I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.
You mad some critical errors. Testing with dyno headers was a giant waste of time and money. You didn’t learn a damned thing doing that. Same with the air cleaner.
Run the engine on the dyno as close to the way it will run in the car. So basically your dyno numbers mean nothing.
Also, stop using ET to calculate your HP from the time slip. ET is hook. MPH is Horsepower.
You have no idea other than guesses what your engine actually makes for horsepower on a dyno. I’ve seen dyno headers beat chassis headers by 40 plus HP. That was header to header. There is now way you are only losing 30 HP going to manifolds unless the dyno headers are garbage.
All data is good data and an opportunity to learn. I do wish that I was able to run the engine on the dyno with the manifolds but, I didn't have that choice. I agree, we would have gained more valuable data if I could have run it on the engine dyno with the manifolds and the air cleaner on it.
I wasn't calculating anything with the post you quoted, just telling the group what mph it ran when it ran 12.25. The HP numbers I have quoted in my posts were numbers from either the engine dyno or a chassis dyno, taking into consideration the 18-22% loss through the drivetrain that seems to be the general rule of thumb, I understand that this can differ between combinations as well and is an educated guess. From there, I've tracked what I ran shortly after those numbers were made. I've utilized the different Wallace Racing Calculators to see if the numbers are in general alignment with what the car actually ran. In the past, they have been almost spot on, today, not so much; which leads me to believe that there's something wrong.
The loss in HP I had from a header to exhaust manifold swap was gauged by past results at the track. Again, with the new combination, it may be a little less or a little more. But, the short block, minus the cam, is the exact same in all combinations. The manifolds, carb, air cleaner housing, exhaust system, fuel system, etc., etc. is the same, from two of the combinations that I've run, and very close to the third. What I'm getting at is, it's highly unlikely to me that with so many similarities with the different things I've tried over the years, that the car was 8 tenths slower today, given similar weather and track conditions and the fact that I've never been this far off from the past combinations, with relatively similar parts. I feel that there is something wrong, like something failing, etc. and was asking for possible common things to look into. Maybe, in the end, I check all these things and determine that it's a miss with the combination and that nothing is wrong, and it is what it is. But I feel like something is wrong. Time will tell.
For example, I had a friend with a 69 Camaro.They switched from a healthy 383 small block to a 468 big block. The big block had several better parts, etc. and should have run much better than the 383. For two seasons, they tried various things. The car never really ran bad, it was just much slower than what the sum of all parts should have netted, and not much faster than the 383. They eventually switched to a whole new ignition system and bang, the car picked up 4-5 tenths. They suspect the MSD box was bad. Something stupid like this is what I feel might be going on with my car. I could be wrong but, with what I've learned over the years, I just think something stupid is going on. I don't know everything though, and would like the opinion of others, some with much more knowledge and experience than I, which is why I'm asking here. It could be a bunch of different things, or nothing at all and just a miss. Just trying to get some ideas.
