VORTEC BOW-TIE HEADS

CNC BLOCKS · Post by **CNC BLOCKS** » Thu Dec 16, 2004 10:44 pm

Has any body run any of the new Vortec Bow-tie heads

shawn · Post by **shawn** » Fri Dec 17, 2004 3:52 pm

They are both pretty good heads. The 203's actually measure a little larger than that, but still flow really well.With a little work the 203's will go in the 270-280 cfm area.The 180's will flow in the 250 cfm area. Is this what you're looking for?

Shawn

CNC BLOCKS · Post by **CNC BLOCKS** » Fri Dec 17, 2004 5:36 pm

Any dyno tests ??

rmbuilder · Post by **rmbuilder** » Fri Dec 17, 2004 8:26 pm

Carl,
I am working on flow #'s now for both sets. The 25534351 small port has 185 cc intake and 65 cc exhaust. The 25534371 large port yields 215 cc intake and 84 cc exhaust. I will pass along the #'s when available.
Bob

shawn · Post by **shawn** » Fri Dec 17, 2004 8:37 pm

The 203 headed motor was a fairly typical late model pavement type motor. Not a killer piece but moderate price, cam profile, etc..It was a flat top piston,flat tappet cam, super victor intake, 750 carb. It makes in the 570 hp area and seems to accelerate pretty good. I think if you did all the tricks, you could see in the 600 hp area with them.The smaller headed one we haven't got on the dyno yet.
Shawn

CNC BLOCKS · Post by **CNC BLOCKS** » Fri Dec 17, 2004 11:47 pm

shawn wrote:The 203 headed motor was a fairly typical late model pavement type motor. Not a killer piece but moderate price, cam profile, etc..It was a flat top piston,flat tappet cam, super victor intake, 750 carb. It makes in the 570 hp area and seems to accelerate pretty good. I think if you did all the tricks, you could see in the 600 hp area with them.The smaller headed one we haven't got on the dyno yet.
Shawn

Shawn did you stay with the 2.000 intake and the 1.55 exhaust valeve or go to the 2.020 and the 1.600 exhaust.

And what was the compression ratio on the engine you tested.
And thanks for the info. Carl

shawn · Post by **shawn** » Sat Dec 18, 2004 12:18 am

I used the 1.55 exhaust valve with a 2.05 intake. It didn't seem to make much difference over the 2.02 ,but i wanted to try it.The compression was a little under 13.0-1.The chambers on the heads don't lend themselves to a dome without a custom piston, and i didn't want to cut or roll them over on bunch the first set i did, without knowing what they would do.I think that with a little more "undercover" work and roll them over some more and you could see quite a bit more power out of them.
Shawn

rmbuilder · Post by **rmbuilder** » Mon Dec 27, 2004 1:17 pm

Intake Small Vortec BT
.100" 67
.200" 136
.300" 182
.400" 223
.500" 251
.600" 240
.700" 240

Exhaust Small Vortec BT
.100" 53
.200" 100
.300" 128
.400" 145
.500" 152
.600" 164
.700" 166

Intake 175 cc
Exhaust 64 cc

Intake Large Vortec BT
.100" 63
.200" 133
.300" 182
.400" 228
.500" 258
.600" 255
.700" 261

Exhaust Large Vortec BT
.100" 50
.200" 100
.300" 134
.400" 154
.500" 168
.600" 168
.700" 169

Intake 206 cc
Exhaust 77 cc

2.00" Intake
1.55" Exhaust

hbps1978 · Post by **hbps1978** » Mon Oct 31, 2005 6:12 pm

rmbuilder, what bore size and inches of H20 was used when you flowed these heads? Thanks

Nwguy · Post by **Nwguy** » Mon Oct 31, 2005 11:20 pm

I am curious if anyone has tried to unshroud the intake valve in the chamber on these heads? And if so, what were the improvements in flow??

I have had a set of these( 25534371, big port ) for a while, but am just now getting around to playing with them. The rules it will run under: cast iron, oem, unported, straight plug. In the last two years they have never pulled a head, they always seem to pull the intake manifold. This leaves me wondering what gains can be made in the combustion chamber.

I would be appreciative of any info, as I don't wish to sacrifice a head just to find out that there wasn't much gain to be had.

Thanks

SStrokerAce · Post by **SStrokerAce** » Tue Nov 01, 2005 9:32 am

Carl,

http://chevyhiperformance.com/techartic ... 6_thunder/

Old Mag article on a circle track motor built with them.

Bret

CNC BLOCKS · Post by **CNC BLOCKS** » Tue Nov 01, 2005 12:45 pm

We worked with PCCW Engines out of VT. on this engine in the pic as this was a little 13:01 big bore short stroke engine 358 and a 750 HP carb with all the bells and whistles as we took care of the block work on the Dart Little-M block and worked with them on the cylinder heads as this engine had a little more power and torque then the engine in the article and this engine was very impressive on the dyno 3 weeks ago.

If you need any more info call Randy at PCCW 802-457-3111

hbps1978 · Post by **hbps1978** » Sun Nov 06, 2005 5:10 am

Carl, may I ask what the purpose of the braided lines that are going into the valve covers on the engine in the pictures are for please? Oil circulation from the block?

CNC BLOCKS · Post by **CNC BLOCKS** » Sun Nov 06, 2005 7:17 am

hbps1978 wrote:Carl, may I ask what the purpose of the braided lines that are going into the valve covers on the engine in the pictures are for please? Oil circulation from the block?

That engine is set up for valve spring oilers as the valve lift is around .700 just to keep the springs cool.

Wolfplace · Post by **Wolfplace** » Sun Nov 06, 2005 1:29 pm

Hi Carl, Who's oil manifold is that?
Really cool lookin deal, I like it a lot better than the usual one that sticks straight up & ends up about in the center of the alternator

Don Terrill’s Speed-Talk

VORTEC BOW-TIE HEADS

VORTEC BOW-TIE HEADS

Bowtie Vortec

Bowtie Vortec