Since we're playing the guessing game and we have the answer for horsepower, how about you Brent, making some guesses.
If you substituted the custom flat tappet used for a shelf 306S, how much would you guess that would hurt power?
Myself guessing that you mean by no porting that only a valve job was done and no tootsie roll action, would you guess the TFS head is the go-to part for this type of build?
Would you guess that a hydraulic roller could have made more power?
Of course you don't absolutely know the answers. Just asking for educated guesses.
Tommy,
On paper, a 306S should be low on duration and lift, with lazier lobes and not enough split to really help things at high rpm. However, I've been surprised before with cams that performed, "that shouldn't have".... My guess is that it would be down 20-25?
? It's just a wild guess at this point, since I've never ran one.
I think there's even more power left in this engine if the owner wanted to get a little more aggressive with it. He's running an A/FX Falcon, in a local (to him) class with a few other guys in it that just want to play and have fun. He wanted something low-maintenance that made good horsepower. This cam uses Comp's "Hi Tech" solid lobe, which is pretty easy on things. I did nitride the cam and use tool steel lifters which have an oiling hole for added insurance. I would have went solid roller, but the way these goofy TFS heads are, I was about afraid to start cutting on them for a T&D race rocker bar mount because I didn't know what I would get into. You already have to mill the poop out of the rocker stands to get any kind of geometry whatsoever.
These have a valve job and no sand roll action at all. Buy them bare, do a VJ, assemble with correct valvetrain parts. So in comparison to another build, a 465 ci Tunnel Port build made 696 hp and 588 torque. Same compression ratio, same rod length, but the TP engine had a solid roller with same duration and about .750" lift. Those TP heads were ported/filled and flowed 370-380 cfm. I think that says a lot for the TFS heads, performance-wise. These were the second set that I've used and I've been pretty pleased with them. In addition, they only needed 30° total timing where the TP heads needed 40-41.
Since I have had two builds with out-of-the-box TFS heads, I'd like to do 1-2 with some worked pieces. They have a turbulent spot in them at around the .650" lift mark and I think they could be improved on a little. Still, for the price, I think they are really nice pieces, even with the hoops you have to jump through to get them to work right.
Would a HR have made more power? Nah. At the level of duration necessary for this size engine and rpm range, the advertised duration for a hydraulic roller would have been astronomical. The drawback to a HR camshaft is that the lobes are normally way less aggressive, so the advertised durations are relatively high.....which increases overlap.....which can make an engine very inefficient. This camshaft has 86° of overlap. A hydraulic roller of this duration range, even with a 114 LSA, would have had probably around 95° of overlap. We're just bench racing here really, but I just don't think a HR would have been competitive at this level.
