Dax high compression head review

SlowBalt

SlowBalt

Member
The most common stock head is on the left and the Dax on the right.
I instantly noticed a difference in power after the install. There was so much more compression that the clutch slipped when trying to start the engine. I had to tighten the flower nut.
I would say it's around the same gain as I had with my Manic head. You can see in the pics that the Dax head is decked and the combustion chamber is more conical, and the stock is a wider dome.


 
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SlowBalt said:
The most common stock head is on the left and the Dax on the right.
I instantly noticed a difference in power after the install. There was so much more compression that the clutch slipped when trying to start the engine. I had to tighten the flower nut.
I would say it's around the same gain as I had with my Manic head. You can see in the pics that the Dax head is decked and the combustion chamber is more conical, and the stock is a wider dome.


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time to bust out my favorite tool in the world ..."the dremel" and experiment with an old head I have here!! does it have to be a mirror finish?
 
Jumpa said:
time to bust out my favorite tool in the world ..."the dremel" and experiment with an old head I have here!! does it have to be a mirror finish?
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It is a completely different head the casting is even different. All that a dermal will do is wreck the head. But if you want to polish the chamber of the head. What I do is. Take steel wool and tape it over the empty chuck of a drill.
 
I used a dremel on my head to reshape and smooth the combustion chamber and ports. I also sanded the surface area to take off some material. I don't have anything to compare it to because this is my first build but I can tell you my engine started right up and has more torque than I expected.
 
want some ridiculous compression? if you run a dax motor (or if your piston's compression height [crown to wrist pin center] is 26mm), use that head in addition to this piston. Stock deck height is 0.7-0.8mm typically, mine's been measured at a whopping 2mm. This piston sits 0.5mm HIGHER than your stock piston, reducing your deck to 0.3mm. If you're running 140psi, this may push it to 175psi or greater, but of course you run the risk of it popping the crown out of the cylinder if my measurements are off (which, they shouldn't be, I've measured these things pretty thoroughly), though worst case scenario, you can just add an extra base gasket..
 
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dodge dude94 said:
^Any MPH increases?
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MPH increases come with RPMs. So if you're already redlining (HT's are vibration governed), no, more compression may actually hurt your top speed. However if you're limited by lack of power, more compression will help you gain more, but starting will be more difficult, and temperatures and stresses will increase.
 
mew905 said:
MPH increases come with RPMs. So if you're already redlining (HT's are vibration governed), no, more compression may actually hurt your top speed. However if you're limited by lack of power, more compression will help you gain more, but starting will be more difficult, and temperatures and stresses will increase.
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Mine stops at 35...lol I can tolerate vibes if I'm going for top speed tests. Grit your teeth, tuck your legs and hang on.


Wonder what it would be like with the BP7HIX plug I've got...
 
Just put some real miles on this head. I can honestly say that it is an upgrade for sure. The power increase is noticeable throughout the power-band, especially mid-range to top-end. Top speed didn't increase much only 1-2 mph on average. Dial in the carb right and there is not much of a temperature increase. Definitely worth the money ($20) compared to other heads. I've ran other HC heads and this one runs just as good if not better then the competition.
 
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