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Discussion Starter #1
i know i am still a noob to the forums but i am in need of advice.
me and my brother have been tossing the idea around of boosting our 1991 ef
d15b7

we are in no rush/ no one drives the car daily..
^^^^i DO NOT plan on boosting with stock internals
things that i know i need
full pieced together turbo kit, t25 turbo
injectors, fuel pump
ecu management,
h beam rods
undecided pistons
3 layer metal HG
y8 intake mani
stage 2 act clutch
obvious rings, gaskets bearings,
arp's


goal is 240ish whp
psi whatever gets us there on pump gas/ t25

the biggest questions i have are....

1 is it a good idea to stay with the b7 head, will the stock valvetrain be able to safely handle 280 hp at the crank? or should i use a z6 or y7 head?

2 also what pistons should i go with if im looking to use hbeams that have a stroke of 134.5. ? i am shooting for some where between 8.5 and 9.5 cr

I CAN NOT FIND ANY D15B7 TURBO BUILDS WORTH READING, IF YOU KNOW OF ANY LET ME KNOW
i do not want to swap, i would prefer to stay non vtec but i have a good z6 head, i know d15 builds are not cheap but me n my bro split everything 50/50
 

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Love the Civic
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2005 Legacy GT
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My b7 bottom end made 184 whp/150 wtq with no issues.

What kind of budget are you looking at? For a budget build, your kind of limited to custom length b7 rods and vitara pistons. If you have no ceiling there are forged b7 parts, but they cost a pretty penny. I was planning to go this route oh so long ago so I've done some of the research leg work.

The b7 head will be fine (it's the same as an A6 head, with a smaller cam). You'll probably want to look into upgrading the springs/retainers cam, unless you don't plan on going over the stock redline. The upgrades will make reaching your goal easier, but I think the stock A6 heads have been taken over 300 whp (correct me if I'm wrong people).

Yes the 1.6 has much more aftermarket support, but it is possible to make power on a b7.
 

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Discussion Starter #5
Yea I was figuring vitaras would be the most reasonable way to go. What compression would I end up with vitaras?

As far as a budget 2500 not including tuning.
I really just want to do something different
I know rods/pistons/bearings/rings/ arps/ hg will be around 100
After injector/ fuel pump and turbo things should be around there.
What are some good d15 springs retainers?
 

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Black/Green Civic HB
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On my t2560r d16y8 vitara build (9.6:1comp) I made 242hp @12psi

A rebuilt stock head will be fine for your goals, the t25's usually start running out of breath around the stock rev limit... So springs/retainer upgrade shouldn't be necesary

the weakest point will be rods
So start looking into what rods/Pistons you want to run
 

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2005 Legacy GT
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Yea I was figuring vitaras would be the most reasonable way to go. What compression would I end up with vitaras? That would depend on if you are using stock length or custom length rods ... I'm not sure if the custom length D15 rods are easily obtainable anymore. Either way somewhere betwee ~7.5 and ~8.5 IIRC.

As far as a budget 2500 not including tuning.
I really just want to do something different
I know rods/pistons/bearings/rings/ arps/ hg will be around 100 You are getting some fantastic deals then (or do you mean $1000).
After injector/ fuel pump and turbo things should be around there.
What are some good d15 springs retainers? You should be able to use any aftermarket springs/retainers for an A6 (same head casting). Pick a company you like/trust.
If the custom USDM d15 rods are not available you are looking at close to $900 for the set (the ONLY place I've found that makes stock length forged rods for that engine is Crower). For forged d15 pistons I've only seen SRP carrying them ... for close to $600 a set. Those will set you up very nicely to make power ... but like I said at a pretty penny. There may be more places producing parts now ... but I haven't looked into building a d15 in a while.

I suppose you could use the stock length forged rods with vitaras if you wanted to, but with out A LOT of block/head work you'll be sitting at ~6.5 CR (that's even with a thin HG). If you decked the block to make the pistons flush (0.096") you would end up around 7.5 CR.
 

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Discussion Starter #9
From what I seen there is some rods on eBay for the d15b2 and b7 they are h beams conrod or something like that. Has anyone used them. They almost look too promiseimg??

Also that's why I was looking into the t25 I am really only looking for good boost between 2k and 5k rpm.
 

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Thinking about trying to hold on to my B7 for a beast7 turbo build...someday, probably get rid of it and buy another one when the time comes, I really have nowhere to store this sort of thing
 

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Discussion Starter #14
Center to center 134.5 . which I believe is .5mm longer than stock.

And they are only 279 with ARP bolts.
How would my compression be soooo low?????
 

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2005 Legacy GT
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They are probably the 134.5mm from cxracing. Those are the only ones I have seen on ebay.
Yup I just went and looked them up. That will get you to almost 7 CR, with vitaras. Still pretty low.
 

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2005 Legacy GT
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Center to center 134.5 . which I believe is .5mm longer than stock.

And they are only 279 with ARP bolts.
How would my compression be soooo low?????
Wrist pin location on vitaras causes them to sit lower (lower compression height) and they have a HUGE dish. I could sleep in them.
 

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94 Civic Cx
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Get a z6/a6 crank machine it to d15 spec use those 134.5 cx rods vitaras and it gets a 8.48 cr on zeals w a y8 head gasket b7 head. Dunno how much it costs to machine the crank or if id even run it but its an option
 

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2005 Legacy GT
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Get a z6/a6 crank machine it to d15 spec use those 134.5 cx rods vitaras and it gets a 8.48 cr on zeals w a y8 head gasket b7 head. Dunno how much it costs to machine the crank or if id even run it but its an option
I don't know that you'd want to machine a crank that much, I have my doubts it would maintain it's integrity.
 

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Discussion Starter #19
Damn so its alotttt of machine work or custom pistons.


Is it even safe to do that much mill work?
Or is there like a d16 piston that would work better?
 

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it is not that tough or expensive to do. I believe I am at about $1,100 or a little less. I did all most all of the work myself though. check out my build thread.
http://www.d-series.org/forums/showcase/123370-my-slow-progess-300-hp-d15b7.html
http://www.d-series.org/forums/showcase/238274-my-little-frankenstein.html

I am probably about 170hp on about 7psi give or take 10hp. I think allI need to do is just turn up the wick a little to make your goals. there was a guy in Hungry running 23psi on an EVO 8 turbo on forged rods and stk crank. if I remember he told me engine lasted a couple seasons at the drag strip before Vitara piston came out the side. He said crank and rods were fine.

I think I would ditch the T25 and go with a holset hy35 turbo. if you keep an eye out they are pretty cheap. The diesel truck guys consider them undesirable (too small for them). The T25 is going to be way out of its efficiency range for that power goal. another cheap turbo would be a 60 trim T3 turbo from a ford mustang.

Spend your cash on good engine management, good fuel injectors made a big difference for me. You do not have to use vitara pistons if you are willing to rebush the custom rods. use your creativity
 
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