Single Vs twin pass?

RobDon

Pro Detailer
OK so I have the Forge twin pass IC kit with both hoses on one side, but is a single pass intercooler ALOT better for performance, will it run alot cooler, be more efficient and perform better or not make much difference at all?
 

wild willy

Full Member
Aug 4, 2003
2,323
0
Wales
OK so I have the Forge twin pass IC kit with both hoses on one side, but is a single pass intercooler ALOT better for performance, will it run alot cooler, be more efficient and perform better or not make much difference at all?
What temps are you experiencing. Compare your temps to the LCR guys running the forge FMIC single pass. Your car is ouputing similar power to the stage 2 lcr owners.
 

m0rk

sarcasm comes free
Staff member
May 19, 2001
27,787
33
Clanfield, UK
I think it's a trade off between twin pass IC, and convoluted pipework to make it single pass

Not sure if either will cool better than each other, it's the pipework between it that makes the difference all things being equal
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
even distribution of airflow within core is an important factor (end tank design for example), dimension of core (depth), and the available core seeing the airflow... twin pass has twice the distance thru halve the cores. Balance of a cool air charge vs losses in pumping it thru. Airflow thru motor is what makes you power, cool charge makes for a denser 02 charge, but worst case scenario is too high and airflow or too small a core will result in power losses, but cooler charge temps.

GRS was an example of an apparent "good" core judging by its output temps.. when reality was it choked airflow badly, and whatever flow could find its way out more than negated any gains in pumping losses. 2-4psi drop even on a small k03 or k03s.

not saying twin pass is'nt ok, its a case of its size being matched to the airflow asked of it.
 

RobDon

Pro Detailer
Ok thanks - I notice that Pro Alloy Ltd. don't do ANY twin pass IC's, all the same side intercoolers are vertical cores and still single pass.

"The flow rate of these coolers is over double compared to a double pass intercooler."

It was comments like that which caught my attention!
 

m0rk

sarcasm comes free
Staff member
May 19, 2001
27,787
33
Clanfield, UK
indeed - but no good if you have to have 10ft of pipework to get it to utilise it

best option for you would be an Ibiza (sided) manifold to single pass IC
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
Ok thanks - I notice that Pro Alloy Ltd. don't do ANY twin pass IC's, all the same side intercoolers are vertical cores and still single pass.

"The flow rate of these coolers is over double compared to a double pass intercooler."

It was comments like that which caught my attention!

and... something else to consider is the original FMIC core on mine, was too small as the sheer flowrate thru that unit did'nt allow much time for the air to dwel and actually heat exchange.. larger core used (x3 size) and the same flow, slowed down in the core, as well as heat exchange increasing from both more surface area and more dwell time in core.

Forge will make a large FMIC and have dimensions of my core and pipework.
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
indeed - but no good if you have to have 10ft of pipework to get it to utilise it

best option for you would be an Ibiza (sided) manifold to single pass IC

or something with pipework along these lines (but made nicer)
Golf4-fmic.jpg
 

DPJ

...........
Dec 13, 2004
7,996
2
NN Yorks / Salento
www.seatcupra.net
Wayne at Pro Alloy has promised to email me some pics and drawings. He says the intercoolers were developed and tested in conjuction with Jabba Sport.

Incidentally, I wondered if their non-R cooler was similar to their Octavia VRS intercooler. Apparently not.

I quite liked the look of the VRS one - single pass - nice short vertical cores.... :think:
 

m0rk

sarcasm comes free
Staff member
May 19, 2001
27,787
33
Clanfield, UK
if you can get the air all the way to the end of the tanks..... but still the same 'side' issue and convoluted routing that you'll get otherwise.

I think it replaces the 'squashed' metal pipe in the wheel arch? you'd need to put stops on your steering rack as the wheel will touch it
 

RobDon

Pro Detailer
A few of the vertical single-pass ones look a much better solution for the Cupra, the EVOMS is/was a firm favourite across the pond.

http://www.evoms.com/

I questioned Forge about the single Vs twin topic and asked if they'd ever consider doing any this way (vertical, single-pass), Richard said they were open to any design ideas.
 
Last edited:

DPJ

...........
Dec 13, 2004
7,996
2
NN Yorks / Salento
www.seatcupra.net
Adrian Flux insurance services - discount for forum members.