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Hey all! i’m learning how to street tune my car, so i’m really diving into the physics of engines. i recently read the “what is torque and why should i car” post and it was a big help. i think ive finally got my head around torque vs hp, and how everything affects it. i have been trying to figure one thing out though. i understand that an exhaust that’s too big can hurt torque bc of turbulence, but i’ve heard that more restricted intake manifolds can generate more? for example the illustrious 2jzge intake is longer and more curved than its gte counterpart and is theoretically “better” for low rpm torque. i’ve heard that swirl ports vaporize the gas and thus allow the combustion to be more efficient, is that’s the same with the rest of the intake? thanks i hope this makes sense
 

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Good look, the info I've posted on here is now 21 years old.

Easy answer, buy an AEM CAI and be done.

Now if you wanna research, start back in 1944 NACA paper from MIT, then in the late 50's Chrysler.
 

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Good look, the info I've posted on here is now 21 years old.

Easy answer, buy an AEM CAI and be done.

Now if you wanna research, start back in 1944 NACA paper from MIT, then in the late 50's Chrysler.
haha yeah most of the threads i’ve been reading we’re closed before i was even born... yeah.

anyways i currently do have the junkyard special ram air lol. i’m about to build a turbo ZC, but for now i’m just tryna squeeze all the power i can outta that b7. i figure i’m at about 125hp by now.

too broke to pay a real tuner so yeah
 

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nope, you are nowhere near 125hp if still with stock cam and stock compression.

the best cold air intake possible would only net 1-2hp and potentially tank your low rpm performance.

Stick with a long intake tube that is the same size as the throttlebody outlet. Also try and find a mild velocity stack style filter to keep dirt out, and spend some time making sure the critical things are working, such as MAP and TPS are working good, coolant temp is reading correctly, valve lash is set properly, no oil leaks, etc...


There are so many thing son a car to keep track of, its frustrating at times. And nearly every single one will cause some sort of performance loss
 

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You have data to back up that the best CAI only gains 1-2 hp?

I have data from 21 years ago next week that proves otherwise. Getting it off Photobucket might be a pain, if it is still there.
 

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was it on a fully stock d15b7? I was pretty sure the B7's factory exhaust manifold and intake manifold prevented it from seeing anything.

As far as I remember, biggest easy gains were from using 99-00 oem Y8 exhaust header and d16z6 intake manifold. Beyond that, it was giving up alot of low end for minor top end.

You are closer with the D15s than I am though.
 

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Stock D15B7 with a Stillen Header (no ET change, and AEM CAI.

16.44 bone stock on 195/50/15
16.28 with Stillen header and a better driver, I was a rookie driver in a Honda once
15.87 with AEM intake and a friend driving, 15.98 with me driving, before how I learned to be angry at the gearbox.

AEM CAI was worth .3 sec and .4 mph with ease.

Even without the D16A6 cam and Z6 intake, the RAM tuning still produced the "humps" in the TQ band and power up top.

The single biggest changes though, were two gearing changes. First going from DX to EX, then to ZC 3-4 later, but also the 20" slicks which made the 4.25 FD act like a 4.83 FD amd all the traction I needed at launch. Including killing a set of spider gears once.

Also the way I tuned my exhaust sizing way back then, Enginemasters has been covering it and coming up with similar results I did back then....which were based on SBC's from 20 years before that from magazines.
 

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Discussion Starter #9
was it on a fully stock d15b7? I was pretty sure the B7's factory exhaust manifold and intake manifold prevented it from seeing anything.

As far as I remember, biggest easy gains were from using 99-00 oem Y8 exhaust header and d16z6 intake manifold. Beyond that, it was giving up alot of low end for minor top end.

You are closer with the D15s than I am though.
ok just to clear things up a bit, it’s more than just a cai, i’ve also got my cam advanced 6* (going a6 cam soon) and i run on 93 gas, and full exhaust. and that’s my bhp estimate. honda manual says that the b7 makes ~130ish at 7200 rpm, so advancing the cam will increase active comp ratio as well as add more fuel + air to the combustion chamber, this bringing that power down into a usable range
 

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102hp is the rating from honda, and perhaps is slightly under rated, but certainly not 120 or 130hp.

93 octane in your car does nothing. There is no knock sensor to tell the ecu its pushing ignition timing too much and needs to back off, and vice-versa, the ecu has no idea if it has room to push harder. If you can find zero-ethanol 87 octane in your area, run that.

Full exhaust, well, if its anything over 2" diameter, its actually giving up low end power. The real power adder from doing an exhaust is getting rid of the factory baffled muffler.

I think you would be very happy with results that come from TUNING the car. Its an awesome thing to learn about, and even a bone stock DX/LX civic can benefit from being tuned. There is so much room on the table to gain from cleaning up what the manufacturer did, because they needed the car to not blow up at the slightest loss of regular maintenance. All the extra fuel being used to keep things cooler. All the ignition timing left slimmed down to prevent an ignorant driver from blowing an engine sitting in stop and go traffic on an hot summer day in arizona, etc...

The best part about these old honda's is the smallest things add to the party factor. I think you will have fun getting the meek old B7 up and running, able to stretch its legs!
 
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Discussion Starter #11
102hp is the rating from honda, and perhaps is slightly under rated, but certainly not 120 or 130hp.

93 octane in your car does nothing. There is no knock sensor to tell the ecu its pushing ignition timing too much and needs to back off, and vice-versa, the ecu has no idea if it has room to push harder. If you can find zero-ethanol 87 octane in your area, run that.

Full exhaust, well, if its anything over 2" diameter, its actually giving up low end power. The real power adder from doing an exhaust is getting rid of the factory baffled muffler.

I think you would be very happy with results that come from TUNING the car. Its an awesome thing to learn about, and even a bone stock DX/LX civic can benefit from being tuned. There is so much room on the table to gain from cleaning up what the manufacturer did, because they needed the car to not blow up at the slightest loss of regular maintenance. All the extra fuel being used to keep things cooler. All the ignition timing left slimmed down to prevent an ignorant driver from blowing an engine sitting in stop and go traffic on an hot summer day in arizona, etc...

The best part about these old honda's is the smallest things add to the party factor. I think you will have fun getting the meek old B7 up and running, able to stretch its legs!
yeah that’s cool, again that’s just a guess. also i did say 130 @ 7200 which is above redline, but this is good info anyways, thanks
 

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D15B7 - 102hp/98ft-lbs torque
Redline of 6500, as proven by my many personal ownerships of a d15b7 in varying stages of health and maintenance. There is fuel cut rpm, then there is redline rpm.
There is also what I have dealt with several times, a tachometer in the dash that reads quite off from what is realistically happening, both low and high at times. Tapping into the (usually) blue tach wire form the distributor and running a decent aftermarket tach can help mitigate that.


Seriously, the best way to get power out of any motor, is to first make sure its healthy, tuned up properly, and making sure the ECU is seeing all the data from sensors properly. If you are building a turbo ZC setup (which I dont understand ZC, unless its DOHC), I wouldnt want to spend any money on the D15B7, except what is needed to keep it alive.

Though there area few things you can translate and swap over to a SOHC ZC when the time comes (sensors, gaskets, etc..)
 

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Discussion Starter #13 (Edited)

D15B7 - 102hp/98ft-lbs torque
Redline of 6500, as proven by my many personal ownerships of a d15b7 in varying stages of health and maintenance. There is fuel cut rpm, then there is redline rpm.
There is also what I have dealt with several times, a tachometer in the dash that reads quite off from what is realistically happening, both low and high at times. Tapping into the (usually) blue tach wire form the distributor and running a decent aftermarket tach can help mitigate that.


Seriously, the best way to get power out of any motor, is to first make sure its healthy, tuned up properly, and making sure the ECU is seeing all the data from sensors properly. If you are building a turbo ZC setup (which I dont understand ZC, unless its DOHC), I wouldnt want to spend any money on the D15B7, except what is needed to keep it alive.

Though there area few things you can translate and swap over to a SOHC ZC when the time comes (sensors, gaskets, etc..)
i actually don’t have the stock tach, so i got an auto meter.

and no i dont plan on putting any money into the b7, or the zc for that matter. all the zc stuff i got basically for free besides the block

as far as the sohc zc it’s basically an a6

so yeah mostly this thread was about my zc since i plan on tuning it all myself, so i want to know as much as possible about all that and the intake thing didn’t make any sense to me. i took a look on a mustang forum and got a lot of good information about the air harmonics and such so that’s cool.

but yeah anyways, horsepower = torque x rpm / 5252 so the theoretical peak horsepower would be above redline. so in theory, if you removed fuel cut, and somehow balanced the engine and such so that you could get it above redline, the peak horsepower would be higher. advanced cam timing actually adjusts the peak torque to be lower.
 

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Revving it higher is not going to make any more power with stock parts. You are already at the downtrend of power past 6k rpm in a d15b7. It is compression and camshaft limited. Compression is too low to make much use of creative porting and exhaust, and the camshaft is too dull in factory form to be worth while revving higher.

That A6 style ZC should give you the best OEM camshaft for the setup for non-vtec, so that will be usable. It should also skirt past the 6k rpm limitation. But it will still fall out quite hard before it heads to 7500 rpm.

A good scavenging header with a good sized collector, and perhaps a megaphone sized appropriately would give a nice boost to midrange torque and help follow power upwards.

If you do decide to have some fun though, the bottom end will support 8k rpm pretty easily if its healthy. Simple valve springs and retainers should let you handle 8k+. porting the oil pump and checking its own tolerances against factory specs will let you know if the engine will survive beyond 7k rpm for very long.

the CAMSHAFT needs a big upgrade to make a fat powerband up high.

And you are correct on cam timing. I had it backwards. advance to lower revs, retard to higher revs
 

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Discussion Starter #15
Revving it higher is not going to make any more power with stock parts. You are already at the downtrend of power past 6k rpm in a d15b7. It is compression and camshaft limited. Compression is too low to make much use of creative porting and exhaust, and the camshaft is too dull in factory form to be worth while revving higher.

That A6 style ZC should give you the best OEM camshaft for the setup for non-vtec, so that will be usable. It should also skirt past the 6k rpm limitation. But it will still fall out quite hard before it heads to 7500 rpm.

A good scavenging header with a good sized collector, and perhaps a megaphone sized appropriately would give a nice boost to midrange torque and help follow power upwards.

If you do decide to have some fun though, the bottom end will support 8k rpm pretty easily if its healthy. Simple valve springs and retainers should let you handle 8k+. porting the oil pump and checking its own tolerances against factory specs will let you know if the engine will survive beyond 7k rpm for very long.

the CAMSHAFT needs a big upgrade to make a fat powerband up high.

And you are correct on cam timing. I had it backwards. advance to lower revs, retard to higher revs
i’m actually going for a y8 head on the zc, and td04 turbo
 

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subby turbo? Toss a set of rods in the block and drop a bumpstick in the Y8 head and have fun
 
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If you advanced the cam 6 degrees, you killed so much power that it would't pull to redline. Maybe if you free reved it, but not under load. I know what 4.5A and 4.5R does to a powerband.

I also posted that dynograph from 1999's dyno pulls at Cave's Honda Haven in Memphis, TN. Just around the corner from CompCams. Who BTW used Dave's dyno for testing the ZEX dry nitrous kit. Where I learned about the kit before it was even known on the market.

Hence the "zex" in my user name.
 
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