Long vs short neck intercooler...

hobieboy · 11-25-2003, 07:56 AM

Just wonder if someone can explain the difference between the 2 for the 930? Heard many times that folks upgraded to the long neck style ones? What's the benefits?

I believe with the long neck, there's also different BOV? What does the new one look like?

thanks...

Slant930 · 11-25-2003, 10:13 AM

You are on the right track. The "long neck" version is one that will eliminate the older style bypass valve that is on the 78-89 versions. This is similar to the C2T version. The 930's don't have BOV either, they are technically BPV, bypass valves. BOV's vent to the atmosphere, while the BPV, bypass valve, vents back into the system. The benefits going to longneck is that the newer BPV C2T style are lighter and work much better than the old heavy cast assembly. Other benefit is that the longneck ones are usually bigger and more efficient intercooler cores.

I've attached a picture of the Kokeln version, which would be considered a longneck version. The circled item is the new C2T style BPV.

Hope this helps.
Timothy

hobieboy · 11-25-2003, 10:43 AM

Hi Timothy,
Thanks for the explanation... so where does the new style BPV plugs into? The old style is "part of" the entire air intake system (sit under the interoolcer outlet to the intake). Where do I tap the path to feed the new-BPV and where do I vent the air back to the system?

thanks again...

David · David's Garage

Does anyone have a picture of the newer system installed?

Slant930 · 11-26-2003, 09:43 AM

O.K, sorry for the delay in response. Once you remove the old cast BPV assembly, there is a new rubber elbow and spacer that connect the CIS metering flap assembly to the turbo intake. The new elbow has a nipple molded in that the new BPV attaches to. I've circled the items in the picture again. It's hard to see all the detail in the pics. In the case of the Kokeln, a hose then connect to the BPV and then to the back of the intercooler. This is where it bleeds back into the system. A small vacuum line goes from the throttle body to the BPV to control the opening and closing.

I don't have any pics on hand but can work on getting some after the holidays for you guys if you like. In the meantime, you guys might want to check out 911turbo.com and turbo911.com for some pics. Might also check out c2turbo.com. These are all great sources for 930 info. There should be some pics somewhere on these sights.

Hope this helps.

Timothy

David · David's Garage

I'm still new to 930 ownership and I'm trying to understand what all is involved with the intake. I pulled off the intercooler and saw this huge cast piece which has the two bolt down points for the intercooler, part of the intake line to the compressor and a valve of some sort that takes air from just above the throttle body. Am I to understand that I can replace this cast piece with the parts in the pic above? Since the cast piece also holds the intercooler, how is the intercooler held down? I already have what I believe to be a B&B intercooler so I won't be replacing it. I've done a search on this on a few different forums and I'm not finding real good info. By good info I mean info so that I understand it well enough to fabricate my own parts. Any help is greatly appreciated.

Slant930 · 12-01-2003, 07:32 AM

Hi David. The big cast assembly is the bypass valve assembly. The Kokeln assembly has everything needed to convert over to the newer bypass assembly. Once you remove the old cast assembly there are some longer bolts and spacers that you use to mount the new intercooler. The front mount is the same as the factory mount. Your B&B intercooler will not be a simple bolt on though. If you are currently using this intercooler with the stock cast bypass assembly, it is not a long neck version and will not work directly. Once you remove the cast assemly you would need to either lengthen the neck on the intercooler or make some kind of spacer to bridge the distance between the intercooler and the throttle body. i.e. you will lose height at the throttle body by removing the cast bypass assembly. In my opinion, it would be best to sell the B&B intercooler and buy a Kokeln kit. The Kokeln is worlds more efficient and larger in size than the B&B unit. But that route is not necessarily cheap though.

Hope that all makes some sense and don't hesistate to let me know if you need any more help. I'll still try and work on getting some pics too.

Timothy

David · David's Garage

Just to clarify: I can remove the cast bypass valve assembly, fabricate a long neck adaptor, a hold down pipe with a bracket on the left side and a hold down bracket on the right side and ?. What do I do about the bypass valve? Would I add a port to the B&B intercooler (or in the long neck adaptor) and run a separate BOV?

Obviously the easiest solution is to shell out $1800 for a Kokeln intercooler but I don't know that I'm ready to spend the money. I work in a machine shop, so fabricated parts are virtually free.

Today I just started hearing a poping noise (not like detonation) under boost. I'm wondering if it's the bypass valve leaking.

john walker's workshop · 12-01-2003, 04:52 PM

i wonder if it's a broken head stud. 24 dilivars on that one.

David · David's Garage

That's my next project after the infamous SC leaves my garage (hopefully after I get the rusty gas tank back from Moyers).

("Infamous is when you're more than famous" -Martin Short)

Slant930 · 12-03-2003, 07:33 AM

Yup, I think what you're proposing will work with the adaptors and bracketry. My only concern would be making sure there is a good seal at all locations, otherwise you will have boost leaks. As for the bypass valve, you can buy the large rubber elbow which has a nipple molded in to mount the valve. It is a Porsche part, don't know the number off hand. I suppose you could modify the one you have by cutting a hole in to mount the valve, but that might somewhat cobbled. The valve is also a Porsche part, again don't know the number, but it is a Bosch valve and is pretty reasonable if I remember, $50 maybe. You'll also need to weld on a nipple to the back of the intercooler for the line which goes to the bypass valve. Another thing you'll need is a section of pipe or tubing to bridge the gap that is created in removing the cast valve between the rubber elbow and the intake line to the turbo. There are a few more little items, but I can go over them more in detail if/when you get that far.

One note, what I'm suggesting for install basically is mimicing the Kokeln/C2 Turbo style. There maybe a simpler way to do it, but I figure it works for those setups, so why mess with it. Others may disagree I guess.

Hope this all helps and let me know if/when you need any more assistance.

Best of luck,
Timothy

arrivederci · 12-03-2003, 08:44 AM

Quote:

Originally posted by 125shifter
Just to clarify: I can remove the cast bypass valve assembly, fabricate a long neck adaptor, a hold down pipe with a bracket on the left side and a hold down bracket on the right side and ?. What do I do about the bypass valve? Would I add a port to the B&B intercooler (or in the long neck adaptor) and run a separate BOV?

Obviously the easiest solution is to shell out $1800 for a Kokeln intercooler but I don't know that I'm ready to spend the money. I work in a machine shop, so fabricated parts are virtually free.

Today I just started hearing a poping noise (not like detonation) under boost. I'm wondering if it's the bypass valve leaking.

A worn out stock BPV will no pop under boost...you'll hear clicking as vacuum pressure changes (primarily on and off throttle changes). There is a seal at each end of the BPV assembly that wears out. It a pretty simple fix after you remove BPV. I think I have some pictures floating around of it disassembled. Obviously I had to replace them on my 930. BTW, I think I have the B&B intercooler as well (installed by PO).

Slant930 · 12-03-2003, 03:01 PM

Thanks for the pics Josh, I'm sure it will help David and others who may be following this thread. I also agree, the BPV will not create popping noises under boost, only under throttle on and off, but then only if the seals are bad. I may have to agree with Mr. Walker and look at possible head stud issues.

One other thing you will need to do is relocate the overboost protection switch and boost gauge sender. These should both be located on the cast assembly. On the Kokeln they both mount to separate nipples on the bottom of the intercooler.

Timothy

beepbeep · 12-03-2003, 03:54 PM

Popping noise can also be caused by blown intercooler seals.

hobieboy · 12-03-2003, 04:48 PM

Given all the fabrication required, is it worthwhile to "upgrade" to the newer style if mine does not seem to have anything wrong?

And how does replacing all the seals in this original BPV compared to the newer ones, performance-wise?

Thanks...

beepbeep · 12-03-2003, 05:00 PM

Quote:

Originally posted by PatrickT
Given all the fabrication required, is it worthwhile to "upgrade" to the newer style if mine does not seem to have anything wrong?

And how does replacing all the seals in this original BPV compared to the newer ones, performance-wise?

Thanks...

I got rock-steady idle after i replaced BPV seals, it also felt as my spool-up improved.

Here is a picture guide on how to change them:
Changing 930 dump-gaskets, pictures galore

That being said, blown BPV seals will give you "clonk-clonk" sound when stepping on gas but not popping noise.

RarlyL8 · RarlyL8's Garage

Is there anyone out there that sells an adapter that connects a short neck intercooler to the throttle body?
I won't part with my B&B unit but would like to simplify the engine compartment by removing that clunky stock BOV.

Slant930 · 12-04-2003, 08:10 PM

Quote:

Originally posted by PatrickT
Given all the fabrication required, is it worthwhile to "upgrade" to the newer style if mine does not seem to have anything wrong?

And how does replacing all the seals in this original BPV compared to the newer ones, performance-wise?

Thanks...

I would say that there would be no real noticable difference by upgrading to the newer style if the old one is working. If the seals are bad, you may notice some benefit like beepbeep states. Only benefits on the upgrade would be to drop some weight and it cleans up the engine somewhat.

Slant930 · 12-04-2003, 08:16 PM

Quote:

Originally posted by RarlyL8
Is there anyone out there that sells an adapter that connects a short neck intercooler to the throttle body?
I won't part with my B&B unit but would like to simplify the engine compartment by removing that clunky stock BOV.

I'm not aware of anyone off hand, but you might want to talk to Stephen at Imagine Auto (imagineauto.com). If that doesn't pan out, I could possibly look at getting something made.

BTW, not sure if you remember me Rarly, but we actually met 3 years ago at Tweeks Funfest. I have the burgundy slant and parked next to you. Glad to see someone I know on here.

RarlyL8 · RarlyL8's Garage

You bet I remember. That is a beautiful car. And you are a brave man for driving something that low in the front on public roads.