PureGarrison

Hey, so, I have a 95 civic hatch that I picked up from a friend. The block, cam, and head are all stock d15b7. It's quick, but I want it to a lot quicker.

There are two options I'm thinking about doing. I don't have a lot of money, but I still wanna get between 200-250 horses on the crank.

The first option I'm thinking about doing is just going with a T25 turbo with the stock block and getting maybe 180-200hp. I've read a lot that the d15 has weaker rods that can't really be pushed past 220hp without giving out. I know a guy who works at a car shop that could replace the rods with performance ones. The problem is their hard to find and hard to replace, which I could do that and maybe push 250hp. I couldnt' find anything about anyone that's gone that route, so I'm curious if anyone knows how that would go.

The second thing I thought about doing, was getting a z6 mini me swap for the d15 block. Then turbo that with a T3 or 4, and get maybe 250hp? Should I stick with the d15 cam, or get a different one?

I'm kinda really new to this, so I could use a lot of help. I guess my real question is which route would get me to 250hp for less money?

theYBLEGAL

Pretty good first post.

If you replaced the stock rods with forged rods, the pistons need custom machined. Stock wrist pin is press fit, most aftermarket rods (that I know of with limited d15 b knowledge) would be forged and floating pin.

A turbo is going to be the only way, you do understand that at the least, yay for that.

Which route is cheapest, idk, but I bet longevity would be best with a d16 replacement rather than d15 anything. But I know B's more, sorry I'm not a ton of help lol.

Mini-me builds are frowned upon around here, due to the vast majority not lasting very long.

PureGarrison

Thank you, I was kinda nervous I'd just get alienated for being new, but who knows.

I'd love to just swap in an h22 and turbo it to like 350 horses, or maybe get a b-series but I'm kinda short on money. I'm looking more for like a way to improve what I already have without spending over like $2grand.

If I got forged rods, how much better forged rods would be for a d15 head in terms of boost? Like what kinda hp could I push with them?

Dammit, I thought mini-mes were a solid upgrade. Why don't they last that long?

PureGarrison

Oh and I'm planning on getting a dynamic ECU that fits what I have anyways, whether I keep the d15 head or not.

Freemananana

iTrader: (3)

You run into a lot of things that were never meant to be with the d15 bottom end and a VTEC d16 head. I'd definitely save for a D16 block and start there. Even a stock D16Z6 with a small T25 turbo would be quick. You could pretty much ignore spool time and shoot for 200 wHP. I'm sure you can source a Z6 from a junkyard (or a A6) for $250.

D15 support is essentially zero.

OneBadTurboCRV

It's all D-series rods that are weak. Some have pushed them higher, but most stock rods fail when you are approaching 190 wtq. Yes, torque... 220whp was the accepted ceiling for a long time, yes, there are many examples higher than that. What there isn't is many examples of them lasting.

The mini-me is perfectly fine. I don't know where he came up with that. The problem you will find is stock rod bolts tend to stretch when the RPM limit is raised significantly. Rod issues can also come back to crankshaft design depending on the engine. You should be fine with the D15 crank. Actually, I prefer running D15's for my endurance race engines, they just last longer, period. There are aftermarket rods and such for D15s but in this instance K.I.S.S.

If you don't have money, either sit tight with what you have (boring), or do the small turbo route. Unless you can find a decently priced turbo kit, you will be spending way more than you think for a proper (reliable) turbo kit. You have to remember there are additional potential costs, injectors, fuel pump, EMS, tuning, exhaust, etc... much to consider here. Keep your WHP goals, but decide on a budget, but be for warned, boost is addictive.

wantboost

iTrader: (2)

A stock T25 off an SR20 would fit the bill. If you wanted even fast response but not break the 200hp mark then a GT1752 off some of the newer SAABs would fit the bill. Both are T25 flanged and internal wastegate but the 1752 uses the round entry flange and has a fairly small turbine housing a/r but it would give what would feel like seamless power. Basically no lag and would make the car feel like it had a much larger NA engine with more torque.

PureGarrison

I don't really wanna do a whole swap, cause if I did I'd have to pay someone to do it for me. I'd rather keep the block and just turbo it. If changing the rods or the head would work well with the block and let me turbo it better, I'd be willing to try that.

I'm thinking I'll put a kit together around the gt1752. I found a good one for like 400$, and I'll need an intake and exhaust mani, a tapped oil pan, and an intercooler, which I'll find a nice little bundle that comes with some pipes, and 450cc injectors and a new fuel pump. And a blow off valve

So yeah, I'm just gonna stick with what I have and turbo the **** out of it. But still, I'm curious, should i get some kick *** forged pistons? How much more hp could I get out of the crank if I got them?

Thank you all for helping me, what I want to do is kinda weird, just keeping the d block, but I have a pretty tight budget.

2kdrift

You say you cant do the whole swap yourself but if you change rods the block is coming out anyway so i guess i dont quite understand the logic. Anyway I had a setup like this first block was a d16z1 (stock low comp pistons). I tried doing a d15b7 with z6 head and blew a rod within the first month. the 1.5's have weaker rods then then 1.6. This was all with the sr20 turbo wantboost mentioned. I would recomend a D16z6 if you can find one it should not be anymore work or money then going with the 1.5 /w rods which would be fine aswell but I wouldnt try the stock rods off the 1.5 they are super weak

PureGarrison

I don't wanna get an entire new engine, I wanna stick with what I have. It's pretty unorthodox for most of the people here, but I just wanna get a bit of a better engine than what I have now. Like I said, my goal is 200-250hp, and I guess part of that is sticking with as much of the d block as I can.

I think I misunderstood the concept of a mini me swap. I'll just stick with the block I have, get some aftermarket parts and turbo it.

I'm just curious about the rods, I'd like to keep the block I have, and if installing the rods means taking out the block I'd be willing to do it.

RazielDelSol

funny enough we're in the same boat, i have a del sol S with the stock engine and to be honest it's been difficult finding a d16z6 around my area so ive been considering building my current engine.

good luck to you bro

wantboost

iTrader: (2)

400 for a GT1752 is a bit steep. Especially if it hasn't been rebuilt and was just pulled from a car. I have one laying around I could rebuild with a billet wheel. It needs a new turbine wheel and compressor backplate but those aren't terribly expensive. It would perform better than a standard 1752 and I could probably get it done for not much more than the one you've found.

Forged pistons won't do anything, it's the connecting rods that are the weak point.

You could do pistons and rods with the engine still in the car if you stay with stock diameter cast Vitara pistons (proven incredibly strong). Pull the head and the oil pan then pull the pistons and rods, clearance the girdle and bottom of the sleeve for the rods, Check bearing clearances, and then assemble and break it in. However it would be wise to replace the crankshaft bearings which means you'd have to pull the transmission but at that point it takes half the time to pull the engine and trans as awhile.

PureGarrison

I've read that it's possible to change the pistons without removing the block, but then there were a bunch of people saying it's not possible. But yeah, I could do that.

Wait, do you mean Vitara rods? Why would I wanna change the crank bearings?

I might take you up on that offer, I could pay for the turbo, the parts, and a bit for you fixing it up.

Build it up dude, turbo the **** out of it and then if it breaks down, then go for a d16

NotARaCist

iTrader: (1)

It's entirely possible to swap pistons and rods with the block still in the car, it's just a righteous pain in the urethra. This Vitara bullshit needs to die, though. IF you want to boost, just boost the stock D15, stop at 180-200 WHP, and have some fun with it. When you decide you want more, get a D16 or B18 block, and build that on the side while you're still driving the D15. Once the replacement motor is built and ready, do the swap in a weekend and continue having fun. Building a D15 is a recipe for disappointment, empty pockets, or both.

wantboost

iTrader: (2)

Vitara pistons...

Why change the crank bearings? Because you don't know how old and how many miles were on the engine, nor how it was maintained or treated. Crank bearings cost like 50 bucks and it's good practice. As is replacing every seal and gasket while the engine is apart. Same with the oil pump and water pump.

and here's the compressor map for the compressor wheel the 1752 uses. Ignore the GT20 part because both turbos use the same compressor wheel

PureGarrison

That's what I'm starting to think, I'll just turbo what I have and get a new block later on. I'll aim for like 199horses.

I know it has 230000 miles on it, and the engine was rebuilt about 10000 miles ago, I totally forgot to say that. Sorry, this is my first time posting. The oil pump was replaced about the same time. It was kept in really good condition, my friend I got it from is a mechanic who constantly checked on everything.

I'd still really be interested in that 1752. If I was gonna turbo the d15, it seems like that would be the one to go with.

NotARaCist

iTrader: (1)

The 1752 should max out around 240 CHP, which would be pretty well in line with your 200 WHP goals. If you can find one in the right condition, for the right price, it'd be worth giving it a shot. I know I'd be curious to see dyno sheets

OneBadTurboCRV

There are many turbos that would foot the bill, why get so hung up on one specifically? Some of the lower trim straight T3 ones work nicely as well.

COMPRESSOR MAPS

wantboost

iTrader: (2)

Still asking a lot for a D15 to spin up a stg1 t3 turbine wheel with any quickness.

OneBadTurboCRV

Then why were / are some of the older stuff off Volvos and such (T3 .42 / .48 - 40 or 45 trims) spooling at around 1,800 RPM on the D-series? There are quite a few options, rest assured.

wantboost

iTrader: (2)

Well yes the 42/48 would but the larger ones are questionable.

OneBadTurboCRV

No doubts there.

wantboost

iTrader: (2)

The nice thing about the smaller journal bearing GT units is they all are a bit more efficient than the older "T" wheels.

OP could really run anything between a GT17 and GT25 based turbo and be fine. As most of these are used on older OEM platforms they are now readily available at decent prices and the aftermarket has created upgrade billet wheels for almost all of them.

TheShodan

iTrader: (14)

OP could really run anything between a GT17 and GT25 based turbo and be fine. As most of these are used on older OEM platforms they are now readily available at decent prices and the aftermarket has created upgrade billet wheels for almost all of them.

But the internals are all a bitch to get regardless of billet wheel upgrades.
Without the design changes in the wheel design itself, they do very little good

wantboost

iTrader: (2)

I've found rebuild kits and turbine wheels for all of the smaller GT series.

Most of the billet wheels incorporate an extended tip design and have hub/blade thickness changes in conjunction with a change in the exducer trailing angle.