206cc vortec heads show potential

[grumpyvette]

chevy has just announced NEW versions of the vortec heads which are designed for increased flow and are similar to the FASTBURN heads but the new vortec 206cc heads are CAST IRON with a 64cc chamber

PART # 25534371 bare# 25534431 assembled

theres also a slightly improved 175cc version part# 25534351

 

read this

 

http://chevyhiperformance.com/techarticles/148_0506_thunder/

 

these new heads are drilled and tapped for both old and new valve cover and both old and vortec style intakes, they have 2.00 intake and 1.55 exhaust valves and 65cc chambers

GM has also released a new 383 425hp crate engine part # `12498772

 

 

25534431 Vortec Bow-Tie Large Port Cylinder Head, Complete

GM Performance Parts' latest and most powerful iron cylinder head with "Large Port" for Street or Racing. This Vortec design Special Performance cast iron cylinder head features revised intake and exhaust ports and includes 2.00" hollow stem intake valve P/N 12555331 and 1.55" sodium filled exhaust valves P/N 12551313. The deck surface is .450" with 65 cc combustion chambers, 206 cc intake and 77 cc exhaust ports. All Vortec intake ports are taller and narrower than early model Chevrolet heads. The valve cover mounting holes are for both early model flange and late model center. This head also includes intake manifold mounting holes for both early model 6 bolt main and late model 4 bolt Vortec design. The head has screw in rocker studs P/N 12552126, large valve spring pocket machining, and will accept up to .530" lift camshafts without modifications. Heads are identified with the Bow-Tie logo on the exterior of the head below exhaust flange and Vortec logo on top of intake port area. They also feature GM logo cast into bottom of intake ports. Includes valve spring P/N 12551483, valve seal P/N 10212810, and spring cap P/N 10212808.

Technical Note: You must use a raised runner design intake mainifold P/N 10051103 (6 bolt mounting), or Vortec design 12366573, 12496820, 12496821, 12496822, and 12499371 (4 bolt mounting) with this head. You can use production Vortec intake gaskets P/N 12529094 (torque spec. 11 ft-lb/ 15Nm) for mounting Vortec design heads or use P/N 12497760 (torque spec. 30 ft-lb) with conventional material when using on early model raised runner or Vortec design intake manifolds, this gasket has both 6 bolt and 4 bolt Vortec attaching holes. Head casting P/N 25534371C.

[280zwitha383]

 

 

I'm trying to talk myself out of ordering them right now........

[5foot2]

So have you seen any street prices on these grumpy? The std gm vortecs are a nice head for the price. If these come in at or under the cost of working over the std vortecs for bigger cam lifts they'll be a sweet deal.

[grumpyvette]

25534431 SB Chevrolet Complete Large Port Vortec Bow-Tie Cylinder Head $499.95 EACH

 

http://www.sdpc2000.com/catalog/3129/GM-Performance-Parts-Cylinder-Heads.htm

 

look the new heads are now approved for some racing , they flow enought better that many teams are currently swapping to them, simply because they are an excellent value in a iron production cylinder head

 

NEW CHEVY HEAD RULE -The new Chevrolet Vortec Bow-Tie Cast Iron Cylinder Head will be approved for competion without any weight penalties starting July 1, 2005.

 

After reviewing performance information from the New Vortec Bow-Tie Heads not available in Nov. 2004 when the PASS 2005 Rules were released, PASS Officials view them as "The Possible GM Head of Choice" starting the 2007 season. PASS will review performance again after the 2005 season and inform competitors if this "GM Head of Choice Rule" is adopted in 2007.

 

The GM Vortec Bow-Tie numbers are 25534351 & 25534371 (bare castings) or 25534421 & 25534431 (fully assembled) and only allowed in "as produced" condition. Valve size must remain stock (2.00" & 1.55"), only normal valve machining, & 1/2" max. port matching.

[5foot2]

Hey grumpy (or anyone who knows), any idea where one may find flow numbers? I'd love to plug this into dynosim and compare the numbers to the std vortec.

[grumpyvette]

http://chevyhiperformance.com/techarticles/148_0506_thunder/index1.html

 

look 1/3 down the page

 

but before you get crazy... look at the DART PLATINUM IRON HEAD FLOW NUMBERS on this same page....a similarly priced aftermarket iron head

 

http://users.erols.com/srweiss/tablehdc.htm#Chevy

[jt1]

Pretty impressive. Those flow results are comparable to my 195 Canfields, for about half the price of what I've got in mine. That's a wicked buildup they are using those on too.

 

John

[5foot2]

Thanks. So I did a quicky DynoSim build using those flow numbers.

 

355cid

9.0:1 cr

new vortec heads

edelbrock perf rpm cam

edelbrock perf rpm airgap intake

600 cfm carb

small tube headers with mufflers

 

I would call this a mild motor, not at all radical as far the cam goes. I ended up with 425 hp at 5500 rpm and 440 lbs ft at 4500 rpm. The motor makes over 340 lbs ft of torque from 2500 rpm to the 440 peak.

 

I've alway planned on a big block in my 280z, but every day it gets easier and easier to build a stout torquey motor with a small block. So other than the cool factor of a massive 454 under the hood, the big block seems like less and less of a good thing to me.