Lets put the record straight for once....

For anyone reading out there I am Colin from 9m Racing (formerly 930 Motorsport)and I am fascinated by all the "misinformation" that is banded about so hopefully this will go a little of the way to helping you all decide what actually works and what does not. As a Professional Engineer the only person that I ever have to prove anything to is myself, you all can make your own minds up!

The following is based entirely on fact, from testing cars at our own test facility and comparing results in black and white. Anybody who wants to see these results is welcome to visit our premises and see for themselves but sorry, I'm not posting them for the competition to "borrow".

We work primarily with the 964RS, but the results are directly applicable to the standard 964, the engines are basically the same.

The best 964RS engine that we have tested fitted with the ubiquitous chip, large throttle body, K&N, cup pipe & cat bypass ran on the rollers at 290bhp. The last one we did (last week) came in with 287bhp @ flywheel and 254bhp @ wheels. This is pretty much in line with most RS engines, we have tested over 10 in the last year and all have posted between 280 and 290bhp.

I have tested two cars with a mass flow conversion, Tony Taylor's 964 and a 964RS. Both had 298bhp, Tony's with the AMD conversion with early cast alloy manifolds and the RS with a.n.other conversion and plastic manifolds with a larger throttle body.

We have results for three Motec conversions; the first one gave 324bhp and 400Nm (290bhp @ wheels) with K&N airbox, large t.b., cat bypass & cup pipe; the second one gave 310bhp & 395Nm with same parts and an engine that has 8% cylinder leakage (probably caused by the overfuelling a.n.other mass flow kit); the third one posted 318bhp & 398Nm (288bhp @ wheels. Other cars that we have done have not been dyno'd but had exactly the same performance on the road.

The only definitive consumption figures that I can quote is for two RS's: with the RS that had the a.n.other mass flow kit the owner averaged 22-23 mpg before motec and 26-28 after, and used 25% less fuel with the motec fitted on a typical Knockhill track day. Another customer with Motec and a supercharger on a 964RS averaged 30mpg at 80-90mph & saw no appreciable increase in consumption overall even though the engine had 355bhp & 445Nm. Draw your own conclusions here.

Now for the interesting bit. Our standard MoTeC package for the 964 consists of an M48 3DFISA ecu, 9m Racing adaption loom, Throttle pot, air temp sensor, MAP sensor & larger flow Bosch injectors. Optional parts are 9m Racing/K&N intake kit (airbox replacement), larger throttle body, cup pipe & cat bypass. A typical installation costs around £4000+VAT including dyno time.
With the options fitted our first ever conversion posted the 324bhp, without the larger throttle body the last one gave 318bhp (Q: why does a 300bhp engine need a larger throttle body??). With standard injectors at std fuel pressure you have to run them continuously to get around 300bhp, no ecu can help here it is simply a flow thing. The 964 injectors on a 911 3.2 with Motec at 964 fuel pressure would only give 259bhp, but our larger ones gave 264bhp. There is more info but I think you can paint a truer picture from this little lot...

Last comments on other posts:
MoTeC software is free, the mapping lead for the M48 is £125+VAT, our maps are password protected and not available to anyone outside of my business without agreeing to a user licence. The maps are not for sale. We do not sell MoTeC kits, we fit them all ourselves, period.

And finally we have not done a standard 993 engine yet, but we struggle to get more than 322bhp & 390Nm from a standard 993RS and I am sure that it is down to the design of its varioram system and the intake port sizes. All 964 oners can now smile at the wisdom of their
decision..

 

Thanks Colin

QED I think!

 

Just another thought....

Idle control with light flywheels.

Anyone who has driven a 964RS knows that the idle is erratic at best and stalls all the time at worst and that the problem can be intensely annoying. I have concluded (rightly or wrongly) that the cause is poor fuel mixture response of the standard installation.

As I see it the insensitivite air flow meter is not fast enough or does not have the resolution to cope with the rapid changes in speed due to the reduced rotating inertia. The poor idle valve opens and closes to try to "catch" the engine, but these responses cause the mixture to swing lean/rich even more and hence exagerates the hunting until it eventually stalls. Steadying the idle using the throttle helps, as does bypassing more air past the throttle plate to increase the basic flow and reduce the demand on the bypass valve, but it really is a nasty compromise. I have no access to the Motronic maps so I cannot comment on the possibilities of tweeking the idle or on the finer points of the control maps, perhaps someone else can help here, but the bottom line is that the darn things stall for fun.

Now for the good bit:

Some of you may be wondering why we add a MAP (Manifold Absolute Pressure) sensor to our Motec conversion when the engine does not run boost? No?
Well we connect the MAP sensor to the plenum (after the throttle body) and add MAP correction into the fuel table so that at idle any sudden air pressure (read air flow) changes are instantly followed by the MAP fuel table and so air/fuel mixture is held constant. Combine this with accurate control of the idle stabiliser and the result is a rock steady idle. We have seen no more than a 20 rpm swing during normal driving conditions with this strategy. Indeed, the 964/supercharger/motec car would drive up to 5th gear AT IDLE and then pull away at full throttle without complaint.


Secondly, because the MAP correction works continuously at all speeds and throttle positions, the engine is incredibly smooth and efficient at all times, hence the improved fuel consumption that we have experienced.


Anyone need to know any more or can I go to bed now?

 

Thanks for that Colin. Though I am new to Porsche ownership (964 RS), I am very familiar with the theory you talk about in your informative postings (I am also a professional engineer, specifically in the powertrain development field). During discussions with work colleagues, the erratic idle that I experience and you discuss has been a hot topic. I was therefore very interested in your route cause analysis, and it does sound the most probable cause. With only generic experience of the early Bosch Motronic engine management systems, and before reading your above posting, we wondered whether it was due to the fact that the airflow meter flap spring had been ‘unwound’ (if this was possible) in order to offer less resistance to flow. A modification of this nature would explain the poor control of idle speed. I have yet to check this, so would welcome your thoughts on whether you have ever heard of it being done or if it is indeed possible.

Prior to reading your comments on Motec, we had previously agreed that an aftermarket speed density system was definitely the way to go!

Thanks.

Andy P.

 

 

Re;stalling,
My C2 has just had a RS LWF/clutch fitted (by 9M) and the stalling is an issue.I have noticed stalling occurs when the engine is not fully warm or if I just touch the throttle at idle, and the car needs more revs to set off and I can`t trickle along at tickover in traffic anymore.The latter two cases are not really due to idle control and I suppose I can live with the former as the problem disappears when the car is warm.
The airflap meter may be part of the problem in the RS since I have a MAF and the idle is steady if left to its own devices. I wonder if the 993RS, which also has a MAF, has a stalling problem?
Colin also mentioned cylinder leakage due to overfueling with a MAF kit, which concerns me (as I have a MAF) and I wonder if he would like to comment on the possibility of the same occuring on my car.

 

[quote]Originally posted by NineMeister:
<strong>
And finally we have not done a standard 993 engine yet, but we struggle to get more than 322bhp & 390Nm from a standard 993RS and I am sure that it is down to the design of its varioram system and the intake port sizes.

</strong><hr></blockquote>

Forgive me for barging in here but...varioram on a 993 RS engine???. The 3.8 RS engine does not use varioram much like the 94-95 993's. Mine is a 95 and I do not have varioram...

<img src="confused.gif" border="0">

 

Danny,
Yup, varioram. Mine is a 95 993RS CS and it has the standard (for Europe) RS large bore varioram intake manifolds, power is rated at 300bhp 350Nm standard. Are the US cars different??

 

Tony,
I cannot comment on the AMD system and overfuelling, but I an SURE that JEff would not send a system out that was over rich at low rpm high throttle and part throttle like the un-named system we removed to replace with Motec.

Regarding idle, an adjustment of the throttle plate will help so that the bypass valve is forced to CLOSE to maintain idle at normal temp, so that the engine will settle to a fast idle then come down, not a slow idle and rise up. You can do this with careful re-adjustment of the throttle plate position and switches, but it really a bit of a frig of the system that seems to work ok. If you are unsure of what I am on about, leave well alone or book it in!

 

AndyP,

The barn door flow meter hardly moves at idle, so how can it tell if there is a miniscule change in flow? The mass flow is better but are we expecting too much as we are talking tiny changes and the flow signal gets to the MAF after being damped by flowing through the bypass valve or past the throttle plate.
You are right, the best method is to look at actual manifold pressure to deduce the air density in the plenum, not at a signal arriving after the event.
Me, I'm not clever, I found this out by trial and error on the first Motec RS conversion that we did, I never thought about it beforehand until the bloody thing stalled!
Incidentally before anyone subsequently questions the mapping costs of Motec, please understand that I did this first engine from scratch over and over with four different strategies before finding the best one, i.e. MAP correction on alpha-n, and that work represents around three man weeks plus rolling road costs. Then I spent two weeks looking at cold start plus another week on bypass valve control & testing. Somebody please remind me why I do this for nothing....

 

[quote]Originally posted by NineMeister:
<strong>Danny,
Yup, varioram. Mine is a 95 993RS CS and it has the standard (for Europe) RS large bore varioram intake manifolds, power is rated at 300bhp 350Nm standard. Are the US cars different??</strong><hr></blockquote>

Do not know! In the US varioram cars came for the MY96 to 98. Mine being a 95 does not have varioram...
You lucky guys over there!!!

 

Colin

I take it your flwhell figures where calculated on the rolling road using coastdown losses?

If so, may be worth looking at this site:

<a href="http://www.pumaracing.co.uk/coastdwn.htm" target="_blank">Puma Racing Coastdown losses page</a>

His other bits, on rolling roads and particlularly flwheel lightening are quite enlightening.

 

John,

I basically agree with the information on coastdown losses referred to in your link, but I have to say that the differences in the calculated losses have been much closer in all the tests that I have done on 911's than the link suggests. Anyway, that is not the point that I am making.

What I said was that the only meaningful results that I have achieved is in comparing the results of the same car, on the same rollers, in the same gear, tyres, tyre pressures, etc, etc. Take the results and look at either the rear wheel Hp or the corrected & calculated flywheel Hp (whichever you prefer) and draw your own conclusions from there. All I know is that the last Motec RS conversion I did came in with 254/287 (wheel/flywheel) and left with 288/318 so either way we gained 30+bhp. The car went like a rocket and the owner was delighted.

The bottom line is that if you want an accurate measurement using an engine dyno is the ONLY true way to measure engine power, but how many of us want to take your engine out to measure every change? Still, I am looking at putting an engine dyno in soon.......

 

Agree entirely. Same dyno, wheels, gear etc - gives comparative assessment, which is the oly important measure when installing upgrades.

Look forward to handing you some of my hard earned soon!!

 

[quote]Originally posted by johnfm:
<strong>Look forward to handing you some of my hard earned soon!!</strong><hr></blockquote>

Hey, what happened to doing it yourself?