kolonelklink87

on a side note... has anyone ever done a comparative assessment on the difference on cooling efficiency between heads? I feel very silly but I only just noticed today that among the casting (not machined) differences between my early and very late e88 heads there is a notable difference in the arrangement of coolant passages on the port side of the head! I haven't read anything comparing the changes in the coolant passages between early and late heads - though it may very well have been overlooked by yours truely. Cheers, Pete

It wasn't my intention to be rude to short... Essentially in my own readings on these topics as you probably noticed there are many conflicting opinions on these issues. Unfortunately there is no manual that says "this way is best 100% of the time". I guess it really depends on application... some people get positive results from portmatching due to a higher RPM focus, some do not and feel it detracts from low-end power. Likewise with the temperature control steps- I read an anecdote about a fellow who was crazy about thermal resistance and ceramic coated every port and surface - the result was an engine barely able to hold idle at 2000rpm due to fuel vapourisation issues. MY personal take at the moment is deciding on the big goals first - screamer/turbo/stump-puller then move to details from there rather then getting a bunch of good parts and slapping them together to make a mismatched engine. FYI my personal experiences with port matching have been positive, I went from 32mm to ~36mm manifold ports and honestly feel i gained low end torque afterwards, however I have no dyno sheets to back this up so I was tentative to post my experience. In my example I think having multi-port EFI really assisted with acheiving this and thus negated the need for a rough sand-cast surface and higher intake temp to achieve fuel vapourisation. I'm sorry if I came around course, admittedly I was having a bit of a rotten day. I guess my main point that im trying to communicate is experiences vary and sometimes you just gotta do a little thinking on how each mod fits into your goals and then go for it! Where do you want to make power? how much? Are you happy waiting for start-warmup? what kind of EFI/camming etc will fit with these goals? Best Regards, Pete

I think almost all of your questions have been answered in other threads, you might need to do a bit more searching. Best of luck, Pete

this is a bit sad to see... from my very limited understanding the focus of home porting on this head should have focused primarily on reshaping the areas on and around the valve guide? I'm messing around with a bit of home porting myself at the moment and this is a great example of a "what not to do". I'd love to hear some reflections on what went wrong and why from people in the know... post mortem? Cheers, Pete.

Thats a familiar story... second most frustrating process behind asking for assistance at bunnings. On a more serious note, you've been a busy boy lately I'm keen to see some simple solutions to the 5# problem... there was talk of opening some of the casting flashings and such inside the head, i'd be keen on seeing some more about that too! I have cylinder head cutaways if anyone wants to run with that ball I can send photos or lend to locals... I'd really love to see it pinned down precisely as to what causes the dramatic increase in #5 compared to 4&6 seen in this and other tests... perhaps that might offer an alternative solution complicated tapping and plumbing. -pete

lol I wish! i spotted it on yahoo japan. If I had it, it'd sell it locally and wouldn't have to beg for scholarship money...for a little while

just found this floating around and thought it would be a nice addition to the thread...

I also would like to see more raw data comparisons... kudos all round guys for putting up some awesome discussion thus far. its excellent to see something so fundamental as this to engine design being debated with data and formulae rather than gut instinct and intuition keep up the good work:icon14:

it does seem somewhat counter-intuitive to polish the valves and then "rough them up" again? Perhaps the use of efi to promote ideal vapourisation somewhat negates the trade-off between flow and atomisation. At higher RPM I hear this can become an issue but combatable by moving injectors further away from the valves. This seems to be in the same territory as singh grooves... why not promote the same increases in atomisation by using a higher surface area intake manifold (if you're carburated and have this concern) for a fraction of the cost? -pete

Wow that looks amazingly close... just the bolt locations are different? If so take your N42 and LD manifold down to a local machine shop... make some calls to find someone who will take on this kind of custom work at a reasonable rate. Ask them to fab an adaptor plate out of aluminium or alternative material... it shouldnt be a huge job, a back-yard operator should be able to manage it easily so just call around to make sure you get a fair price. However, before you get too involved make sure the exaust manifold still fits okay with the LD on the head. Other than that. bobs your uncle... geee i'd love to get my hands on one of those LD manifolds... none around down here that i've seen Best of luck, Peter (p.s.) of course there's heaps of ways to approach this... my personal preference is to avoid expense and welding by the adaptor tactic. maybe even do some cutting, run studs into the head and use a tensioned stud approach on both the intake and exaust studs... kinda dodgey but very cheap *edit* I assume you've seen this: http://forums.hybridz.org/showthread.php?t=120299&highlight=ld28+intake however i beleive the manifold in that thread is slightly different to yours?

mmm heavy fabbing question... i'd befriend a machinist and discuss fabbing an adaptor plate out of aluminium... I've thrown around a few simular ideas myself, even considered some kind of thermostable plastic which might be easier to work and cheaper than aluminium... Perhaps taKe a picture of the head-ends of both manifolds side by side and see what the responses are here? Btw i also have a SWB patrol, recently purchased with a rebuilt l28, they're a barrel of fun. -pete

fyi. I have two manifolds spare that look like they would fit this plus the one in the patrol if you like..

suspect AFM(?)... if you have access to another one try to replace for troubleshoot... check all the cabling (i hear sometimes people can put the connector on backwards) and test the unit as per FSM. Failing that try troubleshooting your problem with "the efi bible".

What engine management are you using?

because of the shape of the NAPS manifold TB mouth you're gonna find a significant need for a pair of giant-ass billet adapter plates in order to make a smooth transition onto the SU flange... The amount of fabbing involved would make it a bit of a hassle. I like the idea but you might be better off finding a smaller twin TB off of a little 4cyl korean-mobile... i've seen a few like that at the junkyard. That way you can pick one that matches the dimensions of the SU flange and just retap the manifold... incidentally the stock 50mm TB fits on there very snuggly once you retap the SU manifold... an alternative approach might be to use those and install a non-linear throttle device to whereever your cable meets your linkages.. effectively just an accentric cam shape instead of a circle. It would be very simple to make one to whatever shape you want with a hunk of aluminium, a dremel and a bit of spare time. -pete *edit* upon rereading I may have misinterpeted your description... with fabbing of custom plenum you could of course throw anything you wanted onto it!

interesting... this may somehwat explain why my experiences with the manifold and twin throttle were by the whole greater than what appeared to be the consensus in the literature.... hmmm... v. curious about that TB mouth measurement. There's a 13mm difference to be acounted for between the reported TB's and the mouth apperture... thats alot of meat to hide *edit* I'm sure OzCon must be lurking somewhere in the background of this post... I wonder what the throttle on that p65 turned out to be? P.s. I need to chat with you... I got into med at Usyd and have a plethora of l24 parts i can deliver to you at request (have crane and ute now... big couple of weeks lol)

*shrugs* could be... it came on a manifold without naps markings but the same layout (where it would say "naps efi" etc there is just blank space). other than that i have no history on it as it was an evilbay unit picked up by my old man in the country and mailed down to me. *edit* I wonder if your manifold TB mouth is smaller too?

I hate to throw my hat in the ring here but you might wanna recheck your measurement on the naps TB. either your memory decieves you or there is yet anther TB version... i've been down this road before! I have in my hand a twin throttle TB with a 40mm and 38mm butterfly. This makes sense because the TB mouth on the NAPS manifold is 40x80mm (thats 3000mm2 after you subtract the round edges) and the two butterflies fit neatly in here with a 2mm divider between them!! The total butterfly area for the TB is 2390.8mm2 and thus outflows the stock 50mm. The upside of the naps manifold is that the mouth also outflows the 60mm TB so no porting is required if you use an adaptor plate. I was using the naps TB as a step up from the stocker before adding my 60mm.... cedrics not so slow now? -pete

from memory the larger twin throttle is ~40mm x2 (it could be 38, i remember it was hard to measure down there)... I'm not sure about the one with two different sizes... if you turn out wanting the larger one i still have it sitting in a box on my garage bench -pete p.s. ... I wonder how many mm a nickel/dime is? not a standard imperial-metric conversion p.p.s. ... looks like i'll have to measure it when i get home; lots of conflicting info on here

I ran one of these for a while after getting the idea off yet another member... they're a good solid unit... brought the temp down to themostat threshold on the highway on a moderately warm day... -pete

... you could always unscrew them and measure...

1. define "decent" - you can make 200-250hp reasonably but will require good quality(expensive) head work. You will not be able to exceed this significantly without exponentially increasing your budget per HP increase. Ie: you will hit the roof quickly and have to go turbo if you end up wanting more. 2. my understanding of prices in the US is you can buy a l28et for less than or approximately the price of a rebuild. 3.Usually a question is proceeded by a question-mark. -welcome to hybridz pete

-- scrapt that he said 300zx... wrong engine, wrong section... just... wrong *sigh*