2004 WRX, £7k to spend on tuning...but what?
Discussion
the gman said:
vixpy1 said:
If you can get afford an Sti, then get one, the internals are so much stronger on them and can take much much more power
What will the standards take?
I have been quoted loads of different figures, from 350-400bhp?
All the tuners i have spoken to reckon upto 400bhp...witht eh right exhaust etc...any more than that and it's fair to say the motor will go pop, not to mention the gearbox as well. After that it's probably got to be forged pistons etc....
The 6 speed STi gearbox is much better than the WRX 5 speed and should stand all the power the engine will safely make. The 5 speeds are marginal at 330 to 350 in my experience, but will last a while.
I've half-killed & rebuilt the 5 speed (DCCD) box in my classic shape 55k mile STi RA once already. The car is only running 330 bhp.
I've half-killed & rebuilt the 5 speed (DCCD) box in my classic shape 55k mile STi RA once already. The car is only running 330 bhp.
dnb said:
The 6 speed STi gearbox is much better than the WRX 5 speed and should stand all the power the engine will safely make. The 5 speeds are marginal at 330 to 350 in my experience, but will last a while.
I've half-killed & rebuilt the 5 speed (DCCD) box in my classic shape 55k mile STi RA once already. The car is only running 330 bhp.
I've half-killed & rebuilt the 5 speed (DCCD) box in my classic shape 55k mile STi RA once already. The car is only running 330 bhp.
I agree...the STi box is much stronger.....But have you seen the size of it compared to a 5speed...it's twice as big and weighs twice as much which is why there isn't such a big performance difference between the standard STi and a WRX, that is until you start tinkering with the STi and then the gap gets bigger and bigger
I don't know how strong the group N boxes are but you do get the choice of Synchro or straight cut gears. The stright cut are prefereable because they are much stronger than Synchro and unlike synchro you lose very little bhp and torque through the drivetrain that way. But they are noisy though and have to be sequentially operated...no skipping gears on downchange. I don't know torque figures though...i'm sure the info must be somewhere. 
hewlett said:
Vixpy 1, you're rolling road is a mere 5.2 miles from where I live, perhaps I could have a look at your Subaru at some stage (I'm guessing this is a car of yours rather than a customer car?). Btw I used to work at QinetiQ and know your site well, small world..
Of coarse you could have a look at my scooby, however.. its in Newbury.. in bits
scoobiewrx said:
I don't know how strong the group N boxes are but you do get the choice of Synchro or straight cut gears. The stright cut are prefereable because they are much stronger than Synchro and unlike synchro you lose very little bhp and torque through the drivetrain that way. But they are noisy though and have to be sequentially operated...no skipping gears on downchange. I don't know torque figures though...i'm sure the info must be somewhere.
The current GroupN gearbox is a 6 speed casing with a special 5 speed gearset inside, made by hewland. A dog box and a syncro box share the same transmition losses, what affects transmition losses is whether the gears are straight cut or helical cut. You dont want a dog box in a road car. The Group N box is a normal H pattern, it's not sequential.
You can get non homologated gearsets from the likes of PPG, for either the 5 speed or 6 speed casings. The 5 speed casing is actually very strong with an uprated gearset, i know of some running over 700BHP through them. The problem with the stock 5 speed is the gears throw their teeth off when pushed to high power levels, that level depends on how sympathetic a driver you are and what aplication the car it put to.
It seems to me that with money being (relatively) of minor concern when it comes to modification in the next 18 months or so. Then the Q car benefits and slightly stiffer bodyshell of the wagen outweigh the benefits of buying an STI. Several websites offer new WRXs imported, at considerably less than UK dealer prices - in fact, less than a 6 month old 6000 miles UK version. Seems to me that that will be the way to go. From what I have read on this forum in particular, people are very happy with these cars and keep them for years. With this likely to be the case with me I'd rather spend the money in the future in improving a car I'm happy with, like a relatively subtle looking sportswagen. I wonder if at higher speeds (occasional trip to Germany), that the estate body shell is less 'tied down' at tha back than the saloon which benefits from a 'wing'?
I might be wrong but i think the sportwagon spoiler is a bit smaller than the 4dr version. However....the Sportwagon spoiler is in the right place to create downforce, and thats at the roofline where it gets to see some clear and unobstructed air so even though smaller it may be a bit more effective than the 4dr version, which is placed much lower down, way past the roofline, and probably seeing very little clear and unobstructed airflow. Therefore with that thinking the downforce should be greater on the sportwagon.
I have seen 150mph on my speedo which is probably 145 true mph and i think that is about the WRX's limit standard, and the standard STi is suppose to be 158mph top end but that's with 265bhp. I am having some mods on my car soon to include ECU mapping and that should generate about 270bhp - 300bhp, and therefore i assume that my top end will increase too as it isn't speed limited. With a bit of luck i genuinely hope it will be off the clock and the clock goes upto 160mph so if i get 155 - 160 true mph i will be extremely happy. And don't forget...trying to push a brick through the air at that speed takes some bhp as scoobys aren't the most aerodynamic cars around. In fact i don't know if there is anything you can do to the sportwagon to make it more slippery through the air.
Johnfelstead and Vixpy1 really know what they are talking about...perhaps one of them can comment.
I have seen 150mph on my speedo which is probably 145 true mph and i think that is about the WRX's limit standard, and the standard STi is suppose to be 158mph top end but that's with 265bhp. I am having some mods on my car soon to include ECU mapping and that should generate about 270bhp - 300bhp, and therefore i assume that my top end will increase too as it isn't speed limited. With a bit of luck i genuinely hope it will be off the clock and the clock goes upto 160mph so if i get 155 - 160 true mph i will be extremely happy. And don't forget...trying to push a brick through the air at that speed takes some bhp as scoobys aren't the most aerodynamic cars around. In fact i don't know if there is anything you can do to the sportwagon to make it more slippery through the air.
Johnfelstead and Vixpy1 really know what they are talking about...perhaps one of them can comment.
johnfelstead said:
scoobiewrx said:
I don't know how strong the group N boxes are but you do get the choice of Synchro or straight cut gears. The stright cut are prefereable because they are much stronger than Synchro and unlike synchro you lose very little bhp and torque through the drivetrain that way. But they are noisy though and have to be sequentially operated...no skipping gears on downchange. I don't know torque figures though...i'm sure the info must be somewhere.
The current GroupN gearbox is a 6 speed casing with a special 5 speed gearset inside, made by hewland. A dog box and a syncro box share the same transmition losses, what affects transmition losses is whether the gears are straight cut or helical cut. You dont want a dog box in a road car. The Group N box is a normal H pattern, it's not sequential.
You can get non homologated gearsets from the likes of PPG, for either the 5 speed or 6 speed casings. The 5 speed casing is actually very strong with an uprated gearset, i know of some running over 700BHP through them. The problem with the stock 5 speed is the gears throw their teeth off when pushed to high power levels, that level depends on how sympathetic a driver you are and what aplication the car it put to.
I have driven cars with straight cut gears and it's very difficult to try and skip a gear up or down. I have driven a single seater like that and you had to go through the gearbox sequentially up or down. Try skipping gears and it just crunches and doesn't engage. So if you missed a gear you had to engage the right gear for the roadspeed having then naturally slowed right down trying to get it back in gear via the 'double-clutch' method.
You are mixing up dog engaged gears with straight cut gears.
Straight cut just refers to the gear tooth pattern that is cut for the mesh between mainshaft gear and the layshaft gear. You can either have a straight cut gear, or you can have a helical cut gear. Helical gears are what you find in road car gearboxes because they are quiet, straight cut gears you find in competition gearboxes because they lose less power because all the transfer of torque is in rotational force, rather than rotational and sidewards force.
You then have two methods of gear engagement, you can either use syncromesh or dog engagement. A syncromesh is basically a cone shaped clutch which matches the hub and gear speed as it engages the next gear, so you dont have to rev match. A dog engaged gear has a set of machined steps on the side of the gear, called dogs, you then have a dog ring which also has the same machined steps on its sides. To engage the gear you slide the dog ring into the dogs on the gear, this engages the gear to the hub which then drives the shaft the dogring/hub assembly is mounted to. It helps to rev match a dogbox because you have nothing to match the speed of the two components, and if you are shit at it you can round off the square edges of the dogs by clattering them against each other, which leaves you with no drive edge, causing it to jump out of gear.
You do not have to row down the box because it has dog engagement, you only have to do that if the selector mechanism is sequential. It's often a lot faster to skip gears on the downshift when braking into a slow corner from high speed, especially on something with a big gearbox where the gear momentum is high. Rowing down the box became obsolete in racing for a while, it only returned when sequential boxes started to be used.
The main reason dog engagement is used on racing cars is down to it's strength, the syncro hubs are a weak link in a syncro box, a dog ring can take enormous load for the same size. The other main reason is speed of shifting, with a dog engaged gear you can shift in miliseconds.
P.S I build and race engineer McLaren and March racecars for a living and have driven Subaru's with 700BHP and dog boxes on track, as well as the usual fare. Hopefully the above info helps you understand the diferences a bit better.
Straight cut just refers to the gear tooth pattern that is cut for the mesh between mainshaft gear and the layshaft gear. You can either have a straight cut gear, or you can have a helical cut gear. Helical gears are what you find in road car gearboxes because they are quiet, straight cut gears you find in competition gearboxes because they lose less power because all the transfer of torque is in rotational force, rather than rotational and sidewards force.
You then have two methods of gear engagement, you can either use syncromesh or dog engagement. A syncromesh is basically a cone shaped clutch which matches the hub and gear speed as it engages the next gear, so you dont have to rev match. A dog engaged gear has a set of machined steps on the side of the gear, called dogs, you then have a dog ring which also has the same machined steps on its sides. To engage the gear you slide the dog ring into the dogs on the gear, this engages the gear to the hub which then drives the shaft the dogring/hub assembly is mounted to. It helps to rev match a dogbox because you have nothing to match the speed of the two components, and if you are shit at it you can round off the square edges of the dogs by clattering them against each other, which leaves you with no drive edge, causing it to jump out of gear.
You do not have to row down the box because it has dog engagement, you only have to do that if the selector mechanism is sequential. It's often a lot faster to skip gears on the downshift when braking into a slow corner from high speed, especially on something with a big gearbox where the gear momentum is high. Rowing down the box became obsolete in racing for a while, it only returned when sequential boxes started to be used.
The main reason dog engagement is used on racing cars is down to it's strength, the syncro hubs are a weak link in a syncro box, a dog ring can take enormous load for the same size. The other main reason is speed of shifting, with a dog engaged gear you can shift in miliseconds.
P.S I build and race engineer McLaren and March racecars for a living and have driven Subaru's with 700BHP and dog boxes on track, as well as the usual fare. Hopefully the above info helps you understand the diferences a bit better.
scoobiewrx said:
I might be wrong but i think the sportwagon spoiler is a bit smaller than the 4dr version. However....the Sportwagon spoiler is in the right place to create downforce, and thats at the roofline where it gets to see some clear and unobstructed air so even though smaller it may be a bit more effective than the 4dr version, which is placed much lower down, way past the roofline, and probably seeing very little clear and unobstructed airflow. Therefore with that thinking the downforce should be greater on the sportwagon.
I have seen 150mph on my speedo which is probably 145 true mph and i think that is about the WRX's limit standard, and the standard STi is suppose to be 158mph top end but that's with 265bhp. I am having some mods on my car soon to include ECU mapping and that should generate about 270bhp - 300bhp, and therefore i assume that my top end will increase too as it isn't speed limited. With a bit of luck i genuinely hope it will be off the clock and the clock goes upto 160mph so if i get 155 - 160 true mph i will be extremely happy. And don't forget...trying to push a brick through the air at that speed takes some bhp as scoobys aren't the most aerodynamic cars around. In fact i don't know if there is anything you can do to the sportwagon to make it more slippery through the air.
Johnfelstead and Vixpy1 really know what they are talking about...perhaps one of them can comment.
I have seen 150mph on my speedo which is probably 145 true mph and i think that is about the WRX's limit standard, and the standard STi is suppose to be 158mph top end but that's with 265bhp. I am having some mods on my car soon to include ECU mapping and that should generate about 270bhp - 300bhp, and therefore i assume that my top end will increase too as it isn't speed limited. With a bit of luck i genuinely hope it will be off the clock and the clock goes upto 160mph so if i get 155 - 160 true mph i will be extremely happy. And don't forget...trying to push a brick through the air at that speed takes some bhp as scoobys aren't the most aerodynamic cars around. In fact i don't know if there is anything you can do to the sportwagon to make it more slippery through the air.
Johnfelstead and Vixpy1 really know what they are talking about...perhaps one of them can comment.
I wouldnt like to comment on what they do relative to each other, aerodynamics dont always work as you would expect from looks. I do know the rear spoiler on my STi5 RA works at high speed, it's designed to be lift/downforce neutral, so the car doesnt lift or squat at speed. Without the spoiler there is some lift which makes the car less stable.
I have driven a rallycar 5 door at about 120MPH and it didnt feel any different to a saloon to me. The wagon has a slighter better weight distribution than the saloon, but it is narrower on track in the newage shape. I doubt you will notice any diference in torsional rigidity between the two, the new age saloon is stiffer than the wagon, but the wagon is stiffer than some of the classic saloons depending on model, the STi saloons have stiffer rear bulkheads and a tiebar that goes accross the back of the seat, hence no tilting forward rear seats on the STi.
Fastest a Subaru has gone so far is 210.4MPH, that was with the STi5 TypeR of Andy Forrest. It looked pretty stable considering, the thing that would worry me is the bonnet catch failing as it was trying to lift the bonnet up.
John...A thousand thanks for that...it's really nice to find out these things from someone that actually knows what they are talking about from a techy perspective.
Ta for the education...and you really seem to know your Scoobys.....would you like an apprentice
P.S. I've just been on the Andy Forrest website....that Scooby is truly amazing and just a bit quick eh!!!
Ta for the education...and you really seem to know your Scoobys.....would you like an apprentice
P.S. I've just been on the Andy Forrest website....that Scooby is truly amazing and just a bit quick eh!!!
Edited by scoobiewrx on Saturday 31st March 22:18
Gassing Station | Japanese Chat | Top of Page | What's New | My Stuff