Deep Singh

Interested to know peoples thoughts who have decatted the 7 (especially jap version).Was the turbo lag and top end significantly improved? Cheers,Deep.

Paul N P

Going to Power Engineering tomorrow to hopefully improve a very disapointing car. There will be a sports Cat in the system though.

We're not sure yet if the T75 will fit the Sti UK yet though!



[Edited by Paul N P - 3/8/2002 10:02:53 PM]

Deep Singh

Paul,I presume your first MOT ia approx 3 years away,so why bother with the sports cat as all? Please post after you have it done to let us know how much difference it made.Cheers,Deep.

RT

MY01 STI RA 16000kms

*****! I'd be careful of the decats on the MY01 STI. Response is very good, power comes on at 4000rpm instead of ~4400rpm with the cat.
BUT! Boost spikes are very high. Have seen some other cars peak at 1.7bar with only a decat downpipe in second gear.

Nothing untoward has happened yet, and maybe the UK STI will be different from the JDM ones. But I'd still watch boost very carefully with a decat.

alexf

Robinsons of Rochdale have decatted their demo car (not sure which exhaust system) and they say it has vastly improved the performance. It now puts out about 290 bhp apparently and has that lovely deep growl I'm putting off a test drive until I can afford it....

Alex

Deep Singh

RT,thanks for that.I actually have a jap one myself.I think I'll hang on until my Link ECU is ready to be installed before I decat.I was hoping you'd say the power came on at 2500rpm!!

RT

HAHA! Wish the power came on at 2500 as well...

Anyway, by 4000rpm I meant, full power by 4000rpm. So that means that the car is already picking up quite rapidly as you past thru 3600rpm or so.

Link ECU for the JDM STI? Are they ready? I know MOTEC and Autronic have not finalised any units for the new car, prob the extra complexity of AVCS has delayed things a little.

May I plse ask what fuel you use in your JDM STI? Have you tried things like Octane Boosters or Broquet? Do they work in postponing det?

tks.

Deep Singh

Hi RT,I d'ont actually collect my car until next week!! I was making enquiries in advance.No the Link is not available yet but hopefully soon.As for det I intend to run it on Shell Optimax(98.5 RON),if my knocklink shows det I'll add octane booster to bring it up to 100
ps though I've been told by my dealer/mapper that Link not yet available check out www.mrtrallying.com.au they seem to think it is.

Deep Singh

Sorry I mean www.mrtrally.com.au

mutant_matt

I'd just like to backup RT's point that decatting the 7 seems to lead to serious boost peaking, but not held. 1.7bar was seen on a friend of mine's 7 when a full SS system (inc up pipe) was put on which he solved with a Dawes.....(first time a Dawes has been used to limit boost? )

Matt

Deep Singh

Thanks Matt.Do you know how much boost your mate is running now,and how much difference did the decatting make to his car in terms of turbo lag.Cheers,Deep.

RT

Interesting! Spoke to the 2 chaps who had seen 1.7bar with a decat, one said that he was scared silly seeing the boost go past 1.5bar and continued rising!! He has since managed to control his boost by putting in an EBC, not the most cost-effective way, but his boost is now back down to a decent 1bar with minimal spiking.

Interesting to hear that the Dawes also can be used to restrict boost. May I plse know:
1. what it is set to now,
2. what is the spike (if any),
3. what is the held stead state boost in gears 3 and 4?

tks.

Mike Tuckwood

The V7 (jap) RA runs 1.5 bar boost as opposed to 1.2 bar in the non RA variants (OEM ECU). (pre de-cat).

Bitten Hero

Talk to Dave T-S as he had his (or rather Carolyn's ) done the day after they bought it a couple of weeks ago.

Cheers
Richard

Deep Singh

Thanks guys.

mutant_matt

Rich,

Trouble is, Dave and Carolyn don't have boost gauges so they probably don't know (yet). I think Dave was going to put it on the Select Monitor but I don't know if he did that before his holiday..... Also, the Select Monitor is only good for the run you check it with, a Boost gauge lives with you and you get a better overall picture over time.....

RT, AFAIK, he's running 1.2bar, held, no peaks/spikes but I'll see if he wants to contribute to this thread himself (as it's not for me to talk in too much detail about his mods... )

Matt

JGRIFF

yes Dave's car has been on the Select monitor and was showing spikes of up to 1.7 bar!, never fear it wo'nt be long before Pete C has finished work on the permenant fix

Andy W

I wonder what would happen if I replaced the uppipe and down pipe (with sports cat), instead of a full decat as I am seriously considering the prodrive upgrade when they get around to it.
Any thoughts folks?

Andy (serving the 1000 mile penance on type UK)

GRANT

O.K its my car Matt is talking about.
I ran the car from new with a full de-cat system so I can't comment on the difference in peformance.
All I know was once I had run the car in and had a chance to open it up the car boosted like crazy.As Matt said it was spiking to 1.7bar(Defi Gauge) and holding about 1.1bar but not very smooth.
At 1500miles I had a Uni-chip fitted.We thought that this may help to curb the boost problem.Unfortunatley not,but I did insure that the car was fueling correctly.
I messed around with various jets until fitting a 1.00mm jet gave some sort of level boost.The car still spiked to 1.5 bar and would still hold only 1.1bar.
I thought about getting an EVC but for a fraction of the price brought a Dawes,and the this has been the best money spent so far.
The car now holds 1.25bar with no spiking at all and pulls like crazy.
Matt and I estimate it to be producing around 330-340 bhp and with two of us in the car it absolutely flies.
Will try and get to PE this week to get some figues.

Grant

Deep Singh

Hi Grant.How do you know that your timing/fuel is appropriate? Do you have a Lambda/Knock link etc ? I'm just curious,not criticising your approach.Cheers,Deep.

sammyh

iTrader: (1)

Grant did you used to have a MY00 with a unichip?

GRANT

DS the timing and fueling were set when the Unichip was fitted ,but you are right it needs to be checked again just for safety sake to make sure its fine holding this level of boost thats part of the reason for trying to get to PE this week,as its alot nearer to me than Powerstation.
Sammy your'e right my last car also had a Unichip as you can see from the Dyno page.Covered 56,000 miles no real problems.
I must confess that I am no boffin but am willing to listen and learn and don't claim to be an expert.
I cover about 30,000 miles a year and while a like the added performance that these mods have given me ,this is now enough and am happy to enjoy what I've got.I'm sure given a few more months people will be producing great figures from the 7 as it really does seem to have great potential.
My 2 pennys worth.

GRANT

sammyh

iTrader: (1)

Thought it was you Grant, I spoke to you when I had a 'problem' with my unichip. Looks like we are going down the same route again car wise.

Sam

Deep Singh

Let us know how yoy get on at PE.Cheers,Deep.

RT

"The V7 (jap) RA runs 1.5 bar boost as opposed to 1.2 bar in the non RA variants (OEM ECU). (pre de-cat)."

Mike, my car is a JDM import, STI Type RA (not the latest spec C). With the original exhaust, I've seen 1.4bar spiked, certainly not held. My held boost is approx 1.1 to 1.25bar, depending on gear.

Dave T-S

Sorry about the delay in replying, been running Carolyn's STi in by way of a 1500 mile round trip to Austria

We actually rigged up a boost gauge temporarily, not put it on the select monitor. Like all the other full decatted STi7's, it was spiking momentarily to 1.6 or 1.7 bar at 3-3500 rpm or so then dropping back. You can anticipate it happening and lift off the throttle slightly to drop the boost back.

A 1mm restrictor will stop the spiking, but will be looking at other fixes as well.

Deep Singh

Cheers,Deep.

urban

iTrader: (1)

Guys

Does anyone know what the fix Pete is working on does, is it an electronic type fix or mechanical?

Dave T-S

Just linking this to the other thread re fixes

http://www.scoobynet.co.uk/bbs/threa...threadid=80851