I have read Julian Edgar's excellent theories on intercoolers and am hopeful
that he can offer a bit of his expertise about my double-pass intercooler...
In basic terms the first
(hotter) pass is through 7 cores and, after the U-turn at the other end, the
second (cooler) return pass is only through 6 cores. I have a difference
of opinion between two engineering friends that I hope that Julian can help
decide. My first friend says that the construction is wrong and both cores
should be either 6 or 7 cores.
My second friend's theory is more interesting. Apparently this construction
is deliberate as after passing through the first (hotter) core with 7 tubes, the
air volume is decreased after cooling by about 15% and the construction of only
6 tubes in the second (cooler) core is deliberate to compensate for this
reduction in air volume.
I hope that the second friend’s theory is correct - the intercooler was
constructed by Radtec, a reputable UK intercooler
If you should need to know, the car is an MG Maestro with a 2-litre 16-valve
turbo engine from a Rover 620ti. It is boosted to 13 psi. Intercooler core
size in total is 600mm x 295mm x 40mm. Thanks in advance for help with this head-scratcher.
The only way to find out
for certain is to do some testing of pressure and charge-air temperature drops
across the core. No theory beats real-world testing.
3S-GTE Wrong Way ‘Round?
I'm surprised that a rear-wheel-drive
Toyota 3S-GTE engine was put into the
front-wheel-drive Celica (at Low Altitude Strike). The injectors in the RWD
engine are not in the same place and the orientation of the block is the
opposite. I would really like to have an explanation about this because I plan
to do the same thing. Keep doing good work on the site.
Hmm, interesting point!
We've long since lost contact with the owner of the CEPER Celica but it would
seem likely the engine was from a GT4 - not an MR2, as we were told.
Overlooked Subie Engine
a reader and customer of AutoSpeed and enjoy all of the articles and technical
bits of information you publish.
In your 2004 Engine Epic on Subaru
(2004 Engine Epic - Subaru Engines
) you wrote that you will
talk about the most desirable engines from Subaru. Pretty good and informative
article, but you forgot to talk about the USDM (US Domestic Market) 2.2-litre
full close deck (EJ22G) engine, as found in the ‘91-94 Legacy Sport sedan. I may
understand your omission because you don't have this engine in
Australia, but I
think you should have mentioned it since it's becoming a very popular (and
strong) base to build 300+hp reliable engines.
More on the XJ-SC
You just knew you were going to hear from me as soon
as you did a Jaguar article didn't you
( Jaguar Speed
Some additional info...
The reason there was no soft-top initially for the XJS was that thanks to
Ralph Nader and his campaigning, Jaguar was told that convertibles were going to
be made illegal in the US by 1977 (a couple of years phase-in period). So they
didn't design or tool up for one. [This law] never happened but then by that time, the
company was in the process of divorcing itself from British Leyland, which slowed
down deployment until the mid-80's. The Cabriolet was the shortcut that allowed
suitable "chassis" stiffness (it's a monocoque so that's not really the right
word) until they could get the real convertible on the deck and certified by DOT
in the US (ADR
Auto trans in the 5.3 XJS is indeed GM400 3 speed (both HE and Pre-HE). 6L
has a 4sp GM equivalent (4L80)
12.5:1 compression happily runs on 95ron but prefers 98, Oz PULP was 91 only
initially at introduction hence they stopped making the high comp engine
available after unleaded was introduced.
6-cylinder first hit the XJS in 1984 not the early 90's but was never a
big seller- it was, however, the only manual gearbox available in the entire
Jaguar range in Australia until the
introduction of the S-type (the
UK got the manual
box in the 4-door XJ6 for its entire production).
The Supra conversion for the V12 releases a new world of performance from the
V12 - it's amazing the difference to the slush box. There are full details on
the Jag-Lovers website on the how to do a conversion using Dellow
I was wondering if it was possible to see a comparison between different dump
pipes? Say between a twin pipe system incorporating a separate wastegate pipe
plumbed back into the system and a large single opening to the back of the
turbo? As I am about to change my exhaust on my R33 GTST, I would love to see
the comparo using this car!!? Keep up the good work.
No, we don’t have any immediate plans
for a dump pipe comparo.
There are simply too many variables to
give any concrete answers – the post-dump pipe exhaust flow, boost pressure, the
amount of exhaust gas exiting the wastegate and other factors make it very
difficult. Testing would also be difficult – a dyno could be used to show torque
and power differences but driveability (ie throttle response) is hard to
It’s a case of ‘suck it and see’, but
– in any case – a big-mouth or twin-pipe dump should be a lot better than the
I have read most if not all of your articles about intercoolers. They are
very informative and have taught me a lot about cooling the charge-air, but
there is one thing that has bothered me about intercoolers. A big pressure drop
across the ‘cooler is bad yet, in the act of cooling the air, it becomes denser;
therefore more air occupying less space, therefore a pressure drop will result.
So how can it cool the air without dropping the pressure?