turboted

I'm new to Rennlist...this is my first post. I could use some helpful advice...

I have an '86 951 with 87K. I bought it a year ago w/ the following upgrades already installed: Autothority MAF and chips, Tial wastegate, BOV, boost controller, and a BB exhaust. I have driven at 18 PSI for the past year with no problems. I'm in the process of replacing the rack, the oil pan gasket, and rod bearings (I have no reason to suspect rod bearings are bad, this is just a convenient time to replace them). Durring diassebmly, I noticed a small coolant leak which I thought was a leaky hose under the intake manifold. Turns out............I also have a blown head gasket. Grrrrrreat!!!

Here's my dilemna...do I pull the whole motor to do a full refresh or just replace the blown head gasket? Considering how far I already have it torn apart (and considering the motor is leaking oil from both top and bottom) maybe this is the best time for a total rebuild. How hard is it to remove and reinstall the whole motor vs. rebuilding/replacing the head?

I don't plan to add more power/boost right now...but I want the option to do so in the future. Hence - I want a stronger head gasket. Suggestions? I've heard some guys use Cometic MLS, some guys like WideFire, and some use factory-replacement gaskets. Which is best? Right now, I am planning to retain the factory studs...but I'm poorly educated about whether or not I should upgrade studs when I upgrade the gasket? Again, it's not my intention to build a 500hp monster right now - but I would like to create options for myself in the future.

Thanks in advance for your advice/comments...

fast951

Welcome to the RennList.

Since you are planning a rod bearings replace & now you need a headgasket, you will be better off removing the engine, reaseal it properly, examine the clutch..... Replace all suspect components, much easier while the engine is out. Refresh the head while apart.

For your goals, stock studs are fine. However running 18psi on pump gas with APE chips is not wise.

toddk911

Depends on your budget and time. If you can handle full rebuild I would do it. If not, then stick with stocks studs/HG other wise on rebuild down the road, you will probably go with new stuff anyway and would have wasted the money on that stuff now.

I think you are the 3rd or 4th guy on the list now that has blown headgasket getting addressed in this month alone....myself included.

KuHL 951

John's suggestion is a good one. It is much easier to do a thorough refresh and reseal with the motor on a stand. The benefit is you can get the cleanlinest and access you need for critical areas like oil pan, balance shaft covers, camseals. If you are doing a rod bearing refresh anyway I would pull the motor and install new motor mounts while it's easy. I'm still trying to figure out if I'm going to final torque on the head after the installation. That 2nd round of 90 deg. torque angle is tough to do on a typical rolling pedestal stand like I have.

87944turbo

Welcome to Rennlist!

Well I think it really comes down to how much time, effort, and $ you want/need to put into it. When you say "total" rebuild I assume you talking about pulling pistons and having your bores refinished, new mains, rings, etc.

If I were you, I would pull the head with the engine in the car and take a look at the condition of the bores. IMHO, you mileage is still relatively low and your bores should be in good shape. However, your HG failed for some reason, lets just hope that it was due to age and not something else. If your bores look good, I would change your HG and any necessary seals and button it back up. If your bores are in bad shape, the engine is of course going to have to come out.

Also, I think most would agree that 18psi is much too high for APE chips. This could have caused your HG problem.

turboted

By total rebuild, I mean piston rings, cylinder walls, new mains, etc. - the whole nine yards. If I pull the motor, I might as well do it all and do it right. Obviously, I need to consider the total cost, too. How much additional $$ will it cost me for a total rebuild vs. a head refresh and gasket replacement?

Why is 18psi too much boost for the APE chips? I have plenty of fuel left (rich) according to my dyno charts. What is a safe boost level for APE chips? To continue running at 18psi, what chips should I use (assuming A/F is ok).

This is somewhat new territory for me...as I'm more familar with N/A engines in practice. I'm compentent with turbocharged motorsin theory/concept, but have never torn one apart.

TRP951

I dont think its the fuel of the APE chips but rather the timing although I know when I had APE chips you could see the exhaust smoking from excess fuel coming out

turboted

CORRECTION - I have drive the car at 16 psi for the past year. Not 18 psi.

Is 16 psi too much for the APE software?

87944turbo

A head refresh by a good shop seems to be in the $300-400 range. That was about what it cost me last year. Of course that price will go up significantly if you decide/need to replace valves, springs, retainers etc. For that price I would expect complete disassembly, re-ground seats, seals, decked if needed, guide clearance check, clean, reassembly, etc. Head gaskets should be around $50 stock up to $150 I think for CLS. Kits are available which help to reduce the cost of buying all the individual parts, like this one from Paragon for example (Head Gasket Kit).

For a complete engine rebuild, I think most vendors are in the $4-5K range. If you are doing all the work yourself, which it sounds like you would be, I would say $2-3K or so. Of course used engines are an option depending on what your plans are for the car. I am in the process of doing one myself, but I don't have exact figures since I am not done yet. Figure another $700 or so if your going to do the clutch which makes alot of sense while the engine is out as others have said.

Hopefully John will answer your question about the APE chips.

87944turbo

Part of what makes engine rebuilds for these cars expensive is the Alusil blocks. Your basic options, if you need to resize your bores are Oversize pistons, Nikasil, dry sleeving, wet sleeving. The first three options are at least $1-1.5K, the fourth probably $2K or more.

toddk911

Then, you will start asking yourself: "well, maybe I should just do 2.8/3.0L conversion with it".

pozican

My head gasket also blew
Got the head resurfaced and pressure tested for $90
Got the gaskets from a local '44 guy.
I think I was out a total including pizza, pepsi and random tools I didn't have but needed, ~$200

Ignorance follows this line
What are APE chips?

toddk911

Autothority

turboted

Exactly. Do I go for the quick fix ($200) or go-for-broke with a nasty rebuild ($4k = 400hp)? It's a tough decision, really. Hmmmmmmm.............

pozican

Thanks -- No worries then, I'm running 951MAX