Finding some more ponies

[SlowTBSS]

Hey guys, I have a 2007 Chevy Trailblazer SS, spun a rod bearing a while back and had the engine rebuilt as a 403ci LS2 stroker. The engine made very good power(662hp@6650) for what it is but I am looking for ways to pick up another 25hp or so without killing the manners the engine has already. It's very street friendly as is and the build was centered around the TBSS being a heavy pig. I didn't have a chance to Dyno the engine with the GZ Motorsports vacuum pump but I don't think it'll help a ton as the rings are just standard Wiseco GFX rings.

Cam swap to a Solid or LLSR?
Different Intake manifold?
Here's the build sheet, where would you start looking?

2007 Chevy Trailblazer SS, 4400lbs
-403ci LS2 11.8:1
-Callies Compstar crank 4.00"
-Callies Compstar rods 6.125"
-Wiseco -3cc forged pistons, GFX rings
-ARP main studs
-Mamo Motorsport 235cc CNC heads, Hollow stem 2.10 lightweight valves, titanium retainers, upgraded Manley Nextek springs(#221435), Mamo hand finish/CNC+ option, 66cc, .036 quench
-Yella Terra 1.8 Ultralite Pro rockers with 10mm upgrade
-Mamo ported FAST LSXrt manifold 102mm
-Mamo ported 103mm throttle body
-Manton 11/32 pushrods
-Johnson ST2126LSR short travel lifters
-Mamo custom cam 243/249@.050 .675/.675 lift on a 114+3
-Cloyes HD timing set
-Melling ported HV pump.
-ATI damper
-C6 pan

PXL_20220120_100342876.jpg

PXL_20220120_100315142.jpg

[allencr267]

Exhaust?
Cool air intake, deeper pan & scraper & thinner lube & std pump.
Loose weight.
I have no experience with whatever you're working on.
Good luck.

[steve cowan]

Hey guys, I have a 2007 Chevy Trailblazer SS, spun a rod bearing a while back and had the engine rebuilt as a 403ci LS2 stroker. The engine made very good power(662hp@6650) for what it is but I am looking for ways to pick up another 25hp or so without killing the manners the engine has already. It's very street friendly as is and the build was centered around the TBSS being a heavy pig. I didn't have a chance to Dyno the engine with the GZ Motorsports vacuum pump but I don't think it'll help a ton as the rings are just standard Wiseco GFX rings.

Cam swap to a Solid or LLSR?
Different Intake manifold?
Here's the build sheet, where would you start looking?

2007 Chevy Trailblazer SS, 4400lbs
-403ci LS2 11.8:1
-Callies Compstar crank 4.00"
-Callies Compstar rods 6.125"
-Wiseco -3cc forged pistons, GFX rings
-ARP main studs
-Mamo Motorsport 235cc CNC heads, Hollow stem 2.10 lightweight valves, titanium retainers, upgraded Manley Nextek springs(#221435), Mamo hand finish/CNC+ option, 66cc, .036 quench
-Yella Terra 1.8 Ultralite Pro rockers with 10mm upgrade
-Mamo ported FAST LSXrt manifold 102mm
-Mamo ported 103mm throttle body
-Manton 11/32 pushrods
-Johnson ST2126LSR short travel lifters
-Mamo custom cam 243/249@.050 .675/.675 lift on a 114+3
-Cloyes HD timing set
-Melling ported HV pump.
-ATI damper
-C6 pan

PXL_20220120_100342876.jpg
PXL_20220120_100315142.jpg

If you have the vac pump and it fits in the car with mandrel etc I suggest that you try it.
Alot will be determined how good the engine is sealed up.

[rebelrouser]

That looks like good power for your combo. As mentioned, the exhaust system would be the easiest apple to pick. Since you stroked it are your injectors big enough? I assume you had the computer tuned after the rebuild? I did a stroked LS for a limited class pulling truck. we actually used a trailblazer intake as they say it is one of the best stock ones, and it had OEM flexfuel injectors, they are just on the edge of being to small. When I tuned it on the dyno I got a lot of power getting the injectors rich enough at wot, so the computer would advance the timing. The knock system would not let it have full advance until we got it rich enough at WOT. And just by the seat of the pants most OEM computers will retard the timing right before the trans shifts, if you disable that it feels like 50HP The engine I did had to hold 16 inches of vacuum at idle, and run on pump gas, we got 525HP out of it. guy was happy because it was a competitive truck before, and now the tires spin before the sled pulls it down to nothing.

[SlowTBSS]

That looks like good power for your combo. As mentioned, the exhaust system would be the easiest apple to pick. Since you stroked it are your injectors big enough? I assume you had the computer tuned after the rebuild? I did a stroked LS for a limited class pulling truck. we actually used a trailblazer intake as they say it is one of the best stock ones, and it had OEM flexfuel injectors, they are just on the edge of being to small. When I tuned it on the dyno I got a lot of power getting the injectors rich enough at wot, so the computer would advance the timing. The knock system would not let it have full advance until we got it rich enough at WOT. And just by the seat of the pants most OEM computers will retard the timing right before the trans shifts, if you disable that it feels like 50HP The engine I did had to hold 16 inches of vacuum at idle, and run on pump gas, we got 525HP out of it. guy was happy because it was a competitive truck before, and now the tires spin before the sled pulls it down to nothing.

I have 1 7/8" x3" ARH long tubes, came with a 3" y pipe but I plan to fabricate a x pipe instead. Also using DW 50# injectors, plenty of room there. Only start pushing the limit if I was to run E85 which is non-existent up here in the north east.

[dfarr67]

Supercharge it.

[PackardV8]

The engine made very good power(662hp@6650) for what it is but I am looking for ways to pick up another 25hp or so.

Another 25 hp is 3.7%, almost down to the level of dyno repeatablity and correction. It's doubtful if you could feel the difference on the street.

Supercharge it was a good suggestion. That, you could feel.

[1980RS]

Put the cam on a 110° LCA.

[SlowTBSS]

The engine made very good power(662hp@6650) for what it is but I am looking for ways to pick up another 25hp or so.

Another 25 hp is 3.7%, almost down to the level of dyno repeatablity and correction. It's doubtful if you could feel the difference on the street.

Supercharge it was a good suggestion. That, you could feel.

The engine made 660-662 4 runs in a a row so it's pretty much dead on. Definitely not going to be supercharging it with the high compression and tight quench.

[Walter R. Malik]

The engine made very good power(662hp@6650) for what it is but I am looking for ways to pick up another 25hp or so.

Another 25 hp is 3.7%, almost down to the level of dyno repeatablity and correction. It's doubtful if you could feel the difference on the street.

Supercharge it was a good suggestion. That, you could feel.

The engine made 660-662 4 runs in a a row so it's pretty much dead on. Definitely not going to be supercharging it with the high compression and tight quench.

Whatever makes YOU happy is all that counts...