ive got a mechanically stock 2011 sti ive never done forced induction cars before, up to now if i wanted horse power i cammed, cranked, race head, valve spring, 4 barreled, so on and so forth, so i need a bit of guidance. 1. i do NOT want to sleeve the block, excess heat bugs me. so i need to stay around 22-25 pounds of boost IMO 2. i do not want to upgrade the transmission so i need to stay under 500 HP/TQ (i would think) i do want to be right in the meat of the 400 HP range, maybe 450. My thinking is upgrade turbo for more boost. but should i go ahead and do a rotated assembly? either way, i want to find a good combo of turbo/cover to spool up quickly, say 3000 rpm or lower if possible? and stay on boost through high rpms. upgrade injectors with it... maybe colder plugs to negate detonation? at that point my thinking is forged pistons and rods are a must. i dont know whether or not to replace valve springs and cam, if i dont need to then i dont want to, i want to keep a nice street idle and want to be able to drive it daily. so a good tune will be important oh and pump gas, 93 again im looking for a sweet spot of 400 to 450 hp and similar tq. any help would be appreciated because the last thing that i want is to be in a situation where i could be producing 6 or 700 hp but have to tune down to keep it safe for the car.
There will be a lot of people chiming in that know a lot more than I do but my advice: 1. You will have to build the block of you want somewhat reliable power at those levels, you don't need to sleeve it. You can pin the block if you are concerned about deformation or get a semi closed deck made for you. Going with larger valves and having some head work done won't be a bad idea, there are cams available that have very street able characteristics. 2. Your turbo option for ~400 whp should begin and end with a Dom 1.5xtr. If you want to get more in the 450 range you will probably need to go rotated and you will start to get in to the realm of laggier turbos. 3. you will need a good amount of supporting mods for either of those setups. Front mount IC, injectors, fuel pump etc. 4. Don't worry about your transmission unless you don't know how to drive a manual.
After I went rotated, I wish I had done that to begin with. You will save money in the long run and will have endless options when it comes to Turbos. Make sure you get a quality kit and start saving your pennies to build your bottom end.
To make that power reliably you should go rotated. There will be essentials as covered, block, injectors, intercooler, and turbo. If you are going for that power expect some lag, If you are ok with some lag then get a front mount. It will save you should you decide to do a track day or just continue to live in GA. I worked out the cost and for what most people pay to get to stage 2, then get bored and upgrade the turbo, you could just go rotated and start in a better position than them. The Dom 1.5 could get you there with the right fuel. Robb's was nearly there without the Dual AVCS that would help the torque. I'd leave the heads stock or just bowl blend at the most. I've started a new build for a friend and we'll be using turn in concept beefy badger, which I am excited to try.
ill probably start with pistons, rods and bearings and break them in for a couple months since i can do that myself(actually i can probably do everything myself except tuning), then upgrade the fuel system and tune. last thing will probably be intercooler and turbo since its the biggest expense. my biggest concern is that i have been told that the block can hold up to around 27 lbs of boost without modification, i dont know if that true but i really dont want to add anything inside the water jacket if i dont have to, if i can run 400 on an unmolested block and not have to worry about the cylinders warping or cracking then thats exactly what i want to do. pins and sleeves dont let heat dissipate the way that the water jacket should so ill just end up having to replace the block eventually from prolonged excessive heat. unless the supports from s&r performance have figured that out. also, im thinking about the garret gt3076r, dyno charts look like peak performance kicks in at ~3500rpm but it also looks like i'd be on boost at 2000 just at like 7psi, its .60 a/r
With front mount ic's you add a lot of volume to your intake system which makes your turbo work harder for the same amount of boost right? would it make sense to go with something like a .48 a/r hot side coupled with a larger bell. in my head, that amounts to faster spool up while at the same time pushing more air to make up for extra volume. if all this makes sense then maybe the garret gt isnt the right turbo
Not really...it is a closed system so once it fills up the pipes and intercooler, it makes the same amount of pressure. The only thing lost is that split second of spool up. .48 a/r would be a waste of time on your motor. It might spool super quick but will not give you the desired volume or pressure. Dont try and reinvent the wheel.......there are tons of PROVEN turbo setups that work very well on your platform.
I'm not the most knowledgable person on this site by any stretch of the imagination, but I'm definitely going to have to agree with Matto. I'm planning on going with a dom 1.5xtr in the next year or so on my car.... Tons of solid power and solid reliability stories with the dom 1.5 Edit: I know reliability has nothing to do with the turbo.... Just sayin at the power levels people achieve with the dom 1.5 seem to reliable with supporting mods--- block,injectors, FMIC, fuel pump, etc..
so what im getting so far is not to pin or otherwise molest the block unless i just want peace of mind because the motor can take the boost that it would take to make 400-450 hp without doing it. correct me if wrong. and that the only time the turbo lag is going to come into play is in an off the line situation, yea? so if im goin down the road at about 2000 rpm i should be atleast partially spooled with the dom which everyone is suggesting i get. but if im going to go with a rotated setup, then is that really the best option? also what exactly is a dual spool ? also has anyone gone with the turbonetic t3/t4 or known anyone who has? its ball bearing and seems like less to go wrong on it than the dom.
Hahah. Man, you're all over the place! A twin-scroll will get you a quicker spool on the turbo, but you will also have to invest in a different header to run a twinscroll. You seem to be concerned with spool characteristics, so again I'll say most rotated setups are going to be laggier than the dom 1.5 in a stock location. It really boils down to if you are willing to sacrifice quick spool for more power. Honestly you probably need to have an in depth conversation with a local shop and figure out a build that will meet your goals.
^What he said. Rotated setups pull big power with the right mods but there's definitely a lag there. I love my 1.5xtr (have the motor mods previously discussed) and I think that a twin scroll would be a completely different option requiring different headers, turbo, ect. Joel from QED Tuning was telling me about a stock location turbo that came out that's capable of 500whp+! May be worth looking into. The money you save on a rotated setup could go towards a motor build?
My rotated setup with the 6262 spooled 200 rpms slower than my 20G did. I honestly didnt notice it at all and surely didnt care after it hit full boost.
Yeah man, you are all over the place.... I would go to TopSpeed/whatever shop you want to work with and sit down with them and discuss your goals... Top Speed has done tons of dom 1.5 builds and they have done tons of rotated builds. They will be able to give you pros and cons of different turbo setups from first hand experience.
Dom1.5 is the biggest stock location turbo I would go with. If you want more out of pump gas (93oct) than about 415whp...then you need to go rotated from the beginning. I wouldn't touch any of the bigger stock location turbos and I haven't seen a single twin scroll setup for Subaru's that has performed as advertised. A properly setup/sized rotated turbo should not spool all that differently given the power you are looking at achieving. If you want to go 500whp+ on 93oct then you are going to increase lag as you increase turbo size. If you want 450whp on e85, you can do that all day long on a Dom1.5. On the block...if you are going to go rotated I would do as much as you are willing to spend honestly. Everyone always says "I only want 450whp" then 6 months down the road they want to turn it up and you will have that ability easily with being rotated. I wonder sometimes on sleeving it though unless you are really going to go big power and it is required. I have seen too many dropped sleeves over the years to be comfortable with that if you are daily driving it.
not trying to be all over the place, just wanted to know if its goin to take too much boost to get to 450 or so hp, i can always break the block down later and send it to a machine shop if i want more power than that....unless i need it in the first place to get to 450, follow? i seemed to be getting a lot of info about what different setups would give me horsepower wise though, but i think matto answered what i needed to know. thats really all i need to know p.s. i think i would go with the closed deck inserts over pinning or sleeving, has anyone had trouble with overheating or anything else with those? plus im going to do my own build, i would just need a machine shop if it turned out that i need more boost than the stock block is capable of to get to 450. and i would also just need to figure out the perfect turbo for what i want.
You're really over complicating this. This platform has been around for forever so there are plenty of proven setups. You don't need to worry about weird turbine combinations or twin scroll. There is no new path to pave. You really need to figure out your goals...then there are proven setups for that goal. Pretty simple really.
mattos still the only one whos come close to answering the question, im not trying to reinvent anything. the question is, (or it shoudl have been from the start) would it take more boost than the stock cylinders are capable of containing to get to 450 assuming i had forged pistons, rods and all the accompanying bearings and rings. thats all im trying to figure out. and no one has actually said yes or no but you've all built and tuned your cars before and you went through the same thing im about to go through. im just asking side questions about turbos because everyone on this forum has bought one at one point and i assume they know something about them. trying to learn here, so i can come up with a plan, like i said earlier, if i was dealing with NA american muscle i wouldnt even be asking questions
At 450whp...you need drop in pistons. The failing point is the pistons below 500whp. There are people on stock rods above that as well. You won't be running more than 23psi or so on pump gas anyway.
If you are going to stay at 450whp...don't overspend on the block. You really just need forged pistons and call it a day. If you were looking to go from 500 to 550whp+ then your motor build would get more complicated. I would get in touch with TopSpeed Motorsports or someone reputable and tell them your goals. They can get you in the right direction without you having to worry. ARP bolts since you are in there. ACL bearings because they are good and you are in there already...and your piston of choice (I had CP in my car). Call it done.
Hi Check out my build thread. 521/437 on the stock block (99.75mm bore, +.25mm) I have around 15,000 miles on it (93oct) and 0 issues. I have a rotated ETS kit with what most would consider a "large turbo" for subaru's (6266) and will tell you that from my personal opinion, lag is subjective. I know how to drive my car so I rarely end up getting frustrated with spool time. STIRHINO just built an almost identical build to mine but with some head work and went with an outfront motorsports closed deck block. He isn't the first to do so around here and there are no issues with heat. Those blocks would not survive track conditions in the south (GA,FL,TX) if they produced aluminum heat issues. Subaru heads get pretty pissed off with deck warp from heat especially with the MLS gaskets so we would know about that by now. With that said Robb is right, and my build just confirms it. If your goals are fixed and you are hell bent on only making mid 400's, the stock block is fine. Even if you intend to go the level I did and do low 500's you are still fine, but that's probably the limit. I would stay away from a stock location turbo for a multitude of reasons including but not limited to the following: 1. Heat removal is better with rotated (more room) 2. Looks better under the hood for sure 3. MUCH EASIER TO WORK ON 4. External wastegate is more flexible and performs better 5. Switching turbo's can be done in 15mins with V-band's If you plan on working on your own car (and it sounds like you do) staying stock location will mean a lot of busted knuckles, burns, curse words and frustration just trying to fix a simple oil leak on one of the banjo bolts. I can get to everything on my rotated ETS setup without even trying, and without even getting under the car. To sum it up, stock location = dom 1.5 (420ish whp on 93oct) Rotated location = **** (sky is the limit) Not really any other stock replacement stock location turbo's I would even consider and as you've seen not many others would either.
Regarding hot side area over radius a/r sizing, consider this. We aren't inline 4's, we are flat 4's. The exhaust ports are very far apart, and even with an equal length manifold (actually even more so) the distance traveled by the exhaust gasses before they reach the turbine is pretty far compared to most other setups. This gives them time to already start expanding in the tubes and the most common cause of bottlenecks on subaru's (from the great Doug Wilks) is choking the exhaust path with a small hotside. Where a 1.06 A/R is ridiculous on a 4g63 inline 4, it's remarkably effective on a high horsepower EJ257 flat 4. Thats an astronomical example but nearer to home would be comparing a .63 a/r with a .80+ there would be no question of the .63 being a massive choke point in the exhaust stream, especially as everything gets nice and hot.
One more thing, if this is a dual AVCS motor, the tuner knowing how to properly tune cam advance and utilize exhaust gas scavenging with overlap will net you the biggest off-boost performance gains and spool up of any "mod" there is. If I disable AVCS on my car it spools like 750rpm later and feels like a dead elephant is on my ass. Doug really set up the cam's properly and utilized my GSC S2 cams to the fullest off-boost and during ramp up. He also starts the burn early with intuitive timing and fueling on ramp up as well which gets that turbine spinning. In short, consider the avcs variable in your equation whether it's present or absent.
Lower line was pump gas. Higher line was Q16 blend. Drop in pistons, stock rods and stock heads. GT35R with .63 compressor side. Spool was insane....was seeing 22 psi @ 3900 rpms. Boosted 28 psi on pump gas, 32 on race. Pump gas included meth injection. Oh and ZERO AVCS.
While all of this is correct it all boils down to what you want out of the car. Massive horsepower = bigger hotside. More streetability and spool? Smaller. I contemplated that sizing for ages and ended up with the .63 at Doug's recommendation....it was the exact same turbo that was on Lucy (the sick Time attack car they had).