porting heads...

[SappySE107]

Nitrous is a power adder, but its still NA as far as I am concerned for my recommendation for your setup. You aren't increasing the atmosphere, just changing the properties of it. Velocity is important for NA and nitrous application. Only a track car that is held at 5k and higher would possibly benefit from stage 3 porting.

The 3500 heads are limited by their port size.

[ForcedFirebird]

You will see more than 5hp with a power adder.

[3400-95-Modified]

I don't see 800 bucks either John. I wouldn't use stage 3 3500 heads for NA. Stage 3 3400 still beats stage 3 3500 heads for all out flow.

One I'm not N/A, I'm Nitrous... I also don't understand how 3400 heads will outflow 3500 heads at the same stage. Seems kinda odd but I guess that just means you can't duplicate what can do on the 3400 heads on the 3500 ones due to the casting changes which is understandable.... But essentially what you would be telling me is I'd be better off with 3400 heads and LIM over the 3500 stuff?

And I got $800 by going to the 3500 heads adding the port work, adding valve job (since you strongly suggest getting that) and also added Milling since its wiser to have you do that then bring them somewhere else after I get them back, that comes to $729 or $789 depending on the milling cut you get. SO for my investment I'm looking at around $800 plus shipping both ways to get this done. I need to know what these "flow numbers" are going to give me in the end to justify the cost. If its only 5hp total I don't know if it's worth it. I'd rather just clean up the casting and polish the exhaust ports myself then and keep using the 3500 stuff.

[ForcedFirebird]

http://wot-tech.com/shop/gm-60v6/350.../prod_342.html

where?

The store has been being revised, I apologize for posting that the 3500 heads numbers were still up. We have been trying to make the listings easier to manipulate and the 3500 head numbers are not back up yet.

[SappySE107]

They will be added to this article and linked once i get them off the database.

[ericjon262]

http://wot-tech.com/shop/gm-60v6/3500-cylinder-heads-2004-2006-/prod_342.html

where?

[SappySE107]

Only the 3400 numbers are up. The 3500 will be up once I find them in the database. They were up but we modified the store and they weren't copied over.

[ForcedFirebird]

I understand pay to play all to well, but you and ben keep emphisizing flowbench data, and I don't see any before and after flow data on your heads.

Look on the store, they are there.

[SappySE107]

I know who Vizard is. I have plenty of his books and have read plenty of magazine articles and his internet writings. My bench is floating depression, and the new bench will be adjustable floating depression. Then I can use dynomation for the cylinder depression to test in further detail. Id rather have the wet bench setup finished though. We publish and compare the 28" because that is standard these days. Used to be 10" before it was 28".

Show me any individual or company that has done 1/10th the R&D on 3100, 3400, and 3500 heads and manifolds as WOT-Tech. With the correct bore at that. The bore was priority number 1 for me in 2004 when I finally built my bench, because I wanted to modify heads for reality. Being the best is our goal. If I just wanted to make sales, I wouldn't own a flowbench. Id have a WOT-Tech banner on every forum instead.

I don't see 800 bucks either John. I wouldn't use stage 3 3500 heads for NA. Stage 3 3400 still beats stage 3 3500 heads for all out flow.

I want someone with a proven setup and experience to do our before and after. Mars is a perfect choice, but if he won't do it, then we will eventually do it ourselves. We have the flow numbers, and they used to be on the store but were removed when I redid the store. It wasn't until a few days ago that the 3400 numbers were put back up.

[ericjon262]

You gotta pay to play. show me any other professional porting company that sells port jobs that cheap - and, besides, where do you see on the store that the porting is $800?

I understand pay to play all to well, but you and ben keep emphisizing flowbench data, and I don't see any before and after flow data on your heads.

[ForcedFirebird]

That.

You gotta pay to play. show me any other professional porting company that sells port jobs that cheap - and, besides, where do you see on the store that the porting is $800?

[ForcedFirebird]

True most of what I have done is with iron heads. However I still don't believe that there is not a set of heads on the planet that cannot be improved. I will agree that sometimes a flow bench will be requires to get results.

As for the flow bench the one described by David Vizard is a floating pressure drop design that uses a shop vac that gets calibrated with an orifice plate before use. If this design is something he recommends then it sure as hell is going to work well. He has 51 years of experience and over 200,000 Dyno pulls under his belt. He has changed industry thinking on 2 valve, 4 valve and nitrous motors. The bench does not use tubes to simulate the bore you simply do the flow testing on the engine block.

No they don't. Most conventional flow benches use a fixed pressure drop. As you open the valve in the cylinder head you increase the volume of air flow to create the 28" difference across the port no matter how far the valve is open.

The bench I am describing is a floating pressure drop. The vacuum source stays constant and the pressure drop across the port changes as you open the valve. The results can be converted to get CFM numbers at 28" if you want. Basically are measuring the change in vacuum pressure instead of CFM.

The reason the industry uses a fixed pressure drop at 28" of vacuum is because of Smokey Yunic and his early work with flow benches and dynos. He discovered that a 28" pressure drop and the CFM increases you see through porting at that pressure drop most closely resembled what he saw in terms of horsepower increases. So it has basically become the standard and it a good tool when comparing heads in a catalog. However a floating pressure drop has many advantages for port development.

Sorry for the confusion. I meant they all measure pressure differential, but yes on some benches you adjust back to 28". Our benches will do either. We can use a small vacuum source and the digital equipment will compensate to 10" or 28" if deviating, but then we can also regulate 28".

I am very familiar with David and Smokey's findings. I am on a forum with David, as well as some other well known figures such as Curtis Boggs, Jack Vines etc.

[ericjon262]

I like your new options in the store for head work, Now my question is I currently have a untouched set a 3500 heads and lower intake... I'd like to have them ported but I'm not sure which stage would fit me well and what the benefits would be. Bottom line I don't want to spend close to $800 for work that wont gain me more than 2hp...

I would be using stock valves, 26986 springs that I have and would have them cleaned before sending out to you. If you can prove to me that the stage 3 porting option will gain me enough to justify the cost then you will probably see my heads coming your way since no I do not know the best things to do. For this new set I was probably just going to polish the hell out of the exhaust ports and texture the intake and not match anything or change any shapes.

I also asked you a while back Ben about a new cam suggestion... do you want me to order the cam profile option and have you do that before giving an answer on the port work?

That.

[young gun]

Very noob here so I have no input on the matter BUT I'd be willing to ACCEPT Ben's stage three heads with my set-up of stock LX9 with CAI, 65MM TB, 2.5in DP, 2.25In Cat-back, Mild tune from Milzy and do a dyno pull as such then swap Ben's heads on and re-dyno for results and if deemed fair tune some more as well to get the full effect..

Willing to do it Ben?? I plan on getting them in the future anyways cause Mars's Rotrex needs room to push all the air

[geoffinbc]

That's basically how ALL flow benches work. You just won't be testing at 28" with a single shop vac.

No they don't. Most conventional flow benches use a fixed pressure drop. As you open the valve in the cylinder head you increase the volume of air flow to create the 28" difference across the port no matter how far the valve is open.

The bench I am describing is a floating pressure drop. The vacuum source stays constant and the pressure drop across the port changes as you open the valve. The results can be converted to get CFM numbers at 28" if you want. Basically are measuring the change in vacuum pressure instead of CFM.

The reason the industry uses a fixed pressure drop at 28" of vacuum is because of Smokey Yunic and his early work with flow benches and dynos. He discovered that a 28" pressure drop and the CFM increases you see through porting at that pressure drop most closely resembled what he saw in terms of horsepower increases. So it has basically become the standard and it a good tool when comparing heads in a catalog. However a floating pressure drop has many advantages for port development.