Questions about early heat exchangers on an SC
 

Recently, i've had the opportunity to pick up some 74 heat exchangers (OEM, not stainless steel) and a muffler and I was wondering what everyones thoughts were on putting them on the SC. I know you pick up a little power, and it certianly flows better, but is it really worth doing based on other's experiences?

I realize that I have to backdate the heater ducts on the motor and I'm kinda leery of trying to free up those exhaust nuts, as they already have a lot of corrosion on them. (last thing I want to do is drill out a broken exhaust stud, been there, done that, never again) I love the sound of the early exchangers with the B&B on my friend's 2.7. Quieter than the GHL and it has more of a "WHRRRRR" sound then the V-8 sound from the GHL.

Anyone have any real results with this? Is it going to be a noticable difference over the stock exchangers and the GHL I already have on there? I imagine i'd also have to richen up the mixture a bit and possibly play with the timing? Smog isnt an issue... Also, should I bother drilling a boss for the O2 sensor or just leave it in default mode by having it disconnected?

Yep....not smog legal in CA though....

as I said, smog isnt an issue for me... long story

I think it will make a noticeable difference, worth the hassle for sure. To really wake it up, some cams would help, since the smogger cams were made to breathe into the smogger exhaust! And then, why bother with old stuff, if you can get stainless SSI that are made just for your application?

Along these lines, I am wondering, didn't the exhaust ports change in shape and size between 74 and 83? Especially on the later SC, don't you have thick flanges???

If your car is a CA car, the exhaust should come off without a problem, just with some rust eater...

George

well for the cost of these exchangers, I cant complain... (college student budget, mind you) even working for Pelican, the cost of the SSI's is pretty high.... I'd only have to bead blast the old ones....

Is there a huge difference in the ports? Will I have interfernce issues with the flanges?

Jared:

I can only tell you that I looked at a set of used SSI from an early SC and they had the thin flanges. I thought about it but it didn't look like a good idea to put them on my later SC requiring thick flanges.

Your car will have thick flanges and you would have to at least replace the exhaust studs (!) with short ones to accompany the thin flanges. I am unsure about size, shape and position of the flanges compared from a 74 to a 83. I doubt things didn't change at all. Someone please chime in for that!

I hear you on the budget issue. I hope you can make them work!

George

Go for it! I just did it and with MB911's muffler it is actually a noticable feel. I did not have to replace the studs and it was straight forward.

Alan Poh
'77 Carrera 3.0

I have the early exchangers on my SC. You'll love them,. Just use lots of penetrating oil.

You won't need your O2 sensor. Just reset the CO % to 3.0-3.5.

If you say you won't have an issue with smog then I'd go for it.

If your car has thick flanges do a search. I'm pretty sure "bb80sc" Brad Brown found some nut's that would work when you go from a tick flange to a thin one.

I was going to put some on my SC but because of smog I declined, even though I'm sure you could find a smog checker with a bad back :rolleyes:

Go for it , I fitted some '73/74 HEs to my /78SC with a Triad twin in twin out exhaust and there is a noticeable performance increase throughout the range. The sound is incredible. I bead blasted and HT painted them and they are standing up well so far. http://forums.pelicanparts.com/uploa...1104161788.jpg

Use spacers if you have too. This is the way to go Jared. I don't know why anyone would think SSI if they can get used headers, and they are out there. If you can budget a couple more hundos get them ceramic coated....and you'll still be under the cost of SSI's by a good margin.

The SSI, versus the stock heat exchanger is a true equal length header. The stock tubing is bent differently, e.g. there is a large nick to allow access to one of the inner barrel nuts. (This is where SSI has a tool to get there without going through the heat exchanger). Minimal differences maybe, in your eyes, but together with the fact that they are stainless, enough to consider them over stock material. If you are anywhere with snow, the fact that they are stainless may be enough already!

George

did the '74 cars have "2-in" mufflers? I know the '73's did. I have '73 HE's on my '83 SC, and they work just fine. No problem with the flanges. You might want to cut twelve roughly half-inch pieces of pipe for spacers so you don't have to stack washers, but there is no need to change exhaust studs.

Have someone remove the old nuts with the "blue wrench." Heat them cherry red and they'll come right off. If you don't do this, you are pretty much certain to break a stud or two.

And you'll have to deal with the oil line issue. Back date the heater at the same time.

The equal-length "tuned" exhaust effect is real.

Oh, and the Triad kicks ass.

I am in the Midwest (rust belt!), George, and I don't drive my car in the snow anymore. If I did, the ceramic coating would help. I recall we had this discussion before a couple months ago, and at that time, you didn't even know early headers would fit on a 3.0. I admit, I'm not an expert, but have you seen and measured the stock headers (with the tin shells removed)?

There seems to be a general belief that the stock headers are not truely equal length, yet no one has ever posted measurements, for the stock or SSI. No one has performed a comparison of the two on a dyno back to back...not that I have seen anyhow.

"Minimal difference" is what the designs will yield in performance. In my eyes, a $1000 difference is NOT minimal.

Sorry guys, but pipes or washer stacks aren't what I call a good fit. ;) Of course you can rig it, but to do it right, the exhaust studs have to be changed.

If you can find a used set of SSI, like I did, the cost isn't prohibitive, over a set of stock HE that you have to buy first and then send out for coating. We are talking about a difference of about $300 here? Used SSI can be found if you are patient.

And yeah, I don't have dyno numbers back to back for stock HE vs. SSI, but you can talk to anyone in the Bay Area that knows a bit about the 911, e.g. Jerry Woods or Rob King, they will all tell you the same. Jerry Woods tells this story where he spent a lot of time and effort to build equal lenght racing headers that were beautiful. They dynoed within a couple of horses to the SSI. :D

Cheers, George

The only down side to using the existing studs is perhaps a half-pound of weight. And a few hundred dollars. The early heat exchanges will fit just fine onto the long studs. And actually, you only need to "space" six of them, simply because they are those small barrel nuts and you cannot get the allen tool on them with the longer stud coming all the way through the nut. Simple. Sure, changing studs (really bad idea) or buying thick-flange SSI's is more "perfect," but you get the exact same performance for hundreds of dollars less by simply using what you've got and what's available.

It's an exhaust pipe and headers! It's not like the parts are moving, and you don't even see them! It's mostly good for bragging rights..yeah, bragging about $900 headers, when a $300 solution can give you the same gain (huh?).

And when we talk of spacers, I hope we are talking about an appropriately sized spacer. If you are crafty, you can weld on a spacer! As an engineer, I can accept fit and finish, but crap..it's just the exhaust! I can gain the 3 HP simply by buying a few less gallons of gas before I hit the track. As an engineer I appreciate function over form!

Early headers can be had for $0-$150 if you look and are patient. Add $200 for coating, and the price difference is $500+ depending on your store. The performance difference may be a few HP,. if that. So that's $160+ per HP that you would spend over early HE's. Might as well spend the money on an E-ram :D

I'm not saying the SSI's are not nice or pretty, but if we don't discuss and accept the viable alternatives, soon folks won't think to use the economy solution. And the myth that owning a 911 is expensive...well, it is not if you know what works, perform a fair bit of research, and stop taking what one reads or hears as fact..the only fact.

Just because "Joe A" wants to or can spend money more freely than "Joe B", does not mean "Joe A" has a better solution. And when "Joe A" looks down his nose at "Joe B"........guess who's the fool? :D

I am having my stock HE's and muffler ceramic coated. They should look as good as new and it only cost me $150. The money I would have spent on SSI's are going towards other projects, like EFI! I will post a few pics when the get them back from the coater at the end of the week.

hee hee, good memory Bob :)

Yep, I used metric coupling nuts with anti-seize and they were superb! I would not risk changing out the studs on any car with corrosion, just asking for trouble.

-B