martyg

My car has mechanical valves, but I have a question for the board.

During the build of my motor it was discussed what to do regarding this issue. The motor before it blew up the first time was given this treatmnet for more HP so during the second build it was the option to go with. Also with the 3.8 litre and the turbos, we (builder/me) thought it would be better for the outcome of the motor. I also wanted some oldtime stuff for the car. I liked the way it sounded and it also put the car in a special category in my opinion. Before I recieved the car it was given two adjustments just to make sure they were right.

I did not drive the car during the week of rain so I guess I forgot what the motor sounded like (valves going). My question is how can I tell if there is something wrong,like valves out of adjustment and can this happen with hard driving. And what is the opinion from the board regarding mechanical and does anyone have any warnings for me.

SPR

You will hear a distinct mechanical tapping because of the slack of the tappets on the cam. It's dangerous in as much that it wears the cam.

Kevin

Marty, all valves are mechanical.. It is the rockers that are hydraulic 993NA and TT or mechanical basically every other 911 and 930.. With the install of mechanical rockers, you will need to adjust the valve lash at least every 10K miles or once a year if your car is driven hard or on the track.. The exhaust valve is the critical issue. It will basically grow in length over time and you will lose your lash. If this condition occurs you will burn a valve and this will lead to valve failure and breakage.. To adjust the valves you will have to remove your turbochargers.. This add labor to the adjustment of the valves.. I'd suggest that you learn to change your oil and adjust your own valves..

martyg

I guess that is what I was trying to say. Oild change no problem. Valve adjusting...? I guess I could.

I posted the message on another board andthe advise I got was if the sound goes higher with RPM then I have a problem. It was adjusted like I said twice before the car left and I do not track it so it is probably just me.

ttAmerica RoadsterAWD

Kevin, are the rockers same thing as lifters?? Or are lifter something in the old muscle car nomenclature?

I'v been told that one can get better "performance" from solid lifter as apposed to hydraulic lifters being that there is a small, yet measureable "give" in the hydraulic. The trade off of course is the relative maintenance free

Kevin

Typically the term "lifter" refer to actual mechnism that rides on the camshaft. Are engines actually have rocker arms that have a pad that rides on the camshaft lobe. The stock 993NA or TT has a hydraulic lifter machined into the rocker arm that replaces the elephant foot adjuster (lash adjustment). In your case you have an adjuster, and no hydraulic lifter. The actual performance gain (or measurable gain) would come from the radical camshaft grinds available to the tuner, when one uses a solid rocker.. However, when building a turbo engine, camshaft grinds with less duration and lift are chosen.

Jean

Marty,

What's done is done, but basically, I would not go for mechanical rockers unless you have a very aggressive cam profile (EVO or RSR or similar) which is not your case. It is just not worth the hassle. FVD likes to advise you to put the mechanical rockers, which in the opinion of some of the best engine builders is not worth it for 99% of our tuned 993TTs. Another thing to consider is the peak RPMs, is your rev limiter set higher than 7100 RPMs?

Porschefile

From everything I understand about the differences between mechanical and hydraulic lifters, there doesn't appear to really be any significant power gains. I think they are mainly a safety measure for higher rpm useage of the engine. The downside, as others have mentioned, is they require constant adjustment to keep everything within spec. Unless you are revving your engine significantly higher and using "hot" cams to take advantage of the higher rpm, there's not much of a point. Please correct me if I'm wrong guys, but aren't mechanical lifters only really applicable above approximately 7100 rpm +/- 100 on 993's?

SPR

Usually the characteristics are that at higher rpm's the hydrolics will float, so solids are enlisted

martyg

I have come to one conclusion. I do not know.

I spoke to Dayton today at DepartStop after a little complaining about not understanding this motor I have. (He is 2 minutes from my office)

He told me I have a motor only a few handfull of people have. Basically he was saying most people only do the bolt on stufff (i.e. ECU or Bigger turbos or Exhaust) but never do a complete (from the case bolts up) re-build.

I do not understand the cams, the valves, the turbos, polishing oil gallies, NIRO rings, cam lift, micro polished cam and crank etc.. I asked Felix today for a complete breakdown of exactly what was done and how it effects the out come of the motor. So I hope over the next few weeks I can get more educated about this car. One thing is for sure, when it comes to the building of these motors and not just people who bolt on parts and claim HP gains that some are in the know and others are just talking. IMO when you build and change like I did you (Builer/Owner) need alot of experience building from the P & C's and not just bolting on.

Very frustrated. Some owners might just pay and go (IMO=Poser). But I like to talk with other owners and be in the know amd understand the mechanics.

But hey my family came out on Sunday from OC and test drives were given. All, scared to death, nevery been anything that fast! Nice to here but I would like to know the whys and whats when I push the pedal down.

Thanks for the help.

Dayton996T

Interesting,
I understand your concern however when you get into the type of upgrades your car has, it takes years of hands on experience to get a complete understanding of these mods. I guess the bottom line is your going to need to spend a few bucks now and then to keep that car performing as well as it does, while also learning about what you have. Very nice car Marty, Felix did a good job.
Cheers
Dayton
Departstop

TB993tt

Marty
We discussed the hydraulic vs mechanical issue a while back here:
https://rennlist.com/forums/showthre...ight=hydraulic

Mechanical give no advantage under 7000rpm (unless you have a very agressive cam profile like GT2 EVO which I believe won't work with hydraulic) just the BIG disadvantage of the maintenance.
FVD's Mr Brombacher aggressively sells the mechanical to anyone who will buy saying it will give you 20hp - this is complete BS for most engines with cams which CAN run with the hydraulic set up. You also have FVD/TTP intercooler which as I mention elsewhere is not as good as stock. It seems like your builder has purchased all the goodies on offer from FVD - not his fault, unless he has an engine dyno where he can try the different parts to test their effectiveness he is not to know - and overall it will still be a potent motor. BTW did FVD sell you the Powerflow snorkel air intake

Dayton996T

Just FYI.
Felix Amore - Gulf Performance Porsche
Dayton Emerson- Departstop Porsche parts
***** Brombacher- German Rep

These Three people were the owners of FVD-USA till a few months ago.
Cheers
Dayton

Jean

Marty the engine that you have is fantastic, and having the engine rebuilt with internals IS a major undertaking and great reliability will be obtained. Hardly any bolt-on engine will match the kind of performance you can have since you can have the luxury of high boost, high torque for much longer miles.
A full FVD bolt-on kit for a 993TT engine is by itself an amazing performer and not many ECU/turbo/cams kits offered by the majority of tuners will match its performance, as these have been thoroughly tested over the years and have thousands of tested miles on them.

In a nutshell, the stuff made on the crank and case etc.. does not give you any noticeable improvement in performance at these levels, turbos will help when coupled with the right cams and ECU, valves etc.. give you reliability, conrods too, niro rings too, the intercooler is great, etc.. a very well balanced engine on which a few things might be an overkill and others bit of marketing. The only weakness I can see with the engine is the 3.8 FVD P&C which are not Mahle and will subject the engine to leaks with time, but you have a looong way to go with before anything happens and even then it won't be a big deal..
Go out and enjoy it, whoever built that engine really did a great job.
Congratulations

ttAmerica RoadsterAWD

FWIW on "Excellence" issue #81 Andial hotrodded a 993tt to some impressive numbers. Andial used hydraulic's instead of solid. Considering this source, I might add that for killer street and track (save professional all-out racing), the hydraulic seems the way to go...my $00.02 centavos.

Jaime