Dark Lightning

Does Vitesse announce anything on their own these days or is the Tool their elected voicebox?

NZ951

Just posting to subscribe

David Floyd

He is "Special" ya know

NZ951

Like Special Ed special? I hear ya! :P

streckfu's

I thought he was just a "tool"

David Floyd

You can bet, once John has the head like he wants, he will let us know.

special tool

Jeff - 16valve is a lot more work.
The "sledgehammer" ( ) is bolt-on.

I will have strictly ("sledgehammer" TM) comparison on the mustang dyno within a couple weeks. Nothing else will have been changed.

I am using a long duration, stock lift cam right now.

For those interested - I believe John is currently designing the "Sasquatch" TM head right now - NA core and race only.

fast951

Once I get a minute to update the site (any surprises here? LOL) I will post more details and pictures.

For the 951 we will be offering the followings: (you can change the name to whatever you like ).
- Stage 1 head: refresh, custom seats, stock valve size
- Stage 2 head: Same as stage 1 but with larger intake valves etc..
- Stage 3 head: Different intake, exhaust, keepers,... and larger intake ports as well (SpecialTool special). This requires intake manifold mods as well.
- Stage 4 head: I'm having this done for my race car.. Larger intake, exhaust valves.. many other mods and will be $$$

Notes:
* The intake & exh. valves used on the head (in the pictures here) are totally custom. You will be surprised at the weight in comparison to the stock items.
* A custom cam with the correct lift, duration and overlap will be needed to get the most out of the big-valve head. However there will be gain with the stock cam
* In general, I prefer to have customers do the performance reporting (good or bad!!!).

Porsche-O-Phile

Looks VERY interesting. I'm not knocking it at all - it looks beautiful. I'm just wondering whether it'd be worthwhile to go 16v or just with something like this. No doubt 16v is a lot more work since you have to redo the entire front of the engine, but there's the issue of cost - a 16v head in good condition can be had for about 500 bucks. This bad boy is going to be (I'm guessing) at least a grand and a half. . .

The flow rates on the sledgehammer might actually be better than with a stock 16v though. . . It's got definite possibilities.

fast951

The 16-V head will flow better than any 8V head, and is much more timing friendly. However, a used 16V head in fair condition is about $1000 then you have to replace the valves add about $1-1.5K, rework the head etc , exhaust manifold, intake manifold and you will be looking at an easy $3.5-5K.
If money is no object, then 16V might perform better, however it might require more maintenance as well...

Dark Lightning

I'm with Vitesse. 16V will dominate but on a dollar-per-horsepower chart an oversized 8V will be superior.

My only concern over an extremely oversized 8V head (or 16V for that matter) is this: if the valves are too close to the edge of the combustion chamber & cylinder wall you'll actually start to see a drop in airflow potential.

MitchB

However much HP it makes, I don't believe you... lol
Had to do it.

I kill myself sometimes...

fast951

Agree 100%. Bigger valves up to a pointe you will see increase in flow. Go any larger on the valves, and no gain. Of course there are ways to get around this issue (to some degree) by reworking the combustion chamber walls.

Of course, valve size is just 1 factor, there are lots of tricks that can take place. Then again it's all $$$. Once you go over a certain level, the gain per $ goes down fast. You got to find a sweet spot and call it the day.

MitchB

I'm not an expert, but has there been a little metal removed near the valves? Does that create increased "squish area" volume with a subsequent change in comp ratio?

Jakerx

are those intake valves bigger than 2.7 valves?