DARTS 9* MISTAKE

[perfconn]

This is for the dirt late model world so you drag racers may have had different experience.
In the quest for decreasing valve angles,Dart came out with the 9* heads for the small block Chevy a few years ago.Most of the engines were spread bore engines in the 454ci range.They made good power & torque on the Dyno but on track they were a pig.After talking to Tony Clements about them,he told me the intake runners were too long.
Not disagreeing with anyone but it looks like they could be made to run on the dirt track by using smaller cams or epoxying the intake runners or something.Tony Clements said they could probably be made to run great with turbo chargers.I immediately thought of the street racers,but that's not my cup of tea.It just seems like a terrible waste of good parts to see these topend go unused for something.
I know where there is one complete topend that I turned down and I could have bought it for a song and dance.If anyone wants to build a killer twin turbo Street racer I can give his number and you can see if he still has it.

[Abbottracingheads]

I bult a 454 4.5 bore spacing engine with the 9 degree heads and it made killer power and torque on the dyno and flat hauls ass on the track. Something sounds screwy to me. It made over 1000 hp with one carb and a cast intake.

[cgarb]

How is that possible? One person can make something run like a scalded dog and another can make it run worth crap...must be darts fault.

[Frankshaft]

[quote="cgarb"]How is that possible? One person can make something run like a scalded dog and another can make it run worth crap...must be darts fault.[/quote

One is drag race, wide open off the trans break, ran in a narrow rpm band, one is a circle track application that needs a wider power band.

[Ron E]

Isn't the 9° Dart a paired runner head? Is the runner height causing this runner length problem?

[T-flow]

Its probably a issue with the combo...
Like the Pro-14 degree stuff in there beginning. Not saying they may not perform well, maybe they just need something that's not being given.

[perfconn]

All I know is that every dirt track racer that owned the 9* stuff hated them.I know one racer that had two of them and traded them both to Pro Power for one 11* engine.Tony Clements told me of one example of a customer bringing one in and wanting to know if he could help it.Tony said after reworking the heads and intake he picked it up 50hp but it was still down 50hp from his 11* stuff.The reason I was asking Clements about them was I heard how bad they were,and a customer of mine had taken his 9* engine to them and was wanting to sell his 9* topend because they were changing it to 11*.I don't build all aluminum open engines but the dude was willing to sell me the topend for whatever I offered him.I just thought I might get a nice topend cheap but after talking to Tony I wouldn't touch them.
I know every engine builder thinks he is the best but everyone that built these for dirt track has changed to the Brodix11*.I also know that some people can't read because I stated early on that it was a dirt track application.Yes the 9*Dart is a paired runner design.Finally do any of you head porters believe the intake runner can be to long?

[midnightbluS10]

All I know is that every dirt track racer that owned the 9* stuff hated them.

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.

[RCJ]

What did they not like about them ,power curve to narrow, no top end power, etc...Does Clement think the rpm band of the runner length doesn't match the rpm band of the port volume or cross section?

[Ron E]

.Finally do any of you head porters believe the intake runner can be to long?

I read what you wrote, from top to bottom.
I can't see why that would be "the" problem. I'm trying to understand it. I've never heard about it before. Being a paired runner, bore centered valve layout I don't see any additional runner length unless the head is super tall. And, that would be a small amount that should be correctable with some extra taper or a slightly different plenum. At worst, some specific cam treatment. I'm just curious as to why there's a problem.
And, I'm not doubting or 2nd guessing the builders who hate them. I leave such judgements for the things I've actually done, not the ones I visualize, or dream about, or only see from a safe distance.

[perfconn]

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.

[Warp Speed]

The 9* head you speak of just never worked as good as they do on paper!
Some of the best engine builders in the country have tried.

[Carnut1]

I am doing some coaching on a custom 6 degree head for a 500" motor and it seems the shallow angle makes the ssr a huge issue as far as airspeed
is concerned. I wonder if these Darts have the same issue? Thanks, Charlie

[Rick Finsta]

Yeah, Carnut1, welcome to the Oldsmobile world of shallow valve angle and high lift port stall! LOL

[Carnut1]

Yeah, Carnut1, welcome to the Oldsmobile world of shallow valve angle and high lift port stall! LOL

It's custom airflow engineering, anyone can do it!