Offshoreonly.com - Dart 8.1 Gen 7 Iron Heads

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Q & A (https://www.offshoreonly.com/forums/general-q-20/)

- - Dart 8.1 Gen 7 Iron Heads (https://www.offshoreonly.com/forums/general-q/245432-dart-8-1-gen-7-iron-heads.html)

Thanks Rage, glad to hear your boat is doing what you want it to.

Ray is no longer with the company for several reasons, but mostly because customer service was not his thing. We're looking to turn over a new leaf with the boat industry (and the automotive industry for that matter).

The CNC Extreme cylinder heads actually have a few things done to them to make em flow as much as they do. We extensively port the heads and increase the valve size to 2.25 / 1.88. These changes help to push even more air into the cylinder and really help to boost the power potential of stroker engines / forced induction setups / large bore big blocks.

Quote:

Originally Posted by crayolacrazy (Post 3987955)

no. one you cant get Tylers heads any more thats why I bought darts bear heads they are available ,I would love to own raylars heads bear ill put my own valves in them. butt.If i make any more power ILL need drives . also pcm 555 game .Im running 8.5 lbs boost.

Do you have flow numbers on the modified Dart heads you installed on your engines?

Hi rage ,, Larry Hofer here. I am curious why you would install different valves in the RAYLAR heads you would assemble?
Different sizes? Thanks for the thoughts.

Quote:

Originally Posted by Raylar (Post 3990701)

Hi rage ,, Larry Hofer here. I am curious why you would install different valves in the RAYLAR heads you would assemble?
Different sizes? Thanks for the thoughts.

Hi Larry. If I said that I miss spoke. I would reuse my 3/8 stem valves in the Dart heads (which default is11/32 stem valves) because that would save me money.

HI rage,, ARE the valve head sizes the 2.190 and 1.720 in the dart head? i think i herd they were 11/32 stem and 2.250 intake, the exhaust has 11/32 stems and 1.800 or 1.880, but not sure. heads would require machine to put the3/8 stems in also. A minor reduction in air flow with the bigger stems . seems to being going backwards.If they had used 3/8 stems,would have made it easier and cheaper . could have used BBC GM valves.To build a good dart head will still cost a few bucks. Richard made this head mostly for the stationary engine market. he sells bunches of heads to those guys.IF you are interested, i will have new heads in 6 to 8 weeks.
Larry Hofer

Quote:

Originally Posted by xx_ED_xx (Post 3637609)

Update on the intake on mine.
Pics first
http://i1239.photobucket.com/albums/...e/DSC01124.jpg
and the raylar
http://i1239.photobucket.com/albums/...e/DSC01040.jpg
So dynoed it with the raylar and mine withe same parts
stock tb with port job 78mm
stock exhaust manifolds for the rear mount turbo
stock 85mm maf
aftermarket cold air intake for a 5.3
3 inch y pipe into a 4 inch collector then reduced to 3 inch single into turbo to a 5 inch down pipe
single 3 inch to increase velocity to 85mm tv8101 turbo outback
raylar made 390 to the wheels and i want to say 480 torque
my intake made 330 and torque unk probably less due to the shorter runners if you go back and look at pics you can see how short i made them.
zz502 camshaft
h beam rods
mahle forged pistons

The good news
took off 78mm tb and put on 102mm tb and hooked up turbo to my intake
7 lbs of boost 680rwhp
Thats almost 800 flywheel hp
I asked him to give me a dyno sheet with all my sessions superimposed
You should see the drop in midrange NA without the headers on it

Here is the dyno with stock intake and headers and a single 4 inch system stock tb and maf
http://i1239.photobucket.com/albums/.../TruckDyno.png
Oh in all these test the heads are cnc ported by tom at champion.
he did 85 sets of heads for the GM marine engines and he used the same cnc job on these heads.
stock intake size but 11/32nds stems and 1.88 exh valves sense the stock ones are kinda small
http://i1239.photobucket.com/albums/...e/DSC02077.jpg
http://i1239.photobucket.com/albums/...e/DSC02076.jpg
http://i1239.photobucket.com/albums/...e/DSC02075.jpg
http://i1239.photobucket.com/albums/...e/DSC02074.jpg

I also fell into a set of raylar heads and a forged short block with je pistons and a raylar crank that i will be building for 30 pounds of boost and a bigger cam
cam specs
244/244 @ .050 .650/.650 hydraulic roller
I am going to upgrade the head bolts to 1/2 inch if not bigger and convert the intake bolts to 1/4 inch since finding really long m6 bolts is next to impossible. I actually tig welded 4 bolts to make the length i needed to hold the fuel rails on since i used 4 intake bolts to work double duty.
If you google, 496 into 04 silverado, you can read more about it usually is the first link to come up

Also thanks to raylar for helping me out with some details a few weeks ago when i called. I have another question since i am in afghanistan. What are the cam specs for the 106 cam?

SPC Coss
US Army
currently deployed

Ed,

Have you considered using your 102mm throttle body on the Raylar intake?

Do you know what the head's intake runner cc's are now with the CNC work done by Champion?

Thanks, Bill

[ATTACH=CONFIG]507773[/ATTACH][ATTACH=CONFIG]507774[/ATTACH]

Quote:

Originally Posted by Raylar (Post 3992481)

Yes, the Dart's spec sheet show 2.19 intake, 1.88 exhaust and 11/32" valve stems. That sheet also says 2.25" intake optional. I have asked Dart if the heads can be ordered with 2.25 " intakes and 3/8" valve stems at same cost. I will post their answer.
Buying all new valves with 11/32" stems would be more costly for me. The minimal flow improvement with 11/32 stems would not be worth it for me either.

Attached are graphs of the published CFM data using 4.5" cylinder bores for the various heads involved (note- the HP3 Gen II head and stock GM 496 head CFM data may have been run with 4.25" cylinder bores since I can not confirm). If these were in fact run with 4.25" cylinder bores the CFM with 4.5" cylinder test bores would be higher than that shown.

No doubt your head CFM data shows better flow than the rest. The Darts with 11/32-1.88 valves however show CFM almost identical to my HP3 Gen II heads on exhaust . The Dart exhaust valves were 12* tulips versus mine were 22* tulips. The Darts could potentially flow better with the 22* tulip exhaust valves. The Dart heads with the 11/32-2.19 intake valves did not flow as good as my 3/8-2.25 valve'd HP3 Gen II heads but the Darts should flow better with the 2.25 valves. What caught my eye is that the intake CFM/valve lift curve slope remained steep above 0.5" lift (like the Raylar Extreme heads) versus the fall off with my HP3 Gen II heads and your standard heads with the 2.19" intake valves. This if extrapolated implies that at lifts above 0.6" the Dart's 2.19" intake CFM may catch up. Of course the flow short fall at the lower lifts would remain.

I am hopeful that someone will investigate the full potential of the Dart heads with 2.25" or 2.3" intake valves and optimum exhaust valve profile. It is my understanding that the Dart heads have additional beef in the port walls for additional porting work...not the case with the stock GM heads. In any case a nice improvement over the stock heads.

Why would you go cast iron? Why not aluminum? With another point of compression, quick burn combustion chamber design and aluminum head dissipation you are sure to make more power.

Quote:

Originally Posted by Keith Atlanta (Post 3993116)

Why would you go cast iron? Why not aluminum? With another point of compression, quick burn combustion chamber design and aluminum head dissipation you are sure to make more power.

MONEY! Not everyone has unlimited funds to pursue their dreams. One has to live within their means.

Has anyone attempted putting 1.88 exhaust valves in the stock heads? I had the heads sent out for ex valve seat replacement for the bigger valves but it looks like there is not enough metal around the seat to do this. Was told pressing in the larger seats could break into the water jacket. Shop performed a Serdi 5 angle on the stock seat the 1.88 valve now seats but is approx. 20 thou shy.