Let me first start off by saying I am sorry if this is a stupid question. Now with that said. I just got done building my 383 stroker. Its complete forged rotating assembly Brand new internal balance. 10.3:1 compression, I bought a Trick Flow 490 HP Super 23 Top-End Engine Kit (TFS-K314-490-440). I followed what they said they used for a intake(Victor Jr) and carb(holley 750 DP) it states you will have 490 Hp. I know you cant believe that but I should be close to that. Now I have Hayes Flywheel and PowerGrip Clutch. My rear end is a built 10 bolt that has been in the 10's with another car. My trans is a stock t5 that came with the car. I know the factory never put t5 behind 350.

Now here my question. I took the car to the track friday for the first time ever. I ran 13.8 at 103 with a 2.091 60ft, I was pretty upset figured i be in the high 11's to mid 12's. Now I know there a 18% Power lost to the wheels with a manual trans which should leave me around 400hp to wheels. Now I ran those number thru and engine calucator and it says i am only make 280-290 hp to the wheels. Can a stock t5 hold the motor back that much? Please help

 

No, the kit advertisement DOES NOT "state that you will have 490 HP"; what it REALLY states is that THEY got 490 HP out of it, in a meticulously built, every detail managed to the hilt, super-tuned, optimum external conditions, dyno mule. That is VASTLY different from somebody buying a parts list and then expecting to duplicate those numbers in a car.

For example, what's your deck clearance? How consistently accurate is it from cyl to cyl? What rings did you use? What's your altitude? What was the air temp and "density altitude" when you ran at the track, compared to the air they used? What oil did they use: was it something common-sensical like 5W-20 while you used "racing" 20W-50 candle-wax and gave up 15 - 20 HP right there? Do you know if their "490 HP" included a water pump, alternator, PS pump? What exhaust have you got? Is it carefully tuned to maximize dyno numbers, or is it something that fits in the chassis? And on and on and on and on and .....

Then there's the matter of the driver. 2.09 is a pitiful 60'; alot of 305s will smoke you right there. That should be AT LEAST .2 - .3 lower. There's a good ½ second of ET you're missing, right there. Then if you have a T-5, I'm sure you shifted it gently to keep from grenading it, which is another several tenths right there. Those 2 things ALL BY THEMSELVES will get you at least into, or very close to, the 12s.

All in all it doesn't sound to me like you need to be worrying about drive train losses. Your greatest opportunities for improvement lie elsewhere for the time being. Some you've already given up, by whatever possible perfections you overlooked during your engine build (and I assure you, no matter how good you think you did, there's ALWAYS more to improve on especially with a stock block), but some are still available to you.