Ported Dart pro 1 pre platinum

[MELWAY]

Chad

Is filling the floor on that ss head mostly an effort to increase air speed

Is the roof raised a proportional amount to the floor?

[user-9274568]

Chad

Is filling the floor on that ss head mostly an effort to increase air speed

Is the roof raised a proportional amount to the floor?

It's mostly an effort to make the port legal! NHRA says 64cc, out of the box the exhaust is 80cc. Stupid.

Also trying to take advantage of the raised port to handle the speeds.

[MELWAY]

Thanks forgot about your cc rule

Over here our cast iron ss rule is port as much as you like but can Not add material

Has anyone found power on dart platinum ex ports pushing the throat up around 1.400

[user-9274568]

Thanks forgot about your cc rule

Over here our cast iron ss rule is port as much as you like but can Not add material

Has anyone found power on dart platinum ex ports pushing the throat up around 1.400

That picture is a Dart Platinum and it's much larger than 1.400..

Here is the legal Edelbrock casting. Much easier to shrink and better shape, IMO..

[mag2555]

With a square shaped port tall does not work the best.
Once the flow on the short turn gets to the crown f the floor the width of the floor needs to be reduced otherwise you end up having a good amount of low velocity area and of course the port acting like it's much smaller at high lifts!

[Carnut1]

With a square shaped port tall does not work the best.
Once the flow on the short turn gets to the crown f the floor the width of the floor needs to be reduced otherwise you end up having a good amount of low velocity area and of course the port acting like it's much smaller at high lifts!

I was trying to ask Chad this earlier but my phone was seconds before dying. Velocity at the center of the floor was 0ft/sec when the port gets very turbulent. I was worried making the floor wider could make this problem worse or make it over a wider lift range. I did change the curve of the ssr a slight bit and made the floor a small amount wider. Turbulence was reduced a small amount and slight flow gains in the mid lifts with same flows at high lifts. Thanks, Charlie

[Carnut1]

0107171119.jpg

How it it going to be port. More work reducing heavy turbulence and a small gain in mid lift. This is port #1 and you can clearly see there is a port bias. Exit floor has not been lowered. I will post flows tonight if possible. Thanks to all who helped. Charlie

[groberts101]

may I ask why you are trying to bias the exhaust port around the guide?.. is the header design asymmetrical from cylinder bank to cylinder bank or something?

and what size pipe is that?.. the same EXACT primary size tube that will be used on the engine?

and also while I'm at it here.. what were the final ssr compared to roof speed differential before it goes turbulent?

don't want to be a dick here because I know this project and this port has been kind of a longer fight for you.. plus I don;t really have a before/after side by side to see what material you started with/may have left to work with.. but I have to say I would have likely done that port differently. Basically turn it into an LT1 style d-port design with 1/4" radii on the floor. That would help you to fix much of these turbulence issues and also use the same gasket with some light mod's. Or I would have just gone with the old squashed port design like Chad already posted a few pic's of. It's a well proven shape that helps settle down the floor speeds while promoting roof flow during lower port demand. While not quite as good.. the D-port has similar effect too.

I would also like to add a helpful reminder that using smaller radii burrs.. 1/4" and even 1/8" at times.. to expose more guide closer to the roof pays off BIG dividends in flow(often across the board)/port stability and has the secondary benefit of increasing the much needed CSA as gas flow is just coming out of the throat and starting its typically much too abrupt turn around the short side. Aside from a killer valve job.. thinning the guide bosses profile and increasing the available csa on either side of the guide on the long side just fixes SOOO many problems. I also like to blow the bowls sides out going past the guide boss too because this helps short side performance as well.. but some castings can really be shifted and cause thinner spots here.

On just about any short turn that has shorter throat section and more abrupt turn(squashed/low floor type port) all you can do is lay it back and break the floor wider as it goes around the SSR right from the edge of throat cut transition point. Sometimes you can even stabilize the short turn by widening the short turns floor(or what is going to quickly become the floor after the turn) going up all the way THROUGH the throat cut right up to the edge of bottom cut. Throat ends up being asymmetrical looking as you start the floor widening strategy right off the bottom cut. Just rattled all that off real quick. I could look for pictures.. but hopefully you get the gist of it. Maybe search "asymmetrical throat"?

I would like to see more pictures of the port in its current state.

[Carnut1]

0107171730a.jpg

New exhaust flows without pipe. Flow with 1 7/8" pipe a healthy 256.3 cfm@ .8" lift

[Carnut1]

The exhaust needed bias due to close proximity to vertilating the intake bowl. Picture is 1 7/8" pipe and engine will have 1 7/8" headers. I have not seen an lt1 port pass this much air and Stan's website seems broken so I was unable to check. Overall I am pretty happy with this exhaust port. Yes, this head has been a huge challenge. Thank, Charlie

[Carnut1]

0107171833b.jpg

Bowl shot angled to cylinder wall roof.

[Carnut1]

0107171833a.jpg

Head on bowl shot.

[Carnut1]

0107171833.jpg

Bowl shot angled to center of cylinder wall and roof.

[groberts101]

Thanks for the pic's Charlie. Some are a bit blurry on the seat and SSR but from what I can quickly see here.. you're SSR looks way too rounded. Look at many of Chad's ports and you will see how he slightly squares up the SSR floors to the walls. Even some as-cast ports already have wider/squared floors. My Kasse P38's and RHS's are cast like that too. The shorter the SSR and more abrupt the turn is the quicker you need to start squaring the floor off the seat. This is a decent enough casting to begin with so I'd find it highly doubtful that you'd need to start squaring the floors corners early(way up near the bottm cut) to get that short side to settle down and reattach. But from the minor-most center of the choke it should start squaring up/widening the floor(more like defining at that point) to gain flow control around the SSR. Might only be digging out .010-.015" corners coming out of the throats minor CS but IMHO, you need to get the party under control even earlier than you are at this point. If you can gain control of the port.. the flow will be there to match.

As for the port bias of the exhaust guide.. maybe someone else with way more experience will chime in here.. but I was taught that aside from roof, apex, or exit shape/size bias.. the exhaust pressures and gas speeds are so damned high in that area around the guide that the primary pipes angle coming off the port exit has much much greater influence on flow bias than working the guide/boss area will ever be able to overcome. Could even become slightly counterproductive if the flow was preferring to move differently than you had anticipated it would. Was just curious about your motives on the guide shape there.

[randy331]

How big is the Ex port now?

Randy