Ken's shop said that. Is 6psi correct? Be nice if it was something as simple as that! I have no doubt that the underlying cause is something that's been wrong with the car from the day I got it - just never manifested itself until the power went up.

Before the conversion I used it on track a lot and it would be right level with a 996gt2 up to around 140, which doesn't mean a lot as the Gt2 may have had issues but the car was fast. Now it's faster, but only for half the time!

 

A leakdown and compression test are different.

Like I wrote earlier, Knock retard and boost retard can be modified in the ECU mapping. It becomes the tuners choice as to what is safe and not safe based off his judgement.

Do not install a EBC on this ECU. You lose the retard functions from the ECU. This is not a apples to apples configuration.

 

Kevin, I just corrected my earlier post. I wrote "we rigged up a manual boost controller" when it should have read "manual boost gauge".

So the EBC comment you make is not relevant. Apologies. Alway write that one wrong!

 

That is a really pertinent question which sounds simple but in reality isn't.

 

Genuine question then chaps, and i'm honestly curious.... When Porsche sell a car in a hot country, let's say Dubai, and they have the Porsche figures in the brochure.... Do they tell the potential client "Yes this 993 turbo has 408 bhp on a good day, but out here where it's hot you'll be lucky to see 380, as it's so damned hot"?

I know the stock map pulls 1.5 degrees of timing at 37.5 deg-C, which increases to 2.25 degrees of timing pulled at 43.5 deg-C, then 4.5 degrees at 52.5 deg-C, and 6 degrees at 70.5 deg-C.

What does 1.5 degrees of timing being pulled equate to in BHP?
With that big engine fan, and a properly sealed engine bay, and the car traveling at speed, what would be the difference between measured static air temp, and actual intake air temp?
Do you think Porsche, with everything they know and have learned, actually sell a car that only works properly in certain countries?
How much does the stock 0.7bar (or whatever it is), raise the intake temps in a 993 turbo compared to a NA 993?

 

Knock retard will give you 3 degrees and then 6 degrees!!

Not only do we have retarded timing, but we have boost being pulled from the ECU.

Knock voltages that are present have a higher impact.

 

Hi Kevin, when would you see knock on a stock engine other than with bad fuel? Or with some other problem that is not usually part of normal running? Or does the stock ECU allow the engine to knock, and then adjust? It's interesting stuff

 

[QUOTE=JBL930;8582561]Genuine question then chaps, and i'm honestly curious.... When Porsche sell a car in a hot country, let's say Dubai, and they have the Porsche figures in the brochure.... Do they tell the potential client "Yes this 993 turbo has 408 bhp on a good day, but out here where it's hot you'll be lucky to see 380, as it's so damned hot"? QUOTE]

High ambient temperature, low atmospheric pressure, high humidity, and high altitude all effectively result in less efficient internal combustion. Talk to any light air craft pilot, about the need for careful consideration of these factors when aiming to fly near MTOW.

It is no surprise that drag strip records are usually set in winter with cold, dry air and a overlying deep high pressure cell.

The reality is though, for a NA car, these factors are significantly less relevant than with forced induction. The more your performance depends on boost, as opposed to capacity, cams, ignition, heads and valves, the more vulnerable you are, not only to reduced lap times, but perhaps more importantly to engine damage through running too hot and relatively lean, risking detonation despite knock sensors and knock control. Recall Jean's GT2 in Dubai, which was built to deliver it's HP without high boost (1Bar I believe).

Here in summer, where we frequently get very hot and very humid (also a factor as it decreases available oxygen) conditions, and as a consequence frequently see very real increases in lap times for the turbo cars compared to NA. In fact, the local Porsche club track days have changed the order of events by having the competition sprint runs now in the morning and the more social passenger and practice sessions in the afternoon so as to help reduce the porblem.

 

They don't tell them but don't have to since all they are required to do is quote DIN hp measurements ie the hp at 20DegC and std Pressure.

The 997GT2 is one of the worst culprits for this and the GT2RS is even worse, they run so much boost as standard 1.5 -1.6 bar that the power falls away as the ambient goes up.

A pal in the middle east has a 7GT2 and he loses 100hp when its 40DegC outside.... and don't even start talking about the effect of less than 99 RON fuels on these puppies

A stock GT2RS in 18 DegC ambient will see 70DegC as it enters intake with hard loading (autobahn 25 seconds ) but thanks to the expansion manifold's cooling effect and advanced/matched componentry it still manages its 620PS

 

That's really interesting, do you have any figures on a stock 993 turbo under load, comparing ambient and IAT? And then maybe on a Ruf TurboR and something like the 520ps kit from RS?

 

Remember this
https://rennlist.com/forums/993-turb...st-report.html

MOD's 530hp RS car, with standard intercooler (ambient 18DegC) IAT at full load (300+kph) was 54degC...... with Secan was 33 degC

So since this was tuned by RS for a standard intercooler you could say that their power quote of 530PS was innaccurate as IAT hits 54DegC in near DIN conditions so would have 4.5 degree less timing..... but knowing RS they factored that in somewhere since......

It all depends at this level how they calculate the correction factor, do they use ambient temp or actual IAT temp (controlled by water cooled intercooler) and if they use IAT what temp do they use for that IAT ? confusing stuff and open to interpretation, I have two sets of numbers from different engine builds from RS and they have used both different methods for correction factor as I describe above so I guess they are both "right"

Certainly makes one ponder on the futility of chassis dyno guesswork doesn't it

 

I remember the thread well.....I didn't realise MOD's car was tuned for the stock intercooler, quite surprising given the test was on a normal sub 20-DegC day, he was loosing as much as 30hp with the temps going up into the mid 50's with the stock intercooler... So 4.5 degrees of pulled timing equates to roughly 30hp on a 500+ BHP engine. Looking forward to seeing what temps mine reaches, i don't have the sealing that the stock engine bay has either, so i would assume higher, we will see...

It would be interesting to see the figures on a stock 993 turbo being held flat out with it's relatively low boost, to see how much the IAT goes up above ambient, and how far into "timing pulling" territory it actually goes.
It's clear the newer water pumpers can deal with higher temps and prevent the heads warping, and can therefore run very high boost right from the factory.

It may be time for me to talk to RC about getting some of those Marston cores welded into my cooler.....

 

Toby, your name is on one of my new dataloggers.. It would be interesting to see Jean's logs.

https://rennlist.com/forums/996-turb...ger-debut.html

 

I would be interested to hear of possible causes of excessively high IAT's. I'm apparently getting up to 15 degrees of timing pulled and 60 Deg C intake temps. Boost is being pulled too.
I'm absolutely gutted, no wonder I've always felt like I've had on / off performance.

Anyone got a standard or 430 ECU going cheap?

 

? maybe clean out your IC, make sure you have a good seal around the IC (I mean very good/meticulous seal - it makes a difference - see my new thread on cf parts).