Big motor, big compression, low boost?
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From: Deep in the seedy underworld of Koonerville
Big motor, big compression, low boost? Ok, answer me this.
If a certain size pulley on a procharger makes 5psi and 110rwhp on a stock motor what would the same pulley do on a built big ci motor(422ci). <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I doubt the actual boost number would be more than 1-2psi on the 422 if any boost showed at all. Since the boost would be very low would it be safe to have around 10.5-11.0:1 compression, with the appropriate tuning of course. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I'm having a motor built but not for boost.(right now anyway) <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> In the future I may want to have a little extra "everyday" power so thats why I ask.
Johnnie
<small>[ March 19, 2002, 06:24 PM: Message edited by: XLR8NSS ]</small>
If a certain size pulley on a procharger makes 5psi and 110rwhp on a stock motor what would the same pulley do on a built big ci motor(422ci). <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I doubt the actual boost number would be more than 1-2psi on the 422 if any boost showed at all. Since the boost would be very low would it be safe to have around 10.5-11.0:1 compression, with the appropriate tuning of course. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
I'm having a motor built but not for boost.(right now anyway) <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> In the future I may want to have a little extra "everyday" power so thats why I ask.
Johnnie
<small>[ March 19, 2002, 06:24 PM: Message edited by: XLR8NSS ]</small>
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From: Bellevue, Wa
Re: Big motor, big compression, low boost? NOW YOUR TALKING!!!!!! <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Keep that sucker. Build the motor 9.5:1, you won't lose squat powerwise N/A and put the 12psi pulley on. Probably see 6-7 psi and push out 650+
Wohoo!!!!!!!!!!!!!!!!!!
Keep that sucker. Build the motor 9.5:1, you won't lose squat powerwise N/A and put the 12psi pulley on. Probably see 6-7 psi and push out 650+
Wohoo!!!!!!!!!!!!!!!!!!
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From: Centrifugal City
Re: Big motor, big compression, low boost? I'd ask an ATI tech. Since they are dual-intercooled you'll be surprised at their answers.
Here..
My ATI chart says:
10.5:1 7-8psi
11:1 5-6psi
ATI references this with FULL timing!
I think they are optimistic tho. I'd pull timing down to 22*. 5psi. 10.5:1 F!, why not build it 10:1 if you are thinking of going either way?
Here..
My ATI chart says:
10.5:1 7-8psi
11:1 5-6psi
ATI references this with FULL timing!
I think they are optimistic tho. I'd pull timing down to 22*. 5psi. 10.5:1 F!, why not build it 10:1 if you are thinking of going either way?
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From: Deep in the seedy underworld of Koonerville
Re: Big motor, big compression, low boost? Hahaha...Hey Heath. I'll get serious with my setup as soon as you get that XB-1A and start running some real boost. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> Seriously though, I can't do both(motor+blower) right now so I am planning to eek out as much as I can from the motor alone.
MelloYellow - I agree with you about the timing stuff. Those charts do look just a bit optimistic. Those specs might be a little hairy in the summer heat or with a bad tank of gas.(even though the dual intercoolers are very efficient)
This motor may never get any type of forced induction on it so I am going to try and keep the cr around 11:1 for the most N/A power I can get. I was just asking about the boost for the future if I ever decided to eek out another 100 or so hp. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> I wouldn't mind running a stock motor 5psi pulley if it would show an extra 100+ hp on the 422 even though it probably wouldn't show any boost. I mean the boost# showing on the guage isn't everything right? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Its late and I'm tired so if this doesn't make any sense let me know and I'll try to word it better tomorrow. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Johnnie
PS - This motor may be going in something that leaves 4 black marks on the ground after a burnout. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
MelloYellow - I agree with you about the timing stuff. Those charts do look just a bit optimistic. Those specs might be a little hairy in the summer heat or with a bad tank of gas.(even though the dual intercoolers are very efficient)
This motor may never get any type of forced induction on it so I am going to try and keep the cr around 11:1 for the most N/A power I can get. I was just asking about the boost for the future if I ever decided to eek out another 100 or so hp. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> I wouldn't mind running a stock motor 5psi pulley if it would show an extra 100+ hp on the 422 even though it probably wouldn't show any boost. I mean the boost# showing on the guage isn't everything right? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Its late and I'm tired so if this doesn't make any sense let me know and I'll try to word it better tomorrow. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Johnnie
PS - This motor may be going in something that leaves 4 black marks on the ground after a burnout. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
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From: the moon
Re: Big motor, big compression, low boost? boost is just backpressure.
If you make 110hp extra with a certain pulley it's because the blower is pumping enough mass air flow into the motor to do it.
If you build this motor now where it makes the same power without the blower, then the blower at the original pulley speed/mass flow rate on the new motor will do nothing for you.
It depends on much more more air the blower can pump in over what the motor is capable of N.A.
On a built 422, It is almost certain to require the same airflow as what it takes to pressurize a stock motor to 5psi,maybe even more.
Steve
If you make 110hp extra with a certain pulley it's because the blower is pumping enough mass air flow into the motor to do it.
If you build this motor now where it makes the same power without the blower, then the blower at the original pulley speed/mass flow rate on the new motor will do nothing for you.
It depends on much more more air the blower can pump in over what the motor is capable of N.A.
On a built 422, It is almost certain to require the same airflow as what it takes to pressurize a stock motor to 5psi,maybe even more.
Steve
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Re: Big motor, big compression, low boost? Thanks Steve! How's the car running? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
That's what I was kinda thinking, but I was <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
So a built 422 should make quite a bit more extra power than a stock 346 at 3-4psi(actual boost on each motor) since it takes alot more mass flow to create boost on the big motor. Right?
I should end up with close to 11:1 compression on this motor depending on what the heads cc after there done. If and thats a big IF I decide to put a blower on this motor sometime down the road do you think 4psi would be alright. I think it should run fine and make quite a bit of power on 93octane with a little timing backed out for safety sake.
Thanks
Johnnie
That's what I was kinda thinking, but I was <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
So a built 422 should make quite a bit more extra power than a stock 346 at 3-4psi(actual boost on each motor) since it takes alot more mass flow to create boost on the big motor. Right?
I should end up with close to 11:1 compression on this motor depending on what the heads cc after there done. If and thats a big IF I decide to put a blower on this motor sometime down the road do you think 4psi would be alright. I think it should run fine and make quite a bit of power on 93octane with a little timing backed out for safety sake.
Thanks
Johnnie
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From: the moon
Re: Big motor, big compression, low boost? Car is running real good. I have been tuning it without the blower on with ls1 edit.
Found out it likes to run rich and likes no more than 26 degrees timing.
The heads are showing awesome gains.
I am redoing my fuel and h20/alcohol systems and then the blower goes on with the exhaust.
Should make an easy 550-575 RWHP through an unlocked converter with a 6200rpm redline.
Plenty for me
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> So a built 422 should make quite a bit more extra power than a stock 346 at 3-4psi(actual boost on each motor) since it takes alot more mass flow to create boost on the big motor. Right?
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">right <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
4psi will give a very nice topend increase. Don't go beyond that though with 11 to 1 comp.
Steve
<small>[ March 21, 2002, 08:03 AM: Message edited by: SJH ]</small>
Found out it likes to run rich and likes no more than 26 degrees timing.
The heads are showing awesome gains.
I am redoing my fuel and h20/alcohol systems and then the blower goes on with the exhaust.
Should make an easy 550-575 RWHP through an unlocked converter with a 6200rpm redline.
Plenty for me
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> So a built 422 should make quite a bit more extra power than a stock 346 at 3-4psi(actual boost on each motor) since it takes alot more mass flow to create boost on the big motor. Right?
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">right <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
4psi will give a very nice topend increase. Don't go beyond that though with 11 to 1 comp.
Steve
<small>[ March 21, 2002, 08:03 AM: Message edited by: SJH ]</small>
