Linksfahrer

Although my wallet will likely require one. I am throwing this one
out for an airing.


Do I need to remap following rebuild re-porting of WRX heads ?


With a view to better spool up I have "mildly" reworked the ports.
This was not a radical exercise, basically I just removed the casting irregularities from the ports, and smoothed the combustion chambers very slightly to help swirl. Now I'm unsure how much risk I will have of detonation following my recent head grinding effort and the latest 0,5mm re-bore.


If the consensus is that remapping is essential , then I will be off to see Duncan at Race Dynamix.

Having just rebuilt my MY05 2.0 Engine Spec is:

JGM Tuned (Easter 2014).
TD05 16G @1.2 Bar Mapped on Super 98
Decat uppipe
Large TM IC
550cc Inject
Prodrive Sports Exh +Cat
Kinguwa WG Controller
Gauges Oil Temp/Pres/TurboPres

Its a STD EJ20 WRX motor but now over bored 0,5mm
around 320-340* otherwise hardware is as Simon tuned it.

* It actualy only made 311 bhp on Surrey RR

Unfortunately I don't have a Air Fuel ratio gauge. If anyone has one spare in a single pod, do PM me.

My replacement STD WRX heads did not need a skim, and I'm using new WRX pistons ( I consider ok < 350 bhp ) The gasket used is a MLS std 1.0mm thickness. I have set and indexed the sparkplugs 3mm down into the chamber to help prevent the crack issue that many of us suffer.

Previous fail History

Last engine suffered big end failure, strip down showed scuffing of all four cylinder walls fitted with Std sized Sti pistons. Head gasket was 0,6mm.
Failure occurred surprisingly slowly at 7000k in fifth gear with outside temp -5°C I'd been driving the car just 10 minutes before opening up to chase a Porsche that then got away. Oil temperature was 80°C mine considerably higher. I concluded that the big ends let go due to pistons higher expansion rate versus the slower expansion of cold block.

The cylinder heads had also suffered around the spark plugs star shaped 4-5mm deep head cracks, not reaching valves or water jacket. These were pressure tested but although not defective I have scrapped them anyway.


Fuel I have available here and normally use is Aral 102 Octane.
I think I can make it to Surrey with 2 extra 20 litre cans , one thrown in at Calais.


Regards Ralph

bludgod

iTrader: (3)

to get the best from the porting you would ideally get the map adjusted to suit the new additional flow. If the changes to piston type and hg thickness have adjusted your compression ratio then again the ECU may need the timing/afr's adjusted to suit that so at a minimum I would recommend getting it checked out (for knock/det, not just AFR).

Linksfahrer

I had thought that after 80 reads someone might have at least chipped in an opinion on this.
Do I need to Re-map post overbore / porting ?

But clearly either nobody can speak from personal experience or does not want to risk an opinion without more info.

I will answer it for myself, what I think will happen , but Id like opinions on if porting and overbore is likely to raise AFR significantly / what is AFR danger point on EJ20 ?

Although I have taken Detonation precautions by removing all the sharp chamber edges , widening grind-pasted the valve seats in to increase contact area and improve heat sinking into the head and even bringing the spark plugs flush to the chamber. I don't personally know if this is enough to compensate for the 0,5mm overbore & improved flow due to the smoothed ports.

Generally I think the MAF will see more air flowing earlier and will help correct mixture thru the map by adding more fuel & eventually the map should pull timing back, but at some point the extra air flowing due to the 0,5mm overbore and my ported heads might cause the mixture to lean out more than the Mapper had anticipated and the extra heat generated causes detonation that can no longer quenched by a touch of over fuel , ( Probably targeted AFR 12 at Sub 1 lambda's. )

Am I over concerned or is there a real danger of detonation ?

Linksfahrer

Thanks for this ,


The CR should have been corrected as Simon originally mapped on orig engine, so that's back to standard with 1.0 mm Gasket and WRX pistons.

BrownPantsRacing

iTrader: (6)

Yes, as they will be flowing differently to the original heads. You'd definitely need a remap to get the benefit from the money you've just spent on the heads!

trevsjwood

iTrader: (2)

my 2.0 wrx heads flowed much better when they were ported, much the same, removing casting irregularities etc but mine's a forged 2.5 bottom so the restriction unported may have been greater than on a 2.0 litre build.
I was always told, any change to airflow should be checked. Thing is, at -5c with foot down that's when it'll run lean.
Trev

Tidgy

100% need a remap, airflow will change alot.

Linksfahrer

All headwork is done in my cellar.
so I don't spend anything except for the SH castings.

But Map benefit is clear.


The problem with mapping is I have to drive all the way from Frankfurt and when I drive over I'm concerned at what speeds that I'd put the engine at risk.

Linksfahrer

Ok , Ok Thanks all I'm convinced.


Just need to find Duncan's contact #
and make appointment at Surrey RR.

BrownPantsRacing

iTrader: (6)

True, but it will be a fun drive home afterwards!

Nick_Cat

iTrader: (5)

Bob Rawle occasionally goes to Germany to do group sessions. Last time he did mine he was about to head over. Might be worth sounding him out?

JDM_Stig

iTrader: (3)

If it was mapped by Simon I would get it on a rolling road to see if it really does need dynamite Duncan too touch it,
I'd rather have a Simon map all day long if I can.

trevsjwood

iTrader: (2)

Duncan took on Simon's book when he sadly passed, he was a great chap.
You have you're opinion, a lot of owners take the opposite view. Can we not just respect that please.
Trev

Tidgy

if he stops ducking up cars then yes, but since he takes shortcuts to save himself time then nope.

I wouldn't let him map my lawnmower.

BrownPantsRacing

iTrader: (6)

If he's changed the engine internals and improved gas flow, it will need a map tweak. You can put it on a rolling road and do power runs all day long but it won't tell you much until a mapper starts trying to increase timing, fueling etc to see if the mods are allowing sustainable performance improvements. It will need a remap, or I should say driveability will massively benefit from a remap by someone who's a dedicated mapper like Duncan, Bob, Andrew Carr etc.


Andrew Carr actually has a 2nd home in France and spends quite a lot of time over there. Might be worth contacting him to see if he would travel to your neck of the woods. Only thing to bear in mind is that if Duncan tweaks it he may honour his agreement with Simons customers at the price of a map tweak rather than a full remap. If anyone else maps it you will have to pay full price for a new map.


Also, I agree with Trev about this constant Duncan bashing. I've used him and had a very positive experience indeed. Unless you have first hand experience you can sort out face to face then constantly pushing negative comments based on no personal experience is not good policy.

boggissimo

Out of interest, what speed were you going at 7K in 5th? And is it 5-speed or 6? I was on the hangar straight at Silverstone a few weeks ago and top speed was 128mph before I had to brake for Stowe, but was only at around 5K revs (in 5th of a 5-speed).

If you get it remapped on 102 octane, will you be able to get back to Calais or need to top up with 99?

Tidgy

and its doesn't make you wonder why?

BrownPantsRacing

iTrader: (6)

Question for you Tidgy????


Would RCM tarnish their reputation and let someone who doesn't know what they are doing use their rolling road and facilities and map their customers cars? Duncan maps at RCM quite a bit these days.


He maps a lot of cars and has done so for years. I'd use someone with that much experience!


As said above, I actually have personal experience and first hand knowledge of Duncan's work and have no issues so feel I can make an informed comment on Duncan based on first hand knowledge/experience.


A lot of reputations can be crushed by word of mouth comments from people with no personal experience.


I don't wish to start an argument, but this has been said time and time again Tidgy and yet you keep posting on every thread you possibly can with a good Duncan bashing session. It's somewhat unfair.


We know you favour Scooby Clinic, and we know the issues they've had and bad press of recent years but again, you don't see me putting bad comments in right left and centre about them, as they are too far away from me and I've never used them. Negative comments are just not needed. Secondly, I'd still use the clinic if I had to as much like Duncan's reviews they are on the whole nearly entirely positive.


Everyone makes mistakes, it's how you deal with those mistakes that counts. In a shrinking Subaru community like ours with an arguably dying breed of cars we don't need to keep bashing specialists to try and force them out of business. We as owners and drivers need as many experienced people around us as possible.


Just my Wednesday morning rant. Right, where's my coffee!!!!

SmurfyBhoy

How dare you speak ill of the clinic,

Blasphemer

BrownPantsRacing

iTrader: (6)

LOL. See that's the difference. I acknowledged they had had an issue not so long ago, but didn't speak ill of them at all. Not my place to do so.

BrownPantsRacing

iTrader: (6)

By the way Tidgy, that was not meant as a personal attack in any way, please don't take it as such. I do like you!


It more a generalised comment (read rant) about trader bashing on open forums.

Tidgy

He rents out their dyno, simple as. and we all know RCM are perfect. right?

I've never met him, on a personal level he might be a nice bloke, but i go on folks experiences who I personaly know who have used him and on the working practices he is well known to use. Add in some of the discussions or 'corrections' hes had from the likes of Andy F and Pat on various forums he doesn't ever go on any more then you can make your own mind up. Not to mention how he very quickly stops responding when things go wrong.

While i favor clinic yes there are other people/places i would use if they were closer. Places like Engine Tuner, AS performance, Andy forrest etc etc but thats just changing the subject and diverting the thread.

At the end of the day dont forget how long i've been around the comunity to see things happen

BrownPantsRacing

iTrader: (6)

I've also been around in the Subaru community far longer than I've been a member on here.

The problem is you're talking about a thread on 22B that is probably 10 years old now? But again, you're quoting someone else's words with no first hand knowledge at all and keep posting negative reputation damaging comments with no personal grounding. It's a little unprofessional to be honest.

I now use Andrew Carr for my mapping, but there are loads of other mappers I would still use based on their personal experience and knowledge. Andrew made a big mistake with the map on my FSTI when he rushed through it originally, He's since corrected it after a long stressful wait and re-mapped it once more again after another round of mods. Even though he made a mistake, I gave him a chance to rectify his work (against most people telling me not to) and couldn't be happier with him and his work. You don't see me going online telling everyone that Andrew Carr will destroy their pride and joy do you? Because it's not professional and I believe mistakes can be made and everyone learns all the time.

Anyhow, we're turning someone's thread into yet another mapping discussion thread.

I've said my part... based on MY first hand experience. That's all I can offer and all I should offer.

trevsjwood

iTrader: (2)

My first hand experience is that my car suffered HG failure on RCM'S rollers whilst being mapped by Duncan, this a few years ago. The only person responsible was me, firstly for not paying notice to the fact coolant was being displaced into the expansion bottle on boost and secondly for not discussing the symptoms with Duncan beforehand or even presenting a car unfit for mapping. Of course, this wouldn't happen now because it's much more talked about on here and I think there is more awareness of HG failure symptoms.
Duncan's always done his best for me and given fair circumstances treats his customers the same.
Trev

uxon

Don't you have any photos of the work done?

Linksfahrer

Have to top up full at Calais with the Canisters , ( empty them and hide some more for the way back , next 102 is in Luxembourg )

Linksfahrer

Yes although I did not bother to try to photo the port walls I have attached this one describing the plug indexing and levelling to the chamber top.


The key to this work was to remove all sharp edges likely to cause a hot spot and pre-ignition. The previous heads are star cracked around the plugs to each valve the crack extended to 6 or 7th thread.


The idea of the plug dipped 3mm into the chamber and chamfered edge is to fully bring them flush to the chamber. The indexing to 12 o clock is to try to get the plug open side away from the exhaust side. Its all designed to bring a more uniform burn to the chamber.

Linksfahrer

I don't know Duncan , but Simon did and yes he will honour what Simon could not finish on my car. But I'm not going to Duncan to squeeze his time , if the mapping takes a little longer so be it, Im straight up with that and time costs money. The Map basis is in place from Simons road mapping. The problem I have is the considerable stutter from low revs, Actually I rather surprised myself on the effect I have had on the porting and the extent of low speed pickup issues. I can only assume I learn't more than a fair bit from my Mini days grinding on 12G295 castings based on the fantastic work and book from Dave Vizard.

Linksfahrer

I have a great deal of respect for Bob Rawle , especially as he has consistently contributed to ScoobyNet in the past.

However I am going to Surrey RR , as I'd like a Dyno print out as well.
in my opinion Surrey RR are a good benchmark.

The work and my research done on a tight budget relates to a TD05 16G and other than, in my view relatively easy / minor head flow improvement. It is an otherwise its a standard MY05 WRX ( +0.05 ) bottom end.

What I am trying to do is get to or over 330hp at 1 bar and be able to say anyone can do it for less than 2k pounds of parts a Prodrive Cat* / tune and own time. The fuel of course is something you don't have in UK but huge diff over say Tesco 99 ? we will have to see next week. If we can keep the knock at bay and it takes a little more boost on the second of the twin maps who knows.

Linksfahrer

The porting / +0,05 seems to have had the most influence in the 2-3 k band. Once I get on boost everything seems fine.


Any abrupt release of throttle at lower revs is signed with an awful kick back. So to get it run in , I have either been pansying around or up and down the motorway at half boost.

Id accept the -5 °C was a contributing factor to my last engines demise
but when I pulled it down, I actually found the Sti pistons were scuffing all 4 cylinder walls , that does not stack up with a single big end that failed.
So it seems that when the Forged Sti pistons expand under a high heat scenario ( high O2 level high density air ) that this restriction caused
a clearance issue. This time and while I won't be taking this bottom end over 350 hp anyway. I have gone back to using the Std new WRX pistons.

The engine sounds a fair bit looser this time, but it all settle's down
as the oil temp rises. At 90° C on 5W-50 its all smooth as silk.
I have >1 bar OP at 700rpm with oil at 100°C.