Bolt-on Upgrades

Every bit of information we have about the Honda City compiled by our members!
User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:53 am

Bolt-on Upgrades for your Honda City Turbo

All of the following info was written by Glenn (aka BOOSTBOY) even though it has been posted by Brendan.

Introduction

In standard form, the Honda City Turbo is a car that can hold it's own against most of the eras four cylinder 'performance cars'. From the factory, the Turbo II was able to sprint across the 400m (¼ mile) mark in a respectable 16.2 seconds. As a comparison, here are some 400m times of some 'hot hatches' of the era:

Suzuki Swift GTi 16.6
Nissan Pulsar ET Turbo 16.7
Mitsubishi Cordia Turbo 16.9
Honda City Turbo II 16.2

So, the little Honda had the guts to waste some of it's more favourable opposition but today a 16.2 quarter mile isn't quite up to scratch. Luckily, because of the Honda's low weight, relatively low power output is required to lower the standing 400m time into the much more competitive 14 second zone. Here's how to do it!

User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:54 am

Exhaust

First modification on the Honda City Turbo, or any other turbo car for that matter, should be an upgraded exhaust. The standard issue 1.5" drinking straw won't help your power output, nor will the standard and very restrictive catalytic converter. If your Honda was built before 1986 it legally does not require the use of a catalytic converter for use in Australia but to be sure, check with the authorities in your state.

The most important part of any turbo car's exhaust system is the dump pipe, directly from the turbo. It is at this point that the exhaust gasses are at their hottest and are flowing at the highest velocities so any restriction here is going to cost power. There are two ways to go in regard to dump pipe design, either a large single dump or a twin dump design that separates the wastegate gasses from the turbine, reducing flow turbulence at full boost. Both designs work well, but if you are on a budget the single large pipe from the turbo is going to be most cost effective. One plus for the twin dump is that you have the option of creating what's called a 'screamer' pipe which dumps raw wastegate gasses straight to the ground, giving a very loud scream upon full boost. This has been said to be the ultimate set-up due to the wastegate gasses never re-entering the main exhaust system and causing flow-hindering turbulence. After the dump, a simple 2.5in press bent exhaust with a simple straight though design muffler is very effective in regard to both performance and cost. It should also be noted that a properly breathing City Turbo has a very nice exhaust note, similar to the 'throbby' Subaru WRX.


User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:54 am

Intake

It's all well and good getting the gasses out of the engine quickly but if you can't let it breath efficiently you are going to loose power. A simple way to obtain more intake flow is to replace the standard air filter element with a higher flowing version such as a K&N. For even more flow however, you are going to have to go custom. The inlet of the standard IHI RHB51 turbo is rather small so you will have to get an exducer made to go from the inlet of the turbo to a pipe diameter of at least 2". From here you can run a new pipe to a place in your engine bay that you have enough room for a pod style filter. Without removing the battery, the best place is over the other side of the engine bay behind the air conditioner pump.

This also leaves enough room for your intercooler plumbing, which will be described later. Leaving a pod filter to breath hot, turbo heated engine bay air is not a good idea though. A simple way to fix this problem is to set up a cold air feed. This can be made from PVC piping and bends. A good air pick up is from the front grille; the pipe can then run over the air conditioner pump and up to the filter. Another good modification is to place a bonnet vent above the filer as this allows the heated air to escape the engine bay from around the filter area.


User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:54 am

Boost

With the breathing modifications out of the way, the next modification is to raise the boost level. In standard form, the City Turbo should be running around 10-12psi. With the breathing modifications completed you could be running 13-14psi and possibly hitting the standard fuel cut out of the computer. To avoid this, you are going to have to install a boost cut lifter. With the boost cut out of the way, you are going to have to install some kind of boost controller. There are many different types on the market, either electronic or pneumatic but they all achieve the same result. Again, we may have a dual stage boost controller kit available soon, designed especially for the City Turbo.

With the standard fuel system, you should be able to safely run 1bar (~15psi) boost with a limit of 17psi at which point fuel lean out will occur. To be safe, I recommend sticking at a 15psi limit, enough to run a 14 second quarter mile.


User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:56 am

Intercooler

The Honda City Turbo 1 was produced without the benefit of an intercooler. The City Turbo II was not much better, it's intercooler was virtually an 'interheater' as it was very small and was exposed to very little airflow. Either model is going to need an upgrade to safely run any level of boost higher than standard.

The biggest problem with installing an intercooler is the tight confines of the engine bay and front bumper region. There are two ways of installing the actual intercooler. You can either cut a big hole out front and install a Japanese import style 'cooler (click here for example) or use a long narrow custom core (click here for example). The first method is probably the cheapest but won't look as neat as the second method. Either way, the piping is going to be similar. From the turbo outlet, you are again going to need an exducer to change from the size of the turbo to the size of the 'cooler pipes (about 2").

From here, the pipe goes up and over the top of the rocker cover and down behind the radiator support panel, which will need a small modification to allow clearance. The pipe then will join to whatever intercooler you are using and start to snake its way back into the engine bay, under the battery and back up near the rear of the firewall, at the plenum chamber. Standard, the plenum has an entrance size of about 1.5", too small for the intercooler pipe. You can either get an inducer made or modify the plenum inlet. Using an inducer isn't the most efficient way to go about it and will certainly cost you power.

There are also several ways to modify the plenum. You can get an aluminium fabricator to enlarge the entrance to 2" of make a new, top mounted entrance (click here for example). Making a new top mounted entrance requires some machining but doesn't require aluminium welding, which can be quite expensive. Note that the plenum design is different on the turbo I & II. The turbo I design allows you to change to a top entrance but on the turbo II, you are restricted to an enlarged original position entrance, or a completely custom design.

With the intercooler system in place you may need to look at boost levels again as it is not uncommon to get a 3-4psi pressure drop across the core.


User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:57 am

Timing

Due to Honda's CVCC system, the City turbo is able to run substantial amounts of ignition advance for a turbo car without problems with detonation. Because of this, it is not uncommon for the ignition timing to be severely retarded by a mechanic, causing poor performance and general engine running. Your timing should be static at 28 +/- 2 degrees BTDC.

If you get any sign of detonation, pull off one of the vacuum advance hoses from the distributor and suck on it. If you can suck air through it then the diaphragm inside has perished and will need replacing.

Also see How Do I Set My Cam and/or Ignition Timing?

User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:58 am

Fuel

Remember to always use premium unleaded fuel as a very minimum, especially once boost levels have been changed. It would be preferable on a modified car to run 98 octane unleaded such as BP Ultimate, Shell Optimax or Mobil Synergy.

User avatar
Brendan
Admin
Posts: 603
Joined: Wed Mar 27, 2002 4:00 am
Location: Brisbane, Australia
Contact:

Re: Bolt-on Upgrades

Postby Brendan » Sun Jan 11, 2004 10:58 am

Results

With these relatively minor modifications, you should be able to pull a quarter mile time in the high 14-second bracket. A time like this will have you going from 0-100kmh in the mid to high 6s region. Compare this to some of today's 'hot hatches' and it is very, very competitive!

Note: Any more modifications than this will require an upgraded clutch, which may already be suffering at this power level.


Return to “The Honda City InfoBase”

Who is online

Users browsing this forum: No registered users and 24 guests