Don Terrill’s Speed-Talk

Seems like Warp Speed. Is the only one who gets what I am saying.There have been other topend that just don't work on dirt.The symmetrical port BD series is another example.I know of another successful engine builder that was given a BD topend by Ultra Pro.After building and dynoing the engine it was a pig.He thought a cam change would fix it.After changing the cam it was still a pig.He then changed the topend to Dart 11* and out the door it went.Another example is the Brodix 12X12.It was supposed to be the latest and greatest head for the late model dirt world.Wasn't wort a crap.
The dirt late model world is a different cup of tea and not everything that works on the drag strip will work on dirt and that's a shame because some of it is really good stuff.

So I have 0 experience with this.

I read somewhere, that builders were having trouble with these super shallow valve angles heads making good power past peak. Someone speculated that the valve angle and chamber angle were not allowing ideal pressure recovery.

Seems possible ?

I never claimed to know why these heads don't work on dirt,I just know they don't.

I guess the Brodix 12-12 came along after I quit dirt track racing. My 410" Sprint car loved the -12RI. Don't know what the dirt late models liked. Did some work for a guy that liked the -11RI on his late model. I have never even watched those run. May have very different needs with a carb. Kindler made an injection set up for the -12s.

Kinsler injection. Sorry.

The Brodix 12X12 and the Brodix -12 are two different heads.The 12X12 are 12* and the -12 is 15" I think the 410 winged outlaws still use the -12 on alcohol.All this talk about valve angles can be quite confusing.The best dirt track heads out there right now are the Brodix 11*.So if an 11* will work then why won't a 12* work.There is more to it than just valve angle.

I had -11s, then -11 RI (Raised Intake ports), then -12RI, had to take some gear out of the car. Very noticing faster, 40+ on the dyno.
Late models may not like them. I have no experience with those, other than minor help with one I never saw run. My winged Sprint car loved the -12s. I was told Ron Shaver was using them on customer's engines as well. Never got to ask him. We used "down nozzles" as well, so less/to no fuel taking up runner volume. 250cc runnners.

Without a doubt the -12 is a great head for alcohol.The Brodix -11 is a 23* head so it is surprising that they run very good at all on alcohol.

englertracing wrote:So I have 0 experience with this.

I read somewhere, that builders were having trouble with these super shallow valve angles heads making good power past peak. Someone speculated that the valve angle and chamber angle were not allowing ideal pressure recovery.

Seems possible ?

It could happen when some get so tunnel-visioned seeking small chambers that they forget everything else. But, with the smart people who have already tried to solve this problem, its hard to believe somebody hasn't sunk the valves and reshaped the chamber to address pressure recovery. But, who knows? I'm interested in the "why" this head only works in a drag race application. Hasn't Ford successfully used 8.5-ish° valve angles in many venues for decades?

Have you seen a dyno sheet?

perfconn wrote:Some of the best and well known and well financed dirt track racers have tried them and got rid of them.Yep,blame the racer.I am not a head Porter and I have no idea why Clements says the intake runner is too long but I can sure trust him and would not buy a set on a bet.Is it Darts fault they won't run on dirt,no I guess the fault is the engine builders for using them.

Who here blamed the racer?

I heard that driveability was an issue....not sure what that means as you'll get ten different answers...

[quote="midnightbluS10"][quote="perfconn"]All I know is that every dirt track racer that owned the 9* stuff hated them.[/quote]


That's about how it seems. You're not even sure why they won't work for your application. Only that people hated it and it wasn't right for them.


Yea, I'd say that all you know is that people tried to make power with them and couldn't so they "hate it". I'd look more to the people than the product, IMO. So far you've presented nothing showing that dart's product is the problem.[/quote]

"I would look more to the people than the product" sounds like blaming the racer to me.

There's a lot of really smart engine builders out there. If none of them can come up with a wining combo using these heads, how likely is that they are all just matching them with the wrong parts?

I guess I need to look in to the 11 degree Brodix heads. If they are 100 hp better than the Dart 9's that would make my 1037 hp 454 into a 1137 hp engine. Somehow that is hard to believe. The 9 degree is a tall head, but so are the Brodix heads. The intake runners on the as cast intakes for the 9 degree are however pretty long. Dart did not invent the 9 degree heads. They are from Don Losito at Ultra Pro. Dart just made castings based on his billet creations.