mstolo

I am clearly on the path for a top-end rebuild, and watching all the posts by Nollie and Boulderbobo has motivated me to do it myself. I have many things to line up before I start the project (time, tools, a clean garage, etc.), but I want to start to do my homework so I can do it efficiently.

The car has 100k miles, has the SAI problem, and I will replace the clutch (among all the other "while your in there stuff"). The car runs well, but I would hate to do a top-end rebuild only to find out I should have done more below the heads. The question I have (for starters) is:

What is the best way to determine if you need to go beyond the top-end? What tests should I perform before and after the engine is dropped just to make sure I cover everything?

MarkD

a leakdown and compression test would get you data on the rings...
EDIT: you will need to look past the valves for leakage. Meaning, if you discover significant exhaust valve leakage you want to check carefully for what might be "hiding" behind it and check for leakage past the rings on that cylinder.

If you R&R the heads yourself you will need the proper timing tools OR you can convert to the earlier timing method... long story there, check Mike J.'s DIY Engine Rebuild for more.

ReinerFink

For starters, you'll want to have access to most of what is on page 1 of this pdf:

http://www.baumtools.com/pdf/porsche_timing_tools.pdf

I would add good rod bearings to the "stuff to do list". There are a few things you can do with the heads (aasco springs and ti retainers, bigger valves, etc) beyond the guides getting replaced.

The slippery slope starts out gradual and then becomes a cliff somewhere around "9m heads and 3.8L pistons and cylinders" :-)

-reiner

JimPA

My car is in the middle of the same process @81K, but it's not a D-I-Y. It had the wire and solvent cure for an SAI check engine light done about 18 months ago. Recently, oil leakage has become more noticeable. I stopped by the shop to look things over after the head was off. There were completely unexpected but visible signs of wear and surface hardening chipping on the cam lobes. So, new cams, rockers and lifters are now part of the deal. The indie shop says it's seen this before. Supposedly, the oil passages that supply this area are fairly small and may sometimes clog. I hadn't noticed any engine performance issues.

Stealth 993

If you got the $$ great time for a 3.8 pistons & cylinders!!

On a well taken care of car, you should not really need any other work with the miles.

Analog Theory

The 3.8 upgrade is a waste of $$. Make certain you outsource the heads to a reputable Porsche engine specialist as that's absolutley critical to know it's done right with the right replacement valve guides. I just completed a full motor rebuild and by far the best money I spent was on the Rennsport ECU. It's the right time (fresh top end) if you have the $1k in the budget and I can't overstate the improvement in the driveability and general responsiveness of the car.

Stealth 993

Why do you say that? more torque, more HP, really the parts are not that much $$.

Analog Theory

What?? For starters a new top end doesn't mean new P&C's, etc..(in most cases). If you did need it though and were you to go for the factory 3.8 kit (for which the set contains pistons and cylinders, o-rings, cylinder heads, intake valves , exhaust valves, camshafts, intake connections, sealing rings, intake manifolds, control unit, mufflers, resistor, pulley and wheel hub) not including $1 in labor to install is $16K USD and change (as of today from Carnewal).

Good value for the $$? You decide but for me....no way. Assuming your top end doesn't require even the standard 3.6 replacement parts above I'd take those potential 3.8 upgrade $$$ (half of it) and re-gear the transmission with a proper LSD. Money way better spent according to every Porsche tech I know.

There is middle ground though. Rennsport's Steve Wiener has acheived nearly the same output from a properly built 3.6 (309bhp). from adding RS Cams, intake, ECU and some other related engine building techniques/upgrades for waaay less $$$. I would say however that this is not a DIY.

Stealth 993

I was talking more just the pistons & cylinder kits that are just under $4k. If you have a tired engine, it doesn't seam like that much more work, while you are getting your heads fixed VS. doing it a year or 2 after you do the heads.

Yes, the whole kit is a ton of $$ for not to much more output.

Analog Theory

The cost of the P's & C's alone are just a small part of the total upgrade parts and labor requirements needed to complete the full upgrade...that's the rub.

Stealth 993

Oh, my shop told me there is hardly any extra labor for doing it with rebuilding the heads. Much cheaper then doing to later, same with doing things like the clutch.

mstolo

Thanks for the input guys. Mark D., thanks for the tips on the leakdown and compression test.

I'm definitely going to have the heads professionally redone, I just need to find someone to do it. Any suggestions would be great...not sure I want to ship the heads, would prefer someone locally in Atlanta.

You guys sure know how to talk someone to the edge of the slippery slope! I'm hoping to get in and out of the engine quickly, and hopefully limiting it to the top-end and the other refresh items on the typical rebuild list.

ReinerFink

Doing new pistons and cylinders would not really make the top end rebuild any harder. In fact, there should be one fewer thing for the machine shop to clean.

The $15k RS package is really only for the deep of pockebook. All you need are stock heads with bigger valves and RS cams to get most of the hp gain (I think this was someones point above).

I'll list my own "while you are in there" list:

RS cams (webcamshafts can reprofile your stock ones)
Steve Weiner doing headwork with bigger valves that flow better than the RS ones
Aasco springs w/ ti retainers
New ECU programming (needed for above mods)
Smartracing rod bearings
ARP rod bolts
rc engineering injector cleaning

That list alone is going to push the parts / machnining costs of the rebuild toward $9-$10k.

-reiner

race911

100K P&C set is likely to last as long as the freshened top end will if it's in good shape now. For a street car. 3.8? That much for less than a 5% displacement increase? Glad the previous owner of the yellow car built it that way, but it's the smallest piece of the performance puzzle on that car. Only for a car being used in timed, competitive events built to a set of rules would it be worth it.

Mike J

I went through this (check out my engine rebuilding articles :http://www.pcarworkshop.com/index.ph...out_the_series) and decided the 3.8 upgrade was very poor "bang for the buck", so I rebuild the top end, changed the cam timing slightly, and went with that.

In my case, i had 123,993 Km on the engine (no kidding), and the bottom end was in very good shape. I split the case since my labor is free, but it was not worth it. I would take out the rods and put ARP rod bolts in, possibly re-ring, valve job and button it all up.

Cheers,

Mike