Pro Design Cool Head

[Durt Cycler]

Billet machined Cool Heads offer significant bolt-on performance gains

---Torque and power are increased by utilizing a 70% squishband to increase compression
---A larger water jacket area supplies more water to offer the ultimate in cooling efficiency
---Added features include O-ring seal (no gaskets required) and removable compression domes

Good or not? Any Pros-Cons of using it?
:uh:

 

[NO HAND]

The price is hard to justify, if you consider that you can have the head of your bike machined to suit your particular bike and usage for a fraction of that price. That's just my opinion. For the water jacket, I read here that the target temperature has been already calculated at the factory so that the head temperature is according to what is best performance wise. They are not that stupid at the factory. Though, the o-ring seal looks like a good idea to me. I think Eric has been talking about a head design before that could change the head volume while riding. I don't remember the details. I think it was a very high maintenance though.

 

[Durt Cycler]

Yes the price is a bit expensive considering I would for $200 more get a E Gorr CR150cc kit or have him port & polish my cylinder for my needs but I am payiing more then 1/2 the price of a new one ($250) and mine is brand new also with both stock size compression dome and a high compression dome. I will try the high compression dome first and run VP C-12. There should be a difference from the stock head and the Cool Head. I've seen MANY of them in magazines and people where I ride use them on their Honda TRX250Rs and Yamaha Banshees and only heard of one guy who has used a Cool Head on his CR250 and swore by that it is a great product.:silly: :cool:

 

[jski]

While they do offer the advantage of changing the domes to increase compression in the end for what you do gain the head is a waste of money. I installed one on my brothers banshee and besides increasing the compression the gain was barley noticeable and I really didn't care for the o-ring seal which to me seemed like a weak point of the design.

 

[Durt Cycler]

Yea I've been getting mixed reviews about the Cool Head, some say it works great and delivers more power and some say it just feels like a stock head with a slight power difference :eek: :ugg: :scream: Only way to see is to test it! Also I heard from someone that marcusgumby talked about the Cool Head awhile ago, like to hear what he has to say about it :cool:

 

[marcusgunby]

Durt Cycler my memory isnt that good but i think the thread was talking about the VHM head which sounds identical in idea.IMO these are a big waste of money-you can copy the shape of any aftermarket head onto the std one for very little money.Eric Gorr does head mods for a very reasonable amount and will set it up for high/low comp, top end or bottom end etc.If you need to change comp ratios just double up on the gaskets-ie for sand use under heavy load run 2 head gaskets for low comp then return to 1 for normal use.As for the cooling effect i doubt anyone we know needs extra cooling-my races are 20minutes max and i dont ride as hard as a pro so my std cooling system is good enough.
I like the O ring head design for heat transfer and relaiblity but it aint worth the serious money they cost.

 

[Durt Cycler]

Thanks for the advise marcus. I was seriously considering a E Gorr CR150cc kit or have my head worked. I only considered the Cool Head from its nice looks and high compression dome which seems like everyone has mixed reviews.

 

[EricGorr]

The Cool Head and the VHM products could be a lot better if they offered a choice of combustion chambers or just raw slugs to be custom machined. Maybe these products would get more popular. The thing I like about them is that they're stiff materials. Cylinder heads are directly connected to the frame, its a high stress point because the shock load intersects that area of the frame. I'd like to see more design attention put towards strengthening the head stay or even adapt some type of elastic insulator material.

I'm surprised those Dutch guys haven't done that yet, of course maybe all those deep sand whoops have shooken their heads loose a bit. Hey Marcus if you're reading this have you ridden in the sands of Belgium and Holland recently? :D

 

[kawaman]

The VHM heads have differend combustion chambers and blinds to make them the way you want them too be www.vhm.nl

 

[marcusgunby]

Eric i was meant to race at Holland this year-our club has a exchange scheme-we race there and they spank us and they come here and we spank them(spank in the form of beat them badly in a race)however i was booked to holiday in Austria so i had no choice but to miss out-all the club riders told me how great it was-ahghhhhhhhh

 

[Pete Payne]

I think the Cool Heads have a bad combustion chamber design when compared to what comes on most modern dirt bikes. The area where the squish band meets the combustion chamber was not thought out too well. there is a rather large step --instead of a good radius that blends the squish band into the combustion chamber.
You can get blank domes though ,right from Pro Design, and machine it to suite you. But they are exspensive.

 

[David Trustrum]

I would also question the "larger water volume for cooling efficiency" bit. In an excellent article by Kevin Cameron he was explaining how water jackets have been coming down in size. The water sticks to the sides of the jacket forming a bit of a barrier & water pumped through it shears through the middle of the relatively still water cooling it which in turn cools the metal. Water wetter lessens this effect, but so does making the jacket passage thinner forcing the water through encouraging more mixing & less sticking to the walls.

When I have made thermosiphon heads for aircooled engines (don’t ask) I always made the pipes large but the jacket narrow to increase the velocity through the head.

The VHM heads are beautiful & you can order different sizes for RSs so I assume CRs as well. But if you are going to run the same gas & area all the time why bother? Well, except to fondle them when they are off the bike.

 

[thorspapa]

I've been looking for a Cool Head for my son's CR125 for a while, but the shops I've contacted says they're backordered. Does anyone have info on who may have them in stock? despite the controversy surrounding them, I'd like to try one on his 2000 CR125, since I've had very good luck with it on my TRX250R ****.
Thanks

 

[RKT]

Without going into too much detail, let's just say that the Pro-Design Cool Head's combustion chamber design could be improved upon GREATLY. The do offer increased cooling and looks.

Having the proper combustion chamber deisgn and parameters can increase performance immensely!! The only way to get the correct chamber design is to have the measurements (deck height, bore, crown drop, target RPMs etc. etc.) of the engine being modified. The combustion process is very complicated and often overlooked. A 70% squish area ratio is WAY much and robs power due to excessive trapped end gases and excessive turbulence.

Kelsey

 

[Pete Payne]

Kelsey,
I know you have some good designs for the 4-wheelers and snow mobiles/watercraft , but do you have any good designes for the dirt bikes yet? I guess the shells with all the different bolt patterns and head stays is the harder part. I like your True hemi designs!!!

 

[RKT]

Pete,

We will be doing more bikes this year. I do need "donor" heads to take patterns from (Any takers??)

Anyway, we currently have the CR500 head and the quad heads. More to come. All these things take time with all the different years and such.

Kelsey

 

[Pete Payne]

Kelsey,
I have a couple of spare CR125 ( 92-99)and CR250 (97-01)heads laying around and maybe a KX80.
Are all of your heads hemi design or are there some conical shapes?
Pete

 

[RKT]

Pete,

I like the hemi design for most applications. For non-normally aspirated set-ups I vary to other chamber styles. It has been my findings that a properly designed hemi chamber will be more responsive and produce a better torque curve.

Kelsey