I called HQ today about some heads. Cool guys to talk to
buy the way. Anywho, the tech asked me what my dome volume
was on the JE pistons. The pistons are 3 7/8 with10.25:1 cr.
So I called JE and the tech told me the dome volume is 12.2 cm.
Called HQ back but they were closed for the night. So now I'm
asking my other techs. What the heck is dome volume anyways and
what should I look for in my heads to accommodate that volume??
I hope this all makes sence to you guys cause it doesn't to me..[&:]

 

You probably mean 12.2 CCs, this is the area that you see as a "pop-up" on the pistion surface.

BTW, that seems like alot to me, but maybe im on crack!

mine are 4.5 CCs on a 95 in C/P piston, which is an out of the box 9.5 to 1 before head milling.
after the heads were CCed, I had a corrected 10.0 to1

 

Probably are cc's. So let's say the piston is flat, what ever is protruding is dome volume? Could it be that he mentioned 12.2 for the pair or isdome volumeusuly mesured individually?
Sorry about all the questions. I just like to be a little more informed
for when I talk to these guys. Thanks man.

 

Hey Crazy....

I think you'll be better off w/HQ. Doug will definitely take care of ya, AND he's on your side of the border!

Sorry I don't have an answer for ya on the dome size. I looked at the JE site and found the pistons, but they do not list that data there. Are you planning to have youe jugs bored? If so, you can send those pistons along with your jugs and Doug can set them up perfectly for you.

Keep us posted!

 

Hey phil!!
Yeah, I'm gonna get my cylinders bored. I was told that it's
better to get the pistons then give the jugs along with the
pistons so they can bore the jugs more accurately to the pistons.
Is this correct?? The only thing that gave me a sour taste fom
HQ was that he mentioned the need to get their ignition module
to work well. He said my DTT didn't have enough adjustability.
I thought I had that all covered with the slope advance, timing
and rpm adjustments. And I just paid 350.00 for the damn thing.

 

It is absolutely correct that jugs can be much more precisely setup to a specific set of pistons than just using a "target" size bore and doing in such a way that it will "work" with any set of pistons. What you end up with, is a much better fit!

I don;t recall reading what ignition module you have, but after "using components that compliment one another", getting a proper (and complete) tune is right up there in importance. The real challenge in getting a complete & "proper" tune is being able to very granularly adjust your timing. There are modules that have a couple factory prest "curves" and other that are completely adjustable. In order to get the most out of your motor (best power, no ping, easy start, etc) it has to be tuned right. Did he recommend the HQ-6100? If so, you need to understand how cool that module is. HQ licensed the unit from DTT and it has some additions only available on the HQ version. Additionally, Doug can set it up VERY CLOSE for your specific HQ build before you ever bolt it on.

I know it sux to hear that, but do not be disappointed. You should feel fortunate that you're talking to someone that has a complete solution. If your unit is pretty new, you should be able to eBay your factory DTT unit or post it here in the Parts For Sale section.

This falls back into my pet peeve theme.... There are tons of great "parts" out there, but they do not all work great "together". ... did I hear someone say "Always use components that complement one another"... It's your scoot and YOU are the one that needs to be happy in the end.

 

Phil,

Please know that I am NOT busting your chops. I read all your posts and it's obvious you are knowledgable, enthusiastic and helpful. I have learned a tremendous amount by reading your posts! However, I think you mean to say complement, not compliment. Compliment with an "i" means to praise or flatter, complement with an "e" means to enhance or go together. I think you intend the latter. I only point it out because you use it frequently and it's in your sig. Once again, only a very friendly observation.

Keep up the good work.

 

Thanks!

Main Entry: 1com·ple·ment
Pronunciation: 'käm-pl&-m&nt
Function: noun
Etymology: Middle English, from Latin complementum, from complEre to fill up, complete, from com- + plEre to fill -- more at FULL
1 a : something that fills up, completes , or makes perfect

 

Good stuff, I agree with most of what is being said here. Doug at HQ is a great guy and is very passionate about what he does. We have seen his heads for years and it is quality stuff. We choose to use the cnc ported heads because it takes out the core shift and the repeatability and quality is excellent with the R&R stuff we use. They also have their DDT ignitions with their chip in thembut I will tell you that these heads will work very well with the DDT that you have. Our experience has shown that there is so much energy in the R&R ports that aggressive timing curves and wild cams are not necessary. We have used a lot of these heads with the ignition you have with great results.

 

Thanks again Phil and King. You guys rock man.