RE: Goodbye STI - Subaru calls time on the WRX
Discussion
TartanPaint said:
Power numbers are less than half the story. I watched a guy get his car mapped by Andy Forrest and left with 30bhp less than he arrived with on the same rollers. He was a very happy customer. More usable torque = faster car.
At least that's the excuse I keep making for only having 350bhp in a forged CDB 2.5.
Choose the style of car you want, and get good turbo choice advice. Don't aim for numbers, because they don't tell you how the car will drive.
So true - I remember driving a very early Evo FQ400. Horrid to drive on the road, comic lag and all fury as soon as the blower span up.At least that's the excuse I keep making for only having 350bhp in a forged CDB 2.5.
Choose the style of car you want, and get good turbo choice advice. Don't aim for numbers, because they don't tell you how the car will drive.
about 450BHP/lbft is the sweet spot for reliable and very fast road use.
I worked with Owen developments to develop a JDM twin scroll turbo that would not lose the spool of the OEM item, but would give a decent improvement of mid range torque and top end power. We tried 4 different designs before finding the right spec, you can now buy these turbos via Chevron Motorsport and they can be speced specifically for your needs, lots now used on rally cars, sprint cars and fast road cars.
The JDM 2.0 engine is a much nicer engine base than the 2.5 for tuning, but you can still get decent performance out of the 2.5 if you install some forged pistons.
If you have a nice condition stock 2.0 newage JDM STi engine you should be able to have 450BHP reliably if well tuned. The Hatchback onwards 2.0 block is a thicker wall casting and is a great basis for bigger power. You dont need a CDB for reliable power in the sub 500BHP range, the newage semi closed deck block is a good unit. Once you go over 500BHP you are into the realms of proper engine builds if you want reliable power.
Turbo choice makes a huge difference, chasing top end power is pointless if you are after a tractable quick road car. If you want to have a cheap route to a fast car just stick with a 2.0 JDM STi with the stock twin scroll and have it mapped properly, that's quite a quick car, once you get onto my spec of car it's a different game altogether and you would need a very quick car to match it on a normal road. It's just very easy to drive quickly because the torque spread is so big.
It's a shame these cars are being dropped from the UK market, but you can still import them in JDM spec if you really want one going forward, we may find in a couple of years they will be 10% cheaper due to the dropping of import duties on Japanese cars, which would be nice.
I worked with Owen developments to develop a JDM twin scroll turbo that would not lose the spool of the OEM item, but would give a decent improvement of mid range torque and top end power. We tried 4 different designs before finding the right spec, you can now buy these turbos via Chevron Motorsport and they can be speced specifically for your needs, lots now used on rally cars, sprint cars and fast road cars.
The JDM 2.0 engine is a much nicer engine base than the 2.5 for tuning, but you can still get decent performance out of the 2.5 if you install some forged pistons.
If you have a nice condition stock 2.0 newage JDM STi engine you should be able to have 450BHP reliably if well tuned. The Hatchback onwards 2.0 block is a thicker wall casting and is a great basis for bigger power. You dont need a CDB for reliable power in the sub 500BHP range, the newage semi closed deck block is a good unit. Once you go over 500BHP you are into the realms of proper engine builds if you want reliable power.
Turbo choice makes a huge difference, chasing top end power is pointless if you are after a tractable quick road car. If you want to have a cheap route to a fast car just stick with a 2.0 JDM STi with the stock twin scroll and have it mapped properly, that's quite a quick car, once you get onto my spec of car it's a different game altogether and you would need a very quick car to match it on a normal road. It's just very easy to drive quickly because the torque spread is so big.
It's a shame these cars are being dropped from the UK market, but you can still import them in JDM spec if you really want one going forward, we may find in a couple of years they will be 10% cheaper due to the dropping of import duties on Japanese cars, which would be nice.
My JDM is standard apart from a Millteck(?) cat back system. It's covered 35000 miles.
The secondary airpump has packed up, and it seems just as cheap to have it removed and remapped
I don't intend making any other mods, I just want a good tractable engine.
At the moment, it'll be Bob Rawle who will tune it?
The secondary airpump has packed up, and it seems just as cheap to have it removed and remapped
I don't intend making any other mods, I just want a good tractable engine.
At the moment, it'll be Bob Rawle who will tune it?
Legacywr said:
I’m soon to get my 2010 JDM 2.0 saloon remapped, I’m hoping for about 350bhp, and better economy?
You get good results with a free flowing exhaust (decat or sports cat) and air filter, not sure on this model if you need a fuel pump upgrade, but you should see around 360BHP, 380lbf with a decent mapper. Getting rid of the stock cats will help fuel economy, but you must remap at the same time or you get boost spikes.Legacywr said:
My JDM is standard apart from a Millteck(?) cat back system. It's covered 35000 miles.
The secondary airpump has packed up, and it seems just as cheap to have it removed and remapped
I don't intend making any other mods, I just want a good tractable engine.
At the moment, it'll be Bob Rawle who will tune it?
Bob is a great guy, speak with him about what you need to do re fuel pump. Getting rid of the Cat improves them a fair bit, they hold the engine back, it will spool faster without.The secondary airpump has packed up, and it seems just as cheap to have it removed and remapped
I don't intend making any other mods, I just want a good tractable engine.
At the moment, it'll be Bob Rawle who will tune it?
I have a full 3" Milltek system, nice and quiet and flows plenty for 500BHP. Without the cat the twin scrolls sound like a motorbike flat out, its a very different sound to the none JDM unequal length headers. (JDM exhaust system is different to UK spec with the exhaust headers all tuned length the same, so you don't get the offbeat scooby rumble)
jsf said:
I rebuilt the engine as a fully forged high compression 2.1 and it uses a motorsport spec stock position Owen Developments Twin Scroll Turbo, so even though its got lots of power it spools as fast as a stock car, the torque delivery is pretty impressive. Engine is controlled by a Syvecs S6 ECU which i have 12 maps available on the fly that cater for normal SUL or a 20% methanol mix.
The Chevron TMIC, Owen TS turbo and Syvecs combo on a 2.1 or 2.35 is pretty much as good as it gets. Not cheap by Subaru standards, but not expensive when you consider how much usable performance you are buying. (If you ever consider selling please let me know
).jsf said:
Turbo choice makes a huge difference, chasing top end power is pointless if you are after a tractable quick road car.
Gospel. I currently own a JDM hawk with front mount and LM450 that has been dyno-ed at 440/440. My previous JDM Blob with stock TMIC and VF37 (decat and remap only) is quicker in most road situations. That isn't just the bum dyno talking - my old car now belongs to a pal and we've driven each others' cars back to back together on the same roads. Given a long enough straight naturally my car will pull a gap, but his just destroys me out of corners.
The standard setup is extremely good once mapped - the low-down spool makes all the difference in the real world (and the LM450 is considered a very fast-spooling turbo for its size).
plenty said:
Gospel. I currently own a JDM hawk with front mount and LM450 that has been dyno-ed at 440/440. My previous JDM
Blob with stock TMIC and VF37 (decat and remap only) is quicker in most road situations. That isn't just the bum dyno talking - my old car now belongs to a pal and we've driven each others' cars back to back together on the same roads. Given a long enough straight naturally my car will pull a gap, but his just destroys me out of corners.
The standard setup is extremely good once mapped - the low-down spool makes all the difference in the real world (and the LM450 is considered a very fast-spooling turbo for its size).
When i was looking to improve my setup i did some side by side on the road runs with my stock VF37 and an LM420 equipped Type 20, i also drove an LM450 equipped car. The LM turbos are not twin scroll, they are twin entry single scroll units. The 500BHP version worked well for those sort of power ranges, but the smaller ones are more compromised compared to what you ideally want from a twin scroll. At the time they were the best option for a twin scroll JDM setup if you wanted more power but things have moved on. The Japanese offerings at the time were really crap, so Iain did a great job compared to them.Blob with stock TMIC and VF37 (decat and remap only) is quicker in most road situations. That isn't just the bum dyno talking - my old car now belongs to a pal and we've driven each others' cars back to back together on the same roads. Given a long enough straight naturally my car will pull a gap, but his just destroys me out of corners.
The standard setup is extremely good once mapped - the low-down spool makes all the difference in the real world (and the LM450 is considered a very fast-spooling turbo for its size).
This is why i started to work with Chevron/Owen to come up with something that was as good as a stock twin scroll on spool but produced much higher overall performance, that's not easy to achieve because the twin scroll exhaust housing is restrictive for high power. This work plus other work on the various power targets has produced a really nice range of twin scroll, twin entry and single scroll stock position turbos for the Subaru engine now, lots of the quick stuff is using them.
My VF37 on this engine produced a peak 1.7BAR at 3250rpm, which gave 390lbft and 350BHP, boost is tappered down to 1BAR at 6500rpm
My Owen turbo produced 1.7BAR at 3300rpm, 2.0BAR at 3500rpm, which gave 540lbft and 475BHP, boost is tapperd to 1.7BAR at 6500rpm
Both on the same stock ECU at the time.
The nice thing is you can tailor the turbo to your targets, anything from a restricted inlet rally turbo to a full on race spec unit is available. My current version is running 2mm larger compressor wheel than the one above to give a bit more top end power for sprints but i only run that at 1.8BAR peak to keep the transmition in one piece!. That's stock, 4th gear doesn't like much more than 500lbft.
Bookmarked. The LM450 certainly drives much more like a single scroll than a twin scroll. I've been waiting for Central Turbos to build me a hybrid VF36 with a larger billet compressor wheel but I might bite the bullet and spend the cash on an Owen item. Don't need big power, just a little more than OEM would be nice as long as it retains the OEM spool characteristics.
plenty said:
Bookmarked. The LM450 certainly drives much more like a single scroll than a twin scroll. I've been waiting for Central Turbos to build me a hybrid VF36 with a larger billet compressor wheel but I might bite the bullet and spend the cash on an Owen item. Don't need big power, just a little more than OEM would be nice as long as it retains the OEM spool characteristics.
Using a bigger front end on a standard back end doesn't work at all well on the VF36/37, the stock rear end is too restrictive. If you have a stock VF36, that can be worked into a full spec Owen item by using the exhaust housing as the start point which could save some money, the stock housing is a high grade stainless steel item. What tends to happen to the stock twin scroll turbo is the wastegate seal fails over time, because unlike the stock single scroll, it has an oblong wastegate button (it covers two small ports rather than one big one) which puts a side load on the support shaft, which wears the housing and cocks it over, losing seal. That's modified to an inconel setup as part of the spec. You then have a different spec exhaust turbine assembly to get the flow without losing the spool and the wastegate ports are all modded to improve flow so you dont choke the exhaust flow. It's pretty trick stuff. The limit on the stock exhaust housing is about 500BHP with all the mods done, then you are into going to a new casting exhaust housing with twin entry single scroll, you can see 650BHP on that.
jsf said:
plenty said:
Bookmarked. The LM450 certainly drives much more like a single scroll than a twin scroll. I've been waiting for Central Turbos to build me a hybrid VF36 with a larger billet compressor wheel but I might bite the bullet and spend the cash on an Owen item. Don't need big power, just a little more than OEM would be nice as long as it retains the OEM spool characteristics.
Using a bigger front end on a standard back end doesn't work at all well on the VF36/37, the stock rear end is too restrictive. If you have a stock VF36, that can be worked into a full spec Owen item by using the exhaust housing as the start point which could save some money, the stock housing is a high grade stainless steel item. What tends to happen to the stock twin scroll turbo is the wastegate seal fails over time, because unlike the stock single scroll, it has an oblong wastegate button (it covers two small ports rather than one big one) which puts a side load on the support shaft, which wears the housing and cocks it over, losing seal. That's modified to an inconel setup as part of the spec. You then have a different spec exhaust turbine assembly to get the flow without losing the spool and the wastegate ports are all modded to improve flow so you dont choke the exhaust flow. It's pretty trick stuff. The limit on the stock exhaust housing is about 500BHP with all the mods done, then you are into going to a new casting exhaust housing with twin entry single scroll, you can see 650BHP on that.
I was going to post a few details about my weird build, but thought I might as well start a Readers Cars post instead and put it there.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
fido said:
Sylvaforever said:
DanielSan said:
The annoying thing is they have access to the direct injection system from Toyota, it’s fitted to the 86/BRZ boxer lump. So surely going back down to the 2 litre engine and having the direct injection would improve economy and it could still produce 300-350bhp.
Indeed!!!!I even told the Subaru dealer who does my BRZ warranty work to get a price on one over here and i'd talk PX, as they can be just as quick as the 2.5 with cheaper running costs.
thanks plenty.
I always find it surprising that people seem to skip over the GF8 when looking at getting an Impreza. It has the best lines IMO, I imagine it handles better in some ways than the GC8, and they're much cheaper even for a V5/6. Shame Scooby Clinic never finished that 3 door wide arch one they were building about a decade ago, they told me they still have it when I asked about it.
Response from Subaru;
With the final edition only 150 vehicles were made, I’m afraid to say that all 150 have been allocated/sold,
If you get to your local dealership they would be able to sign you up to a reserve list. This means that if any of the vehicles became available it could give you the chance to get your hands on the vehicle,
With the final edition only 150 vehicles were made, I’m afraid to say that all 150 have been allocated/sold,
If you get to your local dealership they would be able to sign you up to a reserve list. This means that if any of the vehicles became available it could give you the chance to get your hands on the vehicle,
aaron_2000 said:
I always find it surprising that people seem to skip over the GF8 when looking at getting an Impreza. It has the best lines IMO, I imagine it handles better in some ways than the GC8, and they're much cheaper even for a V5/6. Shame Scooby Clinic never finished that 3 door wide arch one they were building about a decade ago, they told me they still have it when I asked about it.
I'm not sure why you would think the GF8 (wagon version of the classic GC8 shape) would handle better? The CofG is higher, the roofline is 45mm higher, its 15kg heavier and has more weight is over the rear axle. You lose the rigidity in the shell across the rear suspension turrets too as it has no rear parcel shelf steel structure. The spec is not as high on the more cooking versions too. If you like lift off oversteer then it will give you that a little bit easier, but other than that its a step backwards.The newage version of the wagon retained the narrower classic versions body width and is 20mm narrower track than the standard WRX saloon.
Gassing Station | General Gassing | Top of Page | What's New | My Stuff