BTR stage 2 V2 cam
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Narrow LSA's and a lot of advance close the intake valve sooner to compensate for lower dynamic compression to boost Tq. Big exhaust duration extends power higher in RPM in exchange for worse low end Tq. You lose about 100rpm of top end power for each degree tighter on the LSA. You don't need big exhaust duration if the cam wasn't using a tight LSA and so much advance.
Why wouldn't you just run more compression (more power everywhere) and reduce the overlap with a wider LSA? I tried a 230/242 along with the 230/234 and the difference was 3hp. Both pulled to 7K. The intake manifold on both the LS2 and LS3 force the peak around 6300-6400 rpm due to runner length. Cams that dyno great on peak HP are the ones that have a power peak that coincides with the intake manifold's peak.
The reason GM used big splits was not because the heads need it but rather the small intake duration falls on its face at 5900rpm and they used the added exhaust duration to extend the power band higher. Once you get around 230 intake duration, a single pattern cam like Pat G used on his G8 pulls to red line. PAtG's cam then was a 231/231 .617"/.617" 114 LSA +2.
Why wouldn't you just run more compression (more power everywhere) and reduce the overlap with a wider LSA? I tried a 230/242 along with the 230/234 and the difference was 3hp. Both pulled to 7K. The intake manifold on both the LS2 and LS3 force the peak around 6300-6400 rpm due to runner length. Cams that dyno great on peak HP are the ones that have a power peak that coincides with the intake manifold's peak.
The reason GM used big splits was not because the heads need it but rather the small intake duration falls on its face at 5900rpm and they used the added exhaust duration to extend the power band higher. Once you get around 230 intake duration, a single pattern cam like Pat G used on his G8 pulls to red line. PAtG's cam then was a 231/231 .617"/.617" 114 LSA +2.
Last edited by SpinMonster; Aug 23, 2022 at 12:38 AM.
Racer
Joined: Jan 2015
Posts: 375
Likes: 31
From: San Antonio TX
Generally speaking, any cam in a LS3 with 11* overlap or less will still make for a decent daily driver; but at 8.5* overlap, this cam will still have a noticeable chop!
KW
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Not saying any amount of overlap can't be tolerated. I've seen guys say that 14 degrees of overlap is a baby cam. I had one in an LS3 with 9 degrees and absolutely hated it. I hate to see any of my Corvette brothers struggle with a nasty/ill behaving setup. It's just not necessary.
The small intake duration cams with a bunch of advance that create really high DCR's will have more issues than their amount of overlap would indicate. Just know what you're getting into.
If you're depending on a guy's rec that has had all of "one" cam to steer you in the right direction, good luck. Also, if you 100% believe everything a cam seller tells you, also good luck.
The small intake duration cams with a bunch of advance that create really high DCR's will have more issues than their amount of overlap would indicate. Just know what you're getting into.
If you're depending on a guy's rec that has had all of "one" cam to steer you in the right direction, good luck. Also, if you 100% believe everything a cam seller tells you, also good luck.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Not saying any amount of overlap can't be tolerated. I've seen guys say that 14 degrees of overlap is a baby cam. I had one in an LS3 with 9 degrees and absolutely hated it. I hate to see any of my Corvette brothers struggle with a nasty/ill behaving setup. It's just not necessary.
The small intake duration cams with a bunch of advance that create really high DCR's will have more issues than their amount of overlap would indicate. Just know what you're getting into.
If you're depending on a guy's rec that has had all of "one" cam to steer you in the right direction, good luck. Also, if you 100% believe everything a cam seller tells you, also good luck.
The small intake duration cams with a bunch of advance that create really high DCR's will have more issues than their amount of overlap would indicate. Just know what you're getting into.
If you're depending on a guy's rec that has had all of "one" cam to steer you in the right direction, good luck. Also, if you 100% believe everything a cam seller tells you, also good luck.
I saw a guy post a result for ported stock LS3 heads with a 13 degree overlap big cam and made 493rwhp. I see cam only results getting that with 4 degrees overlap. In short, don't try to reinvent the wheel and just go with a proven cam that you can find many factual dyno results for. These results should be posted by the end user and not hand picked to sell a cam.
Example (and I'm not selling anything):
LS3 with stock heads 230/234 4 degrees overlap posted by a forum member that I didn't install or tune:
If a cam vendor says that a cam makes more power, compare the dyno results not just at peak, but at all rpm's.
Now if you do bump compression and use Trick Flow 235's you have 520rwhp 470rwtq with the same cam.
Last edited by SpinMonster; Aug 24, 2022 at 02:21 PM.
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Melting Slicks
Joined: Oct 2010
Posts: 3,029
Likes: 794
From: Tollesboro Kentucky
I figured Spin was wanting a chassis dyno,not the engine dynos on his website.I talked to a couple of guys that were using it and they seemed happy with it.I have the older version and was curious how the curves looked on the V2.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Yes, I'd like to see what it makes on a chassis dyno.
Safety Car
Joined: May 2006
Posts: 3,696
Likes: 490
From: Potomac MD
Spin has been doing this a while and has tested a lot of stuff. Cylinder head, intake manifold and cubic inches can also make things different. A 6.2 liter is going to response differently to cam than a 7.5 liter one (you need about 10 degrees more for similar power ban). I would also agree on these cars the intake manifold especially stock has its rpm limitations no matter what your cam is. So you can have a 220 duration intake and a 250 duration intake cam and the peak power ban may only be a few hundred more because the OEM intake manifold is the limit. However, the rpm needed to get to say 450 rw tq goes from 3,000 rpm to 4,500 rpm resulting in a soggy bottom end with little top end to gain. I run a 246/258 on a 114 (23 degrees of overlap) 650 lift in a 454 with Brodix BR7 heads 12 to 1 compression and a ported MSD it peaks at 6,500 and I could probably take 5-8 degrees out and not notice anything but better street manners. The different duration in the BTR cam in the same family (ie Stage 2) of a few degrees here and there are probably not drastically noticeable but are more of a refinement from earlier versions. PS - a heavy flywheel (for stop and go traffic / idle) and gears can help when you get into larger cams.
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
Just got mine back to from the shop. Ended up going with the STG 1 V2 on suggestion from BTR rep and tuner. According to BTR it makes more power than the old btr2 and within 5 of the BTR 3. I have an A6 and a single disc converter, so it couldn’t be locked during the dyno tune ( and on a stingy dyno too). Made 455@6500 HP, torque was 445@5200 but torque curve was a table top from 3500 to 6500. I’m using a Yank ss3600 converter.
Drove home 3 1/2 hours trouble free, still getting 30mpg on freeway. Other mods were SE headers and catless mid, npp axle back, rod mod intake mod. VERY happy with how it runs. I can nail it at 30 in second and get sideways. Have no doubt that it will get into the 10’s. For a cam with only 217@.050 intake duration (23x @.050 exhaust) it has a little chop. Won’t let me upload startup video, it’s a little too big.
Drove home 3 1/2 hours trouble free, still getting 30mpg on freeway. Other mods were SE headers and catless mid, npp axle back, rod mod intake mod. VERY happy with how it runs. I can nail it at 30 in second and get sideways. Have no doubt that it will get into the 10’s. For a cam with only 217@.050 intake duration (23x @.050 exhaust) it has a little chop. Won’t let me upload startup video, it’s a little too big.
Thread Starter
Melting Slicks
Joined: Nov 2011
Posts: 3,187
Likes: 266
From: Virginia
Just got mine back to from the shop. Ended up going with the STG 1 V2 on suggestion from BTR rep and tuner. According to BTR it makes more power than the old btr2 and within 5 of the BTR 3. I have an A6 and a single disc converter, so it couldn’t be locked during the dyno tune ( and on a stingy dyno too). Made 455@6500 HP, torque was 445@5200 but torque curve was a table top from 3500 to 6500. I’m using a Yank ss3600 converter.
Drove home 3 1/2 hours trouble free, still getting 30mpg on freeway. Other mods were SE headers and catless mid, npp axle back, rod mod intake mod. VERY happy with how it runs. I can nail it at 30 in second and get sideways. Have no doubt that it will get into the 10’s. For a cam with only 217@.050 intake duration (23x @.050 exhaust) it has a little chop. Won’t let me upload startup video, it’s a little too big.
Drove home 3 1/2 hours trouble free, still getting 30mpg on freeway. Other mods were SE headers and catless mid, npp axle back, rod mod intake mod. VERY happy with how it runs. I can nail it at 30 in second and get sideways. Have no doubt that it will get into the 10’s. For a cam with only 217@.050 intake duration (23x @.050 exhaust) it has a little chop. Won’t let me upload startup video, it’s a little too big.
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
My original plan was the original stage 2 but between waiting on my appt (3 1/2 months, busy shop) and getting it there, the new versions came out. This one sounds rowdier than the 224r cam I had in my ls1 z28. Must be the big exhaust duration.
Le Mans Master
Joined: Dec 2005
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From: Southeast TX
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I understand the need for trade secrets but if a cam is an outdated design and no longer sold or if the results are not what was expected, meaning it's a failure, what's the point of secrecy with the specs? Wouldn't it help the end user to not do something with design in order to save people money and heartache? I've always felt that by sharing specs and collaborating, we would have head/cam packages at 535rwhp on a 6.2L
Last edited by SpinMonster; Oct 20, 2022 at 04:32 PM.
Instructor
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