When to replace heat exchangers?

[porwolf]

Originally Posted by Bear911

Yes CO is odorless and colourless, but it won't be present in the cabin without one smelling the other exhaust fumes as well. I've always felt that the 'odorless' chemistry class factoid creates unnecessary paranoia.

But yes, don't use the heater if it smells like your exhaust. CO has a 200-250 times greater affinity for haemoglobin compared to oxygen.

I think the danger was greater (as was the usefulness of CO leak detectors) when generally more people smoked in their cars and wouldn't smell anything out of the ordinary. If you smoke in a 911 you deserve to be poisoned anyway.

Also the biggest danger is if you inhale CO in your sleep. Happens quite frequently with unsafe heaters in bedrooms. I understand that when you are awake you feel getting sick before CO becomes deadly. That's a sure fire warning sign. When that happens while you are driving open the window and get the exhaust fixed. Millions survived old VW's with bad heaters.

[Rich Gas]

Hey tirwin...kulunga.. Don't mean to hijack but I bought a Fabspeed sport cat and it definitely opened up my top end.

Hey AJ, Fabspeed guy, when you getting your 3.2 sport cats CARB certified? Got CA smog coming up. Paid $500 for it through Pelican...didn't think to ask at the time. The guy at Pelican I spoke with neglected to mention it even though my mailing address is SF Bay CA.

[Fabspeed Motorsport]

Originally Posted by tirwin

AJ,

That setup looks great. 24hp? That's like a 13% HP gain from a stock engine. Don't take this the wrong way, but do you have dyno data that backs that up? I'd love to see what the HP and torque curves look like on the same car before and after. Is that something you're willing or able to share?

I'm assuming they are, but I'll ask anyway... are those equal length primaries?

i can not find the one for the 911 at this time but here is the dyno from the 964 they are very close.

[Fabspeed Motorsport]

Originally Posted by Rich Gas

Hey tirwin...kulunga.. Don't mean to hijack but I bought a Fabspeed sport cat and it definitely opened up my top end.

Hey AJ, Fabspeed guy, when you getting your 3.2 sport cats CARB certified? Got CA smog coming up. Paid $500 for it through Pelican...didn't think to ask at the time. The guy at Pelican I spoke with neglected to mention it even though my mailing address is SF Bay CA.

The cats are in the middle of getting carb certified as we speak. As we all know this is a very long process and will take some time to complete. however at that point we will have the only aftermarket performance cat that is carb certified.

[bigel]

AJ,

What's a setup like the one pictured earlier in the thread go for, I'd love a set for my '87...

Steve

Originally Posted by AJ@Fabspeed

i can not find the one for the 911 at this time but here is the dyno from the 964 they are very close.

[bigel]

Never mind, just found pricing on the 'inter-webs'...sorry AJ...

[bigel]

Here's my situation...

I have removed all fasteners from my old, rusty exchangers and I can't even budge the suckers, let alone remove them from the heads. I've given them a few raps with the dead-blow hammer, but have been hesitant to really hall-off on them.

Any words of wisdom/compassion from anyone who has encountered the same situation?

My exchangers are in decent shape overall (save one 'ding' from road contact), but the mounts (flanges) and fasteners were super rusty/nasty.

Please help! Otherwise I'll be forced to take the pry bar to them!!!

Thanks in advance.

Steve

[cmcfaul]

I wonder how much crud is inside the HE's from a 40 year old 911 E. They run rich all their lives. Mine looks funky in there. They just won't die. On its third muffler and original HE's (non stainless). Original muffler had a rattle inside it. I dented the second. Third, Dansk sport (2 in 1 out), should be the last.

Chris
73 911 E

[grizzfan]

Tirwin,

I found some nice, new stainless steel heat exchangers on eBay, not SSI but much cheaper and very serviceable for my '75 engine. My old ones were worse than yours and no heat possible either. This is not the same outfit I got mine from and don't know if these will work but might:

911 Heat Exchangers 84 89 | eBay

Tom

[kjchristopher]

Originally Posted by AJ@Fabspeed

The cats are in the middle of getting carb certified as we speak. As we all know this is a very long process and will take some time to complete. however at that point we will have the only aftermarket performance cat that is carb certified.

Are you seeking certification for the SC years as well?

[bigel]

Hey friends, looking for a little asstance on my questions a few posts higher on the thread about getting my gosh darn heat exchangers safely separated from the heads...bump to the top...

[fanaudical]

I'm not certain, but am guessing you've got the exchangers with the extended ports. I'd try spraying some PB Blaster along the flange joint and in the holes for the studs. Let sit and repeat over a couple of days. There are some vertical tube that go through the exchanger shell - you might try hooking a slide hammer into those and applying a few taps in the down direction.

[tirwin]

Hey guys I've been away for a while. Been tied up with work and other projects. Grant (Uwanna) is coming over Saturday and we're dropping the engine. I'll get a better look at the HE's then and snap some pics. Got a lot of work planned. I've been stockpiling parts and will be banging out a bunch of stuff at once, plus whatever surprises I find. Due to all the other work I'll be doing, unless I find a serious problem with the HEs I will leave them alone for now.

Tom I will check out those HEs.

AJ, thanks for sharing the dyno data. I'm looking at it on a tiny screen right now. I'll look at it more closely when I get to my regular computer.

[PushinRice]

I tested the cabin of my SC for CO with a CO meter today. With the heat on, I had readings of 4ppm to 10ppm while standing and driving. From looking online, it looks like the acceptable indoor limit is 9ppm for an 8 hour period.

Is it safe to assume that the CO is coming from the heat exchangers? They appear to be in good shape from the exterior. I was considering getting SSIs anyways, but was just curious of the findings.

[tirwin]

It’s funny you brought this thread up. I have the car up on the lift to do some work and I have been thinking again that maybe it is time to replace the heat exchangers.

I guess the question is whether your resukts are abnormal. Meaning, if it was brand new and everything was working perfectly would you get a different result?

Good question. Not sure I know the answer.