Iwas driving my car the other day and was getting on the interstate,which had a very short merge lane.Put my foot in it some as to not get runover by a couple 18 wheelers and watching my tach(NEW).The tach rose past my normal shift of about 4500 rpm i let my foot out some at 5100 or 5200 but it was pulling hard even right up to me shifting.I thought the tpi started falling on its face at 4750 rpm but i couldnt tell it does.Its a new engine so i really hadnt been running it up much and hadnt noticed this before especially when i had my 305.Could it be my cam(i cant remember the rpm range on the LT-4 )having more lift and also my msd system?My tpi is stock other than homemede ram air,k&n`s and airfoil so i figured the power range would stay the same because of the bottle neck which ie the tpi.This is my first built performance engine and its not even built that strong.I`m still learning and i do searches daily and i didnt see anything really saying anything extending the rpm power range or the stock tpi othr than porting or aftermarket intake pieces.Was wondering if my tach might be off but its only 2 weeks old.Thats why i guess i never noticed it cause my stock tach was fried.Anyway is this fairly normal to still feel it pulling like crazy even though its power is falling off sharply.What do yall think?Check my sig for mods.Thanks I got a lot to learn.-Grady-

 

The major limiting factors for a TPI revving over 4,500 while making power are valve springs, ignition, and air flow. You're evidently resolved the ignition problem with the CD box. If you installed resonably good valve springs with the replacement cam, that would have resolved the valve float potential (weak springs). The cam profile itself will affect how the induction system delivers fuel/air charge. The fact that the only remaining restriction might be the size of the iuntake tract, and you are realizing the benefits of eliminating the other weak points.