More boost "allowed" on L99? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

general23cmp · 09-11-2010, 02:28 PM

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.

old motorhead · 09-11-2010, 03:54 PM

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.

general23cmp · 09-11-2010, 04:42 PM

That's exactly what I was thinking. Thanks.

Guardian · 09-11-2010, 07:55 PM

Also consider that increasing boost often results in increased IAT's which doesn't help the situation.

ipimpthisc · 09-11-2010, 08:16 PM

Quote:

Originally Posted by old motorhead

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.

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......

Slowhawk · 09-11-2010, 09:25 PM

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.

Supercharged SS · 09-11-2010, 09:43 PM

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.

general23cmp · 09-11-2010, 09:52 PM

Quote:

Originally Posted by Supercharged SS

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.

Wow! What is the rwhp on that L99? Awesome!

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).

Supercharged SS · 09-11-2010, 09:59 PM

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!

general23cmp · 09-11-2010, 10:03 PM

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.

09-11-2010, 02:28 PM	#1
general23cmp Drives: 2010 RS SS Join Date: Aug 2009 Location: Huntsville, AL Posts: 196	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.

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09-11-2010, 03:54 PM	#2
old motorhead Drives: Maggie blown LS3 vette Join Date: Aug 2009 Location: SE TX Posts: 1,490	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.

09-11-2010, 04:42 PM	#3
general23cmp Drives: 2010 RS SS Join Date: Aug 2009 Location: Huntsville, AL Posts: 196	That's exactly what I was thinking. Thanks.

09-11-2010, 07:55 PM	#4
Guardian Drives: 2004 Tiburon SE Join Date: Sep 2010 Location: New London CT Posts: 5	Also consider that increasing boost often results in increased IAT's which doesn't help the situation.

09-11-2010, 09:25 PM	#6
Slowhawk Drives: 1999 Trans Am Join Date: Jul 2009 Location: Bridgewater,Ma Posts: 2,017	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
Supercharged SS Account Suspended Drives: 2010 Camaro Join Date: Feb 2010 Location: Sandy Hook, CT Posts: 11,927	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.

09-11-2010, 09:59 PM	#9
Supercharged SS Account Suspended Drives: 2010 Camaro Join Date: Feb 2010 Location: Sandy Hook, CT Posts: 11,927	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!

09-11-2010, 10:03 PM	#10
general23cmp Drives: 2010 RS SS Join Date: Aug 2009 Location: Huntsville, AL Posts: 196	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.