3S-GTE Boost Control Modification
Date: Wed, 22 Jan 1997 19:28:40 +0000
From: mshields mshields@pacbell.net
Subject: 3S-GTE boost control modification per Team Toyota Europe
I was cruising the net and came accross your page. I thought I would
share some trivia with you. In 88 I bought a Ceilica GT4 (alltrac in US,
model ST165) which used the same 3S-GTE motor. What follows will apply
to any 3S-GTE motor. And by the way, I can not spell in English very
well.
I friend of mine was working for Toyota Team Europe at the time. This
was run by Ove Anderson in Köln, Germany. It was made of ex-AUDI
mechanics and they made the works Toyota WRC cars. The company has since
been sold to Toyota.) They came up with a very simple boost modification
for the cars to go to something like 12.5 psi. As you know many kids try
to go to 16psi and beyond, but this article is a practicle route to
240-250 bhp on pump gas. The modification was used on the limited series
Carlos Sainz GT-FOUR (ST185)sold in Europe.
I drove 90,000 miles with this setup. It is good for any 3S-GTE series
motor, even though the late cars had air/air intercoolers, higher
compression and a a revised ECU box.
1. Remove the turbo VSV (vacume control valve) and bore it out to 4.5mm.
This will increase the boost to 12.5~13 psi.( Remember! The area goes up
with the square of the radius - do not get lazy and use a 5mm drill bit,
you will be way off the mark.) Re-install. It is located under the
intake manifold. On a GT4 it is the hardest job I have ever done to
remove it and reinstall with the engine in the car. (I wonder why they
put it there?)
2. Open up the CPU and solder a 4.3v ziener diode to the PIM sensor pin
on the bottom side of the system board to the ground screw. This is the
fourth pin on the bottom row with the AMP wiring loom connectors facing
your belly and the ground is the phillips screw below and to the right
of the long dual row of data input pins. The band of the diode goes
toward the PIM pin (Important). This will bleed voltage to ground and
raise the fuel delivery cutoff pressure to 14 psi.
So for seventy-five cents you get about 230 bhp from 190. With an big
exhaust the TTE cars were seeing about 245bhp, with a big boost in
overall torque as well (You buy horsepower, but you drive torque). I do
not think the midrange was helped all that much by the exhaust system.
The Toyota ECU will retard the timing if the motor starts to ding. You
will see a rapid rise in coolant temp if running hard under this
condition. Either get better gas or turn down the boost a bit. Older
motors with any carbon buildup will be touchy in this regard. Also, the
stock ECU runs fat up top, so this is not a true high performance
solution, rather it is a solid midrage improvement.
So, for those who do not want to buy trick gas all the time, it is a
very effective solution. I had also installed a adjustable control valve
on the VSV solinoid and caped the return nipple on the intake manifold.
I could turn the boost up by bleeding VSV air to atmosphere and the
waste gate would not open so far. Also I used a Porsche 944T compressor
by-pass valve on the GT-Four much like the stock one on the MR2.
Hope this is interesting for your group.
FYI, I now drive a Subaru WRX-RA, in every way a superior car. It weighs
2600 lbs wet, puts out 240hp on 94 RON and 280hp on 100 RON through a
close ratio gearbox and runs 235/40-17's on all four corners. I use a
Recaro seat, Speedline wheels and the PRODRIVE Bilstein/Eibach kit, but
everything else is stock, right down to the wind-up windows!
Have FUN!
Mike Shields
Date: Tue, 18 Feb 1997 23:03:23 -0500
From: Simon Tremblay (tremblsi@ift.ulaval.ca)
Subject: Boost controler
I write you about certain modifications articles that I found on the
site.
First about the boost controler by Team Toyota Europe, I think that a
resistor must be installed between the zener resistor and the ground pin
to prevent the diode from delivering infinite current to the ground (
short circuit ) I didn't had the time to find the exact specification of
the resistor that should be installed but I think that this mod should
really work if done properly ( with the resistor ).
Simon Tremblay
tremblsi@ift.ulaval.ca