Supercharger on stock compression
Thread Starter
Drifting
Joined: Jun 2001
Posts: 1,625
Likes: 1
From: Zagreb, Croatia
Supercharger on stock compression
I've got supercharger in my future plans so I have a few questions.
I'll probably build a new engine (out of my present) for it but here is
what troubles me.
Centrifugal supercharges won't make boost until some rpm's (lets say
2500 and up). If I build engine with low compression, ~8:1, how will
that engine perform on low rpms <2500?
On the other side, would it be better to build engine with similar to
stock compression, ~9.5:1, all forged, and keep max boost under 10psi?
I'll probably build a new engine (out of my present) for it but here is
what troubles me.
Centrifugal supercharges won't make boost until some rpm's (lets say
2500 and up). If I build engine with low compression, ~8:1, how will
that engine perform on low rpms <2500?
On the other side, would it be better to build engine with similar to
stock compression, ~9.5:1, all forged, and keep max boost under 10psi?
Instructor
Joined: Dec 2005
Posts: 197
Likes: 0
From: Woodland California
Tuned properly, the 8.1 motor will take much more boost & produce much more HP & tork. HP & tork on a graph are curves, and the higher HP tork motor is going to have more below 2500 RPM all things being equal.
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
You drive the BEST Amarican performance car made!
Why are you concerned about -2500RPM?
Unless you are building a truck to slow clomb over rocks.....
Actualy it will be more like 3K-3500 befor you start making any real boost.
You mention centrifical blowers with this effect, but you should know that this will be common for roots , and turbos too.
if you are realy concered about boost lag, then i would go for a Nos Kit.
Your car can be just as fast but there is NO lag. It will have "snap your neck response"
Why are you concerned about -2500RPM?
Unless you are building a truck to slow clomb over rocks.....
Actualy it will be more like 3K-3500 befor you start making any real boost.
You mention centrifical blowers with this effect, but you should know that this will be common for roots , and turbos too.
if you are realy concered about boost lag, then i would go for a Nos Kit.
Your car can be just as fast but there is NO lag. It will have "snap your neck response"
Instructor
Joined: Dec 2005
Posts: 188
Likes: 0
From: Riverside CA
[QUOTE= would it be better to build engine with similar to
stock compression, ~9.5:1, all forged, and keep max boost under 10psi?[/QUOTE]
Depends on the rest of the set-up
If you ar doing a fresh build,
I would go more like 9:1 with aluminum head, and 8.5:1 with iron.
This should also apply th Nos set-ups as well.
However, Lots of guys running 10:1 with no problems.
Good luck
Blwn Bux
stock compression, ~9.5:1, all forged, and keep max boost under 10psi?[/QUOTE]
Depends on the rest of the set-up
If you ar doing a fresh build,
I would go more like 9:1 with aluminum head, and 8.5:1 with iron.
This should also apply th Nos set-ups as well.
However, Lots of guys running 10:1 with no problems.
Good luck
Blwn Bux
CF Community Team
Joined: Oct 2007
Posts: 1,143
Likes: 614
From: NorCal San Jose
With a centrifugal blower like a Vortech or Paxton, I like a compression ratio of aroud 9.5:1, so it's snappy when you are just cruising around. Then use a good intercooler and keep the boost at 10-12 or below and you should have a great combo. An intercooled 7.4psi of boost makes it perform like the motor grew by 50% at higher rpm. From 4 grand to wherever your redline lets you go, it just pulls hard. Great with a stroker so you are pretty strong down low too.
Nitrous I would go with 10:1 on the street with aluminum heads.
Jim
Nitrous I would go with 10:1 on the street with aluminum heads.
Jim
Former Vendor
Joined: Dec 2006
Posts: 2,239
Likes: 1
We build our ATI ProCharger bound engines at a 9.5/1 compression ratio, no matter how much boost we are shooting for. Check out this Corvette that is making 740 rwhp and still gets 28 mpg and you can still takes vacations with it.
http://www.exoticperformanceplus.com...Car.php?car=40 Bob
http://www.exoticperformanceplus.com...Car.php?car=40 Bob
