25 With 26 Internals Or 25/30

[GTXR34]

Hey guys,

I have done some research and was just after some more opinions...

I blew up my turbo a couple of weeks ago at my last track day and my mate running a 3076r in his gtt with stock internals might have done a ring.. My gtt will be mostly used for track purposes and same as his. I decided to get it all done right the fist time instead of doing it step by step, i.e, do my injectors, then my turbo, then,.... I wana do it all at once and pull the car off the road till its all done.. after seeing my mate pullin 290kw and havin done his ring on his secound track day at sandown wasnt really wanting to build the car lil by lil and then having issues because i left out a couple of things.

Orginally I made up my mind to do the 25/30 with the massive response resulting from the 30 bottom end... but then spoke to a couple of people who said that for track the 25/30 arent realy ideal due to the lost of top end power... Then one of them mentioned building up the 25 neo and upgradin all the internals with rb26 forged rods, crank and custom forged pistons (because of the neo head).

power wise im after around the 310-350rwkw mark with a gt35r/3540..

Thanks for reading and hope you can help me make up my mind..

Cheers

Herb

[TiTAN]

the 25/30 doesn't lose out in top end power vs the 25neo, they make more power down low, bring the boost on sooner and end up with the same power up top

[GTSBoy]

The Neo already has RB26 rods. So whatever rods you buy for it will still be equally Neo/26 rods.

[KiwiRS4T]

Go the 30/25 for more low down torque and midrange power for pulling out of the corners. If you want 300 - 330 kw get the GT3076 or if more the 3540. I have a GT3540 with the .63 AR just on the road making 225awkw at 8psi will be retuning to 18 -21 psi . Pulls really well now and is limited to 6500.

[JKR-32]

25/30 + T67 ftw!

[GTXR34]

Thanks for the quick replies...

Sounds like the 25/30 is best way to go..

Kiwirs4t let me know how u go with more boost coz im still tossin between the .63 n .82 AR... Some ppl have hit the 350kw with .63 which sounds quite odd to me but if its true id love the quicker spool..

Cheers

[KiwiRS4T]

Kiwirs4t let me know how u go with more boost coz im still tossin between the .63 n .82 AR... Some ppl have hit the 350kw with .63 which sounds quite odd to me but if its true id love the quicker spool..

Cheers

My engine is stock (not forged or even new pistons) so I will be happy with anything over 300awkw and will post up the results in a month or so (out of money at present!) but here are the figures from Shred Performance Wellington who dynoed the same car with both configurations:

3540 .63 14psi 300kw

18 psi 350kw

with .82 14 psi 330kw

18 psi 375 kw (could have made more - can't remember the reason for stopping at 375).

[bubba]

25/30 hands down, with your Neo head it will be tops.

Anybody who tells you an RB30 can't rev, or doesn't make power up top is a complete idiot and I would stop dealing with them

[Harey]

For a track car I would look at your goals slightly differently. Reliability under high temps and hard extended use should be a priority. Somethings to think about would be keeping the EGT (exhaust gas temps) down.

I would choose the smaller GT3076 turbo with a larger exhaust housing so that you get response without really high EGTs like the 0.63 on the GT35. I think your mate should have dropped the boost pressure a bit down to say 15-16psi while running on a stock engine. Also, buy the best intercooler you can afford.

I wouldnt disregard your current neo engine just yet. Drop the boost down to 15psi, make sure you tell your tuner to tune it for the track and make sure you have a really good intercooler. Are your overall engine temps under control? If not address that as well.

Also, have you thought about using E85 fuel? Have a wider safety margin with ignition timing and can make more power with a smaller more responsive turbo.

I am taking my R34 GTT to the SAU Nationals track day for the first time so this thinking is at the front of my mind! Any tips you have would be much appreciated!

[N1GTR]

Anybody who tells you an RB30 can't rev, or doesn't make power up top is a complete idiot and I would stop dealing with them

[GTXR34]

thanks again for ht ereplys guys.. sorry i completely forgot abt this thread..

375kw on the .82 hosing is wat im gonna be aimimng for i rekon..

Harey yer i dnt think i want to get the EGT too high.. the less strain on the engine the better.. i think with a 30 bottom end i should be haappy with the respponse of the 35/40 with .82 housing.. il be convertin to e85 too.. hopefully by mid next yr they will have decent e85 servos around here.. so far the best around my area is caltex and there e85 is actually around e75 aparently.. :s

defs get a new radiator if u can man.. the ones on the 34's are crap!!!!! ive got an alloy dual core one on mine now (without a nismo thermostat) and temps hit around 120degrees.. the stock one is probs abt 10-12mm thick... next thing is get some aftermarket camber arms and tie rods and get a really good wheel alignment done.. on my last track day at sandown i shaved about 4 secs just with a better alignment.. make sure u do a servicing and check ur brakes, et some good brake fluid (motul rbf 600 if possible), also i usually rit down a list of what i have to do about a week before coz im very very very forgetful.. also if its ur first track day start off in the training group with someone with you.. dnt be afraid of asking for help either.. if ur unsure abt how to take a turn ask someone who probs knows... it will be better than ending up tryin ur own way and going off and yellow flagin everyone.. n probs the best tip would be GO HAVE FUN!!!!!!!!

My mate was actually running around 15psi on the day.. pulled his intake pipe off the other day and found out the reason he felt the car wasnt feeling as quick or responsive as the last track day(see picture below)..

In regards to my intercooler im lookin at one of the plazmaman ones.. the only reason i dnt wana keep pushin my engine at the moment is because i know i will turn the car into a full track car and i might aswell do it all now than waste my money on trackdays when i need the money to build a quick car to get better times.. and also the better the condition the engine is the more il be able to sell the bits off for.. I no breakin stuff when doing track is inevitable but id rather avoid it..

I think ive made up my mind abt the build.. need to go have a chat with my tuner now..