New Much Bigger Cam and Lose 30 RWHP WTF????
08-24-2005, 12:20 PM
#1
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New Much Bigger Cam and Lose 30 RWHP WTF???? My friend and I are flabbergasted we just put in a Comp XER 242/248 .610/.615 111lsa. Heads were reworked by AFR, sodium valves, Comp 921's, and milled another .010 for a total of .034. Pistons were notched, Cometics .040, Ford SVO 30's, and Racetronic Plug and Play.The car this morning dynoed a best of 402 rwhp with af at 13.
Before the latest cam swap, the car had a Comp 224/228 .581/.588 and put down 430 rwhp with a Fast 90/90. Now we're putting down 402 rwhp when we should be putting down 470 rwhp. This is nuts what could be wrong? The cam was degreed in correctly. We notched .100 on the intakes and .060 on the exhausts. This car ought to be putting down 70 more HP than it is, HELP!!!
Before the latest cam swap, the car had a Comp 224/228 .581/.588 and put down 430 rwhp with a Fast 90/90. Now we're putting down 402 rwhp when we should be putting down 470 rwhp. This is nuts what could be wrong? The cam was degreed in correctly. We notched .100 on the intakes and .060 on the exhausts. This car ought to be putting down 70 more HP than it is, HELP!!!
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08-24-2005, 01:29 PM
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Paul at Thunder Racing uses 30# SVO up to and including 427 ci in just not on FI. It can't be injector because the overlay of the old dyno run shows the new run giving up about a 1/2" under the old curve vs the new curve the whole way across.
08-24-2005, 01:31 PM
#13
What RPM did you stop the pull at? Was the graph still climbing? With that cam you just might need to spin it higher to see the peak #s. That is a pretty big cam. Were the LSAs and ICLs of the new and old cam the same, only the duration and lift changing?
08-24-2005, 01:38 PM
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The rockers and lifters are OEM, Comp and Thunder say they are more than sufficient. We did about 6 runs they all sounded great, timing was 30*+ running to 6,900 rpm. If we hadn't checked the cams lift I woud say maybe it was a smaller cam since it idles so well. My friend is going to do a compression and leakdown test.Not sure it will prove anything. If we had only gained 20 hp over the initial 430 wouldn't be all that great, but to lose 30 hp is a bitch.
08-24-2005, 01:44 PM
#16
Isn't a 242/248 cam to damn big for a 346" motor 
? Maybe bigger isn't better in this case. Perhaps with the reworked heads and that much cam your intake charge velocity went into the toilet.
If you think you can make this cam work, you might want to try some bigger injectors for a better margin of error.
? Maybe bigger isn't better in this case. Perhaps with the reworked heads and that much cam your intake charge velocity went into the toilet.If you think you can make this cam work, you might want to try some bigger injectors for a better margin of error.
08-24-2005, 02:20 PM
#18
When you overlay the dynos, is it down on power at all rpm or just at higher rpm? Could be an unplugged injector or spark plug. 402 rwhp/7 = 57.4 rwhp per cylinder. Add 57.4 back to the 402 and you get 459.4...pretty close to your 470 number.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
08-24-2005, 02:28 PM
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Originally Posted by 1CAMWNDR
Isn't a 242/248 cam to damn big for a 346" motor ? Maybe bigger isn't better in this case. Perhaps with the reworked heads and that much cam your intake charge velocity went into the toilet.
If you think you can make this cam work, you might want to try some bigger injectors for a better margin of error.
? Maybe bigger isn't better in this case. Perhaps with the reworked heads and that much cam your intake charge velocity went into the toilet.If you think you can make this cam work, you might want to try some bigger injectors for a better margin of error.
08-24-2005, 02:38 PM
#20
This is kind of related....
We overlayed my dyno graph which is a stock 346 with flycut pistons, AFR 205's milled .024", TSP 233/239, LT headers, stock LS6 intake/ported TB on top of my buddies graph. He runs a stock 346, GTP Stage 3 5.3 heads (flowed 320cfm+ supposedly), TSP 225/225, the same LT headers, cleaned up/ported LS6 intake/ported TB).
I saw that he made 30-40rwhp more in the low RPM's and only at 6200rpm did mine finally make more power. It was only 5-10rwhp more though. My torque from 2500-5000 was way behind his also! Big cams have much higher powerbands that are soggy down low.
We also overlayed his 233/239 graph with same mods as above over mine and they were nearly identical. He did make 5rwhp or so more in certain parts; however aside from that they were about dead nuts even.
For you to make less power than the 224/228 would mean you have other problems. That is one big honkin' cam. Expect your strong powerband to be in the 5500-7000rpm+ range. Below that it will be sleepy compared to the 224/228 setup.
Was this dynoed at the same place with same air temps?
We overlayed my dyno graph which is a stock 346 with flycut pistons, AFR 205's milled .024", TSP 233/239, LT headers, stock LS6 intake/ported TB on top of my buddies graph. He runs a stock 346, GTP Stage 3 5.3 heads (flowed 320cfm+ supposedly), TSP 225/225, the same LT headers, cleaned up/ported LS6 intake/ported TB).
I saw that he made 30-40rwhp more in the low RPM's and only at 6200rpm did mine finally make more power. It was only 5-10rwhp more though. My torque from 2500-5000 was way behind his also! Big cams have much higher powerbands that are soggy down low.
We also overlayed his 233/239 graph with same mods as above over mine and they were nearly identical. He did make 5rwhp or so more in certain parts; however aside from that they were about dead nuts even.
For you to make less power than the 224/228 would mean you have other problems. That is one big honkin' cam. Expect your strong powerband to be in the 5500-7000rpm+ range. Below that it will be sleepy compared to the 224/228 setup.
Was this dynoed at the same place with same air temps?
Last edited by gnx7; 08-24-2005 at 02:54 PM.