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Discussion Starter · #1 ·
I might as well throw these questions out now while I start researching my next project.
I am looking onto building up an OBDI head for my 97 Golf. Along with the susal P&P, I am curious about is installing larger IN/EX valves. I have read that 87-88 BMW 325 valves work. Is this true? What modification to the head, other than boring the valve seat, need to be done? Are the valve stems longer/shorter than VW stems? Will VW guides work?
Any info will be helpful.
 

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Re: Head project questions (tdogg74)

I gotta look for the EC article that had all that info in it. Though you may want to save yourself some leg work and just get the valves from TT. With the valves available all you'd need to do is have the seats milled out. TT has their recommended amounts in the valves description IIRC. VW guides would work as long as the valve stems are the same diameter, which I believe they are.
What are your ultimate goals for the new project? Staying NA?
 

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Discussion Starter · #5 ·
Re: Head project questions (MikeBlaze)

Quote, originally posted by MikeBlaze »
I gotta look for the EC article that had all that info in it. Though you may want to save yourself some leg work and just get the valves from TT. With the valves available all you'd need to do is have the seats milled out. TT has their recommended amounts in the valves description IIRC. VW guides would work as long as the valve stems are the same diameter, which I believe they are.
What are your ultimate goals for the new project? Staying NA?

Hey Mike, long time so speak.
Ya, I am staying NA for sure. I Just want a better breathing head, thats all. I might get my hands on an OBDI head for this. I figured with a mild P&P, some port matching of the IN/EX manifolds, and maybe larger valves, I can get good performance out of this. I figure if I am getting the valve seat in the head 3-angled, why not open it up a few mm's more, ya know? All this work in conjunction with my 272 camshaft, I think at least a 20% increase in overall performance is not out of the question.
 

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Re: Head project questions (tdogg74)

How bout it, good to have ya back.

I like your plans. One thing I would like to see done with the larger valves is a more aggressive port job. I'm not to sure what benefit you'd have with the larger valves if there wasn't much of a port job done. Since the seats would be opened up you'd have to open up the whole port/bowl area to realize all the potential of the valves. I know it gets pricey...
Check out http://www.porttuning.com as well. He can get the valves, nice tapered guides, the whole nine. He does killer port work too.
Any thought on bumping up compression as well?
 

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Discussion Starter · #7 ·
Re: Head project questions (MikeBlaze)

I think I understaded myself when I said "mild". It was meant more like enough to flow nice with my camshaft, but not to where it wont pass emissions or be a beast to drive everyday. Is 178cfm IN / 124cfm EX too much?
Quote »
Any thought on bumping up compression as well?

I was thinking of it. I run 93 octane and have an adjustable cam sprocket to compensate the camshaft postion. I am thinking maybe a small bump..like 10.0:1 to maybe 10.5:1. (I need to research that a bit more). Any suggestions there?
 

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Re: Head project questions (tdogg74)

I don't think you'll have to worry about emissions as long as the chip is matched well to the mods. I would think you'd need to get your chip reflashed after a dyno with all the new stuff in. Plenty of turbo charged cars have no trouble passing emmissions.
Your state going to the new OBD2 testing anytime soon? The new testing no longer requires the use of a tailpipe sniffer, they just hook up a scan tool to the computer and look for codes. No codes=pass.
As far as comp is concerened you would be fine up to 12:1 on 93. I had a head decked .040" which is now close to 10.75:1 cr. No issues but better throttle response. I wouldn't hesitate to do it again, though i'd go a bit more aggressive.
 

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Discussion Starter · #9 ·
Re: Head project questions (MikeBlaze)

Well, I sorta *cough* dont *cough* have to wory about the sniffer test. Lets just say, last year I passed with flying colors.
I hope we get that new OBD2 test instead of the dyno/sniffer...I can just go down to Auto Zone and clear my codes right before I go to inspection!!
10.75:1 sounds pretty decent. I would also need to see about boring out that bottleneck we call the Throttle Body.
 

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Discussion Starter · #10 ·
Re: Head project questions (tdogg74)

I just went on the Port Tuning site. They dont have prices for the x-flow. What gives??
 

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Re: Head project questions (tdogg74)

Quote, originally posted by tdogg74 »
Well, I sorta *cough* dont *cough* have to wory about the sniffer test. Lets just say, last year I passed with flying colors.
I hope we get that new OBD2 test instead of the dyno/sniffer...I can just go down to Auto Zone and clear my codes right before I go to inspection!!
10.75:1 sounds pretty decent. I would also need to see about boring out that bottleneck we call the Throttle Body.

Worry more about the intake manifold then the TB. That lower manifold can be opened up quite a bit.
Regarding the Autozone clear codes then go test thing. I don't think it'll work. If the garage does not see readiness codes on the computer it will fail. Those readiness codes come after the computer sees varying conditions, it runs tests-sees everything good-then writes those codes. When you clear the codes it clears those as well. Actually that's just a theory. My car failed after I reset the computer by taking off the battery cable for a while then took it to test. pretty sure it'd be the same thing though.
Porttuning's prices are the same for the crossflow and non crossflow 8v heads.
 

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Discussion Starter · #12 ·
Re: Head project questions (MikeBlaze)

LMAO!! I am such an idiot! I just looked online....We have been using the OBD test since like 2002!!! Thats why I passed...I had my codes cleared like a couple of days before I tested. I remember talking to the owner of the shop. He asked what I was running for a camshaft.
No CEL light, he plugged in and passed me. SAWEET!!
 

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Re: Head project questions (tdogg74)

I know in the Wisconsin OBD test, the run it through that first. And, if something is iffy or close, they still do the "sniffer" test. FYI.. nothing more.
Also, as far as the larger valves, I've considered the same thing. Although, using an obdii head instead. Increase of a mm in both the intake and exhaust valves. I know you can get them through Autotech as well, although I don't remember the price. And, definitely bump your compression while the head is off, espeically if you're planning on staying NA.
 

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Discussion Starter · #15 ·
Re: Head project questions (ramylson)

Another VW freek I chat with runs BMW valves in his X-flow. An E30 325i's valves are 42mm/36mm (over 40mm/33mm stock). They are a bit longer than VW, but he says they are fine...plus they are shaped better. A stock OBDI head flows 150cfm/115cfm...so mid 170 IN / mid 120 EX is target for this porting.
 
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