CA18DET JDM Head

[ard]

it is brave to tell that there are no 8ports in UK since jdm car importers do their job as i understand difference is in stock head - to low diameter ports in 8port head called LOWport, and high diameter port head called HIGHport. logic?one sided view? maybe, but remember that there are 8ports and nobody uses it. why? the biggest part of imports in US is from jap. mainly lowports. don't you think that they are one side minded?

enough of kicking that dead horse.

[themadscientist]

You have no 8 ports because all europe got was 4 port, not because anybody other than Nissan chose it that way.

Coming from Europe you can't appreciate American desire for the engine. You and I for that matter got the 200SX and the 180SX, they got the 240SX. Not bashing the KA24 but they only got the DOHC CA in the S12 as a DE not a DET. The 8 port is proven to make a ****load of power so it is not a dead end. The 4 port would obviously flow more but when an 8 port will do this, http://www.yellowmunsontuning.com/PT67CA18.htmthe 4 port becomes a luxury, not a requirement.

I said this

You have to be careful with blanket statements like "because this is bigger that is useless" You would find it cuts both ways should you stray into the SR20 home turf.

Because I know this

edit: btw - i own ca18det and sr20de

And the same kind of excessive dogma you are pushing about the larger ports is the same thing a guy with a 2 liter motor will say about your 1.8. The SR is bigger so your CA must be a waste of time. To use your own logic

look at it from builders side - what setup would you use? what setup requires less money/effort?

do you see the irony?

[ard]

you made me laugh!! big time the main reason why i tune CA is that it is rwd. sr that i have is fwd, i do not want to have one wheel drive fwd and be a

but this is waaaaay out of main topic

[themadscientist]

Yeah, FWD just doesn't do it for me either. Now 4WD, did europe get the turbo 4WD CA18 Bluebirds?http://www9.big.or.jp/~nagatom...2.htm

[ard]

no, we did not get any of jdm top versions of their vehicles, only srdet 4wd was a nissan sunny gti-R (pulsar) RNN14. uk has ALOT gtir's, because of rhd and import from japan (including all gamma of skylines). i am thinking of importing one RNN14 from japan/UK and convert from rhd to lhd. ~2-3k pound at UK and about ~3-5k usd at japan. should be very competitive at tarmac and gravel tracks.

[themadscientist]

Check the transmission bell housing for cracks, they don't respond well to launches in high grip situations like asphalt.

[niscort]

it is brave to tell that there are no 8ports in UK since jdm car importers do their job as i understand difference is in stock head - to low diameter ports in 8port head called LOWport, and high diameter port head called HIGHport. logic?one sided view? maybe, but remember that there are 8ports and nobody uses it. why? the biggest part of imports in US is from jap. mainly lowports. don't you think that they are one side minded?

enough of kicking that dead horse.

Im afraid that you are the one that dragged the dead horse of ill informed opinion into this thread.

In english. Diameter refers to circles, also they are either small or big, you can not have a low diameter or a high diameter. I guess your logic fails again.

Anyhow, you just keep digging a deeper hole for yourself... keep on going.

Finally, your naive banter has railroaded this thread, someone doing something outside of the norm that should be of interest to anyone that modifies a ca18. I for one look forward to seeing more.

[ard]

it gets pretty hard to check it, if you buy car via internet @ auction.

[DALAZ_68]

http://www.yellowmunsontuning.com/PT67CA18.htm

a SR to CA PFCDJ conversion...why was i not informed???

god i need to do better research i epically fail

[meminto]

Wow this thread was really quite railroaded

I am intrigued at how one photo has caused such a stir amongst enthusiasts, considering it is only one aspect.. and I didn't provide any more info about the rest of the work being performed..

I am surprised no-one has really asked me for any more information about the build process before speculating (speculation also seems rife ) on port sizing, which is really only one part of the volumetric efficiency equation...

The head is only one part of the build....

[themadscientist]

I'm easy, make em big. I still think centering the injector is a must.

[boost_boy]

WoW, what a thread. All this stuff about 8 port and 4 port, is a dead issue. You can build good power down low and on the top end with an 8 port. I've done better than 170mph in my FWD sentra/sunny with an 8 port without cams and only 17psi of efficient boost, so don't knock the 8 port thinga-majiggie. I can't knock the 4 port because I've never toyed with one, but I'm sure I can get the same results; maybe even better.

Just like those cats who insist on playing with those butterfly valves "Dead issue". Everybody has their desires (ie fast spool-up, pull hard in every gear, blah, blah), but I truly do believe that butterfly valve is near worthless on a high boost, cammed-out, high revving, big injectored CA18DET. I've been through the tricks and have concluded it is just best to leave those puckers open and boost the schnott out of the motor. Could very well be why Nissan didn't offer them to the european countries. Now on a naturally aspirated CA18DE, those butterfly valves had my CA16/18DE powered sentra beating-up SR20 powered sentras and the priviledge of taking-out the civic Si cars when they came out in late 1999. Just my own experiences though! You guys do whatever the hell you want, someone will be around to assist you in your biotchings .

Dee

[themadscientist]

you moving on that item we discussed dee?

[niscort]

i dont know what exact cfm 8runner begins to su$k horse di$k, but you can search at sxoc.com (uk biggest silvia community) for exact numbers etc.

8port runner has two narrow ports - one for low rpms (little diameter - you get better flow, better "air supply" (dunno how to write that in english)), on high rpm both ports are open to maintain the same air pressure and speed in runners.4port (highport) has 4 big ports - not very good air flow at low rpms, but you have no top end restrictors.read some theory about air flow, inertia and try to use your brain thinking about exhaust backpressure (the same air flow principles)

somewhere i had found flowrates of 8port/porter 8port/4port/porter 4port. ported 8port had few % better air flow than stock 4port. ported 4 port was unmistakable the best.

I just had to quote this rubbish again..

after a quick calculation on the pitcure posted by themad and it would seem that the 8port actually has about 3% more cross sectional area at the manifold flange compared to the 4 port.

maybe the 8 port needs to be called a highport

[float_6969]

It's not just the cross sectional area that matters. It's the port volume as well. The 4 port has greater port volume in both the head and sub-manifold.

To say that trying to get power out of the 8 port head is silly. Trying to get a 4 port head, or even a UK spec CA w/the 4 port head over here to the US is a struggle at best, and you'd better be prepared to part with some of your money as well.

Why would you shell out a couple hundred dollars to get a stock 4 port head over here, and then spend the same money that you could spend on the 8 port to get it polished?

With the work that he's done, it looks to me that he's got a greater cross sectional area and port volume.

[boost_boy]

you moving on that item we discussed dee?

Indeed! I just bought two new ballbearing monsters for both my drag and my fun car, so why not add that to the equation . I'll let you know what I see when I see what I want to see .

Dee

[themadscientist]

understood, The llama is frustrated when the sun is at noon on tuesday.

[boost_boy]

It's not just the cross sectional area that matters. It's the port volume as well. The 4 port has greater port volume in both the head and sub-manifold.

To say that trying to get power out of the 8 port head is silly. Trying to get a 4 port head, or even a UK spec CA w/the 4 port head over here to the US is a struggle at best, and you'd better be prepared to part with some of your money as well.

Why would you shell out a couple hundred dollars to get a stock 4 port head over here, and then spend the same money that you could spend on the 8 port to get it polished?

With the work that he's done, it looks to me that he's got a greater cross sectional area and port volume.

Well boys and girls, I guess it's time for me to stop hiding and get those big HP cars I've been so slow at assembling assembled. Oh Yeah, they will be sporting tricked-out 8 port heads as well. Nissan designed them and I don't think the design was flawed. I love the design and we'll see how our numbers stack up against others'. Goal: Fastest FWD CA18DET powered B12 sentra in the world. I got the mph thing down being clocked at over 173mph a few years ago, so we'll see. My protege's goal: Sub 9 second passes in his CA powered S13 (Big goal),but I'll do my best to help him since I am the builder and the tuner. BTW, 8 port as well...............

Dee

Dee

[meminto]

Yep, spot on, cross sectional area is probably obvoious but there is a substantial increase in port volume...

[niscort]

It's not just the cross sectional area that matters. It's the port volume as well. The 4 port has greater port volume in both the head and sub-manifold.

Im pretty sure volume is directly proportional to the cross sectional area though..

Who actually has measured the standard volumes of both heads? or even has flow figures. I doubt there is any such data to back it up, just because it looks bigger, doesnt mean it actually is nor would such a quality make it flow better, so Ill stay skeptical either way until such proof is available.

and yes... memintos head totally surpasses both..

more pics?

[meminto]

Only one more pic to put up for now...

[themadscientist]

If you are going to do that just remove the quench entirely. That is just going to screw with the flame front and possibly be a detonation source.

[float_6969]

You need to take the quench pads out entirely if you're going to mess with them.

[meminto]

I trust my engineers judgement...

I am curious to find out the science behind why you would remove them altogether...

[themadscientist]

The pads are there to cause turbulence in the chamber as the piston comes up the charge is "squished" and forced out into the center right before the spark fires.High boost doesn't respond well to squench or "squish" as it is sometimes called. Many suggest that pocket detonation can occur way back in there as it cannot evacuate the area quickly enough in a higher pressure environment and compression fires.Very few people run the kind of boost pressure that would require this sort of mod and I doubt you need it either but your guy has aready started so he should finish, those sharp edges are not going to help and will likely do harm. He should have left them alone.

[float_6969]

I know for a fact they are a detonation prone area, as I have very visible signs of detonation on those pads in the #3 cylinder.

Granted I have 10:1 compression and was just learning how to tune and ethanol wasn't available locally yet. Regardless, I intend to remove them on my 4 port head.

[meminto]

Thanks all, both the centering of the injector boss and the squish (or quench pads) have been discussed with my engineer and taken on board...

My mate has also come up with the goods yet again and provided another solution for the injectors, this is the most likely route at this point in time, however there is also one other solution that is being discussed at the moment..

Unfortunatley until my cams are fabricated and a few other things fall into place, there is not much else happening...

At least time is now on my side....

[r34 gtr]

Someone needs to port the secondary runner in the head and inject HHO in there. You would have fuel injected into one side and HHO in the other. I see no way this could fail. Your engine would probably run at something like 120 degrees though. You could probably pick up 50whp bare minimum.

[themadscientist]

what is HHO?

[meminto]

Something I won't be using...

No discussion about water based fuels please