I was wondering what the boost levels are with the stock and aftermarket pulleys.
Am I correct in assuming that stock pulley(which is I believe 2.8") - allows the S/C to generate about 4.5-5 lbs of boost.
- So what does the follow pulley sizes generate.
- 2.7" pulley (68.6 mm)
- 2.6" pulley (66.0 mm)
- 2.5" pulley (63.5 mm)
Also am I correct in assuming that the maximum recommended boost that can be run on a stock motor with out an intercooler is about 6 psi.
Y'know if you actually take a few minutes to look for this stuff yourself, you'll find it.
Try it.
14.330 @ 96.37mph
this is what i saw
- 2.7" pulley (68.6 mm) = 6 psi without alky never had on with alky
- 2.6" pulley (66.0 mm) = 8 psi without alky saw 13psi with alky
- 2.5" pulley (63.5 mm) = spins too fast for my liking
You know - BlownBlackZ - did you ever think that maybe I had already attempted a brief search(about 10 minutes) before starting the thread, and didn't find the information I was looking for?
Remember a person who asks questions is attempting to learn something, and therefore should not be made to look like an Idiot, for simple asking a question.
Future Note - next time someone makes - what you may consider to be a silly post. How about giving them a little credit, and maybe offer some helpful information - maybe post a link - instead of jumping on their case, for asking a question. After all everyone here to learn & share useful/helpful information to other j-body owners.
Btw - LAFNGAS, Thanks for the info. It helps, and is basically the kind of information I was looking for.
And actually brings up another question
Does alky injection really increase the boost by about 5 psi? or is it more of a percentage increase?
.
thats just what i saw on mine but i had also swapped out my air intake for a different style as well
Alky injection is more for cooling the air. The smaller the pulley the faster the sc spins the more the heatsoak. Once you heatsoak it any gain you were getting froma smaller pulley will be gone. I would highly reccomend getting alky injection before you go to a smaller pulley. Without it you not be able to use the full potential of a smaller pully. It also has far more benefits one of the biggest being it helps drastically to prevent detonation damage.
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
Wade Jarvis wrote:detonation damage.
and U certainly know about that now dont u!!!!!
bahahahahahahaha!!!
question, scott... how does alky injection create more boost? does it just allow the S/C to become more effient and thus making it easier to make boost?
I would actualy see a slight loss in manifold pressure when the alky system was functioning properly.
With my engine I was seeing:
2.6" 4.5 PSI
2.5" 6 PSI
2.4" 7.5 PSI
Keep in mind this was not a stock top end on the motor. Obviously a stock top end would flow less and your manifold pressure would be higher.
From my(fairly limited) understanding of how boosting works - is this.
If you attempt to force a lot in air into a small space, you increase "boost" pressure. But if you attempt to force the same amount of air in a larger space - then the "boost" pressure is less.
Also if I recall - doesn't cooler air mean - denser air - denser air means increased pressure - i.e. more boost.
kj1168 wrote:From my(fairly limited) understanding of how boosting works - is this.
If you attempt to force a lot in air into a small space, you increase "boost" pressure. But if you attempt to force the same amount of air in a larger space - then the "boost" pressure is less.
Also if I recall - doesn't cooler air mean - denser air - denser air means increased pressure - i.e. more boost.
as you said about the boost pressure and forcing the amount of air in a larger space, boost is a measurement of resistance ie. port and polished head will show smaller boost pressure
So P&P not a good idea for helping to making boost.
What about Compression Ratios - I keep hearing that CR above 10:1 is bad for making boost also - or rather bad for the engine.
kj1168 wrote:So P&P not a good idea for helping to making boost.
What about Compression Ratios - I keep hearing that CR above 10:1 is bad for making boost also - or rather bad for the engine.
A ported head is a GREAT idea for boost. A ported head may show lower boost levels but what your looking for is more CFM entering the combustion chambers. A ported head will be more efficient and create more power with boost. Dont be so focused on boost focus more on CFM as thats what really matters.
Reason being you could create 25 psi through straw sized intake manifold and what good would that 25 psi do... nothing.
Now put 5 psi through a slutty blondes vagina and look we have power now
all because it flows better.
sorry if i went a little OT on that.
^^^Nice analogy
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
Tom........... weard do you speak from.... never mind....
FYI, on my blower with watter injection im seeing up to, what Tom, 158 KPA... or 8-9 PSI with the stock pulley, im just reving out to 7 grand....maby im floting valves... but it pulls nice.
also with the 2.5" pulley i was only seeing 6-8 PSI...... but it was warn out (my first GMSC) this one is being treated better and runs harger with HPT.
. i have my eyes set on the LSJ M-62 and makeing it work on a LD9.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
Ok - So P&P is actually good as for air flow, which helps make more power. Understand that.
Would it be better to find a 086 head and put on the LD9, or just do a mild P&P on the stock head, with the GM S/C.
kj1168 wrote:Ok - So P&P is actually good as for air flow, which helps make more power. Understand that.
Would it be better to find a 086 head and put on the LD9, or just do a mild P&P on the stock head, with the GM S/C.
If you do no other mods id go with a ported stock head as a 086 will bump the compression up too much for boost from the m45 (it gets way too hot to have a safe tune with the compression level)
Now if you rebuild and get lower compression pistons id go with the 086 but remember the intake manifold bolt positions are different on the 086 compared to a stock ld9 head.
Okay. So P&P the stock LD9 head is better than the 086 head for Boosting, since it won't raise the Compression ratio.
I was kind of wonder since I had heard that using 086 head on stock CR really increased the CR by 1.5-2 full points (roughly 11-11.5:1).
And I've always heard that even if running a low amount of boost (about 5-7psi) that it's good to keep the CR at or below 10.0:1.
anyone know were i can buy the 2.6in or 66mm pulley i would realy like one
PulleyBoys
2.4L M45 Pulleys
2010 Subaru Impreza WRX Limited
1999 Cavalier Z24 Supercharged
1999 Grand AM SE (Beater Car)
1997 GMC Sierra
2007 Honda CBR 600RR
2005 Honda TRX450R
well im running 5 psi with the stock pully i have the 2.7 and 6 comming in ill try them both and let you know my supercharger only has about 1000 miles on it now
<img src="http://img46.imageshack.us/img46/227/cave10wf.gif" />
Wrench Monkey wrote:kj1168 wrote:So P&P not a good idea for helping to making boost.
What about Compression Ratios - I keep hearing that CR above 10:1 is bad for making boost also - or rather bad for the engine.
A ported head is a GREAT idea for boost. A ported head may show lower boost levels but what your looking for is more CFM entering the combustion chambers. A ported head will be more efficient and create more power with boost. Dont be so focused on boost focus more on CFM as thats what really matters.
Reason being you could create 25 psi through straw sized intake manifold and what good would that 25 psi do... nothing.
Now put 5 psi through a slutty blondes vagina and look we have power now all because it flows better.
sorry if i went a little OT on that.
Ah! so it IS true! Blondes do have more fun!
I shall never doubt the pron collection again!
any other place to get the pulleys other than pulley boys? I don't intend on changing them out..... ever so whats the point of getting a quick change hub
the eco's a 6 rib belt.... get one on ebay thats for a GTP.......
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
