Help please! MY00 Turbo with PPP. Before swapping pipes, should've been approx 240bhp mark. All was good until this afternoon when I swapped over to a H & S front decat pipe and Magnex centre decat, still using the Prodrive rear silencer. I was aware I would hear a considerably louder turbo spool-up which is true but the power delivery is now just so not smooth. If anything, it feels underpowered. Before, when the turbo kicked in, it would put you back into the seat. Now, its like the car has 'a bit of a cold!!' Certainly louder but not really what I was expecting. Its got slightly more pull lower down the rev range but sod all difference anwhere else. To me it now just feels like it all wants putting back as-was. A bit disappointed

Does the ECU need to adjust to this or am I just expecting too much here? I was expecting at least a 15bhp increase, not a 20bhp loss

Please help me

 

ahhh dreaded lag arent ppp cars only suposed to run what prodrive supply so since you have added a decat down pipe the ppp ecu wont run proper boost with these mods

 

..Apart from refitting the downpipe, what are my options?

 

sell PPP ecu for a nice tidy profit and use the cash toward an ecutek ecu which will give you exactly what you want

 

How much am I looking at here? ££ Both for my PPP ECU and an Ecutek?

 

People often don't appreciate how critical the exhaust system is on a performance car - especially turbo charged cars such as the scooby.

I am learning all the time to be honest, and sitting with one of our engineers (or worse still all of them! ) for an hour talking about it is mind blowing as to the complexities.

I is very easy to create flat spots, peaks and troughs in the power curve if the exhaust system isn't just right.

We have recently discovered (as in yesterday!!) the reason why the (genuine) scoobysport system flows so well, and in particular why it creates such improved turbo response. It turns out that the tuning of the system as a whole creates true negative pressure at the turbo exit into the downpipe which actually accelerates the exhaust gasses away from the turbo. This means, that not only is the exhaust system unrestrictive, it is actually a net benefit. In other words, the exhaust gasses leave the turbo easier and quicker than if you didn't have anything attached to the turbo at all.

This is created by the harmonic resonant frequencies of the different areas of the system, which end up creating sound waves at the exit of the turbo accelerating the gasses away.

I've actually posted this tonight already on another thread.. but here's an explanation.



All the best

Simon

 

Did the same thing with a MY00 PPP - fitted original DeCat and was very dissapointed with the results - lack of power, hesitation etc Sold all the Decat bits and put the Scoob back to standard. Then I read on here about ppp cars and Decats and that the Brass restrictor can be drilled out to assist in allowing the ECU to control boost. So repurchased bits and the restrictor has been drilled out to 1.3mm. This made all the difference This may be all you need to do on yours mate ?? If you need anymore information the please let me know cos there is a thread on here about it

 

Please tell me more... Ta.

 

mines decaterd pulls better more noise but can notice turbo lag more alloy fly weel next but some one tells me the brakes will go poor

 

Brass restrictor can be drilled out to assist in allowing the ECU to control boost. So repurchased bits and the restrictor has been drilled out to 1.3mm. This made all the difference

..restrictor??

 

Simon

Which particluar SS system are you referring to ? (ie which backbox etc)

The restrictor is in the boost pipe, its a very small brass thing that has a hole in it

I have a UK MY00 with PPP ECU, with the following exhaust

Ported & wrapped headers
Ported Up-pipe (Headers end only)
Magnex Twin Dump Decat DP
Magnex resonated centre section
Scorpion Tuner 5 Backbox

Just recently I got 255 bhp 240lb/ft on a Rolling Road
this was with a damaged up-pipe (non ported one)
and a restrictor drilled out to 1.25mm

I changed the up-pipe to the ported one, and the original restrictor (1.1mm I believe)
Back on the Rollers, I got the following figures
265bhp 230lb/ft

So BHP up, and Torque down, I was also seeing peaks of 1.35 Bar (this was down to the restrictor of that im certain)

Ignition timing was being pullled way back (2.5 degrees of negative knock correction) at approx 4.5-5k rpm, which was also evident from the graphs, as there was a big dip

Im going to try the car back with the AE800 ECU, and see how the car runs, although the PPP does make a noticeable difference midrange

Steve

 

Hi Sonic

There is only on ScoobySport backbox (identical for classic shape, and new age), so the tuning for each model is taken care of in the down-pipe / centre-pipe(s) combination.

Both systems do this.

On the 3" downpipe (for bigger turbos) the negative pressure is lower by volume of gas so it really is better to have the 2.5" full scoobysport system rather than the 3" unless you are running big power.. probably around 380BHP+

I'm not totally sure I understood the question, but I hope the answer is in the above somewhere! LOL

Cheers

Simon

 

Thanks Simon

Ill stick with 2.5" then for the time being, as my target is approx 300-310 bhp

once the VF28 Turbo, fuel pump, and remap are done, I should be just about there

I was actually referring to the manufacturer of the SS Backbox, ie Janspeed, H&S etc

But by your answer above, I take it you are referring to the *new* SS System

Cheers

Steve

 

Thanks for all the replies.

Still not sure which route to go down next.

If I put the catted and silenced original centre pipe back in, would this be of any gain? eg: a little more back pressure between cat & turbo? It ran nicely with catted front and decatted centre.

Failing this.. there could shortly be a H & S front decat pipe up for grabs!!

 

I'd also be interested if there's any diff between the H&S and Janspeed in terms of flow. Also, is there an easy way to identify the 2 from each other?

 

Hi Notorious

On the bench, the new scoobysport (Janspeed manufactured) rear silencer flows 7% better than the H&S system.

This, and the benefits of the computer aided design / testing (that goes into each part of the new system), is where the improvement in performance of the latest scoobysport system comes from.

The latest version can be told apart by the ScoobySport logo on the tailpipe. Regarding the other parts, you can probably tell by the weld qualities, etc. Straight forward to tell when they're next to each other, but probably not so easy if you haven't seen the latest version.

In fairness, the old h&s system still flows very well, it's just obviously not possible to produce the same results as we are able to now unless you have all the computer modelling, and flow testing equipment, etc that is available to us.

All the best

Simon

PS. There are a few close-up shots on the website www.scoobysport.com which you may be able to use to help tell if yours is a h&s or ScoobySport.

 

PS..

Also important to note, that whilst flow is absolutely vital for performance exhaust systems, the harmonic characteristics of the system is just as important.

One of the reasons why the 2.5" scoobysport system performs better than almost any 3" system on the market is due to these characteristics.

When the gasses enter the downpipe, they have to accelerate the gasses that are already there. Due to the tuning of the scoobysport system, the harminics are such that the actual sound waves are already accelerating the gasses away from the turbo which means the turbo is completely unrestricted and is actually aided by the exhaust system which effectively "sucks" the gasses away from the turbo.

This is why the latest scoobysport system has always shown such incredible turbo response. It's great to finally have the scientific reasons behind what was previously just considered a phenominon!

Cheers

Simon

 

Very interesting thread this.

This question has probably been asked a 1000 time but here goes.

What are the BHP increases likely to be for the following Scoobysport systems?

Back box only
Full system Ex up pipe
Full system Inc up pipe

To be honest I'm more interested in improvements to throttle response and reducing lag than increasing the BHP. A "tuned" exhaust note would also be good . Just wondering about the BHP for insurance increases.

The car is a MY53 WRX.

Thanks in advance.


Rich

 

Your post is music to my ears for a number of reasons..

1) You are more interested in throttle response.
This is incredibly valid for a number of reasons. Peak BHP does not mean a thing. It is possible to tune an exhaust system to give you an extra 1BHP at peak but still be faster than another one offering an extra 50BHP at peak. It all depends on what happens around the rest of the torqur curve. I do understand though that the BHP increase is a nice figure to gauge an expected increase in performance.

The scoobysport system gives different benefits to different models of cars, but (as a really rough guide) you could expect that a back box will give you around 15 - 25 BHP (real BHPs, not "pub BHPs"! ) increase.
Full system (with or without uppipe) around 35 - 45BHP.
Uppipe BHP will be negligiable, but response will be improved and lag reduced.

The difference is that this is representative of the actual performance benefit. So while other systems may claim bigger BHP, the actual performance of the car will not be as great.

2) You want the performance gains for insurance reasons... as we quote realistic BHP increases, and not "sales" BHP figures, your reason for wanting the figures suits better!

By far the biggest benefit of the scoobysport system is driveability and turbo response.

Regarding the "tuned exhaust note"..

All the best

Simon

 

Im still none the wiser really on what to do next!!

 

Drill the restrictor out as mentioned above, Should cure things, if your not happy, put all back as was & purchase a new/second hand brass restrictor as that will be the only thing that cannot be returned to it's original state

Dean