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06-11-2008, 03:17 AM | #1 |
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worry about stock block reliability @ 23psi boost even with a good tune
hey guys i need some opinion... i think i'm changing my turbo plan
right now i have this i wanted this: but after seeing this: i changed my mind... here's why... I overlaid the 3 graph confusing huh?? so to make it clearer i did some photoshop: you see??? I love torque, especially when it peaks at 4000 rpm. Dom 3 doesn't get me close to the torque of the TD06-20G + meth 380+ wtq on mustang i think its pretty crazy... so i think I'm not going to do the bigger turbo The thing is i only want to fill up with 91... once and a while if i have to add meth + water is no big deal for me. what do you guys think? I think you'll feel torque way more than hp, especially on the street. I kinda worry running 23psi though... stock is 14.5 psi, that's 8.5 psi over stock, even with a great tune do you think the stock STI block should be ok?? Don't want the engine to break. I know I'm just being anal... but think about it the STI engine is designed for 300hp/300wtq crank and 14.5psi. Now 332whp/382wtq on mustang, which is about a freaking 450hp/500tq crank (assuming about 25% AWD drivetrain loss) @ 23psi. THAT'S 150HP AND 200LB-FT OF TORQUE OVER STOCK, IN THIS CASE THE EJ257 IS RUNNING OVER 150% OF ITS DESIGNED POWER OUTPUT. considering physics, and plain common sense... the engine life must be greatly shortened!!! if it is shortened, i just want to know by how much is its life shortened. My STI is now at about 35,000miles... been running Stage 2 since 15,000. If i do this turbo + meth upgrade now, the engine life will not pass 50,000 miles right?? Then i'll have to get an upgraded block. What do you think???? thanks to Stames_wiltz and POPOFF for their dyno graphs.
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06-11-2008, 03:32 AM | #2 |
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You'll be perfectly fine. There are people running 35Rs on pump + meth with no issues on the stock block.
Quit being a vagina. |
06-11-2008, 03:34 AM | #3 |
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It really depends on how you drive / have driven it.
If you don't flog it all the time, it could easily pass 50k. I'd also look around for dom3 charts with meth. They seem to spool about the same... the dom3 won't have the huge torque peak, but will definitely give you much more top end. Remember, that kind of torque is fun, but in the end it causes alot more stress on the motor (provided both setups have the same redline). |
06-11-2008, 07:22 AM | #4 |
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20g on meth is a nice street setup. won't set any records, but nice feel and driveability. after driving it for a while I would imagine like most people you will be wanting more. I would suggest going with at least the Green, if you do not have a ton of money invested in your setup now, consider a rotated 30r. you can add meth whenever you want
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06-11-2008, 09:39 AM | #5 |
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"You want to play you have to pay."
Always take that in to consideration when going for big numbers. The tune has a lot to do with it, but its not going to save your clutch, and other tranny components. A 35R on a stock block will get you gobs of power at the end of your redline, think 4k and on. Unless you go with a built engine, with a higher compresion ratio, which would help with the lag. I would never go that route again, it was a headache, things were always beraking, or needing upgrading. If you have deep pockets, then have at it. To me the Subie lost her routes when going in that direction, which is a fast accellerating rally car, not a drag racer. When you start going into the laggy area, you have gone too far in my opinion. Our cars have a short redline, and you want to make use of all of it. That 39 is fun to play with, an EWG does wonders, with the propper boost control. That said a 20g, or a green will do the same with a great tune and out the lag. You can bennifit from a long power band all the way to redline. -You will need a great tuner -EWG -Better boost control Thats just my 2cents |
06-11-2008, 11:46 AM | #6 | |
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06-11-2008, 12:22 PM | #7 |
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You may want to consider a different frame of mind:
Cars are an expensive hobby that ALWAYS lose money. |
06-11-2008, 12:49 PM | #8 |
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that dom 3 is most likely faster then that 20g. cobbs dyno is a heeeeeeeeeart breaker of epic proportions. those are differnt dynos so its hard to compare these cars. if you want to make 320-350 wheel on pump with a resonable tune do a 20g plus meth. or even a green with a really conservative tune.
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06-11-2008, 02:15 PM | #9 |
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I love how people always compare boost pressure between turbos especially stock to like a 20g. Stop comparing pressure and start looking at flow. Both at 20 psi aren't going to push the same flow and make the same power. Just like the comment about stock being 14.5 and 23 psi being 8 psi over stock! You could push 23 psi on a vf39 all day and the turbo would go before the motor would even sweat a drop. 14.5 psi from a 20g will probably make more power then 23 from a vf39. Theres plenty of motors that handle 100-300% more power then factory form. I dont think you'll have to worry about a 20g on a motor with only 35k miles... Tuning is everything
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06-11-2008, 02:21 PM | #10 | |
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I think the OP is to stuck on the plots. Well I mean just look at the plots on this page he is comparing. Go find a few guys at a Subbie meet and ask for a ride in the different setups Ive never seen a Subbie owner turn down the chance to show you what the cars got |
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06-11-2008, 02:22 PM | #11 |
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iwitarsa..it's good to see that some people(like yourself) actually read up and see that these setups never last long..they rarely do, if you look over time at the ratio of engine failure to long daily driven succes...it's pretty astounding, they almost all fail within 30,000 miles(as you predicted) most don't make it 20,000 miles
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06-11-2008, 03:17 PM | #12 | |
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You're right though, one major det and the motor is more than likely done. I'm not negating that. What I am saying is that if you can get the setup you want know and can rock it for 30k+ miles without issue and when the motor does finally go, you should have plenty of money saved for pistons and other things rather than just doing pistons now. Makes more sense to me. |
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06-11-2008, 03:24 PM | #13 | |
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06-11-2008, 04:46 PM | #14 |
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06-11-2008, 11:07 PM | #15 | |
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06-11-2008, 11:16 PM | #16 |
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LAG= Enemy of Subarus- i dont care how you drive if you are driving above 4000 all day long thats great good luck with the new motor in a few months- the most power with the least amount of boost the better w/o running lean
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06-12-2008, 03:23 AM | #17 | |
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seriously. you want moderately large numbers out of your subie, be prepared to buy/ rebuild a motor. The main reasons I did not go with an 18g for my 03 wrx: 1) Cost 2) possibly needing a new motor/tranny/clutch/all 3 very soon 3) cost 4) 90,000 miles 5) glass tranny 6) cost. Seriously, like the previous statement, you wanna play be ready to pay. Most of the people that pay to play enjoy every minute of it, even while going broke. If possibly spending thousands of dollars to repair your broken dream doesn't get your juices flowing then dont do it. be a *****. like me. but seriously you have an sti. Get a great tune. drive it how you want to. itll either brake or it wont. |
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06-12-2008, 03:35 AM | #18 |
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IDK mang it's all a toss up. I went to go build my motor and found two cracked ringlands and a cracked VF39 (big surprise) and I was making 280 whp and 350wtq on the bay area's heartbreaker (mustang dyno @ GST).
I went forged pistons and rings and threw in some Cossie rod bearings and ARP headstuds and called it good for a built block. Seems to be handling the 360whp/380wtq just fine. Nice thing is I have room for a bigger turbo than my FP 20G 8cm w/porting. I say go built or go home |
06-12-2008, 05:34 AM | #19 | |
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Then you show a 20g + meth that is giving you exactly what you want...which shows that a 44lb/min turbo CAN give you what you want with meth. However, the dom3 + meth will still give you the same (maybe more) low end torque plus gobs more up top....you'd probably be looking at 380/380 or 400/400 with the dom3 on pump+meth. Both the dom3 and 20g only have about 200rpm worse lag than the vf39 in your comparo. The dom3 will outperform the 20g everywhere on meth. I did 375/375 with my Green + meth. It goes like this: - if you are solely gonna use 91 octane get the 20g. On 91 octane the larger turbos will only net you 15-30whp. On pump gas boost levels the 20g is at better compressor efficiency and the bigger turbos are at worse. - if you are gonna use 91+meth anything in the 49-52lb/min range (Green, gt3071, gt3076, dom2/2.5/3) will out perform the 20g by 30-60whp on meth and have the same spool... - anything larger then you start sacrificing the low end more and more. You also have to consider that if you DONT go with a 3" turbo inlet hose, 3" turbo inlet, tgv deletes, and stay tmic you will sacrifice spool. The 2.4" inlets and fmic will make you spool later. You also have to take into account your headers (stock, equal, or unequal) and your method of boost control (stock, EBCS, manual, or external gate w/ ebcs or manual).....all these things will play a part in your spool and all of them played a part in the plots you posted above.....you cant merely compare dyno plots based on turbo alone you have to take the whole setup into account. |
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06-12-2008, 10:46 AM | #20 |
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Here's another idea, hit that search tab. You'll find it to be very usefull. Learn from what others have done. You need to put some serious research in this my brotha. Do not just start adding things and work as you go, have a game plan.
Talk with some of the vendors out there. They can help you come up with a game plan, and help you achieve your goals. Again use the search tab, and head over to the vendor review section. Do not go in to this with iffy thought, you need to be committed and ready pay for what you want. Good luck |
06-12-2008, 02:26 PM | #21 |
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Dom III is hands down the best turbo on that list.
Why no Dom III + Meth? Much more potential in that turbo than the stg 2/20g |
06-12-2008, 03:29 PM | #22 | |
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Brings up another cardinal rule of high boost setups Boost doesn't kill engines, Detonation does Now with Meth, some crazy people run 30psi with 91 + meth. I spike to 27psi ish in 5th gear pulls So I'd say with 23 psi you've got plenty of room for error! Remember the stock MAP sensor maxes out though so you can only run 22psi and still have fuel cut, or upgrade the MAP sensor. But yeah, if you want torque, if you want flat and fat ginormous powerbands that make max HP from 5k-k, you need massive boost. No way around that. I mean, look at that 4.5k-redline MAX HP powerband on the 20g+meth car you graphed Last edited by verc; 06-12-2008 at 03:38 PM. |
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06-12-2008, 04:36 PM | #23 |
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what causes detonation then??
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06-12-2008, 04:43 PM | #24 | |
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http://en.wikipedia.org/wiki/Engine_knocking
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In our cars its a fact that higher boost = more hp = higher cylinder pressure = more engine failures The stock motor may withstand 500 high rpm detonations ~300whp and only 50 ~400whp..... Very good advice. Wish i had the MAP sensor, may have saved my motor. Last edited by Phatron; 06-12-2008 at 05:04 PM. |
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06-12-2008, 07:17 PM | #25 | |
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I think you'll be just fine pushing those types of numbers with an EJ25. Personally I'll be shooting for higher... |
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