<VV> Turbo / 140 heads?

Mon Mar 22 09:06:47 EDT 2010

Doesn't Warren run a big Q-Jet feeding the turbo on the Roe car ?

From: jvhroberts at aol.com [mailto:jvhroberts at aol.com] 
Sent: Monday, March 22, 2010 8:04 AM
To: therobbins82 at gmail.com; virtualvairs at corvair.org; whubbell at umich.edu
Subject: Re: <VV> Turbo / 140 heads?

Now you've done it!!

Anyway, in my own experience, 140 heads DO make a fair bit more punch than
the 95 heads ever will. The engine doesn't run out of breath at the top end,
while not sacrificing ANY bottom end whatsoever. And if you're using an
oversized carb, the difference is even more impressive. 

But don't do this without having the heads THOROUGHLY prepped to keep the
seats and guides in place. And deflashing is even more imperative. 

And a good turbo using stock parts is an early turbine with a late
compressor. <G>

John Roberts

-----Original Message-----
From: The Robbins <therobbins82 at gmail.com>
To: virtualvairs at corvair.org; whubbell at umich.edu
Sent: Mon, Mar 22, 2010 8:57 am
Subject: Re: <VV> Turbo / 140 heads?

Ys Bill, he said that Early Turbos are better than Later Turbos.  :-(

AH of BBRT

-----Original Message-----

From: virtualvairs-bounces at corvair.org

[mailto:virtualvairs-bounces at corvair.org
<mailto:virtualvairs-bounces at corvair.org?> ] On Behalf Of Tony Underwood

Sent: Sunday, March 21, 2010 11:45 PM

To: virtualvairs at corvair.org

Subject: Re: <VV> Turbo / 140 heads?

At 10:14 PM 3/21/2010, tconnolly wrote:

>I was wondering if there would be a performance gain to use 140 heads on a

>turbo engine.  Custom plumbing seems to be an easy fab job.  There must be

>reason for or against.  I would like to hear the pro & cons.

Pros:

More top end power but usually only top end.   For street use there's 

not that much difference between the stock turbo heads and the 140 

heads.   Really.    Unless you're racing there's actually not a lot 

of reason to do it.   The turbo makes up for a lot of that port size 

difference.

Cons:

Expect to spit out valve seats regularly if you stay on boost often, 

or unless you have deep seats installed.   The deep valve seat 

upgrade fixs that issue nicely... but it's not real cheap.   There 

will be a few plumbing issues as well but nothing insurmountable by 

any means.

End result:

A properly set up 140-head turbo engine can make serious power if 

pressed hard.   But, it takes knowledgeable prep to make it live and 

you can NOT run it to overheating on a constant basis.   It will wear 

out quickly.   Hell, a stock turbo engine will wear out quickly if 

you have your foot in it every time you leave the light.

My opinion:

Do not run 140 heads.   Use 95 hp heads with stock chambers.   Have 

someone who knows how, to clean up the exhaust ports, don't bother 

touching the intake ports because they're gonna flow plenty under 

boost.   Use GOOD exhaust valves in the 95 heads.  Do not skimp.   Go 

easy on valve springs... no battleship springs needed; you won't have 

to rev it over 6000 tops.    Use an early turbocharger which will 

spool up quicker than the later turbo or the aftermarket examples and 

still make enough top end boost to bust it if you don't watch 

it.   Use a respectable camshaft... try to find a '65 or '66 

turbo-only cam, or an Isky 280 cam available from vendors.   Yeah I 

know the venerable old Isky 280 is "obsolete" according to the 

computer generation but this is a turbo engine that doesn't have to 

bother with dual pattern lobes like naturally aspirated engines 

do.    A 280 cam in a late turbo engine with 95 hp heads done right 

is a vicious combo that will surprise the hell out of you.

Tweaked right, the combo can get you close to 250 hp at 5500 rpm and 

stay together doing it AS LONG AS YOU WATCH THE TEMP GAUGE.    Get a 

good quality aftermarket gauge.   DO NOT let the engine overheat 

while playing... and this combo will get hot quick when 

pressed.    Never use anything but premium grade fuel, do NOT run 

regular or midgrade.

You can NOT allow the engine to ping under boost.   You can't.   You 

just can't.   Pinging at high rpm under heavy boost can damage the 

engine in about 3 seconds.   Run high test always.  Always.   Hell, 

run race fuel if you can get it.   AvGas if you know somebody.   Now, 

in a pinch you can run regular if you drive like grandma but you can 

NOT push it into boost running regular unless you enjoy disassembly.

Use an aftermarket free flow muffler.   The factory turbo muffler is 

NOT that free flowing compared to modern hi-perf mufflers... and you 

want as little restriction in the exhaust as possible.   A chambered 

muffler (those ones you can see straight through) works nicely if you 

can stand the noise which might not be as bad as you may think... 

turbo will muffle a fair bit of noise by itself.   Remember, big 

inlet, big outlet, lowest possible restriction.

...you may need to play around with ignition curves...  you will NOT 

need to run 24 degrees initial advance with the 95 heads.   That 24 

degree advance figure was because of the MISERABLE bathtub chambers 

that afflict the turbo heads from the factory... to this day I wonder 

why GM didn't use the 95 head chambers instead of those bowls the 

factory 180hp heads used.

Forged pistons are gonna be necessary if you find that it gets good 

to you when the boost gauge walks to the right of center... and once 

it happens that first time you're gonna be doing it often.   Do not 

skimp on the hardware.   Make it out of guns, not butter.

Now-   this is all just me, how I'd do it.   Others with more bigger 

smarts and $ may have differing opinions.

tony..    

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