Chaz
|
| posted on 19/11/15 at 08:06 AM |
|
|
Supercharge with no intercooler, alarm bells?
My original setup was going to be Eaton M45, intercooler into 1.8 zetec, but I have had a friend round who owns GRS Motorsport who says I should scrap
the intercooler idea and go direct from s/c into manifold. Prem Detonation alarms bells now ringing!
I have read (on others forums) that this may be ok, think Elise SC, not sure what CR they have though.
Will ARP con rod bolts help? Or will they just up the available RPM?
Must I fit a 1.5mm decomp plate?
I think the M45 will make 6-8psi
Standard 1.8 silvertop zetec with 130PS cams
Eaton m45 (standard pulley)
Megasquirt
Any advice welcome!
|
|
|
|
|
J90rdn
|
| posted on 19/11/15 at 08:14 AM |
|
|
I'm coming from mx5 world where supercharging and turbo charging is common place. I have a mk1 mx5 running 12psi at 210bhp. I know quite a few
fi builds that don't use an intercooler. I thought (perhaps incorrectly) the intercooler acted to reduce charge temperatures? Whilst running
without one would not be ideal (I noticed a huge difference when I put mine on), I wouldn't have thought it would be dangerous in any way.
Having said that, unless the zetec is somehow different from the mx engine, I would definitely recommend trying to squeeze one in somewhere.
|
|
|
mark chandler
|
| posted on 19/11/15 at 08:21 AM |
|
|
It will restrict your power and create unwanted heat where you do not need it, Elise has packaging issues.
Make room, do it right.
|
|
|
DRM Black7
|
| posted on 19/11/15 at 08:32 AM |
|
|
I had a Downing Atlanta super charger kit on my BMW 318is (eaton charger) that doesn't have an intercooler, your limited to fairly low boast
without a cooler, think it was 7.5 psi but could go to 10.
Your really limiting what you can do without a cooler. Could always use water injection tho.
|
|
|
minibull
|
| posted on 19/11/15 at 09:21 AM |
|
|
My Scimitar ti runs turbo at 7psi with no intercooler (std Nissan s12). At these sort of boosts charge doesn't really get hot enough to require
one (though turbo glows an interesting colour). Compression is probably more critical. Power is dictated by boost pressure, heat has an affect on
power but main reason for intercooler is to prevent predetonation due to high temp. If you are happy with 7-8psi and don't intend to go much
higher intercooler won't improve performance, if your c/r isn't too high it isn't needed to prevent detonation .So personally I
wouldn't bother. Of course it's not my engine we are disscussing 
|
|
|
J90rdn
|
| posted on 19/11/15 at 09:37 AM |
|
|
quote:
Originally posted by minibull
My Scimitar ti runs turbo at 7psi with no intercooler (std Nissan s12). At these sort of boosts charge doesn't really get hot enough to require
one (though turbo glows an interesting colour). Compression is probably more critical. Power is dictated by boost pressure, heat has an affect on
power but main reason for intercooler is to prevent predetonation due to high temp. If you are happy with 7-8psi and don't intend to go much
higher intercooler won't improve performance, if your c/r isn't too high it isn't needed to prevent detonation .So personally I
wouldn't bother. Of course it's not my engine we are disscussing
Interesting. I was initially running at 7psi boost and noticed a marked improvement when putting in the intercooler. Guess different engines react in
different ways. That was a 1.6 high compression engine.
|
|
|
pewe
|
| posted on 19/11/15 at 11:32 AM |
|
|
Both the Volumex and M45 I have don't currently run I/coolers.
To compensate they both run rich mixtures which "cools" the bores.
M45 is hot side and even being driven hard and running during a hot spell in Italy there didn't appear to be any issues (same can't be
said for low grade French Super petrol)
However fuel consumption will increase due to running it rich - Hairdressers achieves 22mpg no matter how it's driven!
As has been suggested it's only when running higher boost and trying for max power an I/cooler is a good idea.
HTH.
Cheers, Pewe10
|
|
|
mark chandler
|
| posted on 19/11/15 at 06:21 PM |
|
|
Eatons are not very efficient either, when boosting you will be dragging maybe 30hp off the crank, most of this goes into heat.
1hp = 0.75kw so when pushing hard it becomes a 22kw heater!
|
|
|
coyoteboy
|
| posted on 20/11/15 at 12:53 PM |
|
|
There's a lot of simplification going on here.
The intercooler acts to cool the air section of the charge. It's not NEEDED but...
a) will generate less power than the equivalent cooled engine because the extra heat and
b) Be more likely than the equivalent cooled engine to suffer detonation and pre-ignition due to extra heat in the chamber
c) be less fuel efficient for any specific power because more power is lost as heat.
d) May require a worse timing maps and more fuel to aid cooling and and reduce det likelihood and ultimately be detonation limited (wrt power).
Current gen (I think) M45s compressor map:
 
M45 SC Map
They're about 65-70% efficient when used in sensible realms. Turbos are more efficient but not massively - 10% or so.
Power lost to the SC (which is offset against power gained, so not really lost, and don't forget turbos take power too by creating an exhaust
restriction - it's just harder to visualise) will be 30HP max, but is totally dependent on the pressure ratio you want to run and the compressor
RPM required to get that ratio.
Heat generation in a fixed displacement SC like an eaton is created mostly by the pure act of compression of the air (all compression systems suffer
this) and the mashing of the air at the rotors. Both of these will be entirely dependent on the pressure ratio and RPM required for the
application.
It's ALWAYS better to run an intercooler in any real world application, if you can fit it. It might make very little difference if you're
running 5psi at 50% of the SC RPM capacity.
|
|
|
