This debate had gone on for long enough, I had conflicting numbers the past few times I switched TB's from 70 - 75mm, well in conclusion I lost a little tq and response with the 75 but gained a nice little 5 hp up top. Now I was reading and writing in another thread and realized I never port matched my elbow to the 75 so hmmmm. Ok I got a 75mm ported edel elbow and went to work, Not only did I gain a nice 5tq spike down low but I gained 1 more hp up top so a nice round 6hp!! I couldnt get my throttle response up to par with the 70mm but I just proved myself wrong in a couple ways:
1. Good power and tq on an otherwise stock shortblock.
2. Throttle body size does make a difference down low
3. I did lose throttle response ( not a huge deal), and with the proper tune can and will get it back.
Ok so now that I have done the research, so far most are correct, stock motor with stock top end doesnt benefit from the 75mm, h/c/i cars can and will benefit from it, the 70 mm still has more than enough to offer. Mind you all as well, this has been an ongoing debate with me and my friends. My buddy Steve said go with the 75mm from the get go I tried then went against it because I thought I was right with the 70mm, (sorry Steve I was wrong), but I was right by saying that it would not benefit a stock motor (stock h/c/i car) a 65 or 70 was much better. Well cleared up lots of my confusion. But I got proven wrong in the process which I hate, but ohh well. I am now wiser than Grasshopper
1. Good power and tq on an otherwise stock shortblock.
2. Throttle body size does make a difference down low
3. I did lose throttle response ( not a huge deal), and with the proper tune can and will get it back.
Ok so now that I have done the research, so far most are correct, stock motor with stock top end doesnt benefit from the 75mm, h/c/i cars can and will benefit from it, the 70 mm still has more than enough to offer. Mind you all as well, this has been an ongoing debate with me and my friends. My buddy Steve said go with the 75mm from the get go I tried then went against it because I thought I was right with the 70mm, (sorry Steve I was wrong), but I was right by saying that it would not benefit a stock motor (stock h/c/i car) a 65 or 70 was much better. Well cleared up lots of my confusion. But I got proven wrong in the process which I hate, but ohh well. I am now wiser than Grasshopper
Thanks for sharing your results. Did you have to add more fuel with the 75mm to get the a/f right? What i'm asking is, did the extra air from the 75mm lean you out a little? Now get some track times which are WAY more important than a chassis dyno.
YESSSS you should have just sold the elbow and got a trick flow elbow. Its already 75mm.
