ej25subie05
New member
will check it out as soon as i settle in my new place.
The Batmobile_Engage Member Journal
- Thread starter Batmobile_Engage
- Start date
Sooo... after some research and advice from others who have built motors in the past, I think I've decided to increase my desired power goal.
For example, one of the guys here on the forum said he made almost 450whp on 14 psi of boost because his compression ratio is 9.1:1 rather than the stock 8.2:1. Originally, I planned to run about 24 psi of boost (after rebuilding my engine) at 8.2:1 and make at least 450whp*. Now, I'm thinking more along the lines of 22psi of boost after a rebuild with 8.7:1 compression pistons.
Thoughts?
@HolyCrapItsFast, @Alin, @IGOTASTi.COM, @Spamby, @Grinder34, @Td_d, @Robert Viehweger, @WRB_STi
*at least 450whp on a Mustang dyno; 475-500whp would be most preferrable (with the 8.7:1 ratio of course).
For example, one of the guys here on the forum said he made almost 450whp on 14 psi of boost because his compression ratio is 9.1:1 rather than the stock 8.2:1. Originally, I planned to run about 24 psi of boost (after rebuilding my engine) at 8.2:1 and make at least 450whp*. Now, I'm thinking more along the lines of 22psi of boost after a rebuild with 8.7:1 compression pistons.
Thoughts?
@HolyCrapItsFast, @Alin, @IGOTASTi.COM, @Spamby, @Grinder34, @Td_d, @Robert Viehweger, @WRB_STi
*at least 450whp on a Mustang dyno; 475-500whp would be most preferrable (with the 8.7:1 ratio of course).
Maybe we haven't necessarily been giving people the best advice of "which turbo to buy for what desired power level", considering that in most cases, the person is going to rebuild the motor anyway. A smaller, faster spooling turbo might be a better choice for someone while still reaching the desired power level, due to the pistons chosen for the rebuild.
HolyCrapItsFast
Drinks beer!
Be aware that when you change the static compression ratio, you need to consider all of the following together when you make your consideration because these effect dynamic compression which is more important IMO... cams, timing and boost.
Larger cams will lower your dynamic compression to the point where a 9.5:1 static compression will perform more like 9:1 or 8.5:1 depending how big and what duration. More boost will increase your dynamic compression and the effect can be exponential. More timing will also increase your dynamic compression.
Choose your turbo, your cams and your tuning strategy to match
Sorry I have been off the forums for a while. Moving, school and a new job is keeping me pretty busy.
Boost pressure does not always equate to HP numbers and vise versa.
Anyways, you need to look at your power goals and use of the car before you start a build or consider buying parts.
For instance, my Evo: I over built it. Like a lot. My bottom end can handle 950+ WHP. I just had a tune last night and its making close to 650 whp. I built it this way so that in the future I can make more power when I want. It is a street monster. I really didnt build it for the track but it may see a few track days here and there. If I was going to stick with auto x, I would have left it stock and bolted up an EVO 9 turbo and make 400whp.
If you want a solid tune locally, let me know and I can set you up with him. Hands down best prices in the area and a great guy.
For your goals I would almost consider the manley turbo tuff rods. Drop on some nice wiseco pistons and nitride the crank. This way you can make more if you ever desire and you will have a reliable bottom end that can take more power.
Turbo selection will be based on what you do with the car. You can use an FP green and make power all over the place and still hit the 450 mark. But at this point, you are using the turbo to its full potential. (probably 25psi or so). When you can step up to a FP red and make more top end power. Its a little laggier but you are not pushing the turbo to its limits. You can make the same power on the red at 20 psi. Im not sure if you plan to stay with the turbo you have now or change out turbos when you build it. And this is just an example showing that pressure does not always equal power. Its the amount of air you are moving through the engine.
As far as compression goes, 9:1 is pretty standard. Since you are running meth, you can go a little higher. Compression does not mean you will make more power either. Its all in the tune, turbo, and supporting parts and most importantly, fuel used.
text me if you have any questions.
Boost pressure does not always equate to HP numbers and vise versa.
Anyways, you need to look at your power goals and use of the car before you start a build or consider buying parts.
For instance, my Evo: I over built it. Like a lot. My bottom end can handle 950+ WHP. I just had a tune last night and its making close to 650 whp. I built it this way so that in the future I can make more power when I want. It is a street monster. I really didnt build it for the track but it may see a few track days here and there. If I was going to stick with auto x, I would have left it stock and bolted up an EVO 9 turbo and make 400whp.
If you want a solid tune locally, let me know and I can set you up with him. Hands down best prices in the area and a great guy.
For your goals I would almost consider the manley turbo tuff rods. Drop on some nice wiseco pistons and nitride the crank. This way you can make more if you ever desire and you will have a reliable bottom end that can take more power.
Turbo selection will be based on what you do with the car. You can use an FP green and make power all over the place and still hit the 450 mark. But at this point, you are using the turbo to its full potential. (probably 25psi or so). When you can step up to a FP red and make more top end power. Its a little laggier but you are not pushing the turbo to its limits. You can make the same power on the red at 20 psi. Im not sure if you plan to stay with the turbo you have now or change out turbos when you build it. And this is just an example showing that pressure does not always equal power. Its the amount of air you are moving through the engine.
As far as compression goes, 9:1 is pretty standard. Since you are running meth, you can go a little higher. Compression does not mean you will make more power either. Its all in the tune, turbo, and supporting parts and most importantly, fuel used.
text me if you have any questions.
Thanks, Joe! I'm sure I will return to this post a few times while in search of parts for the motor build. I imagine that I will have to upgrade my fuel system a bit and I want to add TGV deletes, but other than that I want to run the same turbo up to 24-25 psi (ATP GT3071r) and just change out the pistons and rods at a bare minimum.
The Batmobile got a good wash this morning and a few quick WOT runs to blow the rest of the water off. :lol:
livid_wrx_
Member
Lookin good. I'd be hesitant of running high compression with a turbo. Asking for issues.
Thanks!
The experts seem to agree, 9:1 is the best ratio for a built turbo motor. I'm still thinking 8.5:1 or 8.7:1.
The experts seem to agree, 9:1 is the best ratio for a built turbo motor. I'm still thinking 8.5:1 or 8.7:1.
livid_wrx_
Member
Yep, no problem! I come to Subaru family from the honda community (
) and over there they love super high compression, high compression ratios and high rev limits with big boost. When you mix en all you get bent/broken internals. It leaves you with small amount of room for error.I think that'll be a safe ratio.
I've washed it since then. Jeez. :lol:
I've considered mild, street based (probably 264-268 grind) cams, if even at all. Either way, I want to increase the compression, I'm now thinking 8.5:1 is what I want to do. It's a small bump up from the factory 8.2:1.
-Now the question is, do I choose a larger bore size? 100mm for example? (+0.5mm). I know some people who choose this bore so that when the block is machined, boring out another 0.5mm is not enough to thin out the cylinder walls, but enough to remove any and all scratching and so forth.
How do you feel about that?
I see no reason to go over 500whp. Anywhere between 450 and 500 at the wheel is the goal. I just figured that if I bump up the compression a bit, we don't need to run the balls off of the turbo to reach that power goal.
I really like this GT3071, so I'm not changing that out. It's capable of 24-25 psi at 7,500 rpms. I think that is more than sufficient. I'll probably keep the heads stock, though I considered mild cams like I said above. I don't know whether new valve springs would be a good idea just for longevity's sake or not.
-Who will I be sending the block to around here for the machining work? How do you feel about 100mm, 8.5:1 Wiseco Forged Pistons?
http://www.fastwrx.com/collections/engine-internals/products/wiseco-pistons
-There is a drop down menu where I can select Turbo Tuff I-beam rods, but they a $300 more than the H-beam. Thoughts?
http://www.fastwrx.com/collections/engine-internals/products/manley-h-beam-rods
-I'm adding TGV deletes to the list. I will probably buy those right as we are starting the build so I can send my cores off to Grimmspeed.
-Fuel Injectors. 1000cc or 1200cc. I'm not sure what brand yet. What do you guys think?
-Last but not least, a new timing belt.
I really appreciate all the help from you guys. I hope I'm not over complicating things.
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Well I can hook you up with the parts. No need to pay retail. I can get final prices when the time comes. H-beams tend to bend or snap. Especially when torque comes on faster. IMO, I would not run h beams. I would build it once and right the first time. I went with the turbo tuff rods in my evo. I know its a different platform and engine but I know its bullet proof.
For your turbo, you should be making 24-25psi way before 7500 rpm. Unless you mean keeping that pressure up to redline from the time full boost hits.
For the pistons, Wiseco is a good choice. Ive never had any problems with them. Compression is up to you. I wouldnt order pistons until the block is torn apart. No need to sped the extra on a bore if you can hone it and drop a set of 99.5mm pistons in.
Cams will definitely make more power. Depends on what you really want to spend at the moment.
Injectors: Find something that proven and runs well. Some injectors suck to scale in and are inconsistent. FIC has been doing well for me in the past.
I know a few shops locally that do subaru work for the block.
For your turbo, you should be making 24-25psi way before 7500 rpm. Unless you mean keeping that pressure up to redline from the time full boost hits.
For the pistons, Wiseco is a good choice. Ive never had any problems with them. Compression is up to you. I wouldnt order pistons until the block is torn apart. No need to sped the extra on a bore if you can hone it and drop a set of 99.5mm pistons in.
Cams will definitely make more power. Depends on what you really want to spend at the moment.
Injectors: Find something that proven and runs well. Some injectors suck to scale in and are inconsistent. FIC has been doing well for me in the past.
I know a few shops locally that do subaru work for the block.
Im running 10:1 with 35-40psi. No problems here. Its all in the tune a fuel used.
livid_wrx_
Member
I knew of a GSR running 12.0:1 compression with 25 pounds. He wondered why he snapped his connecting rods. But, the Honda crowd will always leave you shaking your head when it comes to tuning.
-Great! Once I'm ready to buy parts, I'll let you know right away.
-With the GT3071, I'm hitting my (current) target boost of 19 psi at about 3800 rpms. I meant that it should be capable of supplying 24-25 psi all the way to 7500 rpms without running out of breath.
-Got it. Don't order pistons until we get a look at the cylinder walls. :tup:
-Currently, my injectors are (side mount) DW 850cc. I imagine I'll probably need to go bigger. Thinking about converting to top feed IF you think it makes a big difference.
-Local shops doing the machining....perfect. :subaru:
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