Forced Induction Systems
Last updated:
27 August, 2002
Welcome to the *charger section of the Miata Tips From the
Garage. There seems to be quite a lack of hard data on all the various super
and turbocharger systems for the Miata. This page will attempt to collect as
much information on the various products into one convenient location as possible.
It is very incomplete at this time though, so I will really appreciate any input
on any of the systems. If you have direct experience with any of these products
and have any information to add to what is here, please let me know!!
Disclaimer: I have not installed any of these systems (yet).
That's probably good: even though it means I have no direct experience with
any of these kits, it also means I have no preference towards "my system",
as I don't own any of them. All the info is gathered from the Miata mailing
list, various magazines, and advertisements (and hopefully from all you *charger
owners who will now rush to send me more info ;-). Wherever possible, I've noted
the source of the various claims. Note that sometimes there are more than one
conflicting values from different sources!
Introduction
Both a supercharger and a turbocharger perform the same
function - push much more air into the intake. A supercharger is driven by a
belt off the crankshaft pulley, while a turbo is driven by exhaust gas pressure.
Some selection criteria for forced induction systems (based
on article by Corky Bell in GRM)
- Margin of safety: How does kit avoid detonation?
- Air/Fuel mixture: How does kit maintain correct mixture?
- Intake air temperature increase: Any forced induction
system will increase intake air temperature. The system that increases temp
the least has highest thermal efficiency. Ranking of technologies (Best->Worst):
Turbo, Lysholm screw SC, Centrifugal SC, Roots.
- Intake air cooling: If system has intercooler, this will
reduce intake air temp, thus less tendency to detonate, and more air mass
per volume (thus more power, assuming proper fuel ratio maintained). Application
with very low max boost don't need intercooling since the pressure increase
is not large, thus the temp increase isn't either.
- Boost curve: Where is boost produced, peaky vs. early
or broad. Ranking: Lysholm screw-type SC, vain-style turbo, Roots, classic
turbo(?), Centrifugal SC last.
- Lag: How much time between gas pedal application and
noticeable boost. THis is significant at low rpms. Ranking: Lysholm screw-type
SC, vain-style turbo, Roots, classic turbo(?). Centrifugal SC has very little
boost below 3K.
- Power: Ability to flow air at high thermal efficiency
with least power losses to drive unit. Ranking: Turbo, Centrifugal SC, Lysholm,
Roots.
Some generic notes on Miata installations
- How will the driveline stand up? -- The weak point seems
to be the clutch, which will need replacement with a higher performance unit
sometime after the installation of a turbo/supercharger kit. Reportedly, the
1.6L cars' clutch is sturdier and will last for some time with a turbo/supercharged
car, whereas the 1.8L cars' clutch will require attention soon afterwards.
- Some dyno figures for non-*charged Miatas for comparison
(all numers are rear wheel horsepower as reported on the dyno).
![[Superchargers]](super.gif)
3 basic styles: roots, centrifugal, twin-screw
- Roots: positive displacemente units, which means every
rev of the blower pumps out a fixed volume of air, regardless of the blower's
rpm. Result is that boost comes on early. Most application produce full boost
at 2000-2500rpm. Boost can be altered by changing pulley size. Best to underdrive
larger unit than to overdrive smaller one. Manufacturers include B&M,
Littlefield, Sebring.
- Centrifugal: Most popular type for fuel injected engines.
Provides airflow proportional to blower rpm, thus full boost comes as high
rpm. Manufacturers include Accessible Technologies, B&M, Nelson, Paxton,
Vortech.
- Twin-screw: positive displacement, similar to roots.
differences: uses twin screws instead of lobed rotos to compress air, works
best when overdriven. Sample manufacturer: Whipple Industries.
Bell Engineering - BEGI Supercharger
- General description:
- Type: Autorotor Lysholm twin-screw
- Intercooled: Yes
- Misc Info: Significant boost at very low rpm. Lysholm
provides volumetric efficiency, reduced drive power requirement, and lowered
discharge temperatures compared to other superchargers.
- Boost: 8psi
- HP at wheels (from dyno measurements): 155-160 [1]; 167hp
(1.8L) [2];
- Kit Includes: MSD ignition retard module, high flow/pressure
fuel pump, boost gauge
- Street Legal: CARB EO pending?
- Availability: for all year Miatas
- Installation Notes: 6-10hrs
- Approximate Price: $2695 1.6L ; $2995 1.8L
- Testimonials:
[1] Dyno testing, SGOODE@ccvax.fullerton.edu (email
address no longer valid.) [2] Dyno results, Brian Goodwin
Sebring Supercharger
- General description:
- Type: Roots
- Intercooled: No
- Misc Info: Self contained lubrication.
- Boost: ~6psi
- HP at wheels (from dyno measurements): 152hp
[1]; 130-135 [2]; 139.3hp, 123.6 lb-ft (1.8L) [3]; 147hp (1.8L) [4]; 158hp
(1.8L) [5]; 137hp (1.6L) [6];
- Kit Includes: boost-dependent fuel pressure
regulator
- Street Legal: 50 state (EPA EO #D-341)
- Availability: All years.
- Installation Notes: 4-6hrs; 3hrs
- Approximate Price: $2395
- Testimonials:
[1] GRM testing MCA 1.6L car. With JR header, Genie
turbo muffler, NACA duct. [2] Dyno testing, SGOODE@ccvax.fullerton.edu [3] Dyno
testing on 1.8L car with JR header and Borla exhaust, Jim Rich. [4] Dyno results
reported by Brian Goodwin [5] On a 95 with J&S knock sensor, JR header,
cat & catback, on the JR dyno. [6] Reported by Bob Krueger, on a 1.6L on
the JR dyno.
Nelson Supercharger
- General description:
- Type: Centrifugal Paxton Supercharger
- Intercooled: No
- Misc Info: Self contained lubrication. Reportedly
very noisy.
- Boost: 6-8psi
- HP at wheels (from dyno measurements):
- Performance:
- Kit Includes: variable fuel pressure regulator
& ignition retarder
- Street Legal: 50 state
- Availability: For 90-93 Miatas.
- Installation Notes: 12 hours
- Approximate Price:
- Testimonials:
![[Turbochargers]](turbo.gif)
Bell Engineering Aerodyne Turbo
Stage I
- General description: This is the low-end Aerodyne
Turbo. Its principal characteristic is that it lacks an intercooler, which
explains the lower price. [Does this kit still exist?]
- Type:
- Intercooled: No
- Misc Info: Intake air temp @80F ambient: 151F
- Boost: 6psi@2Krpm, 6psi@3Krpm
- HP at wheels (from dyno measurements):
- Performance: 0-60 6.1s
- Kit Includes:
- Street Legal: EPA pending
- Availability:
- Installation Notes:
- Approximate Price: $2195
- Testimonials:
Aerodyne/Aerocharger
- General description: This is the "regular"
Aerodyne kit. It expands the Stage I kit by adding an Intercooler, allowing
higher boost and reliability. Also known as the "Aerocharger".
- Type: Variable vane turbo
- Intercooled: Yes
- Misc Info: Intake air temp @80F ambient: 96F
- Boost: 7.5-8psi @ 2.2Krpm
- HP at wheels (from dyno measurements): 155-160
[1];
- Kit Includes:
- Street Legal: Yes. EO #D-349.
- Availability:
- Installation Notes:
- Approximate Price: $3495
- Testimonials:
[1] Dyno testing, SGOODE@ccvax.fullerton.edu
System III
- General description: This is the most powerful
Bell unit. It is based on the original Cartech turbo kit.
- Type: Warner-Ishsi RHB5 turbocharger.
- Intercooled: Yes
- Misc Info:
- Boost: 10psi; 8psi@3700rpm.
- HP at wheels (from dyno measurements):
- Performance: 0-60: 5.2s;
- Kit Includes: MSD boost controller.
- Street Legal: Yes. EO #D-349.
- Availability:
- Installation Notes: Does not fit 1.8L engine.
- Approximate Price: $3295
- Testimonials:
BBR Turbo
- General description:
- Type:
- Intercooled:
- Misc Info: Kit is Mazda warranted in England.
- Boost: 5.5psi
- HP at wheels (from dyno measurements):
- Performance:
- Kit Includes:
- Street Legal: 50 state
- Availability:
- Installation Notes:
- Approximate Price:
- Testimonials:
Greddy Turbo
- General description:
- Type: TD04H turbo
- Intercooled: No
- Misc Info:
- Boost: 7psi
- HP at wheels (from dyno measurements): 130hp
[1];
- Performance:
- Kit Includes:
- Street Legal: pending??
- Availability:
- Installation Notes: Easy on 1.6L, some extra
work on 1.8L
- Approximate Price: $1500
- Testimonials:
- None! Please contribute some experiences.
[1] Norman Garret, @5psi
Here's the Answers!
All right, all right... actually you won't
find the answers here. That's because there actually is no One True Answer on
this issue, and that's probably the only "true answer" to keep in
mind. As on everything else in life, there is a range of solutions, none of
which can be perfect, so they each implement their own unique set of compromises.
Which one is the right answer depends on which set of compromises you decide
to live with and which you won't.
This section collects some postings that have been
made to the Miata mailing list that I found interesting and informative.
Tech Tips
One constant with all the units is that some extent
of tuning and experimenting will usually be required to get it just right. This
section is intended to collect troubleshooting experiences from owners who have
been through it.
References
- Grassroots
Motorsports 3/95, 7/94, 9/96
- Turbo Magazine 1/95, 9/95
- Sebring Supercharger advertisements/web site
- Bell Aerodyne advertisement/web site
- The Miata mailing list
Addresses/Phone numbers
- Bell Engineering Group, Inc.
- Downing/Atlanta
- Nelson
- PFS (Peter Farrel Supercars)
- The Dealer Alternative
- 541 S. Main Street / Box 308 / Palisade,
CO 81526
- Voice: 1-970-464-0878 / FAX: 1-970-464-0264
- http://www.dlralt.com/
- Refer to the Vendor directory
for a more complete list.
Pointers to miscelaneous items of interest...
- Jackson Racing Cold Air Induction
This section is maintained by
jyri@intac.com