Detailed Legacy GT and GTB differences
20 September 2004, 08:08 PM
#31
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Righto.
Went away this weekend to Pro-Speed in Cardiff, a bud runs the custom exhaust fabrication company there.
Had the cat bypassed and a rather complicated rear system made up. Its std bar the cat removal up to the rear box joint, where it goes from 2.5" to 3" mandrel bent link pipe, to the rear box. The old Jasma rear box had blow itself to peices and there was NOTHING, NADDA, NOWT inside it bar some rust....why the hell build a nice stainless box and fill it with mild steel!?
Anyway, rear box was built from scratch with a 3" entry, 2.5" bore with a crimped/pinched baffle to retain a smidgen of back pressure and then the jasma tailpipe off the old box.
Sounds exactly as it did before (just waiting for it to carbon up and get louder....ooer), the primary spools up much nicer and faster, and the secondary comes in about 200rpm earlier. Its not any more powerful, just some reponse and short spooling.
Dunc, that boost oscillation was there before i removed the cat, its still there, but not as bad. But i'll check out the restrictor issue.
RE the SMT, it cna control basic fuel maps and ignition maps, in a positive and negative manner. Along with a spare injector driver.
I got a blitz BOV on it already, needed re machining of a brass piston and a hone, like new now.
AJ, what methods did you use to tune out the valley and flatten it? Any special methods of boost control as i'm still thinking about the amal valve. OH! and is that a front mount IC your running then?
Oh, whilst under the car, saw the pipe from the primary to the sencondary round the front of the car......its BIG!
Cheers peeps
Went away this weekend to Pro-Speed in Cardiff, a bud runs the custom exhaust fabrication company there.
Had the cat bypassed and a rather complicated rear system made up. Its std bar the cat removal up to the rear box joint, where it goes from 2.5" to 3" mandrel bent link pipe, to the rear box. The old Jasma rear box had blow itself to peices and there was NOTHING, NADDA, NOWT inside it bar some rust....why the hell build a nice stainless box and fill it with mild steel!?
Anyway, rear box was built from scratch with a 3" entry, 2.5" bore with a crimped/pinched baffle to retain a smidgen of back pressure and then the jasma tailpipe off the old box.
Sounds exactly as it did before (just waiting for it to carbon up and get louder....ooer), the primary spools up much nicer and faster, and the secondary comes in about 200rpm earlier. Its not any more powerful, just some reponse and short spooling.
Dunc, that boost oscillation was there before i removed the cat, its still there, but not as bad. But i'll check out the restrictor issue.
RE the SMT, it cna control basic fuel maps and ignition maps, in a positive and negative manner. Along with a spare injector driver.
I got a blitz BOV on it already, needed re machining of a brass piston and a hone, like new now.
AJ, what methods did you use to tune out the valley and flatten it? Any special methods of boost control as i'm still thinking about the amal valve. OH! and is that a front mount IC your running then?
Oh, whilst under the car, saw the pipe from the primary to the sencondary round the front of the car......its BIG!
Cheers peeps
21 September 2004, 10:51 AM
#32
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AJ (Paul), I found the articles on your home page:
http://www.apexjapan.com/news/avo_b4/b4tune.html
http://www.apexjapan.com/news/avo_b4_article/index.html
What were the effects of the weak BOV?
Ben, the link pipe might look big but its mostly heat shield and lagging, like most of the pipes. The standard boost control is so poor it doesn't take much to knock it into oscillation mode. Is it better or worse with the new exhaust?
I'd like to try a Dawes and an SMT as a stop-gap. Ben do you sell the SMTs? If so can you email me a price for the full diy mapping kit. If not where would I get one?
http://www.apexjapan.com/news/avo_b4/b4tune.html
http://www.apexjapan.com/news/avo_b4_article/index.html
What were the effects of the weak BOV?
Ben, the link pipe might look big but its mostly heat shield and lagging, like most of the pipes. The standard boost control is so poor it doesn't take much to knock it into oscillation mode. Is it better or worse with the new exhaust?
I'd like to try a Dawes and an SMT as a stop-gap. Ben do you sell the SMTs? If so can you email me a price for the full diy mapping kit. If not where would I get one?
21 September 2004, 10:24 PM
#33
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thats a very nice writeup AJ.
I take it its them who used the SMT, but i didnt see any means of boost control.
Is the legacy GT engine as responsive to such simple mods as those, or is it mechanically less tough?
Dunc, the oscillation isnt as bad, but its still there. Whats the best method to control this, an EBC? But do you have to run 2 EBC's to make sure both turbos dont overspool and overboost?
Anyway, we sell the SMT6's yes.
You would require the developers kit.
I take it its them who used the SMT, but i didnt see any means of boost control.
Is the legacy GT engine as responsive to such simple mods as those, or is it mechanically less tough?
Dunc, the oscillation isnt as bad, but its still there. Whats the best method to control this, an EBC? But do you have to run 2 EBC's to make sure both turbos dont overspool and overboost?
Anyway, we sell the SMT6's yes.
You would require the developers kit.
21 September 2004, 11:12 PM
#34
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Just 1 boost controller, mechanical or electronic, would do. It would limit the boost level using the wastgate on the primary. Simple MBCs like the Dawes are popular for giving stable boost control.
There are no systems around that I know of that will prevent overspool if the system is unbalanced or you try to run too much boost. Since both turbos feed into a common point its not possible to control them independantly by monitoring boost only. Some of the top-end ecus such as Pectel can use turbine speed for control, but even they only do one turbo AFAIK.
Yes I'd want the dev kit for the SMT.
There are no systems around that I know of that will prevent overspool if the system is unbalanced or you try to run too much boost. Since both turbos feed into a common point its not possible to control them independantly by monitoring boost only. Some of the top-end ecus such as Pectel can use turbine speed for control, but even they only do one turbo AFAIK.
Yes I'd want the dev kit for the SMT.
21 September 2004, 11:21 PM
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Oops, got it wrong.....user kit, not dev kit....saved you money there 
No problems on the boost controller front. But whats the realistic max boost for the GT turbos, and std is what? 7psi for primary and 10psi peak?
I really really tired after today so humour me please lol.
No problems on the boost controller front. But whats the realistic max boost for the GT turbos, and std is what? 7psi for primary and 10psi peak?
I really really tired after today so humour me please lol.
22 September 2004, 02:43 AM
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Paul would be the other bloke His car is the D rev. Mine is a B rev (lower CR, bigger bore MAF etc).
I have ZERO boost issues. The thing is rock solid, but I want some even quicker spool, so a boost controller is going on (I may turn it up a bit for short squirts (using #2 setting)).
I personally stay away from MBCs, but each to his own.
Symptoms of a soft BOV are the usual - worse response, ramp up after shifts is poor, etc., etc.
Tuning out the valley was easy - as I said it is still there as a plateau, but the secret is in the tune and the well designed exhaust + IC IMHO. Better flow is helping everything work better. The IC is a top mount. Gone from lotsa bp at the IC to almost none (at the power I am running anyway). I don't even have a pod filter (due to the scarily weak MAF, and not really liking the noise).
Max boost? I wouldn't run more than 1.1kgcm for long periods, mine was 1 std. Running that now and got 315ps in hot conditions, so should be mucho better now it is cooler (and I had a kink in a hose that was hurting things too
). I'll get it on a dyno soon for some more tuning. I'll likely set #2 for 1.2
Cheers
His car is the D rev. Mine is a B rev (lower CR, bigger bore MAF etc).I have ZERO boost issues. The thing is rock solid, but I want some even quicker spool, so a boost controller is going on (I may turn it up a bit for short squirts (using #2 setting)).
I personally stay away from MBCs, but each to his own.
Symptoms of a soft BOV are the usual - worse response, ramp up after shifts is poor, etc., etc.
Tuning out the valley was easy - as I said it is still there as a plateau, but the secret is in the tune and the well designed exhaust + IC IMHO. Better flow is helping everything work better. The IC is a top mount. Gone from lotsa bp at the IC to almost none (at the power I am running anyway). I don't even have a pod filter (due to the scarily weak MAF, and not really liking the noise).
Max boost? I wouldn't run more than 1.1kgcm for long periods, mine was 1 std. Running that now and got 315ps in hot conditions, so should be mucho better now it is cooler (and I had a kink in a hose that was hurting things too
). I'll get it on a dyno soon for some more tuning. I'll likely set #2 for 1.2 Cheers
27 September 2004, 08:14 PM
#40
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Another question.
Whats the offset of the std wheels?
Oh, and more.
What do the leg and imp share suspension wise, thing like drop links, ARB's, struts and shocks?
And will the 4 pot scoob brakes fit straight on, or only a specific year?
Whats the offset of the std wheels?
Oh, and more.
What do the leg and imp share suspension wise, thing like drop links, ARB's, struts and shocks?
And will the 4 pot scoob brakes fit straight on, or only a specific year?
28 September 2004, 08:56 AM
#41
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The gen2 legacy (94-98) is compatible with the GC8 impreza for all brake and suspension parts except I think for the rear anti-roll bar due to a difference in the wheel well location, but I could be wrong on that. I have a front impreza bar and a rear legacy bar with metal end links from Whiteline. If your struts are tired, KYB AGX adjustables are a direct fit. Rear springs are not compatible with the imp because of the different weights, also the rear top-mounts are different.
The 4-pots will fit straight on but not with the original 15" wheels. If your going to change wheels and brakes you might be better going for a big disc setup such as the Godspeed 335 kit with 17" wheels - do a search on here.
The 4-pots will fit straight on but not with the original 15" wheels. If your going to change wheels and brakes you might be better going for a big disc setup such as the Godspeed 335 kit with 17" wheels - do a search on here.
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