kolonelklink87

Thanks for clearning that up tony! i hope i didnt lead the thread too far astray... any comments on the ports anyone? to my untrained eye the quality of work there doesnt seem on par with the CC's?

I know the e30 is *meant* to be a closed head... but from that photo it looks to be open chamber? can you clean it up a but to get a better view?

Interesting... so why start with an e88 instead of an n42? I guess i should have asked if the valveseats are larger than normal? surely the n42 valves will clear the clinder walls and eyebrowing could be done if required for OS valves.... hmmm... I remember asking myself the same question last time i saw a welded e88...? wikiD?

I really dont know about the "early e88" chambers... i mean, i've heard them mentioned alot but i've never seen a photo of one... on the other hand, i know for a fact there is a late e88 with a very closed chamber desing, i know this as I have two of them . I'm building one up and will get photos on one of these days but in the meantime i can tell you that the chamber seen here is not significantly similar to that one. The "custom head building" sticky reveals some heads with similar CC designs... I would fathom to guess that this has received a similar treatment... Mark: "after-market rods".... ya-kno-wut-i meant

Wow... you got yourself some awesome luck there... was the engine ever in a JDM car by any chance? That cylinder head looks awefully like the type of treatment they give heads in japan, I've seen some examples of people doing it in the states (ie monzter, braap and so forth) but it seems much more common in jap stuff... I've seen lots of examples of this beening done with n42's and only one e88 before... more rarely e88's but it'd suspect it was probably done using an l24-spec head to avoid the inspection nazis they have over in japan. You've got yourself a very nice head: big money spent to get it that far. I certainly wouldnt mind the pistons either... rods are probably forged; worth checking. If you dont want any of it I'd be happy to take it off your hands cheers, -pete(green with envy)

intake ports on the e30: It seems from the images that nissan left the shortside radius alone and moved the longside down to make the narrower port... my un-trained instinct would be to do the oppposite; any ideas on why they took this approach?

1. regarding my "non-quench side of the head" comment - I apologise, i'm not getting heaps of sleep these days... allow me to rephrase: the side of the piston corresponding to the combustion chamber of a quenchpad-equiped cylinder head 2. i agree with most of what you have said, I dont have a specific application in mind, I was just curious about this "line of thought"... I've previously considered removing a peanut dish from pistons however I have some serious concerns about comprimising the integrity of the pistons. Along that line of thought I'm very dubious of removing the full recess depth - do you have any precedent where this has been successful? the thickness of the piston crown to the ring is only 6mm so carving a full 3mm off of this (dish + recess depth) doesnt leave much metal behind in a significant amount of piston head. I understand your logic but I think having a couple of very small areas with this thickness(recesses) is a very different beast to having ~50% of piston head material removed from one side. Any further thoughts? -pete

4.5cc as close as i can get without a zero-surface tension measuring fluid. i'll try to beg a camera for photos, any new input? -poit

i think what they are saying is you set the boost limit based on your tuning results.... In your case if you're detting at say 9psi you need to pull boost before you reach the detonation prone area (not at it)... you need to tune to your engine specs, some one elses boost limit is not applicable. Other than that... the following is pure conjecture and opinion: i'd expect the main limit would be intercooling and residule engine heat - supercompressing air will make it hot and volatile so from an engineering persepctive you need to keep the temperature down as much as possible... There's bunch of complex mathmatical and experimental papers that i am not qualified to interpret (a quick journal search will turn these over). There will be a theoretical maximum derived from a relationship to the critical point of oxygen/nitrogen air mixtures... maintaining vapourised fuel will also be a massive issue at ultra high pressures... All these things could be graphed and you could decide on a value form an artbitrary engineering or theoretical perspective (the theoretical number will be higher). Basically you need to control autoignition, this gets very difficult EVEN with maximal cooling(theoretical) due to the dropping autoignition point associated with increasing pressure (increased density, molecules move closer together, less energy required to get them to "bump" into each other). futhermore.. when dealing with these kinds of pressures and temperatures the laws governing behavior of gases get a but muggy as they approach a supervolatile fluid phase. short story, there is no answer to this question that i can see.. you will run into engineering challenges WAY before you hit theoretical issues... things to consider include: *running maximal fuel pressure and injecting fuel as late as possible before ignition to prevent vapour-liquid transtion *ultra intercooling - like running liquid nitrogen heat exchangers the size of a small house &ultra engine cooling - " "^ *massively reduction the heat transfer within the intake and combustion chambers - think crazy ceramics in the CC and cylinder bore. *exotic fuels with ultra low vapour transition temperature and gas phase pressure and autoignition points... I'm thinking exotic petroleum gases maybe? ^an interesting point because you need temp to help with fuel vapourisation... but due to dropping autoignition points you will have to run the motor supercool... meaning you rely solely on mechanical pressure to vapourise fuel during injection and this will return to liquid phase almost immediately - see the first * i'm sure i can come up with some specific documented attempts... but i dont have have the time to do the readings right now I'll try to add more later or maybe someone more qualified could shed some insight on this. -pete

That I can do easily... just need some time hehe

wasnt the KA24 in nissan navaras??

Don't have access to camera at the moment, I'm aware of that, this is wher ei got the ~5cc... i dont think i can be more accurate than this due to the very slight dish and my lack of accurate measuring apparatus (my calcs put the dish itself at only 3.5-4cc plus some additional volume for recessions) i'll try to get a camera at some point -pete

I also think in J-land there may have been a very short run of glorias with rb20DET's... I've seen one locally however it may have been a transplant motor... guy near my old house in eastlakes owns it... i should ask next time he pulls up... i know his mechanic and its always there blowing massive amounts of black smoke on boost... maybe i should just ask them .

or the right one... i think that was the "engrish" translation

I've always wanted a hako car with an s20 man the coupes look sweeeeet *drool*

I'd be suspicious your comp. ratio is significantly higher than you beleive (ozdat puts it at ~9.25) Previously i've run an l26 w/shaved ported OS valve etc e88 and flatops. I was running N/A and even so It took me a while to dial in the detonation issue (by the looks of 5/6 chambers so had the PO ) I eventually conquered it by a combination approach of tinkering with slightly richers AFRs and bringing down my MAT's with creative pipework. I was able to run full 38* adv. However, that was N/A... You have colder weather going for you but i think its still an uphill battle - considered dished pistons? there are 2&3mm steel HGs available in japan which may also solve problems of a compression-related aetiology I think if detonation was an issue N/A you might have real problems under boost....

Hey guys, I have a set of pistons from a late EFI l24 block(w24): They have valve recessions and a very slight dish (~<1mm) 1: does anyone have any info on these pistons worth knowing? They look like stock nissan parts to me, the engine calculator ive been using (ozdat) indicated a significantly greater dish on l24 pistons =7cc.... even with the valve recessions i'd be suprised if these things broke 5cc. 2: is there a difference in the thickness of the piston head on valve recessed pistons that could be expoited for removing material from the non-quench side of the head? I'm interested on how this can be combined with ultra-thin HG's to decrease head-piston clearance without increasing compression significately. 3. along a similar lines has anyone tried using the longer rods on a l28 crank with a 3mm steel HG rather than machining (-)clearance on the block to acheive v. high compression on an l24/6? would this bring the the rings too close to the combustion chamber? I've done some reading in the past to try to pin this one down but couldnt and picked up the pistons today with renewed interest. Thanks in advance , -Pete

D. - I'm not sure... I think i see flattops on it?? in answer to your second question i think i would'nt be able to bear it and thus commit hara-kiri Mark - I a few words here and there for ordering food and telling girls they are beautiful etc... pointing at fluffy things and saying "Kawaii" is always a good conversation starter Our local expert tried to teach us to say "I want to make hot with you". However, I was unfortunately unable recall the words whenever the appropriate moment arose -Pete

Hello Zeders =) these photos are cortesy of my brother who had the foresight to aviod latenight yakinuki and drinking sessions then take the train yokohama in the early morning whilst the rest of us were suffering... thanks MK (Kampai!!!!!). Fell free to comment, reminisce, secrete etc etc ;p Cheers, -pete

jebus. I wish I had a chance to check some of these monsters out while i was over there... MK took photos of DOHC l-series cutaways and hako cars... they sooo need to be posted here.

I've wanted to bump this thread for a while now because I happen to know some progress has been made in this area which shares significant overlap with the controlling detonation and #5 cooling threads. I'll let the person in question contribute their reflections on the results and challenges but in a nutshell I believe there was an unexpected complication resulting in detonation. I was throwing around some ideas today and having recently returned from japan can tell you that the y70 cylinder head may have been designed for an entirely different climate to our warm shores... Thinking on this and looking at some cutaways of an e88 I began to ponder on the purpose of the cooling jacket running above the intake ports... I've heard stories of extreme porters welding these up for extra clearance with no ill effects - this lead me to think: are they for cooling?? here are some thoughts i would like to get some input on.... *in the cooler climate of japan to assist with fuel vapourisation having a cooling jacket which, in fact, warms the intake tract/port may be advantageous. *Since the ports are narrower a greater percentage of intake air comes into closer proximity to the port wall. This represents a greater surface-area/volume scenario - increasing heat transfer to the intake air *the waterjacket may be larger on the smaller port head (not known) *this problem could potentially be addressed by using an insulating coating on the port walls *detonation from pre-heated air may contribute to or exacerbate the 5# issue however is more likely an issue associated with smaller port heads due to SA/V complications here is a photo from one of my cutaways that shows the coolant passage arrangement around one of the intake ports on an early(ish) e88 head. I'd love to hear some feedback on this -pete

Does this put all aftermarket electric water pumps to rest? I can understand the challenge of both designing a large enough electrical motor and overcoming basic laws of thermodynamics (mechanical energy ->generating electrical energy-> powering a mechanical energy generating device) Does this not mean that to achieve the max 20hp output of the pump far greater HP will be drained through the alternator? Surely the only advantage to such a setup would be to provide indirectly proportional pump pressure to engine output- ie: making the pump activity fully independant and programable. If there is an RPM range that the pump reaches maximal efficiency then the electric pump could be set to this without exceeding it unlike a mechanical pump. However this appears to indicate that the electric pumps just arent up to nosh with the power output? Can anyone else confirm this...??? I've heard claims of guys running these things in track-day cars for events and such... I think this warrants further investigation! Thank you very much for bring this to public attention, you're becoming quite the scientist!! ing Enter machinist? I know a few around town by now, i'm getting lots of work done so we can go to pick and payless and pick up something close it shouldnt cost much to have additional machining done on my account ... I think increasing the mechanical efficiency of the pump is perhaps the way to go given the conservation of energy paradign above? I still have to post pictures of my cutaways and comparisons for late model heads so i'll try and have those up sooon... so busy! Keep up the good work Scienctist-san!!! -pete

*cough* efi.

in order to answer those questons i think people might need a few more details - where did you source a 3.1L? they dont exactly just float around -what are your goals in terms of HP, how much do you want and where do you want to make it -What type of running do you expect from the car? (race/street?) -what is your budget? Cheers, -pete

The plot thickens somewhat when considering all the different cast that are out there.... At home I have a 260z e88 such as is well reported on here.... this is the head that is sliced up as a porting guide. In addition to this I have two very late non-US efi e88's. Each of these has significant notable casting differences(yes, two separate casts of the late-model heads!)... I really have to sit down and catalog the differences between heads but that will have to wait untill my return from japan. Something that I did note whilst doing some porting on one of the heads the other day was there is a significant difference in the shape of the coolant passage above 5-6 intake/exaust and the later model lacked the large hex-plug access point that the earlier head possessed. These are just incidental finds... I'm sure if i sit down and write a list of differences I will find others (I only had the 5-6 cutaways in my hand at that point). It is possible that the cast was modified for EFI purposes.. I'll have to sit the e88 EFI down next to my other EFI head(p90) to investigate this. Perhaps it is coincidence or perhaps nissan made some subtle changes in later models to attempt to correct the detonation issue *shrug* Has anyone else out there noticed this? *Paging Tony D*