Yeah. Bellmouth?

Reason I chose a sports cat though is not actually for a power increase but to help minimise spool-up from the lazy TD05 hence not being overly bothered about a "map to get the best benefits". Think it was a Bob Rawle comment I read last night about a DP not being urgent to map but I don't know if he meant Sports cat on a mapped car or not.

I also read (foolishly in hindsight maybe) a few people saying that just changing the pipe from a catted to sports cat gave them quicker spool but boost came in a little later when they eventually had a map tweak for the sports cat. :cry:

Can boost build too quickly for a WRX ECU or something? :wonder: I thought that was initially what gave me a fuel cut, the boost coming in quicker than what the injector flow could match. :eek:

It's also a 3" dp and I've read a few comments saying any change to exhaust size needs a map too regardless of cats.

Your looking at this entirely wrong IMHO. Anyone's comment on the internet need to be taken with some context when it's about someone else's car and you have no idea of the mods or if standard. Your saying you don't want the benefits of the new downpipe like it's just going to be power when mapped, your missing the safety side of it. You don't want the benefits but if it's spooling earlier into an area of the map it's never been before and detting you won't have a functioning engine soon.

In actual fact due to flow physics a 2.5 inch downpipe will spool sooner than a 3inch as the exhaust gas will flow faster and draw exhaust gas from the cylinder at lower rpm and only become a restriction at higher rpm on a higher power setup.

It's nothing to do with the wrx ecu being able to keep up, it hasn't been tuned for the downpipe so how can it fuel or spark correctly for it.

Often find an unmapped downpipe change on a standard car will make it over boost slightly and the ecu will pull the boost back so you get lower boost at say 3500rpm than it had before hand so yes you gain torque at say 3000rpm but lose it at 3500rpm. But mapped it gains right through the rev range.

Safety would have been of paramount importance if I could have found more than 2 posts saying it was crucial to map for a sports cat but after running on an engine for 4 years with a decat up-pipe and STI TMIC not mapped for with noticeable spool improvement I thought a fairly restrictive 200cel cat on the less efficient but future proof 3" wouldn't have been too sinister.

No I mean a WRX that has been mapped for all mods, is there a point where boost could build too fast for the car's ECU to deal with?

Also which will cause the worst rich running on lift off after a map tweak, VTA DV or blanked? I'm thinking of going down the blanking route to save a bit of weight and the fact my GFB DV has a stiff spring and the TD05 doesn't come to life until 5k it's almost redundant as it is.

TBH JGM when I planned to fit a Walbro 255l pump I got the same 50-50 opinions on whether to map or not or whether it effects how the car runs. Tuners are worryingly split on most areas of modding. Incidentally I ran a few days on the Walbro before the car was mapped again and found that it noticeably quietened the pops and bangs I had but noticed no other effects.

Jeeze, I actually think this is what's happening to me! TD04 with no cats at all. I get huge spikes until the ECU can do its thing. I have to run my duty cycles really low to help it.

Question for JGM, is it possible the TD04 is spooling faster than it can be controlled?

No it just needs mapping to suit

Thanks, thought that. Would you say that BCS duty cycle is the main method of boost pressure control rather than boost target alone?

Check your vac pipes!

A de-catted car with a TD04 must suffer some brutal acceleration if the vac pipe came off. Must take like 100ms to hit full boost from 2000rpm!

All my pipes are new, new solid brass tees and everything has Mikalor clips on too.

I think that the arm on the actuator can get stiff or something along those lines. :/

Does over-boost always cause the car to run lean or does it depend on factors?

Yeah checked my actuator and flap too, no issues there either!

If there's too much air then the mixture will lean out.

I'm going from what I've read again but how come most reported fuel cuts happen in 4th and 5th gear?

Greater load in higher gears so it spools sooner and higher

Wondered why it was ok in 1st and 2nd. When in spirited mood I only use the car for 0-60 dashes (never for high speeds or handling) so it's rare I floor it in 4th onwards. Fuel cut and CEL actually happened in 3rd at 5k on the motorway slip road.

I launched it about 3 times after downpipe was fitted and it felt slow, then all of a sudden it felt stupidly rapid. I thought it was the ECU learning and adjusting to an extent but sadly the P0244 sh*t on my bonfire. :cry:

I know it's safer now (in one way) but I really miss that insane lurch forward. :nono:

3rd gear onwards I have trouble. I'll have a look at mapping now I've checked all the hardware is working. I just didn't want to blame this it that without checking first.

It's safer because the pipes back on but it's still unmapped for the downpipe change

Would lean running from the sports cat only be a problem from sustained hard driving in cold weather etc or could det occur any time the car gets launched? I've done a lot of reading but I'm not sure of the tolerances or whether it's already beyond them.

My driving style is very conservative you see and I end up getting so many mods that I'm trying to limit the amount of map tweaks.

When I went from a TD04 to a TD05 should the restrictor pill have been changed?

It's safe below 3000rpm.

Not necessarily unless boost could be achieved when mapping.

Save your mods up and fit them all at once and drive to get mapped below 3000rpm.

Couldn't be achieved?

I'm not sure if the boost I wanted could be achieved. I asked the first mapper for 1.4bar on the TD04 and he said that's what it'll be, RR printouts after the map showed 1.0bar.

The 2nd promised 1.6bar on the TD04 but I ended up with a TD05 which he said fell just short of 1.6bar, though someone who mapped after said he thinks it was running at 1.4bar when I mentioned it at a later date.

Basically I don't know what is what half the time and is it true a Newage WRX can't make past 1.2bar without a 3 port etc or smaller restrictor pill?

My newage WRX is mapped to 1.3 bar with standard boost solenoid and restrictor pill.
Regards
Phsyo

Cheers bud!

Does a 3 port do away with the pill? I've read many conflicting posts.

If it's true a WRX uses a 0.9mm ID pill Why can't a 0.8 or less be used for the map tweak? Wouldn't it help spool on the laggy TD05?

In theory it would help spool but I think you could introduce boost creep that way.

Oh, and I just converted my 2 port to a 3 port setup. The piping diagram shows a restrictor in the vent pipe going over to the intake tube pre turbo.

So does a 3 port need a bigger pill?

This list suggests it might


MY93-96 ... 3 port solenoid 2.0mm restrictor fitted into the vent pipe between solenoid lower port and intake

MY97 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY97 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY98 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY98 WRX (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY98 Sti 4 ... 3 port solenoid 1.5mm restrictor fitted between the turbo and the solenoid adjacent to the solenoid top port

MY99 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY99 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY00 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY00 (JDM) ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY01-05 (Euro) ... 2 port solenoid 1.2mm restrictor fitted between the turbo and the tee piece

MY01-05 STi ... 2 port solenoid 0.9mm restrictor fitted between the turbo and the tee piece

MY06/MY07 both WRX and Sti 2 port solenoid 0.9mm restrictor between turbo and tee piece

Yeah, I came across that list too and I think it might do. So far I've used my standard pill which seems to have reduced boost pressure somehow and I've tried it with no pill at all. I saw an increase of 0.2bar that way. More trial and error to come!

Am I right in thinking if you never drive spirited for long periods or do track days etc then the odd launch maybe once or twice a week in 1st, 2nd and 3rd won't be an issue with a turbo that is close to maxed out?

I've read a maxed out turbo turns into a flame thrower but only after some hard use.

A mapper might recommend me 1.2 bar for safety etc but would that really suit my style of the odd blast out of a junction or drag strip run. Could I get more?