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Old 08-22-2006, 10:52 AM   #1
greysave
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Default GT35r vs GT30r

Ok, I have been doing some research on the power and spool up difference between a 35r and a 30r, and I am stuck tring to choose between the two. Does anyone know the spool up difference? I will drag the car alot, but I occasionally would like to road race it. I am also slightly interested in autocross, which I know both turbos are probably too big for. I have a completely built motor, ported heads cams over sized valves, pauter rods pistons, a shaved high rev crank, high output oil pump, and 272 272 kelford avcs cams. I currently have an sr55 and want more top end.

I hear mixed stories on the 35r some say its laggy and others say its not. I would like to know for instance where it hits 20lbs by. I see peoples 1/4 mile times all over the place with this turbo, I see times ranging from 13's to the high 10's which makes it more difficult to make the decission. I know the 35r is capable of pushing in excess of 32lbs of boost, I only want to run around 32lbs max. I will still drive the car to work and around town occasionally, so I would like to know if the 35r is truely to laggy for that.

Now with the 30r I hear that spool is good, I see a mixed range of spool up times with them though. Some say it makes full boost around 3700 others say around 4000, I would like to know which is true.

I know full boost is hard to gauge because people are running different max boost's out there, so I feel 1 bar would be more relavent. When do either of these turbos get to 1 bar? What is the hp difference between the 2 turbo's? Are there any 500whp gt30 sti's out there? Any input would be appreciated here.
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Old 08-22-2006, 11:20 AM   #2
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Quote:
Originally Posted by greysave
I will drag the car alot, but I occasionally would like to road race it.
You might get flamed a bit for saying this...

I'm interested in the differences also--thinking about a moderate power upgrade for my car (<400 whp max), probably these turbos are a bit too much for me...
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Old 08-22-2006, 11:42 AM   #3
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GT30R is good up to 400hp with decent spool while GT35R can give you alot more with slower spool than GT30R.
so if u are just comparing the spool, GT30R is better, but if u want to make more power than 400 like 450+ or something, you have to get GT35R
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Old 08-22-2006, 12:21 PM   #4
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Of the people that say the GT35R is laggy... how many do you think have actually driven an STi with one?

<-- daily drives a 35R
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Old 08-22-2006, 01:21 PM   #5
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I've had/have both a 30R .63ar and a 35R .82ar on my car. Yes, the 35R is a little laggier compared to the 30R, but not by much. Here is a link where I show some of the differences between the two.

http://forums.nasioc.com/forums/show....php?t=1065187
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Old 08-22-2006, 02:05 PM   #6
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If you have the SR55 now you should go to the 35R. Get the .82 AR. Make sure you get a kit that uses the GT 3 inch turbine housing. It spools up faster then the old T31 does. The main thing is to choose a tuner thats going to be able to remap the AVCS cam system to get the power back down low. With the proper tuning you will loose nothing to the 30R.

Clark
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Old 08-22-2006, 02:42 PM   #7
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Sorry for out off topic. But is the STI stock motor can hold the GT35? Because I heard you tune GT35 on stock motor and cames out about 500whp+
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Old 08-22-2006, 02:42 PM   #8
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Quote:
Originally Posted by x99percent
Of the people that say the GT35R is laggy... how many do you think have actually driven an STi with one?

<-- daily drives a 35R
i daily drive a 35r too..and actully under the boost, it still makes more power than regular STI, just that after 4k rpm makes wayyy too much different, so that's the thing makes me feel laggy under 4k.
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Old 08-22-2006, 03:05 PM   #9
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I heard that if your pushing ~high 300's to 400 whp, some forged pistons are nearly mandatory, as that becomes the weak link in the STI system, but that the drivetrain (axles, driveshaft, etc..) can handle the power (not the clutch tho). Any truth/comments on that (sorry to go off topic). So in that regards, if you were considering the GT30 or 35, you would need upgraded internals right?
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Old 08-22-2006, 03:44 PM   #10
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Quote:
Originally Posted by AZScoobie
If you have the SR55 now you should go to the 35R. Get the .82 AR. Make sure you get a kit that uses the GT 3 inch turbine housing. It spools up faster then the old T31 does. The main thing is to choose a tuner thats going to be able to remap the AVCS cam system to get the power back down low. With the proper tuning you will loose nothing to the 30R.

Clark

So the gt30 and sr55 are about the same from what I hear. I guess the jump would logically make more sense to use the 35r. Great tuners are hard to find, there is alot of hype out there, I am more partial to tune it myself due to the difficulties I have had. Next question is with modded injectors and a warblo 255 how much power will I be able to obtain before the maf runs out?
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Old 08-22-2006, 03:47 PM   #11
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Quote:
Originally Posted by SloRice
I've had/have both a 30R .63ar and a 35R .82ar on my car. Yes, the 35R is a little laggier compared to the 30R, but not by much. Here is a link where I show some of the differences between the two.

http://forums.nasioc.com/forums/show....php?t=1065187
How big of a difference in throttle response was there? I know spool up is similar, but if I am on the rolling highway is the difference very noticable. Also the .63 ar housing, would help that gt30 spool up faster while hurting the upper end, do you think throttle response would be closer if they both had .82 ar housings?
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Old 08-22-2006, 04:11 PM   #12
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When cruising around and then downshift and punch it, yea the transient response of the 35R is slower than the 30R. But it's not really a whole lot, plus it's worth the wait.
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Old 08-22-2006, 04:32 PM   #13
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Thanks, I am leaning more and more towards the 35r. I honestly want the 35 I just don't want too much lag. I know I am asking for alot though.
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Old 08-22-2006, 04:43 PM   #14
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I think I have finally made up my mind as well. I have been reading a lot of related posts comparing these two. The GT35R with .82 is what I have really wanted all along, but I was skeptical about lag. But even though you don't hit high boost right away you still have a lot of power on tap. Besides, everyone who runs it says it's worth the slight wait.
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Old 08-22-2006, 04:59 PM   #15
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The gearing in the car is so short that "laggy" isn't really the word to describe the STi with a 35R. It's more like fast (<4500RPM's) and fastAr (>4500RPM's).

Or, if you have a problem with lag....DOWNSHIFT!
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Old 08-22-2006, 05:04 PM   #16
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Quote:
Originally Posted by SloRice
Or, if you have a problem with lag....DOWNSHIFT!
No doubt. If you're complaining about lag, you're in the wrong gear.
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Old 08-22-2006, 05:40 PM   #17
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I have a 30R .82 and will be reaplcing it with at 35R .82 in the future. The lag even on the 30R is over rated, it's nothing like driving a big turbo on a 2L imo. The car is just as fun on the streets as it was with the VF39.
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Old 08-22-2006, 05:50 PM   #18
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Ok the 35 seems to be winning big time in everyone's opinion I guess I will go that route.
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Old 08-22-2006, 06:02 PM   #19
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The SR55 is a compromised GT30R. It has never made the power of the real rotated mount 30R. To me the choice is clear... The 30R is great for the 2.0 and the 35R is great for the 2.5ltr engine.

Clark
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Old 08-22-2006, 07:04 PM   #20
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I run the 30R on my car, and if i were you and i had a built motor, i would go 35R all the way. Lag is WAY overatted, trust me. Once i get a built motor in and have a bit of extra money (not for a long time, but eventually) i will switch to a 35R too.

Since you already have a SR55, the lag on that is similar to a 30, so if you went with a 30 you would have about the same lag (30 spools a bit faster i think) with a bit more top-end. With the 35 you'll have a tiny bit more lag, but the top-end will be a big difference. IMO i wouls go 35R all the way, and this is comming from a 30R owner.
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Old 08-22-2006, 07:08 PM   #21
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everyone always talks about how laggy a 35R is, even below 20psi, you are still making more power than a stock STi's peak,

but what do i know, i still drive a stock turbo STi, just my opinion from looking at various charts
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Old 08-22-2006, 07:37 PM   #22
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I would definitely recomend a 35r .82 for your setup, it's begging for it . No one has ever gotten out of my car and said "wow, that was laggy!" but instead I get "holy ****!!!!" Lag is wayyyyy over rated . I will admit though, your setup will not be ideal for autox

however!!!!! you will encounter a few extra obstacles when going with the 35r over the 30r. I believe you will cross a threshold that requires attention to areas that go unnoticed when you are at 500whp and below. For instance, 800-1000cc injectors + walbro wont provide enough fueling to reach the full potential of a 35r. you'll either need dual walbros or an external pump. also, the clutch situation becomes more challenging. An act 6 puck unsprung or exedy twin disc will hold, but not forever. So you will be faced with buying a high dollar clutch (tilton, exedy triple disc, etc). You might also encounter spark/ignition problems, spark plug gap and coil packs begin to show their decencies at higher levels.

The more power you make, the quicker you'll find your weakest link
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Old 08-22-2006, 09:02 PM   #23
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I daily drive my .82 35R. It isn't laggy at all... just a different powerband than stock.
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Old 08-22-2006, 10:42 PM   #24
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Quote:
Originally Posted by burnin4
The more power you make, the quicker you'll find your weakest link
Truer words were never spoken.
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Old 08-22-2006, 11:02 PM   #25
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Just go for the 35R you won't regret it.
<-- happy 35R .82 owner/daily driver
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