mutant_matt

Ray,

I found it. Post taken from this thread.....

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OK. I've now done some logging with Jonno (JDM STi) with his full de-cat with different restrictor (running Optimax + NF) and can compare the results to a completely standard UK STi:

Standard UK STi




JDM STi - Full De-cat with restrictor




As I understand it, Jonno is pretty much now running 1.05bar in 1st, 2nd and 3rd and about 1.2 in 4th, 5th and 6th. You can see that the spiking has gone (at the possible expense of some increased spool up time) but he still gets the occasional spike to 1.4ish (IIRC).

Presumably, with a 3rd party Boost controller, you could have the best of both worlds (fast as poss spool up but without spiking) and hopefully, EcuTek will also be able to modify the Boost maps soon, possibly coupled with a restrictor, to get this best of both worlds too.

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Ray, I think you'll struggle to get the same spool up with a full decat + restrictor without boost spiking. Jonno's car is just under control with his (1.25mm) restrictor and to get the spool up faster, he'd need to try a smaller restrictor and then it would start spiking again. I think the only ways round this with a full decat is either to port the wastegate or to remap the ECU (possibly coupled with a restrictor change).

Remember that the Milltek and the PPP both have a cat in the downpipe which creates some backpressure which seems to help keep the boost under control.

Hope this helps,

Matt

[Edited by mutant_matt - 11/8/2002 8:50:43 AM]

Dave T-S

Ray
The boost figure in isolation is misleading. It's the torque that is important. The STi PPP achieves 46ft/lb more peak torque than the standard STi, at around 1000rpm lower, and holds it around 1000rpm higher too.

This is achieved despite running not much more boost than standard, but achieves it I would guess by increasing the wastegate shut time slightly and controlling it more efficiently over a wider rev band. It will also correct fuelling and ignition advance.

Playing with restrictors only will control the initial wastegate reaction (or, realistically, with decats only it has had to be used to control unacceptable boost spikes) but will not raise the held boost effectively. The restrictor controls the initial boost solenoid/wastegate reaction until the ECU can get hold of it and control it more accurately, as per the map targets.

All the decent aftermarket exhaust systems around will give you good BHP gains, and increase initial and possibly held boost due to more efficient spool up etc, but will not give the torque gains that the PPP (or, for that matter, other remaps or replacement ECU's) will give, and it's torque that matters out on the road.

This is not criticising anybody's exhaust products in any way, but if you want to increase torque and driveability of the STi7, a different map/ECU as well as an exhaust will be the way to go.

[Edited by Dave T-S - 11/8/2002 1:52:15 PM]

Dave T-S

Pete

Sorry, can I just ask where this came from - surely you don't mean with the PPP? - I never see more than 1.35 to 1.4 bar max boost on the gauge in 5th/6th with the PPP.

[Edited by Dave T-S - 11/8/2002 2:02:43 PM]

Razor2001

I guess you could say that me and Jonnos objectives are different. I want as much torque as low down as possible. I want full boost by 3,000 - 3,200 rpms. That is my goal. This is one of the reasons why I chose a 2.5" vs. a 3" zorst system. I hate lag !

Interesting to see that Pete says (well he thinks ) the PPP ecu only adjusts boost and leaves everyting else alone. If this is the case I will be inclined to think that a STI-7 PPP and an STi-7 JDM full SS decat turbo back will look very similar bhp and torque wise. I guess the only way we will find out is to have a dyno / rr done on the above two cars at the same time and same place and see the actual numbers for ourselves.....until then I am right Dave T-S becuase it is my car and I said so

Oh I think the standard JDM STI-7 torque is 265 ft. lbs ?

Cheers,
Ray

[Edited by Razor2001 - 11/8/2002 7:07:40 PM]

Razor2001

Hi Pete,

I was just looking at the boost curve for the "Milltek" zorst by Litchfield Imports. The boost curve is very similar to the PPP on the STI-7.

Out of curiousity there is no reason why a ScoobySport zorst (full decat turbo back with restrictor) should not achieve the same awesome boost gain at 3,000 rpms (14psi Milltek & PPP vs. 7.5 psi standard STI-7) is there ?

Reason I ask is that I am only getting about 8 psi st 3,000 rpms with my full SS decat turbo back, but I think it is becuase I need to play with my restrictor size. I am still getting 16 - 17 psi max and 14.5 psi held on 4th gear blast which is pretty normal; however, my boost is coming in at nearer 4,000 rpms vs. Milltek and PPP at 3,000 rpms.....must be a restrictor issue, no ? Will be installing an adjustable flow valve soon so I can play with the restrictor size with a twist of the ****.

Anyone out there run a DD log for a JDM or UK Sti-7 with full ScoobySport turbo back zorst to compare to Muttant Matts logs for PPP and Milltek ???

Cheers,
Ray

Razor2001

bttt, anyone ?? doesn't have to be Pete

FERRARINUTTER

Pete's out for the evening, I'll mention this thread in the morning.......

Razor2001

Cheers,
Ray

mutant_matt

Ray,

I have I posted it a couple of months back. I'll see if I can find the thread....

Ta,

Matt

mutant_matt

...and for a direct comparison......



Matt

Pete Croney

Matt

The graph is very interesting. I assume the Miltek equiped car does not have a revised restrictor as the boost is spiking to alarming levels, dropping off and then building up again.

Also, what was going on with the PPP boost at high revs? Was it fighting det?

ozzy

Nice flat boost curve with the PPP

OK, dumb@ss question - how can changing the zorst ala Milltek up the boost so much (or any for that matter)? or is it the restrictor that does that?

Stefan

mutant_matt

Pete,

The Milltek does not require a restrictor change and I wouldn't call 1.3bar alarming? After all, it's close to the PPP. I suspect that to hold more boost, you would need to remap the ECU (or get a standalone boost controller). As an exhaust only replacement, I think it does a very good job (and is emmissions friendly which to many is increasingly useful).

The PPP was not fighting det (none at all according to the Knock graph (see PPP DeltaDash Part 2 thread) and Dave's boost gauge did not replicate this "Boost Spiking", nor could it be felt on the road. I am guessing that what looks like this Boost spiking is something to do with the Boost Clamp that Prodrive have used (another assumption but I think a reasonable one ).

How's the Janspeed STi exhaust coming along (I'm of course making presumptions that there is/will be one)? Will it be a decat or with hi-flow cat?

Ta,

Matt

EvilBevel

Pete, if you look in the Deltadash thread, you'll see the solenoid DC is at 0 % higher up with the PPP setup.

mutant_matt

P.S. Ozzy, the Milltek and PPP exhausts are far less restrictive which is the main reason for this. The old Scoobysport/H&S exhaust also has no cat in it so is even less restrictive which is why, to control Boost spiking, you also need to change the restrictor if going for (any) decat system on the STi.

Matt

Dave T-S

Pete

Somehow, and particularly after the gestation period of an elephant, I don't think Prodrive would let the PPP anywhere near the public domain if it was detting Certainly, my PPP was fitted at Prodrive and thoroughly tested on track by them before it left

As you are no doubt aware, certain of the sensor outputs aren't necessarily read correctly by the DD with the PPP fitted.

mutant_matt

Dave,

What you of course meant to say was that the PPP doesn't tell the ECU what's going on correctly (by design of course )

DeltaDash just reports what the ECU thinks in going on.....

Matt

dowser

If you've got 0% solenoid duty cycle and still have boost like that at high revs, the first person to use an MBC to raise boost will have fun.... Seems to me to be highlighting either limited flow through the wastegate or (as per EMS) a dodgy downpipe design. Maybe Prodrive designed it that way to ensure boost at higher revs? But it means there's no way for the ecu to reduce boost at high revs

What were the other solenoid duty cycles above 6k?

Richard

Dave T-S

Matt

Whatever mate...Delta Dash is voodoo to me - you know my attitude to this - I just get in the thing, slam the door and drive it

But I like to keep your techie nerdy needs satisfied by letting you run data on it now and then - then I get the chance to give it a good larruping

Pete Croney

Interesting points.

Dowser, the downpipe fitted with the PPP is a twin dump design, but I have not actually seen one yet. I missed the outcome of Mark's problem, what happened? I would hope that no one would fit a MBC to a PPP car

The boost curve being shown would appear to be what is happening. If you log a WRX PPP, it stays nailed at 10psi, even though the guage shows up to 20psi.

Matt ours are decat

Razor2001

Thanks for the data Matt

Pete,

I would imagine that the PPP and Milltak car are faster than the SS decatted car by looking at the boost curves. It also looks like the boost at 3,000 rpms is:

PPP 14.5 psi
Milltek 13.5 psi
SS 9.5 psi

Not sure why this should be considering the SS is a full decat and less restrictive. I would have thought that the SS would be as good as the Milltek as it is basically the same mod (less restirctive zorst than stock). By looking at the above numbers it is possible that the full decat with restrictor is not the best option but perhaps a full turbo back decat (except with less restrictive down pipe ala Milltek) may be the best option. Or, maybe it is just a matter of playing with the restrictor a bit more. Am I looking at something wrong or am I right to assume that the PPP and Milltek boost curves are more desirable than the SS one ? Not trying to rain on anyone parade I am just trying to figure out how to get a similar boost curve with the SS zorst as in theory it should be as good as the Millteks as it is less restrictive (ie: no cat in downpipe).

I could be way off on the above, just trying to bring the boost in a little earlier in my car

Cheers,
Ray

Sorry if the above is a bunch of crapola

Pete Croney

Ray

The boost curves which Matt has graphed together are from 4th gear. Spiking is only just occuring in 4th and is no where near as bad as it is in 5th and 6th. Dave TS was only spiking to 1.3 bar in 4th with the standard restrictor, but hitting over 1.5 bar in 5th and 6th.

The PPP and Miltek graphs show a spike, which then gets corrected by the ECU. I'm not sure how big this spike is in 5th and 6th.

In your hot climate you may be able to run a 1.20mm, but when we tried that in the UK, the spikes went to 1.3-1.4bar and we felt this was too high.

Another point is that the JDM decat shown here (Jonno's) had a Scoobysport downpipe and up pipe, but the rear parts are HKS in 3", not 2.5" as our system. This will affect the spool up.

On all the STis we have fitted with full Scoobysport systems, full boost is achieved at 3200rpm, with a spike to 1.2bar, then holding 1 bar for the rest of the usable rev range.

Razor2001

Hi Pete,

Excellent ! That is exactly what I want to hear So now that I know the SS system can give full boost by 3,200 rpms I just need to play with my restrictor size until this is achieved That is why I am installing an adjustable flow valve within the next 2 - 3 weeks so I don't have to keep removing restrictor etc

I know my restictor must be the wrong size as I am only getting roughly 9.7 psi at 3,155 rpms with my full SS system. I am getting 16.8 psi (max / peak / spike boost whatever you want to call it by 3,689 rpms. The above data was calculated in a 4th gear blast from 30 mph to 95 mph on DD.

Anyway, thanks again everyone for the help, very useful thread

Cheers,
Ray

mutant_matt

Agree totally with Dave (damn and after he called me a techie geek too [img]images/smilies/mad.gif[/img]) that the exhaust will help the spool up, will help increase a torque a little, and the bhp more so. What counts on the road is torque and not just the peak but "area under the graph" i.e. as much torque, spread across as much of the rev range as possible. You need some sort of remap to take advantage of the less restrictive exhaust (whichever one you choose) which of course the PPP has done.

Don't forget, the Boost curve is not a power or torque curve. Just the amount of boost the turbo is running but note that the amount of torque is linked to the amount of boost run.

Ray in terms of restrictiveness, the exhaust go from the most restrictive, the standard STi to the PPP & Milltek about similar to the decat exhausts (like the Scoobysport) which are the least restrictive. The decat exhausts are not directly comparible with catted exhausts as you need to start modifying other things to make them work properly (on the STi).

Hope that helps,

Ta,

Matt

MikeWood

Matt

What makes you think that the PPP exhaust is restrictive in any way?

Mike

Razor2001

I agree to a certain extent; however, I honestly don't know that a PPP with adjusted ecu (ecu that is still a 'one size fits all') will show that much more difference from a decatted zorst such as SS with no ecu adjustment. We all know that the STI-7 ecu is very intelligent and I would imagine that a full turbo back decatted SS system with the correct resrtictor will show a very similar torque curve to the PPP. To a certain degree boost does = torque, so if the SS is achieving 15 psi at 3,000 rpms and the PPP is achieving 15 psi at 3,000 rpms and they follow a similar boost curve till redline I would imagine that the torque curves would be very similar as well due to the STI-7 ecu activaley searching for the aggresive scenario while trying be on the threshold of boost.

Is the above utter garbage ?

Cheers,
Ray

LitchfieldImports

Yeah Matt What makes you think the other Exhausts are restrictive

Iain

dowser

Pete - Mark's fix was another d/p..... Re. MBC - why not, I did on my old shape PPP...it's just a matter of time.

Hi Mike - is the twin-dump downpipe design intentionally keeping the PPP's boost up? 0% duty suggests the ecu's trying to get the boost down.

Richard

Pete Croney

Dave

You needed to read the whole sentence M8

It came from me sitting in your car holding a boost gauge

You did NOT have a PPP then, just in case anyone else is confused.

Pete Croney

Ah Mike's here

Mike what's going on with Dave's boost at high revs?