Cam + compression choice for built LS on pump gas
10-26-2004, 01:35 PM
#1
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Cam + compression choice for built LS on pump gas
Setup so far:
Stock bore B18B
Stock sleeves (don't flame or tell me to sleeve the block, I don't care to hear it.)
Ported B18B head, ~205-208 CFM/port
RM valvesprings, retainers
Overblown Motorsports equal length tubular manifold
Holset HY35 turbo
Single 46mm WG
3"x9"x24" core intercooler, bar+plate design
The Holset is a big boost turbo. It doesn't really hit its island until a 1.25 PR, and carries it well up to a 3.0 PR for the flow levels I will be dealing with.
Goals for motor:
1. Work turbo as it is meant to be worked, high PR.
2. 400whp on 93 octane
3. 28psi of boost and whatever power comes with it on 93 octane+water injection.
Unresolved issues:
1. Cams: use the RM L21s I have (262/10.2mm on both intake+exhaust) with cam gears or get another cam with different lobe. More lift? Less duration? I realize that revablility is not the forte of the LS head. I'm looking for a cam that's not going to have significant power drops until at least the mid-high 7000s, preferably not until right around 8000 RPM.
2. Piston compression: PUMP GAS IS KEY. This motor will never see race gas if I can help it. The more compression gets dropped, the more boost can be safely run on pump gas. This helps complement the turbo selection well. However, as compression drops, combustion chamber filling/emptying becomes more and more problematic. I'm trying to find some kind of happy medium, and I am torn everywhere between 8.0:1 and 9.5:1.
Any thoughts on the matters at hand would be appreciated. If I can do 400 on pump w/o water injection, 2bar of boost with water injection will be cake. I'm just scratching my head trying to figure out how to balance things before I buy rods+pistons.
If anyone has any resources that offer some concrete math I could do to crunch some numbers and make a better informed decision, I'd be eternally grateful. Opinions without science aren't very valuable to me.
Stock bore B18B
Stock sleeves (don't flame or tell me to sleeve the block, I don't care to hear it.)
Ported B18B head, ~205-208 CFM/port
RM valvesprings, retainers
Overblown Motorsports equal length tubular manifold
Holset HY35 turbo
Single 46mm WG
3"x9"x24" core intercooler, bar+plate design
The Holset is a big boost turbo. It doesn't really hit its island until a 1.25 PR, and carries it well up to a 3.0 PR for the flow levels I will be dealing with.
Goals for motor:
1. Work turbo as it is meant to be worked, high PR.
2. 400whp on 93 octane
3. 28psi of boost and whatever power comes with it on 93 octane+water injection.
Unresolved issues:
1. Cams: use the RM L21s I have (262/10.2mm on both intake+exhaust) with cam gears or get another cam with different lobe. More lift? Less duration? I realize that revablility is not the forte of the LS head. I'm looking for a cam that's not going to have significant power drops until at least the mid-high 7000s, preferably not until right around 8000 RPM.
2. Piston compression: PUMP GAS IS KEY. This motor will never see race gas if I can help it. The more compression gets dropped, the more boost can be safely run on pump gas. This helps complement the turbo selection well. However, as compression drops, combustion chamber filling/emptying becomes more and more problematic. I'm trying to find some kind of happy medium, and I am torn everywhere between 8.0:1 and 9.5:1.
Any thoughts on the matters at hand would be appreciated. If I can do 400 on pump w/o water injection, 2bar of boost with water injection will be cake. I'm just scratching my head trying to figure out how to balance things before I buy rods+pistons.
If anyone has any resources that offer some concrete math I could do to crunch some numbers and make a better informed decision, I'd be eternally grateful. Opinions without science aren't very valuable to me.
10-26-2004, 01:57 PM
#2
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Thread Starter
Oh yeah, it's somewhat implied in this setup, but only subtly so...
A concept I'm trying to build around is spooling the turbo as quickly as possible by using a relatively small A/R hotside (hope to hit 12psi under 4000 RPM, hopefully under 3500) and then minimize exhaust side restrictions by using an "excessive" wastegate setup in order to try to have as high as possible of a intake manifold / exhaust manifold pressure ratio.
A concept I'm trying to build around is spooling the turbo as quickly as possible by using a relatively small A/R hotside (hope to hit 12psi under 4000 RPM, hopefully under 3500) and then minimize exhaust side restrictions by using an "excessive" wastegate setup in order to try to have as high as possible of a intake manifold / exhaust manifold pressure ratio.
10-27-2004, 09:46 AM
#5
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neither.
Uberdata or Crome or some other OBD1 OEM ECU solution for tuning.
Boost/traction controller of my own design for boost/traction control.
Uberdata or Crome or some other OBD1 OEM ECU solution for tuning.
Boost/traction controller of my own design for boost/traction control.
10-27-2004, 09:57 AM
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Re: (blundar)
I'm not sure about 400whp on pump gas (I get 91 octane in my area) but anything can be possible. 28-30psi sounds to me that your turbo would not be very happy reliability wise. Pushing it to that limit as a daily driver would soon cause it to go. I say my best bet is to knock off some timing and run 3inch exhaust.
As for your head, in my opinion, I would use the stock cams. I'm not too familiar with your cam setup but since you already have a valvetrain upgrade, you might as well see how much and how high you can peak out on the dyno. Surely different with a non-vtec head, I use b16 auto cams with my setup which is very efficient in midrange and I can edge a tad bit more power up to 9k on my ITR head.
As for your head, in my opinion, I would use the stock cams. I'm not too familiar with your cam setup but since you already have a valvetrain upgrade, you might as well see how much and how high you can peak out on the dyno. Surely different with a non-vtec head, I use b16 auto cams with my setup which is very efficient in midrange and I can edge a tad bit more power up to 9k on my ITR head.
10-27-2004, 10:03 AM
#7
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Thread Starter
The head has been worked for airflow, particularly up top. I'm looking for a cam to complement this. No stock cam will cut it.
BTW, that turbo is designed for a 3:1 PR @ 50lbs/min and still live within it's efficiency island. That's 44+ psi... Be careful before you talk too much about the Holsets... They're not a Precision.
BTW, that turbo is designed for a 3:1 PR @ 50lbs/min and still live within it's efficiency island. That's 44+ psi... Be careful before you talk too much about the Holsets... They're not a Precision.
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10-27-2004, 10:11 AM
#8
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Re: (blundar)
People keep most setups simple and still make very efficient power for street driving. I feel that making around 400whp with only 17-20psi is a better way of making power instead of trying to reach 2 bar.
Why spend barrels of cash in things that probably wont make the biggest difference?
Why spend barrels of cash in things that probably wont make the biggest difference?
10-27-2004, 10:51 AM
#9
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2bar with water injection - that's not what I'm worried about. If I can hit 400 on pump, 2bar with water injection will be cake.
And to return to the cam selection issue, unless I misunderstand how cams work, I'm going to have zero overlap with the L21 cams (262 duration) even with cam gears rotated a few degrees. I'm looking for a little bit of overlap because I'm optimizing the motor to run after the turbo is spooled up when the intake manifold pressure will be greater than the exhaust manifold pressure.
Am I wrong that the L21 cams will not provide enough overlap? My understanding of camshafts is marginal at best...
And to return to the cam selection issue, unless I misunderstand how cams work, I'm going to have zero overlap with the L21 cams (262 duration) even with cam gears rotated a few degrees. I'm looking for a little bit of overlap because I'm optimizing the motor to run after the turbo is spooled up when the intake manifold pressure will be greater than the exhaust manifold pressure.
Am I wrong that the L21 cams will not provide enough overlap? My understanding of camshafts is marginal at best...
10-27-2004, 11:06 AM
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Re: (blundar)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar »</TD></TR><TR><TD CLASS="quote">Oh yeah, it's somewhat implied in this setup, but only subtly so...
A concept I'm trying to build around is spooling the turbo as quickly as possible by using a relatively small A/R hotside (hope to hit 12psi under 4000 RPM, hopefully under 3500) and then minimize exhaust side restrictions by using an "excessive" wastegate setup in order to try to have as high as possible of a intake manifold / exhaust manifold pressure ratio.</TD></TR></TABLE>
what does the manifold you are using look like? does it give primary flow to the wastegate?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar »</TD></TR><TR><TD CLASS="quote">BTW, that turbo is designed for a 3:1 PR @ 50lbs/min and still live within it's efficiency island. That's 44+ psi... Be careful before you talk too much about the Holsets... They're not a Precision.</TD></TR></TABLE>
Is that 44psi absolute pressure?
A concept I'm trying to build around is spooling the turbo as quickly as possible by using a relatively small A/R hotside (hope to hit 12psi under 4000 RPM, hopefully under 3500) and then minimize exhaust side restrictions by using an "excessive" wastegate setup in order to try to have as high as possible of a intake manifold / exhaust manifold pressure ratio.</TD></TR></TABLE>
what does the manifold you are using look like? does it give primary flow to the wastegate?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar »</TD></TR><TR><TD CLASS="quote">BTW, that turbo is designed for a 3:1 PR @ 50lbs/min and still live within it's efficiency island. That's 44+ psi... Be careful before you talk too much about the Holsets... They're not a Precision.</TD></TR></TABLE>
Is that 44psi absolute pressure?
10-27-2004, 11:53 AM
#12
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manifold is a tubular that feeds the turbo, unfortunately. I'm planning on doing either a 46mm + a 35mm coming off sides of the merge or two 35m gates.
And that would be relative pressure... PR is 3x atmospheric.
And that would be relative pressure... PR is 3x atmospheric.
10-27-2004, 11:56 AM
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Re: (blundar)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar »</TD></TR><TR><TD CLASS="quote">
And that would be relative pressure... PR is 3x atmospheric.</TD></TR></TABLE>
wow, i've never seen a compressor wheel that can do 44psi that only flows 50lb/min. Do you have access to the compressor map? This is something i am definitly interested in.
And that would be relative pressure... PR is 3x atmospheric.</TD></TR></TABLE>
wow, i've never seen a compressor wheel that can do 44psi that only flows 50lb/min. Do you have access to the compressor map? This is something i am definitly interested in.
10-27-2004, 12:01 PM
#14
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http://www.holset.com - you have to dig, hard. The HY35 uses essentially the same compressor setup as the HX35W, which is the one you'll be able to find something for. The "bubble" that holset give you is the 70% island.
10-27-2004, 01:26 PM
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