Knock Detection???

[robwright]

After reading the dr_38's recent post about higher RON fuel and the numerous replies to the post I have a question about knock detection. I have an 88 turbo that has a TIAL DPW and max 951 chips fitted. These are from Russell Berry in the states who makes the chips for Lindsey Racing. As I have after market chips do I still have knock detection? Also is there anyway of knowing what fuel grade my chips are mapped for? I know for sure by installing the DPW the overboost protection function is disabled but not too sure about the knock detection. BTW after said post I think I am deffo sold on the idea of changing to 98 RON fuel. The benfits far outweigh the few extra pence at the pump I think.

 

[Frenchy]

Rob i have basically asked the same question, i am about to fit a Tial to my car, may need to talk to you over the phone about this plumbing wise.
Cheers Jim.

 

[robwright]

Jim where did you get your TIAL from? It is a marvelous thing to behold isn't it!! If you got it from Vic at Pauer Tuning in the states then the install is pretty straight foward as he supplies all the adaptors to slot straight in where your factory wastegate was. You will have to dispense of the wastegate hanger bracket for the original WG that wraps around the torsion tube but not too bad. I presume you have chips to go with. Must also ask where you sourced them from. The plumbing at first amy seem a little daunting but also pretty staraight forward depending on your configuration once you get your head round it. What is that by the way? Will you be running in dual port mode? Do you have manual boost controller or electronic? Yeah anyway feel free to phone me if you like. Once you install it you will feel the benefit trust me. I am currently running 15 psi of boost and the car is bloody quick. There is more to be had but under good advice I am keeping it there at the mo with stock 21 year old injectors. 15 psi is not to be sniffed at though trust me!! I also followed good advice and have installed an after market boost gauge (the dash one is not terribly good) and and an air fuel ratio gauge to keep an eye on how the engine is running. Sorry have waffled a bit lol.

 

[PSH]

I can't answer for certain but i would assume the knock detection was left as factory set and if you drive hard then yes it's best to use high octane fuel as it will allow the car to run a higher boost before knock sets in, as i said in another thread 1 octane is worth 2psi of boost.


Pete

 

[Frenchy]

Cheers for that Pete,firm beleiver in high octane.
Rob bought from Mr Paure in the states he delivered it to my hotel when i was in Florida, dead sexy it is a shame people cannot see it when it is fitted.
I also got the fitting kit crush rings etc along with a fuel rail pressure gauge.
It looks as though the flanges have been fitted arse about and i may need to swap them i take it it sits in the same orientation as the original.
I have a VDO boost gauge fitted to my car at the moment but also have a race logic one which also measures negative (vacumn)
At present i have Lyndsey racing chips which can be set up via dip switches for a wastegate plumbed in as dual port, i have a maunal boost controller valve, bleed valve.
A good mate runs the promax DPW set up and i will be looking at that for some pointers.
Jim

 

[robwright]

All sounds good mate. Yeah I thought it looked arsed about when I got mine but it will slot straight in mate believe me. Take the advice of me and those before and also threadlock the allen bolts as well as wiring them. At least you didn't get bummed for import tax lol. The plumbing is fairly easy take your boost feed from the banjo on your boost tube to the interercooler and plug the original line. No longer needed. Split it and take one side to your controller and then to the DPW. The main boost feed just goes straight from the banjo at the boost tube to the DPW. The original feed to the top of your factory WG is for overboost and is no longer required as you have no overboost protection lol. This is now your responsibility!!! This can also be plugged. Hope this helps.

 

[Frenchy]

Cheers Rob,
Pretty full on at the moment the Turbo S is down at my Mams, and is SORN, i am getting the new 220 in to shape with little bits of jobs,i have said to myself i will keep it standard it is fitted with a promax boost enhancer though and is overboosting at the moment.
I also need to sell my Alpina, i have had loads of interest off PH classifieds but no viewers yet, the first one to come and see it will buy it as it is probably the best one in the country.
When it sold the 220 will get the wheels refurbed and some minor paint then it as i wat it, then i will bring the Turbo S up home and get it sorted []

 

[PSH]

promax boost enhancer though and is overboosting at the moment

If overboosting using the boost enhancer may be worth checking the blow off valve, this breaks down over time and if not working properly will cause the overboost symptom. I replaced mine many years ago with a bailey DV30 when I kept hitting overboost with a boost enhancer, it cured my problem. Coincidently I have just replaced my DV30 with a dump to atmoshere type of valve. This i did due to issues while using higher boost that was giving me problems with crank pressure and also a flat spot between 1000-1500 rpm. The design Porsche use in placing the blow off valve is not a very good one when using a MAF as it upsets the reading when dumping boost back into the system, also it dumps it opposite the breather pipes so again not so good for the engine.
I've only had the new valve on for a week but it runs well, gear changing is far better and the flat spot has gone plus it makes a cool noise... , I'll monitor it over the next few months before I decide it's true value.

[8D]

Pete

 

[944Turbo]

The ECU can only retard/advance the ignition by either 6 or 8 degrees - I forget which so it has a limited range, should be enough to take advantage of higher octane fuel or to be safe with the standard stuff on an unmodified car. I would hope all the aftermarket chip programmers keep this feature in.
The difference between UK fuel and US is complicated and its a long time since I tried to understand it, they use MON where we use either straight Ron or a RON/MON mix, either way MON comes out with a lower octane number. IIRC they use 89 and 92 in the states which is almost equivalent to our 95 99 but I cant remember exactly which is slightly higher.

I do know Toluene increases the octane rating - my old man has had several scoobies out in Botswana where the fuel is 92RON and they hate the standard fuel, MASSIVE flat spots, pops and bangs. 5 litres of Toluene to a tank gives you roughly equivalent to 100 and they run really well like that.

Tony

 

[edh]

ORIGINAL: PSH

promax boost enhancer though and is overboosting at the moment

If overboosting using the boost enhancer may be worth checking the blow off valve, this breaks down over time and if not working properly will cause the overboost symptom. I replaced mine many years ago with a bailey DV30 when I kept hitting overboost with a boost enhancer, it cured my problem. Coincidently I have just replaced my DV30 with a dump to atmoshere type of valve. This i did due to issues while using higher boost that was giving me problems with crank pressure and also a flat spot between 1000-1500 rpm. The design Porsche use in placing the blow off valve is not a very good one when using a MAF as it upsets the reading when dumping boost back into the system, also it dumps it opposite the breather pipes so again not so good for the engine.
I've only had the new valve on for a week but it runs well, gear changing is far better and the flat spot has gone plus it makes a cool noise... , I'll monitor it over the next few months before I decide it's true value.

[8D]

Pete

Some interesting thought Pete - what about the effect on air metering? I get plenty of noise with the recirc. valve and the MAF/K&N setup - although it's only really intrusive when you're pushing on. My car sounds so much better on the track than a standard turbo []

 

[PSH]

Some interesting thought Pete - what about the effect on air metering?

Well it's the air metering that is affected by the recirculating valve which then causes the flat spot, when Wayne Scofield set up my car some 3 years ago he spent a lot of time trying to iron out the flat spot which occurs when first depressing the throttle. He explained that the main problem is due to where Porsche decided to fit said valve, being so close to the AFM it upsets the air in the pipework and hense causes the problem( this is magnified if using a MAF unit.
Recently I've been having issues with breathers and high air intake temps , so I have been looking very closely at various things in the engine bay. When you look at where the valve is and how it's positioned it's obvious that it could be improved upon. First the valve dumps it's boost back into the intake pipework opposite where the breather pipe enters it, so it's easy to visualise that a car running high boost is more likely to have breather problems due to this setup ( perhaps this is why some mod specialists state that the standard breather setup can not cope with anything over 350BHP). Dumping to atmosphere eliminates this problem
I discovered something else too during this, my AFR changes greatly with the bonnet open, at idle it's 14.7 while open but this leans out to 15.4 when partially closed and 16.2 when fully closed, is this part of my problem with lost power on the last dyno run?......especially when you take into account that the bonnet was closed for the run and also that it was pointed out that the car was running lean from 2000-4500rpm.
Later this week I'm planning on doing away with my current K&N cone filter and purchasing the new pipercross venom cold intake system VM7000, I'm just waiting to hear from them what the max BHP rating is plus dimensions, I would have liked to use the K&N apollo cold intake but this has a max rating of 350bhp which can not be exceeded according to the K&N tech guys...lol

Of course I could upgrade the intercooler but first i want to get the intake temp down before worrying about charge temp.[]


Well sorry if I got a little sidetracked but it's all relevent to the air intake don't you think????


[8D][8D]


Pete

 

[Frenchy]

Which begs the question what you doing with your old DV3O Pete ?

 

[PSH]

Which begs the question what you doing with your old DV3O Pete ?

well I was going to keep it till I was happy with new one but on getting home tonight I was informed that it now resides on my son's RS turbo ( which btw did better on the dyno recently than my 944....lol), still he did say he'd try and get me the venom for trade price so i can't get to upset. It's handy having a son in the trade, he's saved me many thousands over the years god bless him....[][]

 

[Frenchy]

No problem Pete gotta ask,
Get your son educated and get him into a proper car, speaking from experience i have had 3 Escort RS turbos an S1 and 2 S2 they are horrible to drive especially when tuuuuuned []

 

[PSH]

Get your son educated and get him into a proper car, speaking from experience i have had 3 Escort RS turbos an S1 and 2 S2 they are horrible to drive especially when tuuuuuned

Oh i've given up on that, what with his brothers cosworth with over 500bhp and his rs with 300bhp i'm a little out numbered in my household. I have to say he's set his car up with perfection and it would embarass many top money cars , including Porsche's. When it comes to my other sons cossie.. well i won't even bother trying to beat that monster, it's a real GT2 killer believe me[][]

I wonder where they get all this car madness from...????hehe

 

[sawood12]

The knock detection is compromised over standard protection when aftermarket chips are unsed, but I don't think it is necessarily significant. I believe with the stock set up as soon as the KLR detects knock it will start retarding ignition upto a max of 6 degrees until no knock signal is present. Decent aftermarket chips will still do this. If it gets to 6 degrees and there is still knock detected the stock system will use the cylcling valve to open the stock wastegate to dump boost. An aftermarket setup with a DPW cannot do this as you bypass the cycling valve and are relying on an external boost controller. So if you've got aftermarket chips and DPW then you only have the first stage of knock protection. That is why decent aftermarket chips will err on the side of caution with respect to air/fuel ratio to keep combustion temps down and minimise the risk of knock in the first place. With a custom chip you can cash in some of this safety for better AFR's, but to be honest the only way you are going to get as good if not better knock protection than stock is to go standalone which can better guard against knock in the first place by better tuning full stop and the ability to vary ignition timing relative to boost pressure - ie. retarding ignition at high boost pressures.

Really the only time this is a real issue is if something goes catastrauphically wrong instantaniously such that you get severe knock all of a sudden and without warning. In this case even the stock knock control might not be quick enough to cause long term damage. However this situation is unlikely to occur. Knock usually happens from using rubbish quality fuel, not controlling boost pressure adequately. All the more reason to use as high RON fuel as possible.