Rydaddy

D series get no love in the tech forum so Im sticking this here. This is an interesting post I swiped from dseries.org, courtesy of Bisimoto. If you arent familiar with Bisi, he has an all-motor CRX with a 1.5L SOHC pulling consistent 10's in the 1320. Here's his low-down on porting our mighty D-series....

"Also From an old post from Bisimoto Ezerioha:

Greetings all,
It is an absolute pleasure to finally see a dedicated page to the mighty d-series motors. I have also been audience to all the comments on my vehicle, and the speculations are pretty interesting and comical to say the least; but I digress. In my vast experience with the d-series engine, whether a full blown n/a race engine or a tame street vehicle, it is wise to only mildly port the head..mostly clean up the bowls and casting ridges. Definitely never take material from the port floor: this kills performance by decreasing port velocity. Even though a common practice, polishing the head should be avoided as well. The intake ports should be kept slightly rough (vertical ridges preferred), in order to keep the fuel in suspension, and not allow it to stick to the port walls. It does not really matter if you polish the exhaust...it will get coated with combustion by products anyway.
An ideal alternative from milling the head is having the combustion chambers welded up on the non-vtec head. Not only does this increase compression, but also increases the quench area: developing an ideal space for proper burn and flame propagation = more, efficient, and less-detonation prone power!
If you need referrals to shops than can help you with these tasks, let me know. I know them all: reputable and cost effective. Note: I keep racing d-series motors because they are relatively inexpensive to build compared to b-series: I hate spending money, and i desire to be fast!

Bisimoto D15"

I thought it was an interesting blurb - I was looking at taking my project d16y8 head to get port and polished before I build it, but now I dont think I will. Food for thought for anyone else doing what I am....

Agent STFU

Wow, that was interesting.. I was considering porting mine, too.

Mr. Thunderlips

Now is this on his race-only motor...Or on our street driven motors that it will negatively affect what he listed?

RSZero1

it sounds like good info, and i believe i've seen him on dseries before. That really is the best point of d series engines, cheap and cost effective. The way d series are going these days, you could prolly even build a few different ways and just drop in whichever suits your mood. One nicely built N/A and turbo for the price of a ITR swap with mods or turbo, lol, maybe, don't quote me on pricing tho...

B18C5-EH2

Well I tried to register and post on the D-Series.org site but I still cannot post because they are on a whack system.

I wonder who could weld up my D16A6 combustion chambers and how much it would cost...

vtecvoodoo

I`d go w/ Bisi.

93eg-EKhybrid

Bisimoto is an active member on this board also, although he is mainly in the EF section of the site, someone should PM him and tell him about this thread so that he can give us some more info and put a few more cents in on the subject.

RSZero1

im'd bisi...

93eg-EKhybrid

sweet, this is gonna be so good to bring the master of the "D" in on a tech discussion!!

RSZero1

okay, just linked Bisi...

nerdsports

okay, waiting for reply from bisi... hehe

B18C5-EH2

Okay I am not for one second questioning Bisi here, but I need to ask a few things and maybe point something out if I'm even correct.

Bisi is a carb guy, so would these methods still ring 100% true for fuel-injected motors? Like the fuel suspension theory - for a carb it's definately the case, but what about a fuel-injected motor that has the injectors already spraying in a fine mist of fuel - is fuel sticking to the walls as troublesome on an injected motor?

What about cutting the valveguides down where they protrude into the chambers?

Is this a good or bad idea?

The manner in which a street car's motor with a normal intake manifold will receive it's air is different than an ITB-FI or carbed motor, right?

What streetable, fuel-injected applications should we be looking for?

I talked to a local guy here that has been all about the D16A6 since like 1990 - he happens to be 40 years old and runs FTD at local SCCA events on occasion with a D16A6 CR-X.

He said that one of the quickest heads he did was just an experement and it was actually one of the more worked heads he has done. He said the chambers were of the biggest he'd done, and he was actually surprised at the outcome of such big ports. He did however say that he made sure to start big and finish smaller so that the "funnel" effect would not be lost.

Your thoughts people?

B18C5-EH2

Okay since we're on the subject, here's a few shots of a D16A6 head before and after some "work" - opinions welcome:

Before. Notice the shadow cast by the valve guides sticking through into the combustion chamber:



After:



And another angle:



Now from these pics does it seem like the work pictured flies in the face of what Bisi said?

Basically here's what the story is on these pics:

I'm building a D16A6 motor. One of the techs at work is a true Rotary wizard and not to shabby on piston engines. He was bored at work, so he said he'd like to show me how to dissassemble the head and then port match the intake and exhaust gaskets on the head.

Well we take the head apart and then I mark the places to be taken away to match up the gaskets.

I have to run a errand or two and upon my return I see that he is doing more than just a "little cleaning" like he was saying to me with a devilish grin. This guy is like 55 years old and has an 11.8 second 13B-powered Datsun B110 and did the 1200cc motor in it beforehand and that motor ran awesome. At this point the head will be finished because he's already done one entire chamber. He's not gutting the hell out of or anything, but more removing casting marks as Bisi says and trying to imposve the angle at which the a/f will be traveling.

It is totally FREE so I'm not really sweating it, but how does the work look thus far? He's basically making the angles a little more direct and cutting diwn the valveguides where they intrude into the combustion chambers.

At first I was freaking out because of what Bisi had posted, but then again it's a free job and I have tw spare heads should this one run like poop.

So what do you guys think?

Rydaddy

Im thinkin that looks good. I never really considered the fact that Bisi is a carb guy...maybe that WOULD have something to do with it. It still doesnt make sense to me though - Flow more air faster = combust more fuel right? It seems logical....cleaning up the combustion chamber and increasing the size of the ports a small amount couldnt HARM performance...or could it? Someone drop some knowledge on this thread!

Mr. Thunderlips

I'm sorry, I don't buy into this "porting is bad" nonsense. People have been porting and polishing for YEARS...One person comes along and says it doesn't work?

Maybe for his application...But I highly doubt that porting hurts...

IS3Fifty

the only way I could see porting causing problems would be what it actually does. allows for more flow, creating less pressure in the valve. I guess in some cases, that could be bad considering how tempermental honda motors are. maybe the basis for having smaller cylinders if for a more powerful, tighter flow. I still dont see any problems, that would be severe from porting. They've done it to about every car imaginable, maybe some cars just handle it better.

JaeOne3345

the thing most people dont seem to understand is OVER DOING modifications. a built motor has to be built with everything in harmony. everything done needs to compliment each other. same with porting. you port according your needs. a turbo 600HP port job is not the same as a "street port with occasional nitrous use". similar to how you dont put a big *** STR drag intake manifold on a stock sohc. its just overkill. sometimes less is more and more is less.

0Bisimoto

Gentlemen,
I do not recall posting that porting is bad. Hogging out ports is bad. This sacrifices velocity for volume...a huge disadvantage for d-series performance. Mild porting and raising roofs, without hogging out port floors are ideal.

Removing valve guide protrutions have improved flow as well in my experiments. Speaking of experiments, polishing intake ports hurt atomization continuity, more so in fuel injection than carburators. The reason that I stick with carburators is due to experiments performed in my senior year of my bacculaurate study.

I tested atomization characteristics of 2 fuel injection systems vs. 40mm and 44mm carburators. For me to obtain the fine fuel/air suspension mist at 2" away from the carb exit, I had to move the injector 3 feet away from the port entrance. I dont recall any of us having the engine bay confines that can allow such advantage. You will be suprised of the size of suspension droplets from popular injectors out there.

Speaking of the aforementioned "funnel effect" in a post above, grinding and enlarging the first few millimetres of the d series port, where it is easy to reach, has very little effect.

B18C5-EH2

Thanks Bisi.



What about those dimples in the intake side at the roof of the chamber?

Thge guy who's doing mine did those and said that it is to help keep the fuel in suspension - what are your thoughts on this?

I mean this guy is no 10 second 1.5L guy, but he has built a lot of motors in Puerto Rico (he's Puerto Rican y0!) and he isn't "hogging" it out at all.

I'll post pics of the one chamber that he is totally done with tomorrow.

What can us street FI guys do?

How streetable are carbs, which ones would you recommend, and would they even pass emissions?

TIA.

0Bisimoto

Dimpling and/or ridges are my friends!! Your aquaintance is correct.

FI is great, for economy, throttle response and emmisions. For WOT power, carbs reign supreme. Call me crazy, but I ran mikuni carbs on the street thoughout my academia years. They proved to be nice and streetable with a beautiful howl form my engine bay.

senpai

How about a "About My Car" website link ... or something

B18C5-EH2

Awesome - you want to see the work and tell me what you think Bisi?

TIA.

I'll post those pics up around 1:00pm ET on my lunch break.

Zer0DazE

agreed... by over doing a head, (or any 1 thing for that mater) and not have an intake manifold or an engine (or whatever) that will pump enough air into or out of it is counter productive. you end up lowering manifold preasure and air velocity causing all sorts of problems (this being in referance to the head), like contaminated intake charge and ish like that. and its not like a b sereis where you have a little more adjustability (2 cams) you get it right the first time or you start over (good thing d series parts are cheap)

its the best collection of compromises. (i think most people know that already though)

and as for the dimples.. dimples rule. larry has been doing that for years. its amazing what a couple of well dents (for lack of a more simple word) can do.

edit: bisi, i would love to see some pics of your chambers.... i would understand if you didnt want to post them though


[Modified by Zer0DazE, 9:23 AM 3/21/2003]

B18C5-EH2

Yes I've seen some ENDYN/FakeDYN heads and they always seem to have those dimples. Some sources (that have some of the best heads for B Series motors) claim that it's not much more than a gimmick, but I think every little bit can help.

The guy who's doing mine has not seen an ENDYN head. He isn't well-schooled on all of this modern Honda crap, but more he is an old-schooler who has done some really awesome stuff with older Datsun motors, 13B and 12S rotaries, and older Corrolla motors in Puerto Rico.

He knows his ****, and when he was doing those dimples on the intake side i could not help but laugh because Larry does the same thing, yet this guy has no clue who Larry is.

I'm sure it's a very old trick from the book of "Old School."

Zer0DazE

most likley... i was just making reference that it wasnt a new thing and that others were doing it as well.