Do I have the right cam for the job?
04-29-2015, 11:38 AM
#1
Staging Lane
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Do I have the right cam for the job? 
Road race/time attack car: looking for max power 'under the curve' - 2500 to 6000rpm. Don't really care for max power as the car will probably never see a dyno. I'll be tuning for around 12.2-12.8 AF on the track.
I emailed and called a few shops and narrowed it down to 3 choices.
226/238 113 + 3
228/240 113 + 4
230/242 112 + 4
And ended up getting cam number 1...
226/238 113+3 LXL Lobe Comp Cam.
Engine:
LS3 block, LS6 crank (24x), LS3 rods, Mahle 4.070 power pack pistons -4cc.
Heads: LS3 PRC CNC heads from Texas Speed with hollow stem intake valves complete with their double springs.
Intake: LS3 with LS2 throttle body. LS7 Airraid cold air. No MAF.
Exhaust: TSP headers, x pipe, no cats and straight pipes.
Tune: self with HP Tuners SD tune
I took the car out last weekend for a few heat cycles and to brake her in with a rough (read safe base line) tune.
Only taking her to 5k WOT she did not feel that much stronger than my old heads and cam (230/234 112+4) LS6 at 435rwhp?
Did I expect too much or is it just the tune? I will be taking her to the track this weekend for a proper tune at full speed...
What do you guys think?
04-29-2015, 11:49 AM
#2
What's the compression on that thing? And what was your previous setup?
But based on what you said, I can't imagine that the new build is going to have that much more torque under 5000rpm than the old one for you to be thoroughly impressed. Above that you may see quite a bit of improvement.
My guess is compression, the lack of a full tune and the fact that you did not spin it past 5k is what made this not feel too different.
But based on what you said, I can't imagine that the new build is going to have that much more torque under 5000rpm than the old one for you to be thoroughly impressed. Above that you may see quite a bit of improvement.
My guess is compression, the lack of a full tune and the fact that you did not spin it past 5k is what made this not feel too different.
04-29-2015, 12:12 PM
#3
TECH Veteran
These LS3 headed combos seem to be so hit or miss.... you go have to do your homework especially if you want that "under the curve" power you mentioned in your post... go be even trickier due to you having less than 400 cubes/ not using a 4.000" crankshaft...
225/238 .612"/.585" 113+3 is a cam I have seen that does decent on the torque curve. It produces 470 rear wheel horsepower and 440 ft lbs or torque at the tire threw a m6 5th gen camaro.
Truth is people overcam these combos. It's a totally different ball game specing a cam for a rectangular head vs a cathedral head...
In my opinion it sound like you like torque and in my book cathedral heads such as tfs/afr/mamo heads is where it's at.
Hope this helps you out... here is a good thread to read before buying a cam for your setup.
https://ls1tech.com/forums/generation-iv-internal-engine/1090339-cam-l92-heads-lessons-learned.html
225/238 .612"/.585" 113+3 is a cam I have seen that does decent on the torque curve. It produces 470 rear wheel horsepower and 440 ft lbs or torque at the tire threw a m6 5th gen camaro.
Truth is people overcam these combos. It's a totally different ball game specing a cam for a rectangular head vs a cathedral head...
In my opinion it sound like you like torque and in my book cathedral heads such as tfs/afr/mamo heads is where it's at.
Hope this helps you out... here is a good thread to read before buying a cam for your setup.
https://ls1tech.com/forums/generation-iv-internal-engine/1090339-cam-l92-heads-lessons-learned.html
04-29-2015, 12:19 PM
#4
Those PRC heads are more balanced E/I ratio than the GM heads and there for do not need so much split (additional Ex. timing)
A friend of mine who ran those heads on his LS3 used TSP's 231/236 cam and made 530 RWHP STD
Car was a Grand Sport Vette M6 with Vararam intake and catless TSP headers, ZO6 cat back
A friend of mine who ran those heads on his LS3 used TSP's 231/236 cam and made 530 RWHP STD
Car was a Grand Sport Vette M6 with Vararam intake and catless TSP headers, ZO6 cat back
04-29-2015, 12:29 PM
#5
TECH Veteran
Those PRC heads are more balanced E/I ratio than the GM heads and there for do not need so much split (additional Ex. timing)
A friend of mine who ran those heads on his LS3 used TSP's 231/236 cam and made 530 RWHP STD
Car was a Grand Sport Vette M6 with Vararam intake and catless TSP headers, ZO6 cat back
A friend of mine who ran those heads on his LS3 used TSP's 231/236 cam and made 530 RWHP STD
Car was a Grand Sport Vette M6 with Vararam intake and catless TSP headers, ZO6 cat back
Only thing about these heads is that the runners are humongous!! Which is said to hurt velocity which velocity is a BIG DEAL when trying to make a stump puller tire frying motor.
I study all motor builds a lot and I notice these LS3/L92 really start to make that power at 4000-5000 rpm..
04-29-2015, 01:18 PM
#6
Only thing about these heads is that the runners are humongous!! Which is said to hurt velocity which velocity is a BIG DEAL when trying to make a stump puller tire frying motor.
I study all motor builds a lot and I notice these LS3/L92 really start to make that power at 4000-5000 rpm..
I study all motor builds a lot and I notice these LS3/L92 really start to make that power at 4000-5000 rpm..
04-29-2015, 03:16 PM
#7
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As mentioned already 280 CC Port is huge for 376" below/up too
6000 RPM when what you want is throttle response on a road
Course especially, and with a better I/E ratio 8* more on exhaust
Especially below 6000 RPM would be plenty. Keeping those heads and
That displacement below/uptoo ~6000 RPM 224*/232* OR SMALLER!
would perform Much better for your goals IMO.
But spend the $50.00 and have a Pro spec it for you
Pat G., Martin, Kip etc.
MMS 220 Heads with 227*/231*-231*/235* Cam from 1500-6000 RPM
would annihilate almost any square port head with those CI and
RPM Parameters, at any point from 2500-6000 RPM!
6000 RPM when what you want is throttle response on a road
Course especially, and with a better I/E ratio 8* more on exhaust
Especially below 6000 RPM would be plenty. Keeping those heads and
That displacement below/uptoo ~6000 RPM 224*/232* OR SMALLER!
would perform Much better for your goals IMO.
But spend the $50.00 and have a Pro spec it for you
Pat G., Martin, Kip etc.
MMS 220 Heads with 227*/231*-231*/235* Cam from 1500-6000 RPM
would annihilate almost any square port head with those CI and
RPM Parameters, at any point from 2500-6000 RPM!
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04-29-2015, 04:59 PM
#8
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I know and realize the L98 engine is different but here is what I found thru trial and error, no other changes
406CI engine 11.0:1 CR, AFR 210 CC heads ported and 3-angle valve job, the heads flowed a max of 297 at .600"
Hyd-Roller Bullet Cams custom grind
225/233 = 276/284 w/112LS = 355-RWHP / 385-RWTQ
233/233 = 284/288 w/112LS = 385-RWHP / 410-RWTQ
238/242 = 293/300 w/112LS = 430- RWHP / 460-RWTQ
406CI engine 11.0:1 CR, AFR 210 CC heads ported and 3-angle valve job, the heads flowed a max of 297 at .600"
Hyd-Roller Bullet Cams custom grind
225/233 = 276/284 w/112LS = 355-RWHP / 385-RWTQ
233/233 = 284/288 w/112LS = 385-RWHP / 410-RWTQ
238/242 = 293/300 w/112LS = 430- RWHP / 460-RWTQ
04-30-2015, 08:40 AM
#9
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What's the compression on that thing? And what was your previous setup?
But based on what you said, I can't imagine that the new build is going to have that much more torque under 5000rpm than the old one for you to be thoroughly impressed. Above that you may see quite a bit of improvement.
My guess is compression, the lack of a full tune and the fact that you did not spin it past 5k is what made this not feel too different.
But based on what you said, I can't imagine that the new build is going to have that much more torque under 5000rpm than the old one for you to be thoroughly impressed. Above that you may see quite a bit of improvement.
My guess is compression, the lack of a full tune and the fact that you did not spin it past 5k is what made this not feel too different.
Old setup: stock block Ls6, 243 heads shaved .010 and a self port job - rocker hump removed, swirl ramp removed, a little bowel work, port matched intake and exhaust with a 3 angle valve job etc...
Flow numbers were around 285@.600 intake and 190@.600 exhaust iirc...
Cam: 230/234 .605/.612 112+4
Self ported LS6 throttle body with half shaft mod and same exhaust.
New motor: Close to stock compression I assume with the 68cc PRC heads. Flow numbers from TSP website are
351/228 @ .600
I have problems with false readings in the spark histogram and I am still dialing in the knock sensor sensitivity so I know timing is not optimal yet.
Hopefully I will have everything sorted out by this weekend...
I would hate to pull this cam and do it all over again! My first race is in 3 weeks
04-30-2015, 08:50 AM
#12
New motor: Close to stock compression I assume with the 68cc PRC heads.
Now rev that thing out to 7000rpm and it will completely blow away your old setup, especially once tuned. So really it's all in the combination and where you use it. You set yours up for high RPM driving and that's where this will shine.
But like 96capricemgr said, this doesn't seem to match your previous statement/goal of
looking for max power 'under the curve' - 2500 to 6000rpm. Don't really care for max power
04-30-2015, 11:15 AM
#13
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I shamely admit that the build started out with that big power dream... It wasn't until later when it came to ordering the cam that I realized more TQ down low could mean less shifting... More average speed infield and less wear and tear.
05-04-2015, 08:21 AM
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Just got back from a day at the track...
Idle video:
http://youtu.be/IcJjZT7WSbk
5 x 20mins sessions, burning thru 120 liters of fuel...
SOTP may not be all that exciting but laptimes show it's much faster. Also had some wheelspin in 3rd at 3500rpm coming of a few corners that I never had before so it definitely has more power down low...
How smooth the power comes on and just keeps going is amazing!
Not a bad setup after all... 1st race is May 24 weekend then the real numbers will show😎
Idle video:
http://youtu.be/IcJjZT7WSbk
5 x 20mins sessions, burning thru 120 liters of fuel...
SOTP may not be all that exciting but laptimes show it's much faster. Also had some wheelspin in 3rd at 3500rpm coming of a few corners that I never had before so it definitely has more power down low...
How smooth the power comes on and just keeps going is amazing!
Not a bad setup after all... 1st race is May 24 weekend then the real numbers will show😎
05-05-2015, 09:05 AM
#16
Staging Lane
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Yeah I have to agree... A TQ build would have been
Interesting for sure.
However this setup works very well on the back straights... Around 5500rpm she REALLY takes off, putting my old motor totally to shame.
And power down low is atually not bad now that's it's tuned... Much better than the 1st time out.
Now that it's broken in, I can't wait to get back with fresh tires and up the revs a bit...
05-05-2015, 09:20 AM
#17
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With 68cc heads, -4cc pistons and I assume stock headgaskets, you are running just under 10.3:1 compression. And with that cam you're right around 8.0 DCR. None of that screams "torque" or "snappy" especially combined with a huge intake port. Now I know you don't necessarily need all the low end torque in the world in a light car
Now rev that thing out to 7000rpm and it will completely blow away your old setup, especially once tuned. So really it's all in the combination and where you use it. You set yours up for high RPM driving and that's where this will shine.
But like 96capricemgr said, this doesn't seem to match your previous statement/goal
Now rev that thing out to 7000rpm and it will completely blow away your old setup, especially once tuned. So really it's all in the combination and where you use it. You set yours up for high RPM driving and that's where this will shine.
But like 96capricemgr said, this doesn't seem to match your previous statement/goal
The car weighs 3100 with me in it lol. And it works so good in the higher RPMs!
I'll be changing my driving style accordingly
Thanks!