Re: [Amc-list] The 'Turbo' Life Cycle (196 turbo?)

[Frank Swygert <farna@xxxxxxx>]

The head gasket isn't the problem, something to do with head bolt stretch and/or thermal expansion/contraction. At least that's what I think. I've never blown a head gasket except when the head wasn't torqued down correctly. TSM says to check it ever 5K miles, I always retorqued every 12-15K and never had a problem. So I don't think 4-10 psi would be a problem -- might want to check torque more often than 15K miles...

The stock head pipe is 1.75". A 2" pipe will fit right onto the 1.75" pipe. 1.75" pipe (or a metric pipe that's basically the same) is still available, but hard to come by at a custom exhaust shop. Keeping the smaller pipe BEFORE the turbo is the idea, as large a pipe as you can stand after the turbo to reduce back pressure on the turbine blades. 

As Brien explained, the turbo doesn't come in until 2K or so, so there is no turbo lag. The tubing all starts to pressurize as you're coming up on the "kick in" point. That's another con of a rear mount turbo -- it doesn't come in as quick as a manifold mounted one. If you want power for a drag car wrap long tube headers then cut the rear floors out for turbo space. There would only be about 18" of pipe between the header collector and turbo, wrap that too! Then you wouldn't be losing much power potential. 

The bottom line is rear mount has a couple drawbacks, but it's still harnessing power that is going 100% out the tail pipe on a non-turbo car. Just harnessing 20% of that power is still better than letting 100% go to waste. The installation is 30-50% cheaper and much faster than a conventional manifold mount, and the average shade-tree mechanic can install it in a weekend easily. There are plenty junkyard small turbos out there that are to small for conventional mount on larger engines, but perfect for rear mount on the same. Not as much increase, but an increase nonetheless. 



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Date: Wed, 19 Dec 2007 18:20:17 +0000
From: Wrambler242@xxxxxxxxxxx

Couple thoughts hit me real quick.
196's don't have the most stable head gaskets as-is, so are we talking O-rings and or possibly copper gaskets to get even 5 lbs of boost to work?
Second thought is, would you even want to increase the pipe size to the turbo? Would not the stock 1 3/4" pipe keep the velocity up better? This also saves on costs.

-- 
Frank Swygert
Publisher, "American Motors Cars" 
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