Header impressions! (long)

JShadzi at aol.com JShadzi at aol.com
Tue Dec 31 00:43:44 EST 2002


> Anyways, this thing kicks ass!  If any of you 10v guys
> are even considering doing something like this, get on
> it!  Honestly, the header wasn't the hard part, it was
> re-doing the rest of the engine compartment to fit
> around it that took the most time.  Yes, I could have
> simplified it using  my existing IM, but I wanted
> something different, plus the MC IM was just in my way
> as far as intake, and down pipes were concerned...So my new > advice to those converters out there is do it all at once!

Well, in the end its nice to say you should have just done it in the first place, but you have to admit you've come a long way in the last 2 years, there was a time when I was wondering if I was the first to do a simple CIS turbo swap in a type 89, you were right there behind me, and all that was only 3 or 4 years ago  =)  I still think that especially for the novice, there is nothing like working your way up in complexity with projects like this, "stages" are very good.  Personally, I don't see the attraction in project cars that take 3-5 years to get off the jack stands (which there are those on this list in just such projects), especially for a street car that you want to drive regularily.  I think you've done it the right way taking it in stages.

> The only other mod on my car that has made this much
> difference is when I put the EFI in.

Well, shucks, I'd have to agree with you there ;)

> Right now the car is at ~ 18 psi of boost, stock MC-2
> cam.  I took the car up I-70 skiing today, the car was
> flawless minus the small issue I talk about below.  I
> can now go in 5th gear the whole way as long as the
> motor is above 3k rpms, which is the new magical #
> where I can get full boost.  Cruising at 3k, open up
> the throttle and in a few seconds it's already at 15
> psi.  I almost always had to downshift to 4th if the
> motor was below 4k in 5th, or anytime someone slowed
> me down.  Especially at higher altitudes.  Did I
> mention I got ~20mpg on my trip!  I wasn't exactly
> keeping my foot out of it either.  The engine is over
> all smoother at higher rpms, and really easy to get to
> the rev limiter.  I would say I've lost a slight
> amount of low end torque, but hardly noticeable. I
> still usually shift by 3k rpms in the city because if
> I go beyond that, well, you can imagine what happens,
> get out the neck braces.

I'd have to vouch for all the above, the header is a major improvement.  Funny, there is this idea in UrAudi world that the 10v is somehow inferior to the 20v, that in order to break the 250hp range you really need to get into a 20v, for big power.  Problem is, the 10v was never on level ground with the 20v, we have no non-CIS, non-crappy-exh.manifold 10v to compare with the 20v (well, not until recent times  ;)  Uncorked, the 10v is a powerful motor, with EFI and a good breathing header and turbo 300hp is quite easy to achieve with mild boots levels, and the low speed response is excellent too, even better than the 20v, and giving a little to the 20v above 6krpm, but can be remedied with more aggresive cam tuning.  To top it off, 10v parts are a dime a dozen these days, well, the ones you don't have to make yourself.

> As far as the other four gears are concerned, 1st and
> second are not the most imressive, easy to get full
> boost, but the engine can't spin up fast enough.  I
> can now see the need for a lighter flywheel.  But 3rd
> gear, ohh, sweet third gear, is where it all comes
> out.  Mind altering torque is a good description.  4th
> and 5th are equally as impressive.

Ahh yes, the darned flywheel effect, I agree 1st is short but brutal, 2nd is quite impressive, if I shift hard I easily get rubber, the burnout kind of cylcles between front and rear for a second as the Torsen does its thing, yes, 3rd is definitely best, and is the gear where the flywheel effect is basically gone.  I've been sourcing a nice billet aluminum piece that weights about 12 lbs, lemme know if you're interested.

> The bad:  Well all that nice ceramic coating has
> already flaked off the header and turbo(started to 30
> seconds after the car was started the first time), so
> if I can't get a refund or something, any of you
> Denver guys want to go help me remind Biff at Applied
> Plastic Coatings where his wallet is?

Bummer, oh well, you don't really need it anyway, the car knows best, it rejects what doesn't belong  ;)

> The other not so bad thing is I think I need another
> bypass valve.  That Forge is really working hard to
> dump the extra boost.  The turbo is so eager to spin
> that if you even let it think it's go-time by opening
> the throttle a little, the valve just sounds like it
> has way to much air being forced through it.  It is
> much louder, and kind of annoying.  Could be because
> of the proximity to the firewall, but I can feel and
> hear it struggling with the airflow by causing some
> slight bucking.  Which brings me to a question.

I have the same valve, I was having a similar problem I think, I ended up shimming the spring with about a 1/16" washer, really tightended up the valve and reduced a lot of the little throttle puffs.  I also hear you saying that you think you're overwhelming the valve with CFM, I guess I'd keep an eye on your boost gauge to see if you're getting any spikes, my guess would be the Forge should be good to at least 400hp without too much trouble, two in paralell would be good for above that.

> Right now the bypass valve is by the TB.  I put a
> nipple on the pipe right after the turbo for another
> bypass valve if I need it.  Any thoughts on how the
> system will work with a valve in both places?

I think it would be fine, I don't think BP valve placement is that critical, some factory apps put it by the turbo, others by the TB, mine is by the turbo, no biggie. I really can't imagine you need two tho'.

>  I snagged a pretty big Pierburg BPV off a Volvo at the
> junkyard that I think I'll try there.  The Forge valve
> may be sticking a little to, so I'll look into that as
> well.

Sure, then sell the Forge on ebay for $100...Forge also has a free rebuild kit for the earlier delrin bushings, I tried using it but it wouldn't seal, I put the delrin back in as it was working perfectly the way it was, and my valve is in a cool spot that doesn't get too much heat anyway.

Anyway, good stuff, I just wish you'd come out to a CA track event so we can pass up the modded S4's together, just like the IMSA cars did in their 1-2-3 wins  =)


BTW- I'm subbed to the s-car list but not getting mail currently, so cc me if you'd like to flame me on the 20v comments above  ;)

More information about the quattro mailing list