I think Hal has a larger GT42R turbo. Not sure on the turbine specs though.

.96 may then be the way to go for you. You can always upgrade it down the road. It's an easy swap.

Keep in mind that the type of dyno will make a difference. Jeff made 463@13psi on pump on a DD. I bet that he would dyno in the low 500's on a DJ. Just going by what I have seen posted.

 

im hoping the .81 ar would get me to 550whp. lol i hate not knowing stuff.

 

It will for sure.

 

when is ur dyno day?!

 

the PL kit has too many nuthuggers as you said, so none of that info was every touched upon. Thats why other PL users suggested the 1.06 housing.



Its good you bought him a .81 housing though, too bad it was after the fact. Good for future customers.

 

lol dyno day? vinny got backed up almost 5 months, moved to new shop and 2 drag car builds before my own. so its just this week he started on my motor while it was payed for in full back in feb. he told me it was going to be a while so im not sweating it. my build is no were near as complicated as Binder tho. sorry for the thread jack!!

 

The .81a/r was waiting for him at IP for a couple of months. The idea was to run/test the .68 housing, and if it is not enough the .81 is right there on the shelf ready to be swaped in. They just didn't have the time to swap it.

 

ahh, thats a bigger kick in the nuts having it there. I woulda guessed during the time it took to do the main seal, that housing coulda been swapped as well.

Grand nationals (3.8L) run the .6AR 6765s so who woulda guessed.

 

Always gotta leave extra time - nothing ever goes as planned. I want my own lift and my own dyno! Local dynojet shutdown over here str8dum1 No more Staples Automotive...

 

i think the grand nationals dont have the flow our heads have even from factory. Does Jeff have upgraded heads? his motor is built to rev above and beyond 8krpms.. this is a very interesting discussion. i want to go with the supra numbers but we have a .5 liter displacement difference. im going to do some more research on the grand nationals before i start talking out of my *** lol.

 

considering not one build makes supra numbers with similar turbo's, i wouldnt get your hopes up.

 

damn those supras lol

 

ok, i decided to do some research and call precision turbo. i figured if i needed some info why not get it from the horses mouth. i called and explained the logs and back pressure mentioned on this thread earlier and explained that the motor will be revving to 7500rpms. explained the a.r situation that came up in choosing an a/r for the vq35 application. the tech explained to me that there is a significant difference between the .68 .81 and .96 ar. according to the tech for our motor/rev range/ displacement the .81 ar is ideal for 625whp considering all else is in optimal working order. he went on to mention that the .96 a/r would be too laggy and not a "fun" street able car.

 

As a point of comparison, I made 505 whp on Injected's DD dyno, 475 on Sharif's DD dyno, and 525 on a local Dynojet STD correction - all with the same tune/mods.

 

Thanks for that. I guess the difference is not that great between DJ and DD. Only about 5%.

Good post. A while ago when I called Precision to discuss some stuff, they told me that the
T3 .81a/r is very close to the T4 .58a/r. This was another reason I decided to go with the T4. With the .58 housing it will work well for the stock block, and it is the standard turbo. The good thing is that you can only go up in size from there with either a .68 or .81, where the T3 is already being maxed out.

There is also the option of going with a 6265 with either one of those a/r ratios. So lots to choose from.

 

I think for the DD dynos that are in "shootout" mode (no correction), atmospheric conditions have a bigger impact since the #s are not normalized at all based on weather conditions. All those dynos were at different locations and times of the year, so binder may make a ton more power with DJ STD correction for hot weather.

 

i wonder what he considers "laggy". It's such a vauge term. Right now hal has it tuned and i'm spooling 13psi before 4k. Say i loose a copule hundred spool to each housing that should put me about full spool near 4600 rpms. Not too bad for spool if you are getting 700hp out of it.

I wonder how significant the difference is on the .81 ar. I don't want to put it on there and then get 40 more hp and it choke off again. I do have ported heads with cams. They are ported pretty heavily as one of my DSM guys said when i had the heads off "damn that's some huge porting"

Also, being that i'm a broke med student i'm not sure i can afford to have another tune. I might build those knock headphones and try those out and do some street tuning.

I won't be able to check backpressure but what i can check is the intake temps. When it chokes off at 15psi the intake temps were going up super fast. So if the intake temps at the same psi don't rise like crazy then we know it's flowing a lot better.

so, what are everyone's opinions, should i get the .96 a/r and know it will flow with some lag or go with the .81 and see how that works?


also, i need clutch suggestions. I'm getting sick of this os giken twin disk. I want something that will hold my power and drive better. This giken holds the power but it's horrible to drive in traffic and makes me look like a 16 year old when i drive. I want something smoother and forgiving so it's fun to drive this car again on a daily cruise.

 

headwork like yours i would go with the .96ar. on my setup im going stock cams and slight porting. im sticking with the .81 ar.

 

Jeff, if the .81 is already paid for and its waiting for you.. I would just take it and do some street tuning.. and bring it to a local DJ dyno for numbers.. if that doesnt work.. then the .96 would be next in line.

 

street tuning e85 is tough because it doesnt knock persay. makes setting the timing very difficult without a dyno to see power changes. But on pump gas, just watch the knock voltage. Dont really need cans.

Since the .81 is brand new, see if they'll swap it for the bigger AR. What is the airbox on this like? 4" intake with big filter?

sounds like your drivability tune wasnt that great either. Did Hal just run out of time?

as for the clutch the Southbend dxd that Tom uses seems like a good bet. Probably be able to sell the OS and make money on the swap.

I think my upgraded Spec will be a bear to drive as well as compared to my original SS model.