09-11-2010, 02:28 PM | #1 |
Drives: 2010 RS SS Join Date: Aug 2009
Location: Huntsville, AL
Posts: 196
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More boost "allowed" on L99?
We all know that the L99 has a slightly lower compression ratio than the LS3 and the bottom ends are made from the same materials (right on that?).
The LS3s are making more HP at the flywheel than the L99 due to camshaft, etc.. My question, given you can get enough fuel to the motor (injectors and pump), can the L99 have more boost applied safely than the LS3 as long as the power limits of the bottom end are not exceeded? If a powdered rod is going to break at 800 ft-lb at the flywheel (for example), then the LS3 might need only 8 psi to do that where the L99 might need 11psi. Providing you are safe on fuel and timing (tune), does the LS3 really have that big an advantage at the flywheel on power output maximum? I know there is some because of some of the extra valvetrain hardware in the L99. If the above is reasonable, then the common comments that, for example, "7-8psi is about the limit for the stock bottom end" isn't too accurate. At 7.5psi, the LS3 on a twin turbo can make much more at the flywheel than the L99 at he same pressure. If they have the same bottom end (hopefully someone can confirm) then the L99 isn't really near its limit at 7-8psi as it would need more boost to hit the same flywheel HP. Thanks for any comments. |
09-11-2010, 03:54 PM | #2 |
Drives: Maggie blown LS3 vette Join Date: Aug 2009
Location: SE TX
Posts: 1,490
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As long as your ride isn't running lean or exceeding your octane's limit to control knock/pre ignition/detonation, boost level doesn't make much difference. The power/rpm your short block/valve train can stand is the limiting factor. You can make 450rwhp on 8 psi or 650+ on 8psi. Guess which one is harder on your motor.
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09-11-2010, 04:42 PM | #3 |
Drives: 2010 RS SS Join Date: Aug 2009
Location: Huntsville, AL
Posts: 196
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That's exactly what I was thinking. Thanks.
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09-11-2010, 07:55 PM | #4 |
Drives: 2004 Tiburon SE Join Date: Sep 2010
Location: New London CT
Posts: 5
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Also consider that increasing boost often results in increased IAT's which doesn't help the situation.
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09-11-2010, 08:16 PM | #5 | |
Banned
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Quote:
umm the 450...because to get 450 on the the (650 at 8 psi) u can boost less, and the the 450 hp motor is hotter n relation to the 650 for that same 8 psi..relatively speaking...... |
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09-11-2010, 09:25 PM | #6 |
Drives: 1999 Trans Am Join Date: Jul 2009
Location: Bridgewater,Ma
Posts: 2,017
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Safe is a loose term when going boosted.There is a ton involved with it. Comes down to more efficient the better for longivity.
Depending on the power adder I would do 10lbs no problem on a roots blower or turbo and 12-14lbs on a centrifical. Tuning would have to be precise though. |
09-11-2010, 09:43 PM | #7 |
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Drives: 2010 Camaro Join Date: Feb 2010
Location: Sandy Hook, CT
Posts: 11,927
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I've been running a hair under 11 psi for a yr now on a Jannetty built and tuned car with no issues what so ever. Oh yeah, I've made a few hard passes with it.
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09-11-2010, 09:52 PM | #8 | |
Drives: 2010 RS SS Join Date: Aug 2009
Location: Huntsville, AL
Posts: 196
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Quote:
The point I was trying to make is that an L99 might be able to take a few more psi than the LS3 since it takes more boost for them to make the same power, considering they have similar bottom ends. Now the 5 percent drivetrain loss difference would have to be factored in though, so the LS3 would theoretically put more to the wheels prior to destruction (all in theory of course). |
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09-11-2010, 09:59 PM | #9 |
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Drives: 2010 Camaro Join Date: Feb 2010
Location: Sandy Hook, CT
Posts: 11,927
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Currently the car sits at 550/555. Within the next month or two we wil be going for 13 psi with a smaller pulley and boost a pump and hopefully 600/600 and a sniff at the 9's....hopefully!
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09-11-2010, 10:03 PM | #10 |
Drives: 2010 RS SS Join Date: Aug 2009
Location: Huntsville, AL
Posts: 196
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I would've guessed more than that (not that it is bad or anything). I was thinking in terms of turbos, not superchargers... Mine is getting 6-7psi and should be in the 530-540rwhp range.
Good luck. |
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