Hey, I did a search and wasn't able to find any pictures. Anyone have a picture of an open deck h22 and a closed deck h22? I've just never seen them side by side and wanted to see the major differences.

 

H22a4 (Open deck)



I have a picture of my closed deck h22, but that is on my desktop at home. If no one posts a pic of one by this afternoon, I will post mine up.

 

 

it's my understanding that open deck is better for street but closed is better for drag. Reason being is closed deck is great for short huge boost runs but longetivity is less as cooling isn't as efficient as the open deck. Open-deck may not be able to take as much power but cools much better allowing for better longetivity. All of these scenarios are based on turbo + built motors of course. Is this correct?

 

thats what i hear too.....can the gurus confirm please

 

When you are referring to the lack of cooling efficiency of the closed deck design, are you talking about them not being able to disburst heat quick enough resulting into over-heating?

If that is what you are talking about, from my exprience, this does not hold true. I live in Houston, TX where the summers get very hot/humid and on my boosted Closed deck h22 I've never had a problem with cooling. The temp gauge gets to the middle and stays there no matter what I'm doing (sitting in traffic, boosting, cruise). I run 70/30 water/coolant mixture with OEM t-stat and my fans on all the time. Basically my cooling system is stock.

I have not been able to take my turbo setup to the track yet, so we will see if it'll be able to handle the stress of 30 min sessions in VTEC and hard boosting.

Also if you've noticed, when you get a block sleeved from AEBS, GE, or Darton, they all come back with some form of a block guard installed. This resembles the design of a honda closed deck motor. Also many people use the alternative of "block filling" to acheive the similarities of a closed deck design without cooling issues as well.

I don't have any technical data to back up what I stated, but from my personal exprience, as well as others, I don't believe it is a major problem in the real world.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DfwBB6 &raquo;</TD></TR><TR><TD CLASS="quote">thats what i hear too.....can the gurus confirm please</TD></TR></TABLE>

Yes and no.

The open deck of the a4 does allow for open coolant jackets around the cylinders, but a closed deck has plenty of coolant passages around the cylinders. I don't believe there is any quantitive evidence that one "cools" better or is more reliable than the other. Of course this varies widely with tuning and other components in the build.

When boosted on a stock bottom end, both the a4 and a1 are still vulnerable due to the piston ringlands. Upgrading to forged pistons require the same procedure of resleeving or you can try running the Mahle FRM compatible pistons. Either way, a sleeved block will take alot more abuse than the stock FRM sleeves. So there is no distinctive advantage to running an open or closed deck block. You can probably find closed deck blocks for cheaper, but that's about it.

 

^^ there may be no hard evidence to support these facts. I beleive you won't see any overheating issues. I would like to see the sleeve and piston temps of both blocks under hard boosting. After overlooking both I'm sure the temps are higher on the closed deck. The longer the temps stay high the more it begins to wear on your longetivity. You may not see any cooling issues because your gauge is only reading your coolant temperature. It's not reading the sleeve or piston temperature. Of course all of this is just theory.

 

There is one fact though. Closed deck like 4th gen is a little lighter.

 

how is that?