Engine Choices

[BrandonDrums]

This info is incorrect. There are drastic differences between the EJ255 and 257. The heads are much much different too. It's not the easy lego put together people associate subaru with. Subarus are like legos but they need to be fitted together correctly or else you have massive problems like the many before. Check hybrid builds and see how long and how much trouble people went through and still go through today with them. There's even 1 thread in built motor with a guy who ended up with over 10:1 CR cause the shop didn't know D25 heads have a smaller chamber then the B25. Subarus are finicky and must require ALOT of attention to detail.

The info I provided stating 2.5T engines from USDM Subaru's being more or less the same isn't that far off. There are differences, namely with the pistons and head chambers as you pointed out but that's not all that relevant to the discussion of OEM engine options which is the point of this thread. If anyone wants to get nitty gritty on the specific differences between these 2 engine variants, here's a good thread where some of the misconceptions about the differences of the 255 and 257 are somewhat put to rest http://forums.nasioc.com/forums/show....php?t=1667168

To your point though, if you're splitting a block to do mods to it, then you absolutely need to pay attention like you said but that goes for every engine. If your engine builder isn't blueprinting the engine and recording all the exact specs along the build, then I'd argue they aren't paying enough attention if you are paying them money to do the work. But that's not what we're discussing here.

To my point if you're sourcing a Stock 2.5T as this thread is talking about OEM engine options, not built or aftermarket, you can essentially treat them as interchangeable. Also, because we're talking about stock engine options and I was simply talking about OEM 2.5T longblocks, any discussion about 'hybrid' longblocks aka 2.5 shortblock w/ 2.0 heads aren't even on the radar of the conversation.

Not saying you're wrong but just saying we're having a far more simple and basic conversation here for the sake of non-subie guys looking for OEM engine choices.

[Etos]

Sorry, I see "these 2.5ls are all the same cause they are 2.5" and it always bothers me to see people say that. More so that others will read and then start making huge mistakes based on that.

[crobin4]

http://mendeolamotors.com/trans-prot...d=47&Itemid=29

not cheap... but a sequential could be fun.

I think I can get a discount if I spell his name correctly.
I think this was one of the first requirements for Dave getting such a good price for the GTM guys.

I'm curious though. Lots of good ratios available. I still don't think I will need one, but some of us might. I do think it would more cost effective in the end though vs. Subie 6-spd.

I don't know just throwing it out there as a possibility.

I'm sort of thinking that perhaps a slightly modified version of the GTM tranny they're doing may be the ticket for say Phil @ Element ( oooo, spelled it right can I get a discount on a tune? ) or others like him.

[crobin4]

This concludes my contribution to the thread jacking of thread named Engine Choices.

[Evan78]

For those who don't know of him, PhilElement is Phil Grabrow, owner (I assume) of Element Tuning and driver of their time attack Subaru. You can read his posts on Nasioc under the screen name "Element Tuning". I don't know him personally or even follow time attack, but I thought I'd throw out a little info so that people are aware of where he is coming from. Needless to say, he has more experience than the average Subaru owner.

[Evan78]

2nd, the STI's gearing is short, very short. On a 1800lb car, you'll be hurting your performance by having such short gear ratios, I mean 2 shifts to 60 when 60 will be coming in 4 seconds or less is just dumb. Also, achieving full boost is difficult in lower gears because the engine simply has too much mechanical advantage to build full boost easily, the engine will build revs faster than the turbo can build boost. Shed 1500 lbs, gearing as short as the 6 speed's will just make that even worse.

This is not an important point, but I just want to point out what I see as a flaw in your logic here because I see the same argument made occasionally. Building full boost in every gear should not be your target. Going fast should be. Building revs faster than the turbo can build boost is a good thing. Peak boost is achieved at a higher RPM in 1st gear than in 5th, but you don't see people arguing that a taller 1st gear would result in faster times.

Everything is about compromises, and you may very well be right that the 5 speed ratios are better than the 6 speed ratios, but it would not be due to the engine having less mechanical advantage and is achieving higher boost levels. It would be simply that the time spent shifting could eliminate the gains achieved by the lower gear ratios.

Unless all your races end at 60mph (or you're really into auto-x), does it really matter if your 2-3 shift is at 55 or 65? If you're heading for 80, you have to shift twice either way.

[Xusia]

I really want to thank everyone that has contributed to this thread thus far. It's been incredibly helpful to me, and I've learned a lot!

Until FFR releases more details on the kit, I can't make any final decisions, but I'm thinking 1 of the following 2 options is likely:
1. Buy the basic kit and obtain an '07 WRX as a donor. If possible, outfit it with an STI turbo and tune.
2. Buy the complete kit and source an '07 STI engine and an '07 5-speed transmission (which if I understand correctly, should hold up OK).

I'm leaning toward #2 if it's not out of my budget because it uses more parts that would be new, and eliminates the need to remove said parts from the donor (making it "easier"). Still, according to folks on this thread, either way should be good for around 300 whp - less than I really wanted, but based on what I've learned, it's where I should be to meet my primary goals. If newer components wind up fitting OK, I would prefer them, but I don't want to have to fabricate or make any serious alterations to do it.

Again, a sincere and heartfelt thanks to all of you. You've been great. And this thank you is not a call to end the thread by any means! I'm sure I'll continue to learn more as the discussion continues.

[Street Rate Parts]

Or #3, buy a complete build kit.

I am working on getting one together and once the powers that be release the parts list and get back to me on sponsoring I can post up pricing etc...

I know I am buying a kit when they are released (if the body looks right)...hell the motor is already sitting on the stand in the engine room all done, waiting.....sigh

[DrieStone]

I really want to thank everyone that has contributed to this thread thus far. It's been incredibly helpful to me, and I've learned a lot!

Until FFR releases more details on the kit, I can't make any final decisions, but I'm thinking 1 of the following 2 options is likely:
1. Buy the basic kit and obtain an '07 WRX as a donor. If possible, outfit it with an STI turbo and tune.
2. Buy the complete kit and source an '07 STI engine and an '07 5-speed transmission (which if I understand correctly, should hold up OK).

I'm leaning toward #2 if it's not out of my budget because it uses more parts that would be new, and eliminates the need to remove said parts from the donor (making it "easier"). Still, according to folks on this thread, either way should be good for around 300 whp - less than I really wanted, but based on what I've learned, it's where I should be to meet my primary goals. If newer components wind up fitting OK, I would prefer them, but I don't want to have to fabricate or make any serious alterations to do it.

Again, a sincere and heartfelt thanks to all of you. You've been great. And this thank you is not a call to end the thread by any means! I'm sure I'll continue to learn more as the discussion continues.

Personally I'm going to do something like #1 drive it for a year to decide what I want from there. Then, especially because the donor is probably going to have 60-100k on the clock, do an engine rebuild/upgrade. Even a tired motor putting out less than the stock 227 is going to rock, and since the car is going to be used 99.9% on public roads 300HP is going to be plenty of insanity for me.

[Xusia]

I assume said kit would include the parts that the FFR "complete" kit doesn't? Meaning NO sourcing of ANY parts? Depending on price, that's an appealing option. I don't have a lot of time, so the less I spend looking for stuff, the more I can spend building it!

Or #3, buy a complete build kit.

I am working on getting one together and once the powers that be release the parts list and get back to me on sponsoring I can post up pricing etc...

I know I am buying a kit when they are released (if the body looks right)...hell the motor is already sitting on the stand in the engine room all done, waiting.....sigh

[imom]

To all the subbie folks here...do you know if the BRZ 2.0 engine will work? Is it the similar design as before but with direct injection from toyota... I'm curious to know of the BRZ as being completely brand new and unproven or it's from past family of 2.0 engines from Subaru. That said... curious to know if the BRZ would be smaller to take up less valuable engine space for the 818.

[PhyrraM]

To all the subbie folks here...do you know if the BRZ 2.0 engine will work? Is it the similar design as before but with direct injection from toyota... I'm curious to know of the BRZ as being completely brand new and unproven or it's from past family of 2.0 engines from Subaru. That said... curious to know if the BRZ would be smaller to take up less valuable engine space for the 818.

The big question for now is if they changed the bellhousing and/or motor mounts for the RWD only chassis. If they DID NOT, then the BRZ motor should bolt up just fine (electronics, as always, are another matter).

As soon as the FSMs are out for either the Subaru or Toyota, the answer will be all over Nasioc.

[Etos]

The big question for now is if they changed the bellhousing and/or motor mounts for the RWD only chassis. If they DID NOT, then the BRZ motor should bolt up just fine (electronics, as always, are another matter).

As soon as the FSMs are out for either the Subaru or Toyota, the answer will be all over Nasioc.

BRZ will be using a variant of the FB2xx series engines. The mounting points are different but I do not believe the bellhousing is. They first secretly released the FB engines on foresters using the same 4EAT from the EJ powered cars. I'm sure there would be an easy solution to get it to mount up.

Honestly I would stay far away from an FB engine. It's the first new engine subaru has made from the ground up in over 20 years. It's unproven in not just performance but reliability(which going back to the foresters, they had quite a few issues).

The FB is sorta a step back in terms of performance. It's a more economical engine in every shape. It even requires 0-20 weight oil. Maybe when they release a forced induction version and has seen a few years on the road I would consider it. That's at least 3-4 years away.

[PhilElement]

I'm hearing conflicting information regarding the engine and transmission mounting but hopefully it's compatible. Let's face it the FRS/BRZ is competition for the 818 if its priced under $25. We will be buying whichever comes out first and starting the motor R&D as soon as possible.

The motor however is not as performance oriented and will be tough to bring it to the performance level of the STIs engines. For the 818 the EJ motors will be the best choice as they are proven and mod well.

[BrandonDrums]

This is not an important point, but I just want to point out what I see as a flaw in your logic here because I see the same argument made occasionally. Building full boost in every gear should not be your target. Going fast should be. Building revs faster than the turbo can build boost is a good thing. Peak boost is achieved at a higher RPM in 1st gear than in 5th, but you don't see people arguing that a taller 1st gear would result in faster times.

Everything is about compromises, and you may very well be right that the 5 speed ratios are better than the 6 speed ratios, but it would not be due to the engine having less mechanical advantage and is achieving higher boost levels. It would be simply that the time spent shifting could eliminate the gains achieved by the lower gear ratios.

Unless all your races end at 60mph (or you're really into auto-x), does it really matter if your 2-3 shift is at 55 or 65? If you're heading for 80, you have to shift twice either way.

Actually, people do argue that a taller 1st gear will yield faster times. Many of the most popular aftermarket gearsets for the 5mt provides a taller 1st through 3rd gears(yet tighter spaced) for this very reason. Now, building full boost isn't the absolute goal but saying that building revs faster than the turbo is a good thing is misleading...I can do that in neutral quite well...

I got the below chart from this link. It shows popular aftermarket gearset ratios for subarus with the oem ratios up top. Lower numbers mean taller gears. Nearly all of the sets are taller than stock.
http://www.wrxtuners.com/forums/f69/...grading-13846/

What gear ratio choices are available?
3.636 (1st) 2.375 (2nd) 1.761 (3rd) 1.346 (4th) 0.971 (5th) 0.756 (6th) STi (USDM)
3.454 (1st) 1.947 (2nd) 1.366 (3rd) 0.972 (4th) 0.738 (5th) Stock WRX
3.454 (1st) 2.062 (2nd) 1.448 (3rd) 1.088 (4th) 0.780 (5th) Stock RS
3.166 (1st) 1.882 (2nd) 1.296 (3rd) 0.972 (4th) 0.738 (5th) STi (Non-RA)(5 speed)
3.083 (1st) 2.062 (2nd) 1.545 (3rd) 1.151 (4th) 0.825 (5th) STi RA(5 speed)
3.167 (1st) 2.267 (2nd) 1.667 (3rd) 1.250 (4th) 0.964 (5th) Kaaz
3.083 (1st) 2.154 (2nd) 1.500 (3rd) 1.059 (4th) 0.738 (5th) TurboXS
3.180 (1st) 1.940 (2nd) 1.350 (3rd) 0.966 (4th) 0.740 (5th) Chalak (now PAR)
3.180 (1st) 1.910 (2nd) 1.350 (3rd) 0.967 (4th) 0.825 or 0.738 (5th) PAR Street Perf.-Drag
2.916 (1st) 1.910 (2nd) 1.500 (3rd) 1.160 (4th) 0.920 or 0.880 (5th) PAR Rally-Track
3.000 (1st) 2.000 (2nd) 1.480 (3rd) 1.170 (4th) 0.963 (5th) Sport Gimmie Gears
3.450 (1st) 1.940 (2nd) 1.360 (3rd) 0.960 (4th) 0.760 (5th) Street Gimmie Gears
3.000 (1st) 2.000 (2nd) 1.480 (3rd) 1.170 (4th) 0.760 (5th) Sport/Street Gimmie Gears
3.454 (1st) 1.947 (2nd) 1.366 (3rd) 0.963 (4th) 0.738 (5th) APS
2.917 (1st) 2.090 (2nd) 1.556 (3rd) 1.176 (4th) 0.900 (5th) Group N Quaife
2.917 (1st) 2.090 (2nd) 1.556 (3rd) 1.250 (4th) 0.962 (5th) Clubman Quaife
3.454 (1st) 2.333 (2nd) 1.750 (3rd) 1.354 (4th) 0.972 (5th) Synchro Quaife
3.180 (1st) 1.860 (2nd) 1.320 (3rd) 0.950 (4th) 0.738 (5th) PPG SC dog&synchro
3.080 (1st) 2.060 (2nd) 1.500 (3rd) 1.050 (4th) 0.738 (5th) PPG HC dog
3.170 (1st) 1.860 (2nd) 1.320 (3rd) 0.950 (4th) 0.738 (5th) PPG HC syncro

[Evan78]

Actually, people do argue that a taller 1st gear will yield faster times. Many of the most popular aftermarket gearsets for the 5mt provides a taller 1st through 3rd gears(yet tighter spaced) for this very reason. Now, building full boost isn't the absolute goal but saying that building revs faster than the turbo is a good thing is misleading...I can do that in neutral quite well...

I didn't think it needed to be stated that I was referring to building RPM while the car is in gear.

If I were changing gear ratios, I would want a taller 1st also, but not because I care about 0-60 times. Just the opposite in fact. I would happily trade off any changes in 0-60 times for a taller 1st gear that I can use in tight corners more often.

[BrandonDrums]

I didn't think it needed to be stated that I was referring to building RPM while the car is in gear.

If I were changing gear ratios, I would want a taller 1st also, but not because I care about 0-60 times. Just the opposite in fact. I would happily trade off any changes in 0-60 times for a taller 1st gear that I can use in tight corners more often.

Well yes, I was just making an example really. I'm also not talking about just 0-60 times either, I think the fact that the majority of aftermarket performance gearsets for these vehicles suggest that taller gears as a whole work better for these cars.

It makes sense too, the WRX has a 2k towing rating, the STI has a 2500lb tow rating which is really quite a bit when you get down to it. They were built for street speeds and for being multipurpose sportscars. If you want your WRX/STI powered vehicle to be a real race car, having slightly taller 1st-3rd gears makes sense. I drive my 5mt every day and i literally pull as hard of acceleration G's in 3rd gear as I do in 2nd gear. If my car was geared more for outright performance, I should feel the maximum amount of acceleration in 1st, then 2nd, 3rd, 4th and 5th should be the slowest obviously. Instead, I'm pretty sure 3rd gear is my back into the seat gear, even more-so than 1st which is done in like .5 seconds.

I believe in a very tightly matched set of gears so you can keep the car in the powerband though, I still think people get that confused with the overall ratios.

[gwader]

Ducati powered!
http://www.spartan-v.com/spartan-v.com/Home.html

[Evan78]

I'm guessing that you perceive 3rd gear as being strongest because you stay in that gear longer than 1st and 2nd. Lets break down some approximate numbers for a WRX. 0-60 in 6 seconds, and a 14 second quarter mile time reaching 95mph. You spend 6 seconds in gears 1 and 2 and accelerate from rest to 60mph. It then takes 8 seconds to go from 60 to 95mph. Obviously, your rate of acceleration in 3rd gear is much less than gears 1 and 2. I'm neglecting drag here, which is significant, but not more significant than the mechanical advantage of the gear ratios.

Regarding aftermarket gearsets, I think 1st is taller for the reason I mentioned earlier - it makes it more usable for slow corners, rather than a gear you only use for starting from rest.

What do you see as the significance of the tow ratings? It seems you didn't finish that thought.

I wonder how much boost curves differ between gears if the X axis is time instead of RPM.

[fateo66]

It would be nice but making the 6spd front drive only is a true *******. There is a ton of items in that tranny that cannot be removed (easy and cheap that is) and keeping them in makes the front drive option an issue.

I am actually working on this issue right now, I have two 6spds on the bench and I have been on the lathe and mill making parts to try to get this to work properly. I have a billion rally prep hours on Scoobies so the motor is already built for my first car..hahah The tranny....this is going to be a hard one.

3rd, the STI transmission has a very complicated, very fancy and expensive center differential. It's a DCCD or Driver Controlled Center Differential. It's the bees knees for an AWD subie but in an 818 you'd have to weld it shut like a drift car or ditch it for a solid dummy piece in it's place which doesn't exist (while there are pre-made options available for the 5mt). That's like a $1k part that you have to destroy or remove.

They already exist and are around $400 from what I hear


http://www.possumbourne.co.nz/trans_diff_parts.html

[BipDBo]

Subaru hopes to get 270 out of there 2.0 for the near future WRX.
http://www.autoblog.com/2011/12/08/n...four-thats-up/

I'd like to know if they plan to do this by boosting the direct injected BRZ engine.

[Evan78]

From you link (emphasis mine):

WRX. Those three letters tell automotive enthusiasts the world over that they are not dealing with an ordinary Impreza, and it all began in rally racing with a 2.0-liter turbocharged flat-four engine. Though some models – including the current WRX and STI in the United States – had engines displacing as much as 2.5 liters, the WRX earned its reputation with 2.0 liters, and that's the displacement specified for competition use.

According to Motor Trend, the 2013 WRX, which will likely debut sometime in 2012, will go back to its original engine size. The new powerplant will reportedly be based on the engine found in the 2013 Subaru BRZ, a clean-sheet design for Subaru, with the addition of the expected turbocharger. That ought to bring power up from 200 horsepower to about 270.

Now we come to the question of what platform in which the engine will reside. While common sense would dictate that the latest version of the Impreza, which was recently released as a 2012 model, would get the WRX treatment, we've heard rumblings that Subaru would keep its current WRX shell around for a few more years while it continues development of the next chassis. Only time will tell.

[Steve91T]

Ducati powered!
http://www.spartan-v.com/spartan-v.com/Home.html

Not that this power plant would work with the 818, but I would buy this thing for the sound it must produce alone!

[Evan78]

Not that this power plant would work with the 818, but I would buy this thing for the sound it must produce alone!

110,000 Australian = 112,000 USD

Only weighs 350kg though! (170hp)

818 would need 400hp for the same power to weight ratio.

[Twinspool]

Not that this power plant would work with the 818, but I would buy this thing for the sound it must produce alone!

The sound of cursing while adjusting desmo valves?

I keed. :-)

[Xusia]

I keed. :-)

But only a little! LOL

[BrandonDrums]

They already exist and are around $400 from what I hear


http://www.possumbourne.co.nz/trans_diff_parts.html

Oh awesome! That's pretty cool! Would that require keeping the center diff housing in place though? If it does, the tranny will be sticking way out past the bumper on the 818...

[BrandonDrums]

Subaru hopes to get 270 out of there 2.0 for the near future WRX.
http://www.autoblog.com/2011/12/08/n...four-thats-up/

I'd like to know if they plan to do this by boosting the direct injected BRZ engine.

It sounds like the new WRX will use a turbo version of the BRZ engine but I imagine they'd have variable valve timing on the intake and exhaust vs. just the intake as on the BRZ.

The JDM STI's have always been 2.0L putting out 300+ hp so I think here pretty soon they'll be saying that they'll be using a better tuned version of that same engine on the STI as well keeping 2.0L across the line. I'm glad about this, at one point they were talking about 1.8L and smaller engines in the next gen WRX and STI.

Also, I read about the BRZ chassis that subaru developed it to be lengthened and accept the AWD system. I think the next WRX and STI which are being split from the Impreza line will be on the BRZ platform and will return to being 2 doors or even 3 door hatch like many of the WRC cars these days. It will be interesting to see.

To bad they aren't doing a mid-engine version, otherwise they'd have my business haha.

[Etos]

It sounds like the new WRX will use a turbo version of the BRZ engine but I imagine they'd have variable valve timing on the intake and exhaust vs. just the intake as on the BRZ.

The JDM STI's have always been 2.0L putting out 300+ hp so I think here pretty soon they'll be saying that they'll be using a better tuned version of that same engine on the STI as well keeping 2.0L across the line. I'm glad about this, at one point they were talking about 1.8L and smaller engines in the next gen WRX and STI.

Also, I read about the BRZ chassis that subaru developed it to be lengthened and accept the AWD system. I think the next WRX and STI which are being split from the Impreza line will be on the BRZ platform and will return to being 2 doors or even 3 door hatch like many of the WRC cars these days. It will be interesting to see.

To bad they aren't doing a mid-engine version, otherwise they'd have my business haha.

I doubt this highly. They already have a better impreza platform from the 08-11 coming out. They already stated there will be an STi version of the BRZ. The BRZ will most likely use the 1.6T for the turbo version.

People who get the WRX/STi don't just want a performance car, they want all the practicality too. SOA expressed that they don't want to further get into the coupe market. Coupes are the poorest selling cars by a HUGE margin. I believe there was also a video from the JP auto show where they said they are bringing back the WRX/STi as 2.0ts of the new impreza.

[Oppenheimer]

I doubt this highly. They already have a better impreza platform from the 08-11 coming out. ...SOA expressed that they don't want to further get into the coupe market. Coupes are the poorest selling cars by a HUGE margin. I believe there was also a video from the JP auto show where they said they are bringing back the WRX/STi as 2.0ts of the new impreza.

Perhaps not exclusively as a coupe (though I think for a better WRC entry they will offer that, at least in some markets), but I do believe the WRX/STi are going to split paths from the Impreza line. The extra cost & weight of the solid structure required for performance applications is a compromise to the economy aspirations of the base Impreza, and there are Impreza economy compromises that aren't ideal for the performance aspirations of the WRX/STi.

[Etos]

Perhaps not exclusively as a coupe (though I think for a better WRC entry they will offer that, at least in some markets), but I do believe the WRX/STi are going to split paths from the Impreza line. The extra cost & weight of the solid structure required for performance applications is a compromise to the economy aspirations of the base Impreza, and there are Impreza economy compromises that aren't ideal for the performance aspirations of the WRX/STi.

Except SOA already announced the WRX/STi for the impreza. The new impreza is also a huge step up from the old one. It's a whole 150 pounds lighter and more room. There's no reason for them not to use the new impreza for their WRX/STi line which it has for almost 2 decades now.

[PhilElement]

Well yes, I was just making an example really. I'm also not talking about just 0-60 times either, I think the fact that the majority of aftermarket performance gearsets for these vehicles suggest that taller gears as a whole work better for these cars.

It makes sense too, the WRX has a 2k towing rating, the STI has a 2500lb tow rating which is really quite a bit when you get down to it. They were built for street speeds and for being multipurpose sportscars. If you want your WRX/STI powered vehicle to be a real race car, having slightly taller 1st-3rd gears makes sense. I drive my 5mt every day and i literally pull as hard of acceleration G's in 3rd gear as I do in 2nd gear. If my car was geared more for outright performance, I should feel the maximum amount of acceleration in 1st, then 2nd, 3rd, 4th and 5th should be the slowest obviously. Instead, I'm pretty sure 3rd gear is my back into the seat gear, even more-so than 1st which is done in like .5 seconds.

I believe in a very tightly matched set of gears so you can keep the car in the powerband though, I still think people get that confused with the overall ratios.

That's not really the case overall. The reason the stronger 5 speed gears change has to do with available gearing for the larger and stronger teeth along with the fact that most get the stronger box for drag racing. The drag racing ratios are the most popular in the US because that's what the average enthusiast does but they also offer shorter gears for rally.

The 6 speed was originally designed for the JDM 2.0 which pulled to 8k RPM from the factory and when you run that kind of RPM the 04-06 6 speeds are phenomenal on the track. I can pull just about 70 mph out of 2nd gear on my race car. Fast forward if you like to 1:14 and in 2nd gear exiting "oak tree." My car does run larger wheels/tire and I have up to 8500 RPM if I need it.



My point is that everyone needs something different. Without some extra RPM the 04-06 6 speed requires more shifting but the car will accelerate faster than the 5 speed. The newer 07+ 6 speeds have similar gear ratios to the 5 speed boxes and many prefer them for drag racing and or street. For smaller sized turbochargers the 5 speed gearing is fine but for larger turbochargers that shift the power to the right the 6 speeds with the shorter gear ratios are really sweet.

Thanks,
Philip Grabow

[crobin4]

That's not really the case overall. The reason the stronger 5 speed gears change has to do with available gearing for the larger and stronger teeth along with the fact that most get the stronger box for drag racing. The drag racing ratios are the most popular in the US because that's what the average enthusiast does but they also offer shorter gears for rally.

The 6 speed was originally designed for the JDM 2.0 which pulled to 8k RPM from the factory and when you run that kind of RPM the 04-06 6 speeds are phenomenal on the track. I can pull just about 70 mph out of 2nd gear on my race car. Fast forward if you like to 1:14 and in 2nd gear exiting "oak tree." My car does run larger wheels/tire and I have up to 8500 RPM if I need it.



My point is that everyone needs something different. Without some extra RPM the 04-06 6 speed requires more shifting but the car will accelerate faster than the 5 speed. The newer 07+ 6 speeds have similar gear ratios to the 5 speed boxes and many prefer them for drag racing and or street. For smaller sized turbochargers the 5 speed gearing is fine but for larger turbochargers that shift the power to the right the 6 speeds with the shorter gear ratios are really sweet.

Thanks,
Philip Grabow

Thanks Phil!

[Xusia]

Dude, that is one rockin' video. I love the combined views with the accelerometer, track position, etc.

[BrandonDrums]

That's not really the case overall. The reason the stronger 5 speed gears change has to do with available gearing for the larger and stronger teeth along with the fact that most get the stronger box for drag racing. The drag racing ratios are the most popular in the US because that's what the average enthusiast does but they also offer shorter gears for rally.

The 6 speed was originally designed for the JDM 2.0 which pulled to 8k RPM from the factory and when you run that kind of RPM the 04-06 6 speeds are phenomenal on the track. I can pull just about 70 mph out of 2nd gear on my race car. Fast forward if you like to 1:14 and in 2nd gear exiting "oak tree." My car does run larger wheels/tire and I have up to 8500 RPM if I need it.



My point is that everyone needs something different. Without some extra RPM the 04-06 6 speed requires more shifting but the car will accelerate faster than the 5 speed. The newer 07+ 6 speeds have similar gear ratios to the 5 speed boxes and many prefer them for drag racing and or street. For smaller sized turbochargers the 5 speed gearing is fine but for larger turbochargers that shift the power to the right the 6 speeds with the shorter gear ratios are really sweet.

Thanks,
Philip Grabow

Sure, for a JDM STI with less torque and 2k more revs to play with, shorter ratios make sense. I still say shaving 1500lbs from the vehicle would have you wanting taller gearing overall, you can hit redline at higher speeds at the same rate with 15k lbs less to haul around. You also have larger wheels which make your gearing taller and you have 2k more revs to play with over a stock 2.5L wrx or sti and still 1500 more than a 2.0 usdm wrx making some of the shortcomings I'm referencing about shorter gears on these cars a moot point.

Also, in terms of the USDM STI, I wouldn't say the 6 speed accelerates faster than the 5 speed, not even the 07+ (they changed 4th-6th to be taller but 1st-3rd remain pretty close I believe).

The current 2011 STI with 305 HP is rated 0-60 by most formal tests to be around 5-5.2 seconds and rated on the 1/4 mile by similar tests to be in the 13.35-13.5 second range. The most recent WRX at 265 hp which has the 5 speed usually achieves 60 quicker at 4.7-4.8 (Motor trend once saw 4.6 on a WRX hatch) seconds and the 1/4 mile at around 13.5-13.8 seconds.

I know these are all straight line acceleration times but having the WRX beat the STI to 60 by 2 to 4 tenths of a second with 35 LESS horsepower is a significant difference. Further the 1/4 time differences are NOT significant given the power difference...the STI's advantage in trap speed is almost erased by the quicker acceleration off the line seen on the less powerful wrx.

Saying everyone needs something different is accurate, I just am trying to illustrate that with all the mighty 6 speed's amazing capabilities, I just don't think the 6mt will ever be a good choice for the 818 unless you decide to swap gears. I'm all for MORE gears but the STI's transmission with all it's weight and girth and fancy AWD features is simply a waste in something like the 818.

I don't want anyone to think I'm just a fanboy of the 5MT because I'm not, I actually want to perform a 6 speed swap in my WRX someday for the DCCD and it's ability to handle way more HP than my 5mt. I do wish it had taller gears even for the WRX, but for the 818 powered by USDM engines, the 6mt simply makes absolutely no sense given most of the advantages the 6mt provide are in it's AWD technology.

If you had an N/A 818 with a 8500 Redline i'd be singing a different song.

[PhilElement]

Sure, for a JDM STI with less torque and 2k more revs to play with, shorter ratios make sense. I still say shaving 1500lbs from the vehicle would have you wanting taller gearing overall, you can hit redline at higher speeds at the same rate with 15k lbs less to haul around. You also have larger wheels which make your gearing taller and you have 2k more revs to play with over a stock 2.5L wrx or sti and still 1500 more than a 2.0 usdm wrx making some of the shortcomings I'm referencing about shorter gears on these cars a moot point.

Taller gearing is only better if you have a shorter powerband and weight has no bearing on this. Your workable power range dictates your best gearing. Weight helps with acceleration..agreed. Both the WRX and the STi can easily be tuned to handle 7500 RPM which is usually when I shift on the race car so I know it's a sizable range with a substantial turbocharger. Stock turbochargers will fade after 6500 RPM so sure I can see the 5 speed being more attractive with that setup.

The current 2011 STI with 305 HP is rated 0-60 by most formal tests to be around 5-5.2 seconds and rated on the 1/4 mile by similar tests to be in the 13.35-13.5 second range. The most recent WRX at 265 hp which has the 5 speed usually achieves 60 quicker at 4.7-4.8 (Motor trend once saw 4.6 on a WRX hatch) seconds and the 1/4 mile at around 13.5-13.8 seconds.

I know these are all straight line acceleration times but having the WRX beat the STI to 60 by 2 to 4 tenths of a second with 35 LESS horsepower is a significant difference. Further the 1/4 time differences are NOT significant given the power difference...the STI's advantage in trap speed is almost erased by the quicker acceleration off the line seen on the less powerful wrx.

The 09+ WRXs are underrated from the factory plus new STis are pigs! So much fluff now to justify the $38K price tag. A new WRX is a performance bargain for sure!

Saying everyone needs something different is accurate, I just am trying to illustrate that with all the mighty 6 speed's amazing capabilities, I just don't think the 6mt will ever be a good choice for the 818 unless you decide to swap gears. I'm all for MORE gears but the STI's transmission with all it's weight and girth and fancy AWD features is simply a waste in something like the 818.

I don't want anyone to think I'm just a fanboy of the 5MT because I'm not, I actually want to perform a 6 speed swap in my WRX someday for the DCCD and it's ability to handle way more HP than my 5mt. I do wish it had taller gears even for the WRX, but for the 818 powered by USDM engines, the 6mt simply makes absolutely no sense given most of the advantages the 6mt provide are in it's AWD technology.

If you had an N/A 818 with a 8500 Redline i'd be singing a different song.

I think for many people buying the "street" version of the 818 a 5 speed will do fine and for the guys that want more power the newer 5 speed will be even better.

To say the 6 speed is a waste in the 818 just isn't true. There will be plenty of people including myself who will want the "Track" version of the 818 to be their personal DP car. There are plenty of race cars that have the power to weight ratio many will see as overkill (500 HP 818 with a race weight of 2200 lbs) but are exactly what I want and some others have expressed. I already race a car with this power to weight ratio but I want more.

[bromikl]

Can I just build mine the way I want it?

[Draco-REX]

Can I just build mine the way I want it?

I think the moral of this thread, and it's derailment, is that, due to the 818's light weight and small size, bigger might not always be better and choosing parts should be done with an eye towards the big picture.

For my 818 build, I'm going with a 5MT for its lighter weight. There are close-ratio gearsets available, and I can leave the 5th gear alone for highway use. So I have no need for a heavy 6MT.

[PhilElement]

Can I just build mine the way I want it?

Isn't that the whole point of a kit car? Some want a light weight, low power setup and others want the light weight, high power setup. Some want a street car and some want a race car. I just want the chassis to be able to fit the 6 speed (physically) so that I have the option to build what I want.

[Etos]

Phil, you should know as well as anyone else no race car resembles the car it came from outside of a dedicated nascar frame. Just accept that it won't look pretty with a 6 speed just as many race cars don't always look pretty. 6MT is overkill for anything but what you want to do with it. I just don't see the justification to change up the chasis to make the 6MT look pretty.

Even so shouldn't you consider a 5 speed case with swapped gears just for the weight? Having that heavy 6 speed really far back isn't going to help weight distribution. I know you have a PTWR you want but PTWR isn't everything. Will a 2000 pound car with 400HP going to react anywhere near the same as a 4000 pound car with 800hp? That lower weight alone is going to make a huge difference in the corners you can't make up any other way no matter how much power you throw at it.