Jump to content
SAU Community

Recommended Posts

This is my thread for the things I find out as my engine gets rebuilt.

I blew the ringland between the 2nd and 3rd rings in no.6. All the other pistons were pitted etc.

The rods are indeed the same as GTR rods (anyone want to buy the set I bought in case they weren't :))

It appears that the head uses quite a different design than previous RB25's. More details to come.

It uses a RB26 style oil pump but retains the short drive on the crank like early RB26's and all RB25's so I'm going to try to source a Jun crank collar.

At this stage I'm thinking of 8.8:1 compression ratio to give me a bit of safety with the tune but hopefully not losing too much in the way of response or power. I've had everything from 8.2 to 9+ recommended to me which has been confusing.

Removing the engine wasn't too hard with the help of Duncan and Ed. Thanks guys.

I think that's it for now.

Link to comment
https://www.sau.com.au/forums/topic/95854-my-rebuild-and-what-ive-found-out/
Share on other sites

  • Replies 183
  • Created
  • Last Reply

Top Posters In This Topic

Stock compression wasn't measured.

Blew it - http://www.skylinesaustralia.com/forums/in...topic=87738&hl=

Can't rely on the availability of Optimax 100 just yet.

Bass junky with the same setup to what I will have (ie cams and turbo) could only put 0.9 bar into his engine but got great power there so I thought that with a little less compression I might be able to squeeze in the extra boost to make up for lower CR plus a little more for happy days.

Some pics to come.

I spoke to GCG today about my turbo maxing out at 14 psi.

He said that he's never heard of one making that power at that boost.

He said they were most efficient at about 17 - 18 psi.

I'll get to the bottom of this. Maybe RacePace are just the worlds best tuners.......

Abobob,

Its definitely a concern, go with an 8.5:1 to be safe. :D

On that note I believe Freebaggin is still running the stock 9:1, he hasnt mentioned the use of a thicker headgasket.

He's running an internal gate .6 something GT3040R. I remember back when it was first fitted, ~270rwkw on 17psi, he has since fitted 256duration cams and cracked 300rwkw. Its not on an optimistic dyno either.

It's not a NEO. Maybe the Neo has some issues with cam timing or something silly? I'm not 100% sure on the NEO VCT, is it constantly variable or??

Edited by Cubes

I will be fitting the Tomei Tybe B Poncams which are 260 degrees both sides and 9.15 lift. This will lower my dynamic compression ratio a little and hopefully make it a little more resistant to detonation.

I don't know anything about the VCT. As for cam timing, all I know is that adjustable cam gears have been proven not to work on the NEO.

Bass - maybe GCG are making better turbos than they think because I had 228 at 0.85 bar, no cams and auto. One dyno operator reckoned that was close to 250 in a manual although I think the R34 auto seems to be a less lossy transmission than some. It makes me wonder if Sydneykids GTT had a turbo with different specs (ie GCG are doing them different nowadays) or that it had a thicker head gasket in place before he saw it because with the same cams it takes an extra 0.5 bar to make not that much extra power.

And let's not forget the reputable workshop who told me not to expect more than 220 at the limit of the turbo. Methinks some people have an agenda.

Here are some photos my engine builder sent me last night.

post-7957-1132695461.jpg

post-7957-1132695538.jpg

post-7957-1132695580.jpg

post-7957-1132695645.jpg

post-7957-1132695667.jpg

Agenda? Definently.

SK's 265rwkw figure was recorded in Shootout mode which at 250rwkw reportedly gives about 10-15 rwkw higher figure.

Until the next dyno day on a shootout dyno, I'll not know what my car makes in shootout.

I have the same cams Abo Bob.

Here's my power curve.... It's fat.

post-6399-1132702031.jpg

post-6399-1132702079.jpg

Agenda?  Definently.

SK's 265rwkw figure was recorded in Shootout mode which at 250rwkw reportedly gives about 10-15 rwkw higher figure.

Until the next dyno day on a shootout dyno, I'll not know what my car makes in shootout.

I have the same cams Abo Bob.

Here's my power curve....  It's fat.

Thats a nice curve, must be pretty damn quick on the street.

So you guys really rate the GCG hi-flow as the best option for the 34GTT? I have an auto as well and probably chasing 250rwkw for the time being. How much extra kw will this turbo give just by itself :D I'm currently on about 200 so I don't know. If it's a long way off, I might as well get a different turbo.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • In a few years from now, you'll regret that. It'll eat away at you, knowing the truth of the ugly hiding beneath the beautiful exterior... 😛
    • I don't think the G2 profile is particularly dangerous for the engine per se, more just are you actually ok with the turbo lag trade-offs? If the answer is yes then go for it. I personally don't think I'd be ok with it because I spend so much time at lower RPMs and I really enjoy the feeling of being able to stay in 5th gear on the highway and just roll into the throttle to get boost. Or staying in 3rd gear on "gentle canyon cruises" without feeling the turbo lag too badly. The 525 pump should be able to run flat out on factory lines but I would bet the pressure drop from pump to regulator is quite impressive. I don't know how much it would be exactly but I've seen figures like 30 psi thrown around.
    • It's interesting seeing everyone talk about what level of risk they are happy to tolerate.  Building a GTR always has a level of risk, you could be that lucky guy that drops 20k on the engine build alone and still has the thing go pop on the dyno. Life is fun like that.  The way I see it, the thing is a toy to be enjoyed. I'd be happy to turn up the power on stock motor and limit the risk with sensible tuning and engine protection. If it still goes pop, it is what it is. The car isn't a daily driver so it can happily sit while a plan is made to sort it out.  Given this thing will be a street car only, I really feel it's worth the (relatively small if managed well) risk to turn the power up to around 350KW on e85.  I don't think anyone getting into the skyline game now is doing it out of logic. Surely it is a purely emotional decision so I'm not sure how important it is to think about the engine build logically. The heart wants what it wants.  @joshuaho96 little note for Josh, I run my 525 pump flat out all the time and through the factory lines without any issues. (excluding the melting connectors, that's sorted now. we'll pretend it never happened lol)
    • But the Nexus S3 is very expensive and won't be as purpose-built for the application as a separate electronic boost controller :^) More seriously my pet issue here would be that the Walbro 525 running at 100% duty cycle is going to require more FPR than the stock setup can handle. I'm also pretty sure from what I've seen elsewhere you might want to slow down the pump regardless unless you're going to come up with some way of upsizing the fuel lines coming from the fuel tank. Factory 8mm fuel line doesn't actually flow very much if you want to keep pressure drop down between the fuel pump outlet and FPR. If you really want to "keep it simple" I would run only as much pump as you need and source a fuel pump controller to slow down the pump in the vain hope of being able to run stock-style FPRs which are pretty dinky. Or just use the HICAS lines and it should be mostly fine. OP should also really think hard about what profile they'd want out of the turbo. My pet choice here would be the G1 profile rather than anything higher power but YMMV. I already think ~stock turbo lag is pretty bad so I don't want to make it worse. In "gentle canyon cruising" I found that I spent a lot of time around 4-4.5k RPM. I also recommend DIYing labor if you're detail-oriented enough. Costs are high for labor + if you do it yourself you can be your own quality control.
    • GTSBoy is again on the money. My actual advice? Sell the car. (really). For what it's worth as is, you can sidegrade into something much better. If you care about function then this is the actual move. If you want a Skyline to perform, set aside about $100K to do it. This is NOT a typo. You will see right away these are two very different mindsets. Realistically we're talking full restomod for any Skyline still kicking around. Have an honest think about which one you are.. and what you want to do, and how much you want to invest in this (with no return).
×
×
  • Create New...