My 1970 KGC10 2000 GT

Super X · **Posted:** Mon Aug 27, 2012 9:01 am

ericbauer wrote:

Need to revise the math above, because I just got some new info...

The head was cc'ed last night...
A stock N42 head is 44.6cc

My N42 head is actually 37cc

So the red car's compression (when new) was actually 12.1:1 !!

These compression #'s seem about right for this engine especially due to your probably extensively modified head; But I believe your initial numbers were off.

A standard factory Nissan "flat top" piston in a L6 should yield you around 10:6-10:7:1 on a stock N42 (give or take head/block deck height & hg); However w/ the machined 2.7mm valve relief cuts it should more likely be around 10:1-10:3.1;

Mario

ericbauer · **Posted:** Mon Aug 27, 2012 9:40 am

Hi Mario

The valve reliefs in the stock looking pistons haven't been cut in
The pistons were cast that way - that's one of the odd things about my set-up...
They do look like Nissan OEM, but I don't believe they are KA24E flat tops

I've been doing some reading on some older threads on hybridz relating to high hp NA L6s from Japan, and I'm seeing a lot of similarities with what I've inherited...

I had the head flow benched and while i don't have the numbers in front of me the consensus was that it wasn't capable of more than 300hp
The gigantic port job on the intakes only makes a big difference above 7500rpm, and the car came with a 8250rpm rev limit... lol... pretty insane...

I'm having the cam degree'd so it will be interesting to find out what it's closest to and will help to figure out where it came from...

I don't race professionally so keeping everything a secret is pointless...
Honestly I wish more people weren't super secretive about their builds... it would help to get correct information out there, and stifle a lot of the inaccurate heresay...

FYI I did the math using the following formula:
http://atlanticz.ca/zclub/techtips/calcs/engine%20builder/index.html

head: 37cc
headgasket: 90.5mm bore, 1.2mm thickness
block: 89mm bore
piston: 33.5mm pin height, 2.7cc valve relief
rod: 133mm
crank: 83mm

that gives me 12.1:1 and 3098cc Mario... feel free to check my math...

Super X · **Posted:** Mon Aug 27, 2012 2:19 pm

Hey Eric, A few year back I was at a shop near Osaka and saw a 3.1 being assembled and they were using a very familiar piston too me, since I had them for my own 3.0 build at the time. I asked about them and were told they were in fact KA24E's that have been machined for with valve reliefs as are the Kameari's. The also told me that Kameari's send the pistons to be treated (not sure which method) and ceramic coated. A casted piston w/ the reliefs is a pretty big deal especially since they bare all of Nissans casting numbers and markings. Nissan isn’t really known for doing bespoke parts for anyone other than Nismo, Autech or Impul. It would be great if you could get your hands on a OEM set of KA24E’s to compare the two side by side.

I though you were 100% spot on w/ the 12:1 comp on your setup because the numbers sounded right. I remember the guys at the shop telling me that the highest compression the modified Nissan piston was in the 12:1-12.3:1 range. I was supposed to go back to check out the custom 13:1 forged pistons when they came in stock but I left before they arrived.

ericbauer wrote:

Supposing a stock combustion chamber volume of 44.6cc for my N42 head, that puts compression ratio at 10.5:1

But the calculator shows your spot on w/ that also. I didn’t notice where you said your hg is 1.2m I was thinking along the lines of something slightly thicker and I was also free quoting the numbers off the top of my head.

Sorry it's been a while since I started digging back into the L6 archives part of my brain. I’ve moved on a few years ago and sold all of my big bore L parts in exchange to get something more modern, even though my Z still has the L24 in it; But I still get an itch from time to time to build one just for the hell of it. For now i'll live through awesome L6 builds like yours and the other guys on this forum :mrgreen:

Mario

jncr · **Posted:** Wed Aug 29, 2012 6:40 pm

With your compression confirmed, are you going to be changing it in order to make it run on Ca pump gas? A race motor that only runs on special fuel is no fun on the street.

kev · **Posted:** Wed Aug 29, 2012 6:58 pm

ericbauer wrote:

So the red car's compression (when new) was actually 12.1:1 !!

So was mine

We managed to get it down to 11:1 by sinking the valves a bit and reshaping the chambers. Still on the high side for pump gas, IMHO, it would be nice to be able to run a bit more advance to help out the Webers.

jncr · **Posted:** Sun Sep 02, 2012 9:42 am

So your head was shaved and cam towers shimmed? Or were the chambers welded and reshaped? I have an extra ported/polished N42 head if it you need it.

ericbauer · **Posted:** Sun Sep 02, 2012 9:57 am

hi jncr

you're talking to me or kevin?
my n42 was welded and reshaped

thanks for the offer but i dont need another head (i have a spare n42 in the garage already)
im leaving everything as is on the skyline... just maintaining it in its present state...

-e

jncr · **Posted:** Tue Sep 04, 2012 9:16 am

OK -e,

see you at JCCS.

Kennymonster · **Posted:** Wed Sep 05, 2012 12:18 pm

Will this be making an appearance at JCCS still? Sorry if that seems like a silly question, not sure on what you have planned for the rebuild/how extensive.

ericbauer · **Posted:** Wed Sep 05, 2012 1:20 pm

i do plan on being done in time

i've got 10days left to finish everything i want to finish

i still have plenty of work left to do
i don't have the engine back in the car yet

but block might go in tonight
head might be tonight or tomorrow

if it goes according to plan i'll fire it for the first time on saturday morning
which would still give me 7 days to go before the show

-e

ericbauer · **Posted:** Fri Sep 07, 2012 8:25 am

Does anyone know for certain if hakos were painted body color inside and out from the factory?

Or were all the interiors done in a plain off white, regardless of exterior color?

I ask because I've found evidence of a third previous color in my 1970...
I found off white inside the car, hiding under grime and rarely removed components (like the ebrake)

My inner door skins, behind the door panels, show some evidence that the exterior was silver before it was red.

I'm wondering if my car was maybe white when it first rolled off the assembly line...

I've also found some evidence that would SEEM to indicate my coupe started out life as an AUTOMATIC... pics to follow...
Interesting what you find when you dig deep enough... Talk about a storied past...

DmK66 · **Posted:** Fri Sep 07, 2012 9:09 am

I'd have to say I've never heard of them being different colours from new but I've seen pictures of many that are different colours now. Sometimes they dont bother spraying the engine bays or door shuts !
Sounds to me like yours started off white, the doors got damaged or rusted out and replaced with second hand silver ones which then may have been painted to match the car or at that point the whole car was painted red. Possibly.
My car's white, has a couple of doors that are silver under the white but the original colour, judging from a few hidden places, was dark green.

ericbauer · **Posted:** Fri Sep 07, 2012 9:22 am

the whole car was silver at one point, i found clues to that all of over...
the current red was merely painted over the silver...

-e

Norcal510 · **Posted:** Fri Sep 07, 2012 3:58 pm

I also found the original color of my car was blue before it was white. However under that blue I recall seeing another color. Will double check my pictures when I get home.

ImPo · **Posted:** Fri Sep 07, 2012 8:05 pm

Looks like mine was originally green before silver. Every piece I've removed is green underneath. I haven't found any signs of a third color which makes me think the entire shell must be painted with the base color the car will be finished in. The best was when I removed the brake booster. The paint beneath the rubber seal on the firewall was immaculate. Gave me a good idea of what the car originally looked like. Very similar if not identical to the JDM Legends green sedan they recently had.

G · **Posted:** Sat Sep 08, 2012 7:17 am

Looks nice, how much did you end up paying for the red skyline?

familycar · **Posted:** Mon Sep 24, 2012 3:57 pm

not to be rude, but i'm intrested as well. i'm looking to buy one after i sell my bnr32 here in japan...curious to see how the pricing compares to here (it's not cheap here haha). if you'd rather not discuss i understand :oops:

ericbauer · **Posted:** Mon Sep 24, 2012 5:16 pm

Hi guys

Whatever I paid for my car nearly six months ago will unfortunately not have much bearing on what you might pay for yours in the future.

_ Exchange rate fluctuates, and is currently not in the favor of the US

_ The number of intermediate parties between you and the actual purchase of the car matters
(I bought my car from the importer JDML, who in turned bought it at auction in Japan)

_ The level of tune of the car will make the price vary dramatically
(Do you want to buy a stock car for cheaper and then pay someone like Rebello $10K to build you a bitchin' 3.XL?)
(Or do you want to buy a used hotrodded car where you don't know the condition of the motor but pay more for it because it was "made in Japan"?)

There's several importers / dealers that can get you these kinds of cars into the US.
Shop around and see which vendor you prefer working with...

-e

G · **Posted:** Mon Sep 24, 2012 7:05 pm

I would say between 25 and 30k.

jncr · **Posted:** Mon Sep 24, 2012 7:23 pm

@familycar, definitely get your car over there. The ones for sell here come from there with the middle man fee factored on. Use TMO to bring it back as well. Buy the bee body you can. L6 building is a lot cheaper here than in Japan. If you end uP not liking the vintage skyline I might trade you a MotoRex car for it, if you miss the BNR32 that bad.

My 1970 KGC10 2000 GT

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