434ci small-block HP & LB-FT -- Take your best guess

We tested our Dart 434ci short-block that was topped off with a pair of Dart's CNC ported 227's and a single-plane manifold. Compression was at 10:1 with a mild hydraulic-roller (236/242) and fed with a Holley Ultra 750 HP carburetor; what do you think it made?  

Guessing 475 HP 410 Ft. LBS torque.  

any more details?  Are those heads out of the box from dart with their program, or somebody elses program?  You have numbers on the heads?  Any velocity numbers and was the min CSA measured?

What about valve lift and LSA on that cam?  What lifters did you use and what spring pressure(seat/open etc)

475 is a reasonable expectation, but the devil is in the details.  530 plus is doable if everything is right.  

greg_moreira:
any more details?  Are those heads out of the box from dart with their program, or somebody elses program?  You have numbers on the heads?  Any velocity numbers and was the min CSA measured?

What about valve lift and LSA on that cam?  What lifters did you use and what spring pressure(seat/open etc)

475 is a reasonable expectation, but the devil is in the details.  530 plus is doable if everything is right.

Sure thing:

*Heads are out of the box Pro 1 CNC 227s and the only flow numbers I have at the moment are 309 cfm @ 0.700 (intake) and 226 cfm @ 0.700 (exhaust). Springs are COMP 954.  

*Lifters are COMP 853-16, retro-fit

*Cam has 0.555/0.576 with 1.6 rockers and its on a 110.  

My guess is around 550Hp and 530tq with proper tune.  



Professional Hi-performance engine builder

huge heads low lift( flow test was at .700) street able comp. 425-430HP/450tq.At 7 grand it could be making some power but will it rev there under load.about the same as a big block 454.but Henry what were you Guy's trying to do at that comp/lift/cu.in./head combo.it can't be a race engine.probably a bowser till 4 grand.  

.. X 2 with PontiacMan... If it didn't do 550HP and 525 lb.-ft., retune it... I assume you got the quench close... 2.08"/1.625" valves... open 1 3/4" headers...  

+1 buzz  



Professional Hi-performance engine builder

Darklark:
huge heads low lift( flow test was at .700) street able comp. 425-430HP/450tq.At 7 grand it could be making some power but will it rev there under load.about the same as a big block 454.but Henry what were you Guy's trying to do at that comp/lift/cu.in./head combo.it can't be a race engine.probably a bowser till 4 grand.

We wanted a mild combo with big-block like torque for the street and we got it. This little gem was already making over 500 lb-ft at 3,200 rpm.

I have several more ideas in the works and you can expect everything from camshaft swaps to nitrous hits, and possibly a supercharged version of our big-inch mouse.  

.. Yeah, the cam duration isn't that big... about at the outer limits of daily street drivable... is this going to be in the CHP magazine?  

485-525 if properly set up.  
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Max HP @5500 = 525, Max Tq @ 4500 = 555
BUT, all that, only with a pro tuning it and rounding up horses.  
When The Flag Drops,,,



The Bull Chit Stops,,,

P. Engineer.,. Engine Builder

.. Too late... Guessing closed after Henry told us part of the torque info...  

BuzzLOL:
.. Too late... Guessing closed after Henry told us part of the torque info...

Where does it say the guessing is over
We didn't get all the specs until a few posts ago.  
When The Flag Drops,,,



The Bull Chit Stops,,,

P. Engineer.,. Engine Builder

.. Some of us could get within 1 HP and 1 lb.-ft. with just the info in the 1st posting...

.. What was Pepsi smoking with that 410 lb.-ft. torque guess?