The Definitive Idiot's Guide to Tuning the D15B7 (performance mods)

[Missouri_Civ]

Hello all. I decided to make this compendium of information and tips to help disspell some of the repeated questions we get about the D15B7 engine and to make a "one-stop shop" of info on these engines.

Many of the members of this board have D15B7 engines in their Civics (myself included). Many of us also wonder about how best to tweak these engines to get the most out of them if a swap is not in the future for our cars. This guide will attempt to guide (no pun intended) you in the right direction with your car.

The first thing to remember about the D15B7 is that it sucks for performance purposes. This engine was built to do two things: have high fuel economy and be reliable. At these two pursuits the engine excels. However, throw in the need for it to be fast and you have a lackluster platform to work with.

For the most part, the D15B7 does not respond to "bolt-on" mods well. Short ram intakes (or cold air intakes), headers, exhaust systems, throttle bodies and intake manifolds will all produce fairly small gains for the type of investment you will make in them. Therefore, for the tuner looking for a cost-effective way to boost the performance of his car, bolt-ons for a D15B7 are not the way to go.

However, there is quite a bit of room for improvement in the way of increasing the amount of power that is actually put to the ground in a car with the D15B7. For one thing, changing the transmission out to the Si or EX transmission with its shorter gears will produce a noticeable increase in acceleration. Couple this with the addition of a lightweight flywheel and your car should feel quite a bit quicker than it used to. Add in an LSD and you should see even further gains, not only in acceleration but in overall handling as well.

In addition to increasing the amount of power that is actually put to the ground in a D15B7-powered car, you can also make some gains by reducing the weight of your car. This is nothing new to most hard-core racers, and in fact, most dedicated drag cars are simply sheetmetal shells with an engine attached. The amount of "gutting" you do to your own car will be up to personal preference. Generally, even with lightweight racing rims, carbon fiber hood and trunk, deletion of A/C, removal of carpeting and sound insulation and even the removal of the back seat you are still only looking at a few hundred pounds at the most of weight savings. Basically, don't expect miracles, but do expect your car to feel a bit quicker off the line.

So there you have a bit of an overview of some of the things you can do with a D15B7. Now, let's get down to specifics.

Transmission Upgrades

Si/EX transmission - a cost-effective way to increase the acceleration capabilities of a D15B7-power Civic due to shorter gearing

Lightweight flywheel - this mod will augment the effects of an Si/EX tranny swap or at least make the DX/LX tranny perform a little better


Engine Upgrades

This seems to be an oft-overlooked avenue of making more power of out a D15B7, but there are a surprising variety of choices.

Mini-Me head swap - a cost-effective way to boost the power output of the D15B7 while also giving it VTEC; expect to gain around 15 to 20 horses with this mod

Stronger rods - if you are planning to build your motor up for a turbo setup in the future, these will be one of your more important components; Crower is the only brand I am aware of for the D15B7

Different pistons - this is an area I am not particularly familiar with for the D15B7; however, there are some choices out there for boosting power and providing increased reliability in a turbo setup

Adjustable cam gears - these are only important for turbo setups or otherwise highly modified engines that require the increased tunability; moderately modified cars usually need not apply

Metal head gasket - you may already have one of these if you did a Mini-me depending on what gasket you decided to use, but Cometic and a few other brands also make these specifically for the D15B7


More to come; feel free to add all you like.

[ke98248]

good info

[Midori Green]

Originally Posted by ke98248

good info

x2 ... im guessing this also applies to the d16y7 which is very similar to the b7 engine...correct? besides the intake manifold

[Libertariat]

Depending on which b7 we're talking about, the usdm b7 only had 8 valves.

the y7 has 16.

Which leads me to believe the OP is talking about the usdm b7 because a 16valve head upgrade really would be a big benefactor.

Good write-up

NVMD.
[edit] D15B8
Found in:
1992-1995 Honda Civic CX (U.S. model)
Displacement : 1493 cm3
Bore and Stroke : 75 mm X 84.5 mm
Compression : 9.1:1
Power : 70 hp @ 4500 rpm & 83 ft·lbf @ 3000 rpm
Valvetrain : SOHC (2 valves per cylinder)
Fuel Control : OBD-1 MPFI



Modified by ek forever guy at 9:44 PM 5/21/2007

[Syndacate]

I like this...

Obviously not my cup of tea but at least ur taking a smart approach about it...

[EG-lowrider]

Originally Posted by ek forever guy

Depending on which b7 we're talking about, the usdm b7 only had 8 valves.

the y7 has 16.


Modified by ek forever guy at 9:44 PM 5/21/2007

not true, the usdm b7's have 16 valves, the b8 has 8 valves. trust me, ive had two b7's with 16 valves.

[Libertariat]

Originally Posted by beaterbangin

not true, the usdm b7's have 16 valves, the b8 has 8 valves. trust me, ive had two b7's with 16 valves.

That's right, easy to remember, b8 = 8 valves.

[caeavesRSX-S]

I think the d15 can take fairly well to bolt on mods.

I had a 95 DX sedan that put down 100 hp to the wheels. This was in line with the usual 105 whp from the stock EX. I had a chikara header, short ram intake, tenzo R axle back exhaust, lightened flywheel, and a full MSD set up. These are embarrassing mods to think about today but the late nineties were tough for imports.

Throw on the Vtec head and some better parts and the d15 should be getting close to a stock b16a in whp. Not bad for a lowly DX.

[Boomboy14]

great info...thanks

[baller status]

DONT: do intake, header, exhaust (you'll be disappointed) and then modify the fuel and ignition system (will get you nowhere at this point).

DO: raise compression (pistons) and upgrade the cam. Then do the things I told you not to.

[tsgxjaydub]

good info

[DerangedEG]

subscribee

[JCDC5R]

Not to bump a old thread but tis true I have a D15B8 in my coupe, had 8 Valves. Had a break down cam snapped, mauled my head up. Not easy to find a B8 head so i got a B7 head instead. Upgrade to 16v was a performance boost. Ran better too considering my car had been previously swapped from a B7 to B8 (why idk, some tard must have owned the car before me) anyways it still has the P06 ECU from the B7. Not the most powerful honda engine ever but does great on gas mileage. I've removed the a/c and p/s and ricer vatozone cold air intake.

[guardian_ang3l]

Side note. And rebumping an old thread. The z6 head swap is actually good for more than the guide suggests. Granted before doing the head swap I did have the supporting mods I/H/E, EX transmission w/LSD and a lightened flywheel.

In any case this head swap netted me approximately 40whp.

Stock d15b7 ~80ish WHP
b7/z6 mini me ~120ish WHP

Just sayin.

[JWhip1]

intake mani is another way to go to add a little hp

[aeschbi277]

good to know

[dinged]

how much would a mini me head swap cost? what engine is the head actually from? d16y8? or d16z6? is it just swap the heads over, anything else? any ecu tuning?

[alania]

nice write up! tnx!
how do you think, what would be more fresher :
1. mini me D15B7 block + D16Y8 head
or
2. swap D15B7 to D16Y8

thank`s for all advices!

[lendo_21]

This is great info! but I live in CA and doing a mini-me head swap won't pass smog. So I was wondering if any of you guys have any other advice on how to create more hp and torque to this engine without having to get the engine bar'd or have any other probs with emissions. I already plan on changing my trans to a better one with shorter gears like mentioned above, but I was wondering what else my cali people have done to their engines and are still able to get it smogged legally without any problems. Thanks!

I was also wondering if I should put in an Si trans or put in a b-series trans? any ideas? I just want more torque and power bc my hatch really doesn't have any lol

[sextav6]

not to be a jerk, there is some good info, but when I read the title I expected the thread to start with something to the effect of:

1). remove old motor
2). swap in new
3). ????
4). profit

[Jhicks]

So your saying that I'm not going to get any kind of real power out of my b7?

[baller status]

Definitely agree swap to Si/EX tranny. Gearing is EVERYTHING on a Honda.

LSD tranny = waste of money for this level of modification. And I cringe a little at the author saying it will improve "handling". The only time it does anything at all is when you're heavy on the throttle exiting a turn, or when launching hard. It doesn't engage unless it's under heavy load. "Handling" mostly refers to body roll IMO. The ITR is the only stock LSD worth spending money on, but this thread is about retaining the B7.

Definitely swap the head to one that will give you higher compression. Then get yourself some cheap N/A parts ie header, intake, exhaust. Call it a day. If you're sticking with the b7, the point is bang-for-your buck.

The alternative is to piece together a junkyard/ebay turbo kit. This is for people who are both smart and sick and twisted. Your older sister handed down her 4 door Civic auto and you have a chip on your shoulder. You're the quiet one in class and all the jocks have Mustangs. I knew a ****er like this He spanked everything he went up against but eventually rolled the car down a steep hill, saved by a tree, and walked away.

Wait, how old is this thread? Apparently I posted in it already.

[98civdx]

Originally Posted by Jhicks

So your saying that I'm not going to get any kind of real power out of my b7?

Mini me and boost it. Other wise no.

[Jhicks]

I paid 50$ for a motor and tranny (b7 5speed) all it needs is rings. The guy thought it was something worse. I was told the b7 was Jdm. I don't give a rats *** about Jdm but I was hoping it would have potential. Well, it don't sound like its worth my time.

[dinged]

It's not worth it man, you're better off using the B7 to get good fuel economy and saving up for a decent motor