2860 Help Please

[donkey]

hey all,

so ive just had the full garrett treatment; 2860-5, 115mm FMIC+ pipping, LINK G4, 770 inj, profect b, hks twin, nismo pump, standard mint engine running 18 lbs, 7500RPM limit, 320AWKW......

i dont want to have to go through the whole forged rebuild yet, but will eventually, i am really only using this car for street, and am guessing if i start winding these buggers up to around the 380+awkw its going to put a strain on the rest of the car

QUESTIONS

i think i would like to trade down to the smaller -7's

i miss the big kick of the smaller turbos, im not after massive power

1. so the -7's are maxed at around 330awkw, what kind of boost is needed for this figure?

2. are cams needed?

3. has anyone driven same car, but with the different turbos, is there quite a big difference?

4. am i stupid? i kinda was given wrong advice on turbo sizing

5. have tryed searching but it aint working

cheers robbie

[Bakes]

Read this thread:

http://www.gtr.co.uk/forum/99765-gt-ss-gt2530.html

2530s are similar to what you have -5. A good tuner will get similar response out of -5 to the -7 (only 500rpm difference) but with more power from 5000rpm onwards.

There are some in the thread that started with the -7 and went to the -5. They say they prefer the -5 set up.

Id be listening to people who have had both set ups, but thats just me.

Heres a link to GTSS vs -5 done on the same car on the same dyno if that helps.

http://sthitec.blogspot.com/2008/05/gt-ss-...or-2560r-5.html

[rev210]

The setup of the -5's it's bundled off with the 0.64 AR rear as opposed to the smaller hot side on the -7's , so at 250rwkw plus it's got an easier path to push the compressor to it's potential.

The -7's at 330rwkw are going to need lots of boost and due to the efficiency range will be pumping much hotter air than the -5's or -9's.

The -9's are better than -7's and if setup correctly will get you the same power you have now (320rwkw) with 1,000 rpm or more of earlier spool and a larger amount of power in the lower / mid part of the power band.

The key factor in getting the turbos to do what you want is to set them up correctly. The -9's are very tune forgiving and this is clear from the compressor map.

I reckon -9's with a larger 0.84 housing (and custom dumps to suit) would be the ultimate with a serious build/cams.

[donkey]

The setup of the -5's it's bundled off with the 0.64 AR rear as opposed to the smaller hot side on the -7's , so at 250rwkw plus it's got an easier path to push the compressor to it's potential.

The -7's at 330rwkw are going to need lots of boost and due to the efficiency range will be pumping much hotter air than the -5's or -9's.

The -9's are better than -7's and if setup correctly will get you the same power you have now (320rwkw) with 1,000 rpm or more of earlier spool and a larger amount of power in the lower / mid part of the power band.

The key factor in getting the turbos to do what you want is to set them up correctly. The -9's are very tune forgiving and this is clear from the compressor map.

I reckon -9's with a larger 0.84 housing (and custom dumps to suit) would be the ultimate with a serious build/cams.

[donkey]

hmmm, maybe i should just increase the boost to 20lbs, and see how they feel then, dont get me wrong its a sweet car to drive, but miss the ol' "chuck back into seat"

[Bakes]

Show us your dyno graph, you should be getting a fairly big chuck back with -5

[rev210]

hmmm, maybe i should just increase the boost to 20lbs, and see how they feel then, dont get me wrong its a sweet car to drive, but miss the ol' "chuck back into seat"

At 320rwkw you should be thrown back alot more than the stock turbo's.

You could tune the bottom end power band with adjustable cam gears and lop off the top end power to keep the stock motor alive.

It will be a nice suprise for your tuner to be one of the few people who walk in and say " up the boost to 20lbs we are aiming for the best mid range and I want to limit the top end to 300rwkw and 7000 rpm ".

[donkey]

hey there,

will get the dyno graph soon

cheers robbie

[Redman180]

My rb26 has the 2860 -7 and is making 300rwkw at 16psi it fairly throws me back into the seat... was enough for a passenger to bend the support for the backrest lol. i'm thinking about winding them up to 18-19psi and going for 330-340rwkw with a more aggressive tune.

[joeyjoejoejuniorshabadoo]

At 320rwkw you should be thrown back alot more than the stock turbo's.

You could tune the bottom end power band with adjustable cam gears and lop off the top end power to keep the stock motor alive.

It will be a nice suprise for your tuner to be one of the few people who walk in and say " up the boost to 20lbs we are aiming for the best mid range and I want to limit the top end to 300rwkw and 7000 rpm ".

that's what i did with the 33

hks 2835 pro s on stock rb25 with adj ex cam gear

i'm gettin 265 where most people are gettin 280 BUT i have stock turbo response and couldn't be happier

[Redman180]

yeah i get full boost by about 3200 - 3500 and with the bottom end of a 26 it's not too worrying to have it alitlle later at least you can drive off boost around town easier but it's still super responsive and doesn't stop pulling till the rev limiter.