Supercharged Alky BBC Heads

As stated before, Scott Filkins with Lonnie Houde tuning we as fast as 5.96 @ 242 in 2700# door car with Big Chiefs. And we have gone 6.25 @ 227 with Dart 360 Heads. Both utilize a PSI C Rotor.

 

What are you running for boost, compression, cam, and trans?

I am running 360's ported and flowed to 410, 11.5 to 1 compression, 548 cubes, .810 lift Harold Brookshire Cam, 38 pounds of boost out of a 14-71 high helix littlefield and a powergliide and all I am running is 7.60's @ 2900 pounds.


That was with an old bowtie block with some issues, but I am replacing the bottom end as we speak with a 526" Aluminum Rodeck. Running the same heads, cam, compression, blower... etc. Should I see any difference in et besides what I loose in weight?

It just seems like people are going much faster than me, with very similar setups and weight. Is the powerglide killing me or somthing?

 

As far as boost, we ran around 55-60 lbs, compression around 10.5:1.

The supercharger is the main difference, and the camshaft.

Before we put the screw on it, we ran a Kobelco K-11, and a different cam shaft, and went 6.54 @ 211 best. Routinely 6.60`s @ 207-210.

We run a Bruno drive, so we utilize an automatic as well. The powerglide will hurt it a bit, but not much really. You just get better splits (an extra gear), and the ability to fine tune low gear through different ratios.

Once we put the screw on, it went 3 tenths and 20 MPH quicker with the 360`s.

If your like any more info, e mail me @ jason@lhpracing.com.

Personally, if it is a door car, you should be able to run low 7`s with that combo.

Have a good day

 

Cyl heads

Ran 14 stuff years ago Just remember Valve train and cyl pressure on the ex. It does make HP>

 

We ran 427 SBC Brodix -12 head 14/71 HH Littlefield Th400 3065lbs 7.20’s @ 192mph 1/4 mile run
Changed to an Oddy BBC 526 18* head Th400 3165lbs 6.85 211mph 1/4 mile.

There is a lot more than flow of cylinder heads to make these cars go fast.

 

Dart 360's

We also run the Dart 360 heads, and a psi 206D. we have had great performance with them we are only running 38 to 40 LBS boast in a index class were we run 6.30's best MPH is 230, we have never pushed it on the e.t, we have Lonnie Houde helpping us tune also, He sure knowns how to make a BBC HAUL A$$. GOOD LUCK

 

Head flow blown vs naturally aspirated

Originally Posted by WJ Birmingham
I just went through this education process myself not too many months ago.
Here's what I learned, via some good sources.
GM 990 Rectangle ports, fully ported, will Peter out around 1500 HP.
Dart 360s, with a full port by an expert (other than Dart), will produce from 2100-2300 HP. Ported by Dart, up to about 2100HP.
Dart Big Chiefs, again ported by someone other than Dart, up to about 2800 HP. Ported by Dart, up to about 2400 HP.
Now, supposedly, the baddest conventional cylinder head out is the BMF 405. It's the one most talked about over on Yellowbullet.com when the blower guys ask about the best conventional head. http://www.thebmfstore.com/SearchResults.asp?Cat=20
"So their is all this info out there regarding NA motors and little on blown. A Big Chief vs 360 is about 100 HP difference in a NA motor but your thinking it's 600 HP diff when blown?
I'm wondering because I don't have any good data to support numbers like this and right now I'm going to a head that will make 65 more HP naturally, so I need to figure out what that will be blown so my fuel is close."

Reply,


I ain't no blown head guru, but since no one else answered your question let me take a stab at it.
On a naturally aspirated engines, as a general rule when you increase the cross section of the port you also decrease the velocity ( exceptions to this being when you improve the contour/design etc of the port) for this and many other reasons when you deal with big ports on a N/A motor the (even with excellent countour/design) gains are small with all but the biggest displacement motors.
On a blower motor since you are pumping the air into the motor big ports and valves will yield much bigger gains than on a N/A motor particularly with a big blower and proper cam selection.
I am sure anyone with blown head porting experience can shed more light on this than my dumb ass, but that is the basic eye dear.

 

I appreciate your opinion, anyone else??
How dose NA cyl head power increases compare to blown?
If the head makes 65 more HP on a NA motor how much more will it make with 30 lbs boost?

 

Jason,
With that much boost, what do you run for piston pins and rods that make it survive? How many runs to you normally get on each before you change the pins and/or rods?

 

Jason
I would bet those were solid 360's? What did you run for a block?

 

Yes, solid heads, and a Donovan block, non side-studded...