book about tune of Bosch Jetronic

[dooley]

How did you conclude I was trashing the entire book?
Did I say the theory section was garbage?
What would you recommend I read more carefully?

I have read this book (and the Probst book) and understand very well how the
CIS systems work.  I have owned over 20 VAG products and successfully
turbocharged from scratch with CIS fueling. 

Whether bell housing bolts or transmission bolts were broken is irrelevant.

A throttle body mod adds a marginal power increase and can be verified with
a seat of pants ride, no dyno needed.  
I have built turbo VW motors with twice the stock HP, installed in
transverse mounted VW's with stock motor mounts and never broken a tranny
mount bolt.
The mere suggestion that a tbody mod would induce fastener shearing torque
in any driveline configuration is ludicrous and has no place in reference
material.

That is my point.  
Now I am off to go reading, understanding, and writing more carefully.


-----Original Message-----
From: quattro-bounces+pdooley=gte.net at audifans.com
[mailto:quattro-bounces+pdooley=gte.net at audifans.com] On Behalf Of E. Roy
Wendell IV
Sent: Thursday, September 22, 2005 10:23 AM
To: quattro at audifans.com
Subject: RE: book about tune of Bosch Jetronic

> From: "dooley" <pdooley at gte.net>
> Subject: RE: book about tune of Bosch Jetronic
> To: <quattro at audifans.com>
> Message-ID: <0IN700GDK1ML4MJ1 at vms046.mailsrvcs.net>
> Content-Type: text/plain; charset=us-ascii
>
> Look in the performance section in the back of that book-
> I think it specifies a big bore throttle body as a great power 
> booster, even
> says an enthusiast installed one and broke all his bell housing bolts 
> due to
> power increase.
> Funny reading those books, I guess they were written in late 80's.  
> Another
> popular VW performance book discusses the problems using turbos due to 
> their
> peaky adiabatic efficiency under a certain curve..
>
> Makes me laugh every time I read that crap..

Go ahead, have a good laugh if it makes you feel better. Your time 
would be better spent reading, understanding, and writing more 
carefully. You are trashing a whole book because of three pages of 
material (the Performance Modification chapter) which essentially says 
don't mess with anything you don't need to. Point taken that the 
performance modification section of the book is light to say the least 
but I stand on my statement that it's a decent reference for stock 
stystems. The point that the author made is that most systems, 
especially the K-jetronic systems, have excess capacity to handle 
higher airflow rates. This has been proven again and again with the 
type 44 turbo systems where we up the boost via the QLCC or SJM chips 
and don't experience a lean out condition. I would point out that the 
author doesn't say that the addition of the big-bore throttle body 
broke the bell housing bolts, rather the transmission mounting bolts, 
which to me means the ones connecting the transmission to the body. 
Transverse engine cars as a whole are hard on the engine and 
transmission mounts and associated hardware due to the drive axle 
torque effects being applied to the engine and transmission combo 
rather than a separate final drive unit. Combine that with the normal 
FWD/worn shocks wheel hop and a throttle that reacts more like an 
on/off switch and less like a proportional device and he could very 
well have broken the mounting bolts. If it's the power increase 
attributed to said throttle body that you question then you may be 
right. The book was written before dynamometers were very common and 
therefore the "butt dyno" was all that was available. It wouldn't 
surprise me in the least if the author and customer noticed an apparent 
increase in power due to the larger throttle body. It may only have 
been a illusion due to the nonlinear response to pedal input with 
little change in ultimate power but if the car felt faster the customer 
was happy.

Roy Wendell
Morgantown WV, USA
turbo quattro type 44 times 3

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