Having designed and built half the setups being talked aboutin this thread, I'll offer my opinion.
Firstly, high and low mount makes absolutely ZERO difference to power if you purchase a quality manifold from one of the forum supporters. If you go cheap affetrmaket stainless item, then I'd suggest a high mount, as I'm yet to see an acceptable low mount.
Secondly, I agree with Tempest, if its a street car and manual, a GT30 with .82 rear on a good manifold will be as responsive as a hiflow and make 60-80hp more. Many cars have proven to run the numbers, Tempest run a 11.9@121 in full weight calais with stereo, street tyres and pump fuel first time out on only 340rwhp. With rajab plenum this has since moved to 380rwhp. Andy's car with GT30 is just an animal and dusts most respectable cars on the street. It made 363 on pump fuel and 393hp on pump and tolulene, he run a 10.84 with no more than slicks and that was off the footbrake!!
If you intend to go for a good quality auto in the future, get yourself a GT35 with .82 rear now, as the extra lag is well and truly masked by the converter, and the difference would be negliable in feel and the hp gains would be more than worth it, however if you'd like to stay manual at least in the forseeable future, keep the 30.
If you'd like any advise with selecting camshaft, intake or any other bits and pieces, feel free to pm me anytime.
Cheers......................6BOOST
what Kyle said
by the way, a GOOD manifold such as kyle's will make a MASSIVE difference to your car response wise... i have had my car lined up against another gt30 with a .63 rear (which should hammer mine off the start) with a standard mani, and i SMOKE it, not by a little, by a LOT. by the time the other vl spooled up i was already half way through my next gear 5 car lengths in front. Whilst there were a FEW other variables, the manifold was the main difference.
Some original photos have not been recovered yet.
I used to run GT30 with power ported comp and exhaust housing(.82) in a full weight calais on pump fuel and wearing G60's, managed a 11.2 @121mph @ 20psi.(AUTO) Jatco 4spd with 3k stall.(gee, that was like 5yrs ago now!!)
car made 280 odd rwkw. I later changed to a GT35R(.82)ex/hsg (no power porting this time and then made 310rwkw @ 20psi,on pump.(new owner)felt the same as the GT30 for response just went alot harder!!! With power porting, i'm sure that would be around 320-330rwkw at 20psi on pump also.
Both good turbos, just depends what further plans you might have i guess.
PSI_Adam.
Some original photos have not been recovered yet.
wat have u found wen u put the gt30/40 on with a iw with clearance to the car im puttin mine on and wondering i no u gota take sum of the block do u have to grind sum off the turbo aswell
I have driven a mates GT35r .82 RB30DET 5speed quite a bit and found the transient response in the lower gears is not all that flash.
Its the transient response that I'm after which only a smaller turbo can offer; I 'think' the GT3076r will do this for me. :S I have a GT3076r .6 port shroud comp & .82 IW.
There's a few over on SAU with these GT3076r (.6 port shrouds) .82 IW's pushing high 280's on around 17psi and 320kw odd with a shade over 20psi on pump.
One is running a GT3076r .63 IW with water/meth injection and pushing 295rwkw on 18psi! I will be interested to see how far he can push it with the WI and ultra responsive .6 housing. I believe he has said the WI has picked up 40-50rwkw. I'd love to see the scroll pressure of the .6 at that power. lol
Years back a mates HKS3037S .87 (same as the garrett GT3076r 56t) pushed 320kw on 22-24psi (I forget exactly) on his rb25 that was running a nice exh. manifold, pump and baby 256 cams.
All though most likely not comparable to a stock SOHC head the turbo's can flow this sort of power... So.. Drop a nice set of cams in the SOHC. Surely that will get the SOHC close.
All the examples I've referred to are all running garretts newish Internal gate 5bolt turbine housings.
I intend on dropping WI on mine and pushing slightly over 300rwkw with the .82 IW housing. Fingers crossed all goes as planned.
But as mentioned.. If its an auto I wouldn't think twice about going the GT35r .82.
Some original photos have not been recovered yet.
i have found that DOHC drive VERY differently to SOHC, i have driven both with gt's on them, the DOHC always seems laggier than a sohc, purely because of their power bands being in very different places...
Interesting...
The RB30DET with the .82 GT35r on the brake was able to make 1bar at 3000rpm. But rolling on in second gear it saw 1bar+ at ~3600rpm. I thought that was fairly respectable and can't see an SOHC coming on much sooner?!?
Another mate with an RB30DET GT35r 1.06 see's 1bar+ by 3900rpm in second gear but the power delivery is very linear and screams right out to 7500rpm.
The .82 feels like it starts making more boost much sooner, basically off idle and comes on quite a bit harder giving that turbo feel rather than the 1.06's N/A linear smooth power delivery.
Darren (470rwkw R31) told me that his experience was the DOHC made power sooner and came on smoother, so in other words linear; where as the SOHC comes on like a light switch.
Could that be what you mean by laggier? The DOHC is more linear with its power delivery?
i agree on the power deliverly, the twin was much smoother and less 'violent' than the single. however, it does not make power anywhere near and quickly as mine though and is not as torquey down low (<2800rpm). mine (single) definately come on sooner than the twin i drove, but how much of the comes down to compression and cam setup i can not answer.
It would be good to compare 2 identical setups but one with a DOHC, same static comp both with std cams.
I do remember reading some where the nature of DOHC causes them to be a little less pokey down low but provide a wider power band once up in the rpm. Most likely the case.
Some original photos have not been recovered yet.
Time to update this thread with how mine went with the GT3076R .82 IW.
The 6blade .6 Port shroud comp cover version.
I'm running the R32 Rb25DE head with a set of gtr valve springs, std cams (240duration 7.8mm Inlet & 232duration 7.3mm exhaust) std inlet manifold/plenum, std exhaust manifold, 3" turbo back bell mouth dump. So a bit of a budget build up.
Off the actuator boost is quite lazy, 10psi at 3000rpm and then 15.5psi ~4000rpm. With the boost controller I see 19-20psi ~3100rpm. I suspect the actuator is lazy as I have it setup quite loose with only 0.5-1mm preload.
If I place much more preload on the actuator it boost creeps due to the IW housing and small std flap.
I had it tuned up for off the actuator to help keep this rb20det gearbox alive until I source a good rb25det box. :S
15.5psi made 268rwkw at 6000rpm which drops to 252rwkw by 7000rpm
20degree's advance at peak power.
Z32 AFM is seeing 4.79volts and the 444cc injectors required a little more line pressure as they were max'd out.
AFR's are mid 11's dipping to low 11's after peak.
Extremely happy with the way it drives. With the lazy gate it feels strong and progressive; turbo spools great and has excellent response in the quicker flicking low load 1st and 2nd gears. Definitely hasn't lost any drivability over the std turbo; never bogs or is caught lagging.
Pulls really well to its 7k rev cut; wouldn't be able to pick peak power has been made and falling off.
So next a set of cams, adjustable cam gears a rb25t gearbox and then back on the rollers for 20-24psi with a flat 12:1 afr. Hopefully the injectors handle a little over 300rwkw.
Following that I will drop a water/meth injection kit on it and see what I can squeeze out of the little GT3076r .82 IW.
A mate of mine has recently dropped a set of GTR cams reground by Tighe cams (~254duration 8.5mm lift in and exh) so far results look good; its swallowing more air for the same boost and more interestingly low end mid range torque off boost is definitely up. Also apparently sounds a little nicer.
With the stock cams his GT35r 1.06 was making 1bar by 3900rpm so it will be interesting to see if it brings spool on a little earlier.
If it works out well I'll throw a set of these in mine. Can't complain for the cost of them.
Some original photos have not been recovered yet.
Im using a rb26 pfc that I adapted to use with single afm. Can't really go wrong with the pfc's on a jap car used primarily for street.
Cost me $830 delivered.
If it wasn't for the price of the pfc I probably would have looked at the Wolf3d v500.
Has some fairly nice features for its price.
