, this is not an issue of major concern. The thing I didn't anticipate is there won't be room for precats (or bullet cats). A center cat will be the only option. On my car, with sidepipes, I reinstalled bullet cats just to lower noise (resonance). They worked perfectly for that issue.

Now I have to decide if I want a louder exhaust.

If loud and sporty is what you want, I still think these headers are a great choice! And, cutting off the flange is no where near a must.

Gregg

 

I will update as I go along.

Steven

 

Thanks for the info!! I am sure you are correct on the cats. However, I have to get them to fit/work for my car to pass emissions. Do you know if its possible to put the cats further down stream?

Thank you!

Steven

 

Assuming you want to stay with a dual setup, you might be able to stagger two "bullet" cats in the mid-section of the car. That or a single center cat would be your only options.

Technically speaking though, I'm not sure what they'll do. I have no idea if LTx cars use air tubes to heat the cats. With them further downstream than stock, I would investigate the question of whether they'll be hot enough to do be as effective.

Many cars use a single CAT that is located in a similar position so you have reason to be optimistic. To be sure, you might want to start a new thread on that question (since many won't look in here).

Also, it could depend on the visual inspection laws of your state. According to Federal Guidelines, altering the factory configuration of emissions equipment is considered a "no-no" -- even if you keep it clean. So, it might depend on how your state interprets that. Ask so local shops/inspectors, etc... to be sure

You may even want to ask the question in your regional forum?

gp

 

I just did the visual / measuring, that is round one of my installation.

The following applies to my ’89 L98, .

I have had a free flow CAT, and a 2-1/2” SS header pipe that "Y’s" into a 3” receiver at the Cat. The car has been without Pre Cats for a couple years . I pass Ga. Emissions with better numbers [ go figure].

The free flow is just that, you can shove a Tennis ball through it, it is wide open, and has that handy 3” slip fitter on the header side.

It is a bolted flange on the exhaust end. In my mind it makes an ideal X fitting.

The difference in the free flow vs stock is that it is shorter than stock and has and has about 8”- 9” of 3” pipe to work with on the header side. . This should [ that is “should” ] be enough room to do a Y pipe with back to back 3” mandrel bends into a New Y, and then into the cat.

The sequence looks like

#1 Install headers

#2 Fab up the new 3” Y pipe. The existing Y pipe is a reasonable template that any shop should be able to follow, and the fit should be Plus or Minus a few inches..

#3 Slip on, over the Vette Tech Connectors.

#4 Slip in the Cat and adjust, by cutting the cat inlet tube to allow the flanged end to meet.

Sounds easy? Worse case is you have to cut the rear Y pipe but that’s just aggravation and could be a welded connection.

The cat is $150.00 but works, at least on Ga. Tests. I passed again, today.

The ugly part is that the 1st bend may extend into the floor pan? It will be close.

Maybe I need to ask Brian what he does after the connectors? I mean prepping race cars does not stop at the connector? The gas goes somewhere, and there are mufflers are on IT class cars.

TJM

 

#2... I know the distance for the headers will be different than what you have now. If you don't take the car, aren't you worried about a shop getting the separation at the "Y" end the correct distance? (In other words, getting the "Y" end spread apart the correct distance?)

 

Yes, that is a likely problem.

After both Headers are installed the distance becomes a fixed dimension, though.

At this point the "template " is used and distances adjusted to fit.

I am a little cavalier, because I have access to a hydraulic bender that works to 4" pipe, in tiny increments, so I will make a "dummy" using EMT before doing stainless.

Toying with the thought of using mild steel and just getting the things coated. Jet Hot pipe to the Cat?

If I can produce a good product I'll post that on the forum.

Getting ready to wallow in the problem, more.

Have to get the car up high enough to access in a home garage. Like Bob, my car is a toy and no hurries.

More jack Stands of high quality!

TJM