TB993tt

Seeing that you now appear to be speaking on behalf of FVD products, can you share with us your opinion on the following subject:
Herr Brombacher says that there is 20hp+ to be gained on a 993tt by switching from hydraulic to mechanical valve actuation. He says there is float at high revs which occurs with the hydraulic system and eliminating this by the mechanical system allows much more accurate following of the cam profile at high revs and hence no power is lost giving an effective 20hp+ gain against hydraulic.
Is this correct ?

AMG ETR

Hello,
Yes this is correct. At around 6,000RPMS the hydraulic system begins to float and therefor the engine is no longer running efficient. The mechanical system eliminates this problem and allows the car to run smoothly up to redline. To get the full potential out of this switch you would also want to switch to new cams (I am not sure if you have already done this or not). There is one down side to this switch however. The mechanical system must be readjusted every 12,000 miles or so. The cost for this runs about $450.
Hope this helps, and let me know if you have any other questions.

TB993tt

Sorry AMG ETR, I am being deliberately contentious Your reply is what FVD believe, but it is in fact not true. The hydraulics do not "cost" any power until about 7200rpm - Herr Brombacher uses this line to flog his mechanical rocker conversions which are completely unneccessary for most 993tt engines.
Good to see you are towing the company line

AMG ETR

I realize what you are doing by the tone of your first post and your previous comments about our company... I tried to handle the post with a mature response instead of calling you out and asking why you would ask a question you think you know the answer to...guess that did not work...I still stand behind my post however. Think what you like, I may be wrong, but untill you can prove your statement I have no reason to change MY thinking....
Can't say I am very impressed with you or your post...

AMG ETR

ALSO:
Andial (basically the Michael Jordan of the Porsche world)uses the same method along with Porsche Motorsports...I guess they are both wrong also AND MOST 993 GT2 (both street and race car) used the mechanical lifters.... The hydraulic systems were used mainly because of warrenty on the 993TT's.
I am not sure what your mechanical background is, but if you have proven your claim maybe there is an opening at Porsche for you
PS-RS tuning and FVD work together on many products and their relationship is like a brotherhood, so not sure why you have so many negative comments toward a company that works very closely with your tuner

Kevin

A little words of wisdom if you install the mechanical rockers...

Make sure you install new camshafts or have them reground... With our cars aging, the lobe profiles and rockers have definate wear patterns. If you install the new rockers.. You will wipe out your camshafts.. I have seen this happen to 2 engines lately...

For most street engines the hydraulics are great.. However, if one is going to do a topend overhaul and or strengthen the bottom end with better rods. Do a camshaft change and dump the hydraulics.... Adjusting valves in a 911, should be a must do for every owner, at least one in his lifetime!

AMG ETR

Exactly, thanks for you comment Kevin. As I did mention new cams are a must with the new system. Can't imagine those 2 people are very happy .

TB993tt

Firstly, I don't have "so many" negative comments about FVD and have purchased plenty of gear from them over the years and have recommended them freely - it is this one issue that winds me up.
Secondly, yes I am calling you out since you are now making yourself known on Rennlist as an FVD employee. Rennlist is a technical discussion forum and I would think this issue would be of interest to people, especially those who have been told the FVD line on mechanical versus hydraulic tappets.
Andial do not use mechanical with the RS cams -(they are hydraulic) which they use on most of the 993tts they do, the mechanical system is only used where it is NOT possible to use hydraulic (or for racing), ie where GT2 EVO cams or similar are used.
The GT2 street car uses HYDRAULIC actuation. Mechanical is used on the race cars - no argument there - for obvious reasons. Hydraulic system was not used for warranty issues, it was purely for savings on maintenance bills !
It is FVD which needs to prove its claim, because 993tts and other 993s which only rev below 7000rpm will not gain any power benefit from mechanical lifters - can YOU prove otherwise ? dyno sheets perhaps, one with hydraulic and an identical motor with mechanical ?

AMG ETR

As much as I would love to (and could) speak about this all day, I have the worlds largest boat show (Miami) calling my name (it is Saturday). I will return to this thread when I get into the office on Monday and would be glad to keep discussing this issue.
Speak with you Monday

viperbob

Wow, a contenscious post, and I'm not part of it. Go figure. OK, I am forced to add in my 2 cents and I am not taking any sides as I feel that FVD provides some very good products, and TB you make some very valid points (me a diplomat???)

Hydraulic lifters - Put in Porsches purely for maintenance reasons. $450 to adjust the valves? Not at a dealer. And on a TT, you would need to pull the turbos to get there, then there is the matter of that giant pump on the passenger side. I can not even imagine what I would charge to do this on a TT... I even gave up this notion on my own car because of the "you just can't get there from here".

Float? At high RPMs the pressure required by the hydraulics to keep the valve open starts to fall. THis means that the hydraulic actuator can not maintain full valve lift. Float refers to a valve that is not seating or following the lifter due to high RPMS and hence the valve is open outside of the cam proifile. Stiffer springs are generally required to fix a float condition, not mechanical lifters. There is a balance between spring pressure and the hydraulic lifter as a stiffer spring can amplify the issue with hydraulic lifters. If you turn to the Chevy world for a moment, you will find performance hydraulic lifters that stay pumped up with more pressure to allow for higher RPMs and higher spring rates.

Well Kevin, I have adjusted many a valve on a 911, so I guess I that I have passed the test...

JJayB

Are we talking about turbo motors. My dyno sheets say max torque is at 4500 rpm and max hp is at 6100. Why would I want to rev to 7000 in a street car? I know Ruf says its ok to go to 7200 rpm, that how he get his cars to 200 mph with a tall 6th gear. How many have gone 200 on the street.

Does anyone on the board run a solid lifter cam set up? Andial advised me not to use the GT2 solid lifter cam as it has no benefit in a street car and they are maintence issues which others have mentioned.

I think a little contenscious post livens up the board; thanks TB. Its better than what is ones favorite color 996 or 993.

Autobahn

TB & Viperbob,

thanks for clarifying. Tuners can say whatever they want and we are very likely to believe it. It's good to have 'independent' people around who know what is going on.

Re: AMG ETR

Since he started working for FVD what do you expect from him? He states that he is the Recaro seat expert, therefore any answer regarding any mechanical issues will reflect the opinion of FVD. How could he know any better? How could you blame him for that?

I'm just happy to have people around 'here' with first hand experience.

ca993twin

I rev my turbo to 7000 RPM frequently. Not in 6th gear, or even 5th gear, but in shifting from 1st to 2nd, and from 2nd to 3rd. I do that for briskest possible acceleration, so that when shifting into the next gear, I don't drop out of the sweet spot in the RPM curve. Also, although I haven't tracked the turbo (yet), I have found that on most road courses, there is at least one straight where I either need to rev the snot out of the car or shift to the next gear just before a corner, where I would need to down shift two gears... sometimes revving the snot out of it is the better choice. Am I alone here?

I'm following this thread with interest, although adjusting the valves (yes I've done it on my earlier cars) is not anything I'd want to tackle on the turbo... especially if viperbob thinks its a miserable job.

AMG ETR

Hello Everyone,
Just returned from my Cigarette break (and no I don't mean smoke, I mean the boat ). I am now home with strep-throat(have had it since last night), so I am not going to continue this discussion right now. I did want to post this however:
In response to:
.Since this is the way you feel, I will stop posting my opinion on here. While I am no 993 expert the information I am posting is information that has been proven to me by the same person TB993tt is talking about Mr. Brombacher the owner of FVD. I will pass this on to my boss and let him post from here on since my comments are not expert enough for some. I am hurt that you think I would just start lying because I work for a tuner now. This is far from true and if somthing is good its good and if its bad I am going to say it. I still reccomend products that are not made by FVD if I feel they are better.
I understand what you are trying to do, unfortunatly I disagree with the way you went about it. Trying to help others on this forum is why the forum is here and your question is valid, BUT trying to make it look like you wanted help when all you really wanted to do was have me post what I and the company I work for believe so that you could state how we are wrong and why you are right isn't right. I wish you would have just posted how you disagreed in the first place instead of "luring" me into the thread. If the title of the post would have been what it is now it also would have been helpful instead of deceitful. Not upset, just kinda confused why you went about it in this way...

As I said guys, I am sick and feeling like crap so my posts will end here, but I will pass this on to my boss (name is "tuner" on here) and try to get a comment from Mr. Brombacher himself next time I speak with him.
Geez, its like a new sponser hazing period

TB993tt

Can you share with us this "proof" which you claim to have been shown ?