11.9:1, customer wants to mix fuel (hopefully he does it every time), Tf 270 heads, not tooooo large solid roller cam, KB block, Molnar crank and rods, Icon pistons. Really wanted 800HP but 795 is pretty close....

https://www.instagram.com/p/Crmg8_2rLF4/

What time of year and were was the testing done?

800 hp is a high bar to hit with a stock offset rocker arm and stock location exhaust port. I haven't hit it yet with those heads but we've come close a couple of times. What do you think of the new TF intake? How does it compare to the Super Victor? I think the SV is better out of the box than the Indy stuff but I don't really like the cloverleaf. The TF doesn't have the cloverleaf so that gives us another choice.

795 sounds like a really good number to me from that combo of parts.

Andy I was going to use the SV intake, had it here....but TF sent me this one and after measuring it up against the SV, it's about .250 in area larger than the SV in the plenum, very clean plenum transitions, and slightly shorter runners. So it was a no brainer really, less work for me, and I really wanted to see if it would make the power. It did!

Thanks Dwayne, I was concerned with it making anything over 750HP given the constraints of this build (stock ex. placement was one of them). I did however not leave the heads alone....I did a bunch of sonic testing on the ports, and had TF supply me with engineering info on the water jackets in the head.
I added a 2.25 hollow stem intake valve, changed the valve job, and did some porting to them. Andy, I believe I know the reason why you say this head likes a certain kind of cam timing, and after reworking the heads, I think I was able to remove that sensitivity issue.

My guess would be ....... larger throat %, and/or a steeper seat/top angle perhaps?

I just moved the install on my cam from 110.5 to 108 and lost 3 hp, but picked up 1 hp average, all of it gained between my stall speed and half way to the shift point I plan to use. So the magic number I was looking for means a little less to me now. I would love to see what this motor does in the lower half of its usable rev range. I bet it will make up for that 5 hp he was hoping to see . It may very well look better than most 800 hp street/strip builds of that size motor.

Brian, are you going to provide TF with some feedback on the head porting? Be interesting to see how well they understand the cam timing sensitivity. I'm not sure if that is a feature or a bug to them. I think it is a bug for racers although it might be a feature for street guys.

I didn't have the capability of porting the heads so I had to make my changes with the cam. Between Dwane and myself we found a solution. I was surprised at how sensitive the TF heads were to cam timing and lobe profile. If you don't get the right combo the heads aren't happy

Correct, throat is probably the largest deal...

I don't think they care what I found, and they aren't asking for any feedback. It's not a bad head, but I needed to make it work for low'ish compression and this CID so that's why I reworked them. In the process of doing that, I found at least a few things that I'm sure are causing the heads to act like you observed.

I spent quite a few hours on just finding and correcting the problems, so I'm keeping them close to the vest...but if you start measuring the ports out in the critical areas it becomes clear where the problems are...but until you actually make the changes and run the engine there's still a bit of doubt about the power they can produce. And I was not able to make them as large as I really wanted to in certain area's to get the air speed down, as the castings are really not as thick as I had hoped. In fact, you have to be very careful because they are thin is quite a few area's from a porting stand point. They aren't thin as they come out of the box, just a bit too thin to really open them up to work with larger engines or more rpm.

Yeah I remember the engine. Customer wanted 800 hp but needed to use those heads for a reason. He could've made more power with less investment by using a different head but that wasn't in the cards. Looks like you managed to work around the constraints and deliver what the customer needed. Looks like you also learned a few things in the process.

I think we can say the power limit for TF heads is around 800 NA. They make 750 easy as pie but that last 50 hp is the killer!

More compression and cam, and use of a vacuum pump should net another 30+HP I would think...

I realize the head mods are special, but can you share the cam specs?

Cam is 268-278@ .050, 112 lca. Lift at intake valve is .750 with the springs we're running. I used some of Comp's new inverse roller lobes...I've actually been using them in other engine builds for a while now, really like them.

Doesn't take a huge cam to hit 800 hp with those heads. It would be interesting to put an old Comp 290/290 0.650 flat tappet in an engine like that and see what happens. I'm thinking it would lose at least 100 ft-lbs and 100 hp if not more. Might lose 150 hp.

Yeah at this cid, roller cams are king!

Brian,

Nice work as always!

I'm curious where in the curve and how many cfm you were able to pick up on the TF 270's. They are only a 2.19" valve not a 2.25" is that correct?

I've not seen them up close I'm curious how they would compare side by side with my Chapman Stage VI 285's from back in the day, i always wondered if TF or Edelbrock modeled anything they did off the Chapmans.

https://board.moparts.org/ubbthread...-flowed-my-chapmans-today.html#Post12418

The Trick Flow castings could be used to create a high port, standard port intake like the Chapman heads. I looked into that when they first came out but TF wasn't interested in the idea. I think it would make a killer 470 type engine but the market might be too narrow for them to mess with.

The intake port went 368cfm at .700 and 375 at .750 but is very unstable...just can't get enough area in the port to slow it down enough for higher lift flow and stability. It bounced between 371 and 376 cfm but managed to stay there for the test. After .750 lift it dropped down to 367 or so.

Yes they come from TF with a 2.19 valve.

Another impressive build Brian! Thanks for sharing.