Kenny_Powers

iTrader: (1)

Hi folks

As in the title, I've just last week had my 2006 WRX remapped by Antony at Indigo GT, and it managed to make peak power of 260 bhp at 4900 rpm. Torque is 310 at 3900 rpm. Supporting mods are K&N panel filter, 2.5" Afterburner full decat exhaust system, and Walbro 255lph fuel pump.

For some reason it is running out of puff too early. The mapper believes that this is down to the decat downpipe being a bit restrictive, and said that it could do with opening up a bit. I'm just wondering if anyone on here has had a similar experience with the Scoobyworld Afterburner decat downpipe, or if anyone has any other suggestions as to what could be causing this issue? I'm led to believe that max power should be around 1000 rpm higher, and be 270-280 bhp with my mods?

Don't get me wrong, the car has been transformed from how it was as standard. It's much smoother and faster and is a joy to drive, but obviously I want to get the full potential out of my current set up.

Here is my dyno graph, I would be really grateful for any advice or observations. Cheers.



Sorry, it the graph wont attach in landscape for some reason, even though it is saved in landscape on my laptop.

DmcL

forgetting that different dynos can give different numbers for a minute here..

i put an HKS panel filter and a 3 inch catback on my 06 WRX and had it on the dyno (with about a 50/50 mix of 95 octane and super) and managed 256bhp/262lbft:



just going by the numbers i got there id think a turboback should see more, expecially with a remap. as far as im aware mines not mapped as it had no mods at all when i bought it nor anything suggesting any mods or mapping in the paperwork with the car.

Kenny_Powers

iTrader: (1)

Thanks for posting this mate, it's a very good reference for me.

My issue is not that the car is making 260 bhp, it's the fact that it's not making any more than that after 4900 rpm. 260 bhp at 4900 is pretty damn good, and I doubt that any more power could be made at that engine speed without a turbo upgrade. I want to try and find out for sure what is causing the restriction, is it intake or exhaust related? Looking at your graph I can see that you are making about 230 bhp at 4900 rpm, so going by that ratio, I should be getting around 280 by 5500 rpm. I may be wrong on that, as I'm no expert.

I wonder if any tuners or mappers are around on the forum, if they could give me any advice on this please?

BTW the car had a full tank of V-Power when it was mapped.

Gear Head

iTrader: (2)

2.5's make their max power at a lower rpm anyway.
I think the standard rating for the 2.5 WRX is 225bhp at 5600rpm, so yours is not a million miles out.

The fact that it holds similar power all the way to the redline is surely a good thing?

I'm sure some of the mappers will be on here in a minute to help you.

GazJenno

Why would they say the de-cat down pipe is restrictive...its not got a cat and 2.5" wont be that restrictive at that power level.

Has it got a cat in the up-pipe on that year?

BrownPantsRacing

iTrader: (6)

Thats very odd. I got 253bhp from my 2.5 2006 Hawk WRX with standard exhaust and only a back box change. No re-map, no other mods at all.

They do vary a lot and as said, dyno results vary.

2.5 engines don't have a cat in the up pipe from factory.

Kenny_Powers

iTrader: (1)

Thats a good point about the power holding on Gear Head, the car really is amazing to drive after the remap. It is like owning a different car. I suppose there is more to a car than just raw power figures.

Hi Gaz, I too have been wondering why a decat downpipe would have been described as restrictive but the mapper said that although it started at 3" it tapered down to 2.5" quickly and "needed opening up to a full 3" pipe", his words.

To give you an idea of the performace, the car pulls like a train and does 60-100 mph in 7 seconds, or thereabouts. I just can't help thinking that it should be giving a little more...

BrownPantsRacing

iTrader: (6)

I always thought 2.5" exhaust was good up to 300bhp. No need to go 3" if your not aiming higher.

Got a 3" to 2.5" downpipe with 2.5" system on mine now running 334bhp & 381lb/ft.

Kenny_Powers

iTrader: (1)

This is what I have been led to believe. Which makes me to think that the issue may be intake related. I have a K&N panel filter, that I cleaned and oiled about 6 months ago, I'm wondering if its possible to over do it on the oil and restrict the flow through the filter? Although I think that given these filters are good for 400 bhp, I don't think it could be that badly clogged!

Or maybe the dyno was just having a bad day lol, Antony did say that his dyno reads on the low side.

GazJenno

I have a 3inch decat to 2.5 centre to 3inch back box... 348bhp

What turbo is on it? td04 are pretty poor at flowing air at high rpm.

Power (W) = Torque (Nm) x 2Pi x RPM/60 (RPS) ... so if your power curve remains a straight line from a certain point it's because the torque is decreasing at the same rate your RPM is increasing. Similarly if you have a constant torque the power will increase linearly with RPM

Torque curve is effectively your volumetric efficiency, which is the ability of the engine to fill the cylinder with air... obviously at higher RPM the time to fill the cylinder is a lot shorter and you need to fill more often so need flow rate. If you have a restriction i.e. turbo cant flow enough, poor intake track, backing up exhaust etc. the torque will die off as RPM increases due to the higher flow rate demand.

Gaz

The Pink Ninja

iTrader: (23)

What boost is it mapped too?... AFR`s 10.7 a little rich but its a 2.5

tubbytommy

iTrader: (20)

it will pop before long so i wouldnt worry about it.

Kenny_Powers

iTrader: (1)

Thanks for this good explanation mate, I've been a Jap car enthusiast for quite a few years, but my Scooby is the first car that I have owned that is not normally aspirated, and this exercise is my first experience of mapping/tuning.

The turbo is the standard TD04. I know that these turbochargers run out of steam at high revs, but I did read somewhere that they shouldn't start to run out of puff until around 5500 rpm.

Like you, I also have a 3" down pipe to 2.5" mid section to 3" back box, so I doubt that it's the exhaust system that's restrictive.

Maybe I should go down the normal route of looking at the simplest component first and trying a different air filter?

Hi Gaz, I don't know what boost it's been mapped to, but I imagine that is an important question. I will contact the mapper and find out.

Haha, I was waiting for someone to come along with that one! Hopefully being a MY06, I will be ok. From what I have read, that is more applicable to slightly later models?

With hindsight, I would have bought a 55 plate blob sti if I had done more research, but you know what they say about hindsight......The 9 grand that my car has cost including performance and styling mods would have got me a nice one!

DmcL

my understanding of 2.5 vs 3 inch exhaust (from my background with older 2.5 inline 6 BMW's + a turbo) is that 2.5 is perfectly fine up to the 300's, it can start to become a bit of a bottleneck after around 300 or so (though the info i have seen is from people in the US so 300hp is most likely 300WHP and not BHP in these discussions).

allthough im new to scoobs and as many would say the 2.5 i meant to be weaker.. i dont think as bad as the hype about it. it seems like the ones suffering the major issues are hatchback onwards. i know that the newer ones had major issues with blocks cracking and when i looked into what blocks they are all associated with either new supplied blocks from subaru or standard blocks in newer model 2.5's, it seems like the ones people in the know go for when building a 2.5 is what we we happen to have in our 06's (702 casting from what i gather).

@brownpants, thats nice to know you saw 253bhp essentially standard. i was seriously wondering why i saw 256bhp from a panel filter and catback when book figure is like 230. they must have either deliberately quoted low figures or something.

also prior to this thread i thought my somewhat flat powerband with the TD04 on a 2.5 was unusual as alot of people say the TD04 tails off at higher RPM's so i was expecting to see a bit of a hump in the mid range after my dyno run instead of the broad and fairly linear band that i got.

jura11

iTrader: (7)

Hi there

Without the knowing what boost you run,I would suspect at this power something like 0.7-0.9bar should correspond with yours power

If car has been mapped on 1.3-1.4bar then you should be looking at 270-280bhp(rarely,but yes is possible to see 300bhp on TD04),but you must keep in mind TD04 doesn't hold the full boost(1.3-1.4bar) to the redline,usually at higher RPM above 5000RPM boost starting to drop to the 0.8-0.9bar

2.5" exhaust shouldn't cause restriction at this power or at this level,2.5" can be limiting factor around 350bhp,but seen on 2.5" exhaust too 450bhp

AFR is slightly higher,what I would like to see,but really depends on mapper and what fuel has been used,I would try different dyno(Rolling road),usually on one RR you can have 250bhp on next one you can see 265bhp,some RR reads low and some reads higher and what most counts is how it drives

Jura

Kenny_Powers

iTrader: (1)

Hi Jura. Thanks for looking in!

Just heard back from Antony at Indigo. He mapped the boost to 1.2 bar.

He did actually say to me that his dyno reads low, so maybe I should get the car on another dyno for a second opinion, as it were?

I think the next closest one to me would be Powerstaton, or I often go home to Hertfordshire, so maybe someone could point me in the direction of somewhere in that area?

Thanks

TimH

iTrader: (11)

Surrey Rolling Road - very consistent results from there. It would be on your way back home and not too far from Hertfordshire anyway?

Kenny_Powers

iTrader: (1)

Nice one Tim. I'm going back to Hemel Hempstead next weekend to see my son, and Surrey Rolling Road is only 35 miles from Hemel.....plus they do power runs on a Saturday for only £40. I'm sure my son will enjoy a trip down there too. Thanks mate, I'm gonna get booked in!

BrownPantsRacing

iTrader: (6)

260bhp does sound a little low for a TD04L at 1.2 bar boost.

But at the end of the day, if the car feels good on the road and you are happy with how it drives, don't bother chasing figures! Not worth it, gets far too expansive for little gain.

Just drive it and enjoy it!

boosted

I would like to see boost plotted on the dyno graph, I would sugest as Jura said above, it makes lots of boost down low then drops off, this would give a high torque/power figure low down and remain at that power as the boost drops off, instead of making more power.

ajsscooby

iTrader: (5)

I have a 2.5 Hawk which made very similar bhp/lbs to yours and an equally disapointing drop off when it had the TD04 fitted, supporting mods were (and still are) prodrive sportcat, afterburner centre, racebox rear, walbro255, K&N panel.

Fitted a VF34 and STI topmount and made 320/370 with no other mods (opensource remap)
Ringland failure occured :-(

API rebuild with forged pistons & Ecutek remap by Bob Rawl and it now makes 347/5750 401/3900

In hindsight I should have got a VF48 which are usually reasonably priced second hand and more suitable for the 2.5


As the previous posters said, on the 2.5 - the TD04 runs out of puff earlier in the rev range so your next logical step that will make a worthwhile change is a turbo upgrade.

BTW, mine was on the standard clutch up to 370lbs, the increase to 401 was too much for it so a pinkbox was installed and that works fine. Also, on track days with >300bhp I found the standard 4pots were a bit out of their depth so I now have a ksport 330 kit and much more braking power.

All the best.

AJS

adz556

iTrader: (5)

I would have thought the 95 octane fuel won't be helping your cause either.....get a full tank of v power in it and see if that helps

dynamix

iTrader: (3)

260bhp sounds fair for the fuel in there.

I have mapped on the rollers at indigo gt and dont think there read much different to srr or others tbh.

If it drives good then I would stop obsessing about the printout. It is safe at 10.7:1 and for the fuel in there he would have had to run it rich to stop it detting.

Run it on 99ron and you would see your missing 20bhp.

Kenny_Powers

iTrader: (1)

Thanks to all who have replied above for taking the time to read this and give me your advice.

The car has always been run on V-Power Nitro, and was mapped with a full tank of it, I did put that in my first post.

I think you guys are right, the car is amazing to drive compared to how it was before the remap, and I think it would be silly of me to chuck any more money at it in the hope of 20 more horse power. As you said, AJS, I would be better off forking out for a turbo upgrade and going from there. Any reason why you would have got a VF48, rather than the VF43 which is standard on the 2.5 Sti?

Dynamix, thanks for the advice on the accuracy of the Indigo rollers, I will take your very experienced word for it and not waste any money trying to get a better result at another rolling road! Would you say an AFR of 10.7:1 is still ok knowing that I did have 99 ron in the tank?

BrownPantsRacing

iTrader: (6)

Vf43 and vf48 are practically the same, vf48 is just a later version as fitted to the 09 sti upwards. I have a vf48 fitted to my 06 wrx that Duncan mapped!!!

dynamix

iTrader: (3)

ah ... sorry thought i had read that 50/50 on 95 and super. Probs someone else's post.

I mapped a hawk wrx down on those rollers and made 285bhp and 330lb/ft or thereabouts so am confident that the rollers are close to what I see elsewhere. 10.7 is a little richer than optimum power but I would say chat to them as to why it was like that as it is too easy for armchair observers to critique without actually having the car in front of you with det cans on or connected to it laptop wise. Sometimes they make better power running richer with more timing than leaner with less timing but obviously only they will know what the car wanted.

Boost on yours is optimum at 1.2 peak but this starts to tail off quickly and beyond 4500 rpm it is a question of asking the turbo to give everything it has as it just cant deal with the flow required to fill a 2.5 engine lol. I wouldn't be in a hurry to run more boost than that as boost isn't always the answer.

dave_t

iTrader: (1)

IMHO......and strike me down if you i'm wrong...

I would not worry too much about ultimate values especially BHP. That's usually best left to the younger ones. Torque is and always will be your friend.

Its all a balance, maybe a few extra bhp could be squeezed at the top end but usually at the cost of something else.

1. Remember rally cams in 80's cars? +20 bhp (and gutless unless on the redline)
2. BHP values in the redline areas are IMHO insignificant, its the torque curve leading upto the redline which dictates how quick ya going to get there!

Glad to read above that Indigo reads low, mine was done there (gotta be worth an extra 10bhp down the boozer). By the way my 2.0l wrx (standard besides cat back, filter, center decat only, standard catted up & downpipes) is giving 280bhp ....yours will be quicker

p.s. Dunc's ya man should you need future tweeks..

GazJenno

Although what you're saying is right Dave, that the torque curve is more valuable than BHP figures, the OP's torque curve drops off at a fair rate as RPM is increasing which is why the OP is concerned there may be a restriction in his setup or a more than normal drop off of boost. As I pointed out earlier, power is a function of torque and engine speed and ideally you'd want to hold peak torque to the red line, that would give you peak power at the red line also. As much as you want a high peak torque, ideally you want to maintain it through the revs... Not sure I'm allowed to say that as one of the "younger ones" though, if you'd class 26 as young.

... maybe the original issue could be cause by something a little different, if the clutch started slipping slightly once the car had reached peak torque and beyond?

Kenny_Powers

iTrader: (1)

Hi Fellas, I've been crazy busy at work so havent had time to reply for a while.

Normally I wouldnt be too worried about the extra bit of power at the top end but the fact that I have gone to the trouble of going full decat but am making less power than some cars that only have a centre decat, like yours Dave, is bothering me.

I have noticed that my turbo is quite loud, you can hear it hissing away from outside and inside the car. Is that normal with my level of boost pressure on a TD04 with full decat exhaust.

Dave, I may just give Duncan and shout and see if he can have a mess about with my map and either find the missing horses or at least find out whats causing the problem.

I am planning on a VF43 and Sti top mount intercooler and Y pipe next. Should I just go for it and see if the car makes the power that it should with those mods after a remap, or should I try and find out whats going on with my current setup first?

Haha Dave, I do remember the rally cams of the 80's, I had a mate who spent a fortune on his XR3i Cabrio lol, kent cams and all that, and got about 25 bhp more but with virtually no low down torque.

Tidgy

just seen the graph, the graph itself doesnt look right? look at the bhp ftlb cross point.

260/310 is about right power wise so it looks like its just the graph itself is displaying wrong.