SRi Turbo

da_rude2k2 · Post by **da_rude2k2** » Mon Jan 15, 2007 9:00 pm

I have PM'd this to Niz who appears to be the oracle on all things blowy around here but I will paste it into a topic in case anyone else has any comments.

Im new round here. Got given a 406 turbo before christmas and I love the car but 150bhp seems a bit poor considering how much fuel it uses! What would you reccomend to gain a few ponies? Im pretty good with the spanners but dont have much experince of turbo'd engines. How well does the 406 ECU + injectors cope with extra boost as far as fuel delivery goes?
I realise that before I start playing Im gonna need a boost gague. Where is the best place to put one?
And lastly, If I do fiddle with the boost how much of a hit will my fuel consumption take based on normal driving (no one expects good consumption when caning it!)
All comments well received.

Thanks all

Tim

jameslxdt · Post by **jameslxdt** » Mon Jan 15, 2007 9:09 pm

i think the factory boost controller wont let it run more than 9psi, a 205 gti camshaft is a good upgrade as the turbo one is very lazy, a decat and induction kit are also a good place to start

niz406 · Post by **niz406** » Mon Jan 15, 2007 9:54 pm

I've replied chap, see your PM...

Max boost is set to 0.9 bar... james you were right with the digit, just the wrong measurment

Thats around 13ish p.s.i before fuel/boost cut! The stock map sensor is 1bar I believe and the stock electronic boost controller fluctuates the max boost based on speed / gear data..

James, I have to tell you something... it appears that the 205 GTi cam story is actually reversed.... its actually the other way round... it is recommended that 205 GTi drivers use the Turbo cam on their XU9 engines for increased performance. Not the other way round.. someone correct me if I'm wrong, because then I can invalidate my source......lol

If you do correct me please, quote duration / max lift figures / valve diameters!

many thanks!

acqu135c3 · Post by **acqu135c3** » Mon Jan 15, 2007 11:06 pm

150 bhp doesn't sound all that much but its only half the story, the other half is the 173 odd lbft of torque the little hamsters generate. Much to the displeasure of quite a few other car drivers. I have to agree though the fuel economy isn't that good in mine either. Does anyone know what sort of mileage i should be getting from say a tenners worth of fuel? it does vary quite alot depending on how i drive it. As for the boost tho mine seems to vary with no seemingly logical pattern between .5 bar and .8 ish and you can feel the difference when its higher. I would also like to know how it will cope with fueling if i adjust the actuator a little...

Thanks
Andrew

mjb · Post by **mjb** » Tue Jan 16, 2007 1:32 am

I've been told I should stick a 205 GTi cam in mine to improve responsiveness because the turbo's got a really lazy engine. But I say balls to that - I love it lazy!

I find I can get up to 38mpg from mine by slipstreaming trucks on the motorway. 30 is a reasonable figure for variable 70mph motorway driving. It's all down to how much and often you stamp on the accelerator. I've come close to single-figure MPGs in the past on heavy countryside driving. Don't forget that the 406 isn't the world's lightest car either!

Malachy · Post by **Malachy** » Tue Jan 16, 2007 5:50 pm

niz406 wrote:I've replied chap, see your PM...

James, I have to tell you something... it appears that the 205 GTi cam story is actually reversed.... its actually the other way round... it is recommended that 205 GTi drivers use the Turbo cam on their XU9 engines for increased performance. Not the other way round.. someone correct me if I'm wrong, because then I can invalidate my source......lol

If you do correct me please, quote duration / max lift figures / valve diameters!

valve diameters? why do we need to know that for starters its got nothing to do with the cam..............................

as for putting them in 205's? your source must be smoking crack i have been an active member of 205gti drivers the largest 205 site and most knowledgable XU engine site around for a good few years now (back when i had my miami blue mi16) and never heard this in fact ill go find some figures for both cams

ok here they are
205gti 1.9 cam
230deg duration 11.5mm lift
turbo cam
160deg duration 11.5mm lift

the fact that it is a great degree milder than the 1.9 cam for starters (160deg duration! lazier than a lazy man doing lazy stuff) ok it gives the same 11.5mm lift but still the 1.9 cam give 230degs duration obviously this gives a tiny bit of overlap but in all honesty this is outweighed by the better cam performance. The turbo cam is so mild ther eis no way in hell you would get any valve overlap so this is a bonus (you want next to 0 overlap on a turbo) but sacrifices throttle response and peak power by far too much for my liking.

why the hell you would want to "increase performance" on the 1.9gti by adding the lesser duration same lift turbo cam is beyond me.

Also as said the exhaust manifold sucks (just cheap production for mass market) and the inlet manifold is tuned for low down torque (high air speed at low rpm) great for low down torque crap for high power. take a peak here for inlet manifold track lenth tuning formulas (been messing about designing some myself)

as for some topics on this

general mods

16v head mod

more reading

another bit of proof if you really need is the 205TT standard this make 170bhp using a smaller bore, worse flowing head (smaller ports poorer flow and smaller valves than the xu10) , less boost, same turbo,same compression ratio, and terrible management (5th injector system that you mayaswell just be pouring petrol into the throttle body by hand), ok it has a better exhaust manifold but its not at the power and flow that it really comes into making any difference. The fact the 205tt uses the 1.9 cam might just prove something for you sceptics.

niz id change the people you get advise from

they may be getting confused with the fact that some people do use the XU10 head on 1.9gtis as it is a far better head (although needs 1.2mm shaving off to keep the right comp ratio) the head is sourced from any xu10 8v as all the heads are the same either from the turbo or n/a (same part number) the lower compression on the turbo is achieved by pistons.

some more usefull info on head work etc on the XU is here clearly stating that modding a turbo cylinder head will give a proportinal gain in power on forced induction, in fact even more so as its multiplyed under boost conditions. so it is well worth while on the turbo

niz406 · Post by **niz406** » Tue Jan 16, 2007 10:08 pm

Sorry dude... my fault!

I stand corrected... well I would have if I'd of read the email properly... it was the XU10 head and not the cam, will teach me to scan read emails... Opps

Malachy · Post by **Malachy** » Tue Jan 16, 2007 10:16 pm

damn double posts!

Malachy · Post by **Malachy** » Tue Jan 16, 2007 10:19 pm

niz406 wrote:Sorry dude... my fault!

I stand corrected... well I would have if I'd of read the email properly... it was the XU10 head and not the cam, will teach me to scan read emails... Opps

yeah the xu10 head is very very good its not easy at all to gain power by porting polishing etc most tuners who make these power claims dont make them, it needs skilled people with flow benches to make any improvement or lots of luck

this is why the pug tuning field is a minefield when compared to the likes of ford etc etc where there is more easier scope for tuning.
A prime example are some tuners claiming to be able to mod the 206gti180 engines head to make +20bhp in a stage 1, not being funny but Mechachrome (guys who done the work on the renault f1 engines) designed and manufactured this head (from the 206 gti 130 ), if they think 180bhp is about what it can get with the level of there expertise not many small tuners will be able to better this.

ill be doing a small bit of polishing etc on my 16v head but nothing else id be more likely to make less power

also polishing the inlet can be a bad idea as yes it will make the air flow faster, but the petrol will stick to the walls (imagine rain on a glass windscreen) and not flow as quickly into the combustion chamber as if it was a slightly rough finish.

If you fancy doing some home work on your head there are some good guides here this is for the c20let but the principe is the same for all heads.
and here

niz406 · Post by **niz406** » Tue Jan 16, 2007 10:34 pm

But in the same sense, the rough surface can cause messy turbulance, which disrupts flow as well !

And good linking to Puma Race engines... I was going to have my head done by him about 3 years ago, but he had stopped taking orders at this point as he was flat out and overloaded ! ! ! Would so be worth it though! ! !

I wan't to stick with 8Valve so will possibly use the CatCams turbo cam, which prevents the overlap associated with the 205GTi cam as the duration is slightly under @

264deg @ 0.1mm with 12.25mm of lift for the inlet with 267deg @ 0.1mm with 11.6mm on the exhaust

What do reckon to that?

Malachy · Post by **Malachy** » Tue Jan 16, 2007 10:37 pm

niz406 wrote:But in the same sense, the rough surface can cause messy turbulance, which disrupts flow as well !

And good linking to Puma Race engines... I was going to have my head done by him about 3 years ago, but he had stopped taking orders at this point as he was flat out and overloaded ! ! ! Would so be worth it though! ! !

I wan't to stick with 8Valve so will possibly use the CatCams turbo cam, which prevents the overlap associated with the 205GTi cam as the duration is slightly under @

264deg @ 0.1mm with 12.25mm of lift for the inlet with 267deg @ 0.1mm with 11.6mm on the exhaust

What do reckon to that?

is a good cam and qep will do it for about £180 i think if not less
and what i mean by rough is basically so its smooth to the fingernail but not mirror finish

niz406 · Post by **niz406** » Tue Jan 16, 2007 10:45 pm

Well my head is in the shop now, being skimmed / recon'd etc.. so might get the cam and hve it put in also if labours not too much, well actually it shouldn't be more as they've still got to put the original cam back in, so substitue the cam for the catcam LOL

da_rude2k2 · Post by **da_rude2k2** » Fri Jan 19, 2007 4:41 pm

Oi! Stop hijacking my post :-)

So Niz, Would it be a good idea to start with the decat and induction kit?
Am I likely to feel any gain from this before fiddling with the turbo?
Also do I need to replace the whole exhaust or will the standard system from the cat back suffice?
Im not really after a bean can!

Thanks mate,

Do you have MSN or anything? I would like to chat real-time about this sometime.

Tim

(MSN:[email protected] AIM:tlawrence127)

niz406 · Post by **niz406** » Fri Jan 19, 2007 5:05 pm

You will notice a difference with the free flowing exhaust system as the stock CAT is so restrictive ! It'll help lots when u increase the boost !

Thedrill · Post by **Thedrill** » Thu Jul 12, 2007 11:06 am

Hi all, I know this is an old post ..but has anyone on the forum fitted a 205gti camshaft to thier 406 turbo and if so what performance gains/losses?

Cheers.