Lex Luthor

I'm on Long Island, you and Angel can take a ride over.

Anybody notice how nice the moon is tonight?

vipsoarer

i have a question...you said you are using the sc400 driveshaft? are you having it lengthened or does it fit up with the proper supra end connectors added to it? sorry for probably sounding retarded but this would be a nice thing to have if i dont have to lengthen it. thanks

marshall

William N.

iTrader: (2)

Lex,

Sounds good. Once I go there, I won't know anyone..Best to meet people on clublexus in person

Marshall,

Yeah, I used a SC400 driveshaft. No lengthening required.

racing fan

Congrats on getting the car together william. I know its been a long process for you to get trid of the "bigass" distributor you despise You better come down to austin before you leave for PA.

Scott,
I ran the numbers for William a few months ago and I got around 9.2X:1. Hopefully William won't boost the **** out of it j/k BTW The idea I had for the injectors at first is a no go but I'm working on a solid solution. I'll let you know when its figured out.

William N.

iTrader: (2)

Hey Zohair,

Thanks! Hopefully the car will make decent power on the stock twins for a while. It has been a long process but everything came out pretty nicely. Thank god I got rid of that big nasty distributor! I will definitely come down to Austin before I move to Philly.

motorheaddown

Yeah... I ran the numbers starting from the NA and TT clearance volumes, respectively. The *average* of the two calculations is 9.2:1. See?... great minds think alike.

Cool... Thanks! Jeff at Induction Motorsports is looking into this problem, too. I pinged Lar about it, and he said SP machined out the intake runner to accept a collar to seal the injector: http://www.supraforums.com/forum/sho...hreadid=182455 See Jon? I'm *not* imagining this problem.

O.k... back to William's thread. Could someone *please* explain to me *why* he has a distributor *and* a separate crank position sensor? His distributor test at the top of the page shows *four* signals: NE (crank), G1 (primary cam), G2 (secondary cam), and ground. Here's a block diagram showing the signals on a 2jz-ge distributor: http://www.mkiv.com/specifications/ncf/ncf93/ncf064.jpg

Zohair?... what's the deal?

Thanks,
-scott

William N.

iTrader: (2)

Well, Zohair and I discussed the compression with the gte head, 2 mm headgasket, and ge block(with stock ge pistons) and what we came to is this:

From motorheaddown's calculations, the gte head and ge head have identical volumes.(thus not changing the compression whether you're using a ge head or gte head)

So what 2jzge NA guys do to lower the compression from 10:1 to something boost friendly is that a 2 mm headgasket is used which gives the 2jzge motor a ~8.6:1 compression ratio.

The only thing that contributes to lower compression with either setup is the 2mm headgasket. This is how I get a 8.6:1 compression w/ gte head, 2 mm headgasket, and ge block.

If anyone else wants to chime in, please do so.

thanks
William

motorheaddown

I'll chime in. Here's a copy of a reply sent to William:

Well, until someone posts some numbers, I'm standing behind my analysis. Plus, you missed the main point of my last post. The TT pistons have 14cc's of volume (dished) compared to 7cc's for the NA pistons (flat). How do you/Zohair account for that difference?

The last numbers I computed started with the TT motor. Suppose we start with the NA motor.

C/R = 499/55.1 + 1 = 10.07:1

You've added 2mm - .3mm = 1.7mm (new hg minus the OEM NA hg). However, the new hg will compress ~.3mm. Therefore, the head has only been raised by 1.4mm. That equates to 3.14159*(4.3)^2*0.14 = 8.13cc's. However, the GTE head has approximate 3cc's less volume than the GE head (remember, I said the two heads were "close"). So, your effective clearance volume has only been increased by 5.13cc's.

Here are the numbers again:
C/R = 499/(55.1 + 5.13) + 1 = 9.28:1

Until someone posts numbers that say otherwise, it's still ~9.2:1

Now, suppose the GE and GTE heads *are* absolutely identical.

C/R = 499/(55.1 + 8.13) + 1 = 8.87:1 not 8.6:1 QED.

To steal a phrase from Jerry McGuire... "show me the numbers".

-scott

BTW, the C/R will be 8.6:1 as I've stated in the past if you account for the hg getting crushed. My ideal hg would be 2.4mm thick uncompressed; not 2mm as referenced in this thread.

SupraCoup3

if I'm being redundant, just point me to the link (I couldn't seem to find it) but I was under the impression that the GTE head wouldn't fit the GE block... does the JDM head fit?


Yeah, I feel like a noob for asking what's most likely already been answered elsewhere, but I can't find the info!


Thanks

JT

William N.

iTrader: (2)

Hey Scott,

Well, I have been doing some more research on the head differences.

I was reading on supraforums.com and there was a debate on the ge and gte head volume differences.
A guy named Ryan(screen name is ryan23) who is pretty known for his experiences with the 2jz engine, posted this:

I have BOTH heads sitting in my garage right now. There is 1 cc difference between the two heads. The compression difference between TT pistons/TT HG with either head is NEGLIGIBLE.
I have built MANY 2JZ's....ask around.
Ryan

So if the head difference is only 1 cc compared to 3 cc, then my compression with the gte head, 2 mm headgasket, and ge block(ge pistons) comes out to be 9.018:1 which is more boost friendly than 9.28:1 perfect for me.

sc3boost

hey i really like that set up, and i think it is good that you guys squashed whatever was between you, anyway i was told that those heads will not swap then i saw a Is300 with the gte head in a magazine, so now i'm sold, and it would be nice to get to my spark plugs with ease.
i got a couple questions if you don't mind, since you swaped the head do you still have the distributer?
i just want to know what all is involved with a swap like that because i have to take my head off anyway, i think my head gasket is broken, what about all the sensors and vacumes off the old manifold.


and i don't mean to change the topic or steal your thread but since the head will be off anyway shoud i put in the thicker head gasket even though i don't have a turbo yet, i'll be going turbo in a couple months
thanks

William N.

iTrader: (2)

sc3boost, for your questions...

no distributor, the factory gte coil packs and ignitor is used for spark
The swap is like doing a 2jzgte engine swap but a little more complicated. Most people that put their gte motor in their SC's don't pull off the head to put a thicker headgasket on. They normally just take out the ge motor w/ tranny and drop in the gte motor w/ tranny. What I had to do is pull out the ge motor w/ tranny, take off the head from the ge motor, put on a thicker head gasket on the ge block, put on the gte head w/ cams, tap the oil feed lines from the turbos, put on the turbos and intake manifold, then connect everything else up.

The tedious part about the swap and most involved was the wiring.

If you put on a thicker headgasket with your stock ge head and ge block, you're car will be SLOW w/o force induction.

sc3boost

alright thanks alot.
but i don't think this head swap is for me. but thanks anyway

racing fan

I've been using the 3cc difference between the heads and that was what I used to result in the same 9.2x:1 cr when I originally ran the numbers. When you said "close" I assumed <1 and agreed with William's estimate. 3ccs however is a different story

Did you and Joe ever measure the heads you guys had?

No idea on the crank position sensor....

William N.

iTrader: (2)

Zohair,

Ryan on supraforums.com (screen name ryan23) said that he measured both the gte head and ge head and posted this:

I have BOTH heads sitting in my garage right now. There is 1 cc difference between the two heads. The compression difference between TT pistons/TT HG with either head is NEGLIGIBLE. I have built MANY 2JZ's....

ask around.
Ryan

Like what you said Zohair, I assumed "practically identical" would be = 1cc or <1cc. 3cc difference changes the compression quite a bit.

I *guess* we know now...