ok, this is going to just be a big list of questions i have regarding my D16z6, and possibly a Y8, so answer what you can, i'll really appreciate it.

I'm wanting to do a D16 with vitara's, but i'm having trouble answering specific questions i have about decking and milling for low compression and issues with the timing belt tension after decking and milling. SO, here goes..

from what i understand, honda says you can take off a MAXIMUM of .040 inches from the top of the block on a D16y8 and z6, so as to still keep enough tension on the timing belt.
Vitara pistons sit 1.7 MM below the top of the cylinder on a Z6 and y8 according to the vitara thread, or about .066929 inches. now, if i take off .040, i can still keep the same timing belt, but i have to use the stock Z6/Y8 headgasket, and that keeps my CR below 8.2:1, which is WAY lower than i'm comfortable with. I'd like to have ATLEAST 8.5:1, but i'd be happier if i could get closer to 8.7:1 or so..

what i'm wondering, does anyone make some high CR valves for this motor, and if so, what am i looking at gaining compression-wise from getting them?

OR, is there any way i can use the 2 layer y8 headgasket, along with milling the block .040", and use a shorter timing belt? and if so, which one?


now, holset questions..

i'm looking at a Hy30, or an HX30 from the cummins diesels. i know a lot of B series guys use them, but i can't find any D series guys using them, but i don't understand why. i'm planning on doing about 20ISH psi, shooting for around 350whp, and that boost range is directly in these turbo's efficiency range.. for what, if any, reason are people not using these turbo's on D series?

thanks in advance for all of your help...

 

well 40 thou off a head shouldn't leave you with timing belt issues. the tensionor will let you tighen that thing up quite a bit. the only problem that you might run into is centering the timing of the cams, that could be curred with some adjustable cam gears and some thinking.
And i believe that the vitara's sit lower than a stock piston so you could probably take off a tad more to bring combustion efficiency back up.

 

yeah.. that's what i was saying.. i know i can take off UP TO .040 but that still leaves my compression in the low 8.'s, which is way lower than i want to run, so could i take off more and use, for instance, a vx timing belt? if i use a y8, i can come out even better yet if it is possible to use a smaller belt, as i can also use the 2 layer headgasket along with the milling and come out closer to 9:1...

if i go .040 off the top of the block, i HAVE to use that stock headgasket with all 3 layers to keep the same belt... BUT if i can take .040 off, and use a smaller timing belt, then i can use the 2 layer Y8 gasket, and put me to roughly 9ish according to solblu's compression calculator which is about where i want it because i would like to use a holset HX30 and run a pretty decent amount of boost.. shooting for 350 on pump, and i don't know what on higher octane..

 

bump.. anyone know? i got a Y8 i can get this weekend if i can get an answer to these questions..

 

Wouldn't taking 0.40 inches off will make you compression higher, not lower?

 

I am doing the same setup, but with a bigger h1c w/ 12cm housing.... If you use a use a shorter timing belt, you will throw off cam timing futher than the differnece in the deck height. The shorter the deck, the more retarded the cam. In every case that I have seen, D's make more power @ ~3 deg retarded anyways. I am postitve the tensioner will have enough movement to get the correct belt tight enough.

You are going to have to run more than 20psi to get 350whp... more like 25+

my stock and very tired d15b went 119 @ 24psi on a bigger turbo so that's around 300whp w/ 2350 car

 

I have a built y7 with vitaras and tt rods, stock head and valvetrain, d15 intake manifold running the holset hx35 at 10psi for now and i have full spool at 4500rpm all the way to 7k. I don't know why more people don't use holsets, they work really well. If i were you i would go bigger than an hx30, go hx35 or hy35.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by da_dude &raquo;</TD></TR><TR><TD CLASS="quote">Wouldn't taking 0.40 inches off will make you compression higher, not lower?</TD></TR></TABLE>
yes
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wilham320 &raquo;</TD></TR><TR><TD CLASS="quote">I am doing the same setup, but with a bigger h1c w/ 12cm housing.... If you use a use a shorter timing belt, you will throw off cam timing futher than the differnece in the deck height. The shorter the deck, the more retarded the cam. In every case that I have seen, D's make more power @ ~3 deg retarded anyways. I am postitve the tensioner will have enough movement to get the correct belt tight enough. </TD></TR></TABLE>
manual says that .040 is the max you can take off and still keep sufficient tension on the belt. why do people use different belts on mini me swaps? i've basically got the same problem if i take off more than what is recommended because thent he belt will become too slack.. i can take care of the timing issues and whatnot right? the tuner should be able to handle that if i have any problems correct? saying of course that i have a competent tuner lol..

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wilham320 &raquo;</TD></TR><TR><TD CLASS="quote">You are going to have to run more than 20psi to get 350whp... more like 25+ </TD></TR></TABLE>
i'm not disputing you because i'm sure you have more experience than i do, but with the holset flowing the amount of air that it does, wouldn't 20 PSI be sufficient for that amount of power because of the CFM's that it flows? 28 was good for JFK to get 475 on a (i believe) t3/t4.. again, i'm not arguing, just trying to learn more, because i've heard 20 from this will be enough for over 400 from a guy that has built numerous 500+ hp B series... again, just asking for more info

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wilham320 &raquo;</TD></TR><TR><TD CLASS="quote">my stock and very tired d15b went 119 @ 24psi on a bigger turbo so that's around 300whp w/ 2350 car</TD></TR></TABLE>

can you explain what you're saying here? D15B with a bigger turbo than the HX30 on 24 PSI did 119 in the quarter so estimated 300 WHP in a car that weighs 2350? did i get that right? lol..

what was your setup? where did you hit full boost at?

 

honda400ex, how much boost are you running?

 

bump

 

another thing you could do to bring compression back up is to have someone weld some more quench into the combustion chambers. to make a clover combustion chamber. as for the turbo i'd reccomend running a hx35 with the 12cm housing and making a pulse paired manifold. Pairing cylinders 1&4 and 2&3 help dramatically with boost lag. don't be scared of big turbos with a correctly built manifold. twin scroll is the way to go!