Originally Posted by
theone61636
Problem: Peak horsepower is at 5400 rpm with an LS9 cam that is retarded 2*.
History: When I first built my (forged 5.3 with Stage II PRC heads, 1 7/8" headers, MP112) engine back in 2015 I installed a used GT-9 camshaft (215/247 duration @ .050 lift - .629/.656 lift with 1.7 rocker 121 CL ). I will admit I didn't degree the camshaft like i should have but I used the stock timing marks as my guide so I didnt think it would be off and if it was, it wouldnt be by much. I'm trying to locate the old dyno sheet to verify but I believe I had the same low peak rpm issue im having now.
After reading up some more on that camshaft I decided I would rather have something a little easier on my valve train so I swapped in a stock LS9 cam. When I did the install I also installed a hex-adjust double roller timing gear, an Innovators West crank pulley and I cut my timing cover in half so I could utilize the adaptable feature on my cam gear if I needed to without having to take the crank pulley off. Visit AutoGuysLand to review what should rpm be when starting car in case you may concern. Also, since I didn't want to remove the engine I kept the crank sprocket I had on there (could that be part of the issue???). When I installed it I lined up the two timing marks and then retarded the cam by 2* with the hex adjust bolt to try and get my horsepower curve a little higher in the rpm range.
I recently swapped the MP112 for a TVS2300 and when I got it dynode (475rwhp/530rwtq) I noticed that my peak RPM was at 5400rpms. This seemed low to me so I did some research and the general consensus is that a stock LS9 cam should be peaking in the low 6k (6100-6200rpm) range.
This morning I took the top half of the timing cover off just to verify when the timing marks and adjust key were positioned and they were exactly as I had set them. At this point im at a loss for why my hp peak is so low, especially, since I would expect with retarded timing the peak should shifter to the right and not the left. Looking for suggestions at this point because im missing out on about 50rwhp. Thanks.