I just had my new CNC ported BT HR heads flow tested. Thought I'd post the results for anyones interest or comment. Numbers are at 28".

Lift Intake Exhaust
0.1" 73 61
0.2" 136 112
0.3" 209 150
0.4" 279 178
0.5" 328 223
0.6" 345 241
0.7" 357 250
0.8" 375 260

The heads are fitted with 2.19/1.72 valves, and were CNC ported by ET Performance, supplied by Barry R. The exhausts were not flowed with any pipe, just the open port. I'm happy with the results, should support my goal for 750hp from my 482 quite well.

Should make 750 HP without too much trouble. What intake will you be using?

Jay Brown
1968 Shelby GT 500 Convertible, 492" 667 HP FE
1969 R code Mach 1, 490" supercharged FE, 9.35 @ 151.20, 2007 Drag Week Runner Up, Power Adder Big Block
2005 Ford GT, 2006 Drag Week Winner, 12.0 Daily Driver
1969 Ford Galaxie XL, 460 (Ho Hum....)
1964 Ford Galaxie 500, 510" SOHC

I realize a 482 is a 4.25/4.25 engine. I wonder how those heads would work with a Dove HR Tunnel Wedge and a pair of worked 660's.

I'm wondering the same thing, as that is the intake set up I have to use, Dove HR tunnel wedge and modified 660's. I also have a pair of sideways mounted 750' to try.

maybe by that time I can afford to swing for a aftermarket block, but for now all I have is a .060 428 that I'm planning on grouting at least up to the water pump holes. I have the intake and the stock carbs. Was going to use a 4.125 or 4.25 crank.

Larry

With the smaller valves in the tighter spaced Edel heads we had no clearance problems with a 4.165 bore, the Blue Thunders may be spaced differently though. The question I have is why us a smaller valve in a 4.25 bore?? With a high riser manifold and head, why would you possibly be concerned about port velocity, are you only RPM'ing it to 6500 RPM? I would have went with bigger valves since the choke point of these flow numbers at 482 cubes is 8200 RPM and a conservative HP of 780.

the Blue Thunder MR and HR heads are available with "large bore" (427) and "small bore" (428) valve spacing as well as "wedge" and "Quench" chambers. A .060 over 428 would have a 4.190 bore and a 1.72 exhaust would be close to the cylinder wall. I think it would clear (not 100% sure), but it would be close.

The Edelbrock head has the exhaust valve on a 427 spacing, not sure if the BT (small bore) exhaust is on the 428 spacing or on a 427 like the Edelbrock???? Maybe BarryR will chime in with the final answer.

You could use the 1.65 valve size no problem, plenty of flow on a 428 bore. The 2.19 intake valve isn't an issue with either head on a 4.19 bore.



68 Cougar XR7 street and strip car, 428 4-speed, 3560# of fun, new best 10.43@131.2 1.47 60 ft

They make them in a narrow valve spacing where you can run them on a 428 FE with a smaller valve. You might want to be careful as you will probably make enough HP to break the block down the middle. You would need to cross bolt at the least.
If you get a 427 block later you would be better of with the wider valve spacing and then these will not work on the 428FE block. I use a 2.25 and 1.75 valves on the High risr Blue thunder heads that I do. They will flow about 400 cfms on the intake and similiar to the ETs on the exhaust. This is on a Super Flow 1050 @ 28 inches.
Good luck, Keith Craft

That is what we use on virtually everything unless the customer specifies otherwise.

So far, in my packages, I have not seen any benefit to the large bore head, nor to the larger valves. That noted, my comparative testing has been most focused on combinations with target RPM ranges of +/-7000 RPM, and +/- 650-750HP. As they say - your mileage may vary.....

The flow data I quote is based on a SuperFlow 1020 computerized bench. The port work is done on either a Boston or a Deckel-Maho - we have a few machines on the floor, and programs to run heads on both. The valve job is done with a single point CNC cutter Newen Contour. You will not find better equipment anywhere.

I hate quoting flow numbers, but the market demands it. Every flow bench in the country seems to be different - but our data is consistant with our testing, and generally repeatable. There is a LOT more to a cylinder head than flow alone....

Barry Rabotnick
Survivalmotorsports.com

Considering the valves are spaced 2" apart on the BT-HR heads i've got what would you run for valve sizes? I know i've gotten away with 2.19/1.72 on stock 390 iron heads and 1.94/1.65 on 289 iron heads.

How close to them touching each other is acceptable?

A .015 over 406 w/28 crank and CP pistons.
Can I step up to these heads at that bore size?
A THICK wall crossboltable block.

On a 4.08 with stock position LR, a 1.66 exhaust is tight, with lots of room on the intake side, maybe 2.15 being about thr perfect space to the bore wall. Have you tested maybe a 2.15/1.6 BT combo on the 4.08 bore at about 440 ci? That just seems like it would be pretty good with room around the valves to prevent shrouding on the really small bores. On a set of C8AE-Hs I have, on a 4.05 bore block I stuck a 2.15 intake in, rolled the block over and measured between .226-.230 clearance on all eight intake valves to the bore wall. A 2.19 was still clear at .220-.224 on all 8. On the exhaust side,a 1.73 hit the wall, a 1.71 hit too but barely. A 1.66 was between .030-.034 clear, and a Chevy 1.6 I had laying around was .060-.064 which theoretically should be a cylinder full of as much valve as it can handle. Going to 4.08 would gain you .015 on each side, so a 2.165- 1.615 would be about it. Good clearance for flow, and about as much valve as can fit. An intake from 2.15-2.19 would be perfect, and a 1.6 exhaust would be perfect with no scalloping required. I just how much flow a 1.6 valve would cost you with a BT port over the bigger valves? If you could get real 245/160 cfm at .300 280/180 cfm at .400 300/195 cfm at .500 and 310/205 at .600 with those valves I think you could break something (like a Prison Wall?) before the head flow is an issue. It would be a whale with mid lift like that. Most folks aren't camming over .600 on a street engine. Any thoughts?

To re-iterate, these were just some valves I had laying around from different heads that I stuck in the guides of an old stripped doorstop C8AE-H head, and a 4.05 bore bare block with no ridge that was laying around the shed. It was a couple of years ago but I wrote it in an Excel spreadsheet, so my screen reader can recall it. Probably not scientific, but it was pretty accurate for this specific pile of junk parts

I've never tried a BT head on a small bore, 390 based engine. Most of my BT customers are building toward the higher/larger end of the spectrum. I have run quite a few modified Edelbrocks on 390s though - its safe to assume that similar rules will apply. Like you, I have seen no issues with larger intake valves. I have had one engine that was at 4.070 we ran with 1.71 exhausts - it just clears on the engine stand but scrubs in operation. I'd recommend staying to 1.65ish exhausts. Realistically the BTs greatest benefit lies in the intake and chamber anyhow, and its nearly too large on port volume unless you're running a 4.25 stroker.

Barry Rabotnick
Survivalmotorsports.com

BT port and chambers. You would have nearly a ram effect going on without turbulence. That would make a sweet match. At 445 ci, it would be a screamer. On the exhaust side, with a 1.6 valve on the small bore, I wonder if the higher outlet and straighter shot would offset the smaller valves? The 1.66s are tight but they do work, I think a little .030-.035 scallop would help a little there. But those intake sides are nice and roomy. With the free space and the long stroke, I wouldn't doubt that a very flat power band with a wicked 6000-6300 peak with a 9.8:1 with a 294S would be pretty doable and still live a long timeon the street and strip. Put on a 2X4 BT TW and a pair of tricked Holleys...

If I was in the money, I'd build one. I think it would be a real over achiever for the money.