Stock 2.0 HE vs. SSI Stainless, Is there a performance difference? |
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Stock 2.0 HE vs. SSI Stainless, Is there a performance difference? |
Nozzle |
Jan 11 2015, 08:55 AM
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#1
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Member Group: Members Posts: 158 Joined: 6-November 08 From: Lexington Park, Maryland Member No.: 9,725 Region Association: MidAtlantic Region |
I've got the impression from several posts that 2.0 stainless steel heat exchangers (SSI or other?) are a performance improvement over the stock 2.0 heat exchangers. Have I got that right and if so what about the stainless design leads to the performance improvement?
I've got a set of original 2.0 HEs that look OK from a metal standpoint but could use a serious refurbish. I'm wondering if it's worth the effort to do the referb or try and find a used set of stainless replacements. |
TheCabinetmaker |
Jan 11 2015, 09:24 AM
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#2
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I drive my car everyday Group: Members Posts: 8,301 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
It's my understanding that the 2.0 stainless are the same interior diameter as the oem giving no enhanced performance. However, the 1.7 ssi's are bigger than the oem steel giving an increased performance.
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GaroldShaffer |
Jan 11 2015, 09:29 AM
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#3
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You bought another 914? Group: Benefactors Posts: 7,623 Joined: 27-June 03 From: Portage, IN Member No.: 865 Region Association: None |
My understanding there is no performance improvement, just no issues with rust. The SSI do have their own set of problems that you need to make sure are not a problem before you buy them. The pipe inside the exchanger can crack over time and can allow exhaust fumes to get into you cabin.
I do a simple water test to check for cracks. Put the exchangers on a couple of saw horses and raise the muffler end an inch or two. Fill both pipes with water until water comes out the muffler end. Let them sit for 30+ min or so. If you see no water drops coming out of the shield area then chances are they do not have any cracks. Click on this link ---> BAD SSI Exchangers for pictures of what can happen. |
JeffBowlsby |
Jan 11 2015, 10:10 AM
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#4
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914 Wiring Harnesses Group: Members Posts: 8,522 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None |
Depends on how you define 'performance'. The factory HE's are quieter than SSI's if that is important to you.
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Dave_Darling |
Jan 11 2015, 11:03 AM
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#5
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914 Idiot Group: Members Posts: 14,991 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
The SSIs are the same diameter for both the 1.7/1.8 version and the 2.0 version. That diameter is larger than that of the stock 2.0 exchangers. In theory, that would result in more power. In practice, it doesn't seem to.
The stock HEs do a much better job of sound damping, as Jeff stated. The SSIs are noticeably louder. The mounting ears can also be more problematic on the SSIs than the stockers, though that's not to say the stock ones never have problems. I got them because they won't rust. Period. --DD |
Tom_T |
Jan 11 2015, 05:18 PM
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#6
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TMI.... Group: Members Posts: 8,318 Joined: 19-March 09 From: Orange, CA Member No.: 10,181 Region Association: Southern California |
The "performance" improvement is in rust resistance, as stated by the others, & not much else.
Also ditto on the SS HE's mounting ears tending to crack, but they're easy to TIG weld back on (SS needs TIG, MIG won't work well). You should also test your OE mild steel HEs inner pipes for leaks too - &/or any other stock ones - cuz that exhaust leaking from the inner exhaust tubes into the out air channel of the HEs ~ & therefore into the cabin with heat on ~ is a malady of all types of HEs on the old aircooled cars - Porsche, VW, Tatra, etc.! That said - you can now again buy SSI HEs now that Dansk has restarted production (+/- $1000-1200 per side new IIRC), but an NOS set of stock ones are like Hen's Teeth!! The SSI's can be painted or ceramic coated to a grey close to the stock steel exhaust color too, if you're worried about originality or that look. |
Maltese Falcon |
Jan 11 2015, 07:40 PM
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#7
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Advanced Member Group: Members Posts: 4,673 Joined: 14-September 04 From: Mulholland SoCal Member No.: 2,755 Region Association: None |
We sent our 2.0 heater boxes to Extrude Hone for them to get the i.d. opened up. Then off to the metallic ceramic coating shop.
Result was a real decent set of original heater boxes, better exhaust flow and no rust issues. Going on 10 years use (street+track) and they look brand new. |
Chris Pincetich |
Jan 12 2015, 02:36 PM
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#8
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B-) Group: Members Posts: 2,082 Joined: 3-October 05 From: Point Reyes Station, CA Member No.: 4,907 Region Association: Northern California |
A light weight 914 - all else equal - will accelerate faster, turn quicker, and stop shorter.
The SSI HEs weigh quite a bit less than OEM (IMG:style_emoticons/default/beerchug.gif) |
Nozzle |
Jan 12 2015, 06:22 PM
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#9
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Member Group: Members Posts: 158 Joined: 6-November 08 From: Lexington Park, Maryland Member No.: 9,725 Region Association: MidAtlantic Region |
Thanks for the feedback folks. If I'm understanding right, the stock HEs and the stainless HEs share the same basic flow characteristics so the only real benefit is the rust resistance for the stainless versions.
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Jett |
Jan 12 2015, 08:27 PM
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#10
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Senior Member Group: Members Posts: 1,640 Joined: 27-July 14 From: Seattle Member No.: 17,686 Region Association: Pacific Northwest |
Thanks Garold for this insight!... My 73 1.7 has SSI's and no matter what I clean, refurbish or replace the exhaust is coming into the cabin...
I'll do the water test this weekend. THANKS! |
r_towle |
Jan 12 2015, 09:41 PM
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#11
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Custom Member Group: Members Posts: 24,584 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Older 2.0 liter stainless or plain steel heat exchangers are a big improvement over later 75/76 heat exchangers.
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