ras62

Agreed on a £15k+ engine Motec starts to look more cost effective.

BTW you don't have to scale the Motronic for MAF, there is an alternative system where signal conditioning is used so the MAF works with Motronic 0-5 volt input.

alexjc4

True, a lot of the MAF replacement systems use some variant of a "piggy back" controller or interceptor to map the MAF voltage to the equivalent AFM voltage before it reaches the ECU so the ECU sees the same "curve" as the AFM would have given. BUT life's easier if you can directly replace the transfer function inside the ECU that maps x volts = y air flow, which is something people have figured out more recently - originally this wasn't thought possible because of the odd way Bosch chose to do describe the function with three tables and a formula rather than just a single table as is often used.

You do come back to the issue that the MAF is measuring Air Mass and the AFM is measuring Air Flow, as far as I can see this means you need to cancel out some adjustments the ECU will be making to turn Flow into Mass so it can correctly meter the fuel. Ultimately the AFR is determined by Mass not Flow. For a given Flow you will have a varying Mass under different conditions (temp, pressure, humidity).

You can create a ROM for the standard Motronic that will properly use a MAF and allow you scale injectors so you can pass through the ceiling you come to when you max out the injector duty and max out the AFM (around 320rwph i believe - not sure on that). The unavoidable Motronic three part map, for three throttle positions is a bit clumsy still, and in an ideal world sequential injection and wasted spark with individual coil packs are so much nicer than what you get in the Motronic.

WRT what people advise and like to use and even swear by. My casual observation is that NA race car tuners like to start with Aplha-N (throttle vs RPM) and work from there. Road car tuners like to start with Speed-Density (MAP sensor) - there's something reassuring in the certainty of a empirically derived VE table and explicitly set target AFRs. Ricers like me are happy with an easy life using MAF and reading the AFRs of a wideband lambda sensor.

KaiB

Thanks Colin for the effort. You shouldn't have to justify anything at all.

The above is almost precisely my experience, given the difference in prices here. Add to this the EXPERIENCE and EXPERTISE shops such as yours, Rothsport, Ring and precious few others offer which gives our engines the magic they have.

I can tell you that the mapping of mine took quite some time and was done by one of the best in the country.

NineMeister

Thanks.

The prices up above were not to justify what we charge, more down to showing that you have to compare eggs with eggs and omelettes with omelettes. You can fit a Motec ecu without the injectors and the other 9m parts and you will get 305hp from a typical 964RS. You can remap the same car on stock Motronic and achieve 305hp. You can also fit a MAF kit to the Motronic and achieve 305hp. Spot the trend yet?

NineMeister

Or you run hybrid Alpha-N/MAP which gives a rock solid idle that pulls 5th gear at zero throttle and provides the benefits of both strategies.

boxsey911

+1! I don't see what good comes out of having a go at someone for making a living. If none of the Porsche independents made a living out of what they do and they all went bust, most of our beloved 964s would soon be on the scrap heap. These sort of guys play an important role in keeping our cars going and I for one will continue to help support them.

FeralComprehension

+964. I'm pretty much a ***** once you **** me off; if I was on the receiving end of such 'criticisms' I'd be markedly less inclined to share my hard-won experience for free...

If the experts we have available began to jealously guard their knowledge and stopped sharing it so graciously, we'd be flat out f'd.

Be nice to the guy that gives you something good merely for the asking.

SuperUser

Agreed, thanks to all

Chris Buckenham

Colin,

Thanks very much for your information , I have found your posts on this forum very interesting and informative. We recently bought a one owner 964 which my wife loves. It was either that or a VW camper. I could not abide the idea of somebody else's camper restoration job so the 964 has been brilliant in placating the Wife. She loves the car and I am very happy to have another Porsche to look after. I have been using this forum for a few years as a 928 owner and appreciate the input of some of the specialist experts out there like you.
Chris Buckenham

Chiefyb

Porsche makes cars as powerful as is practical. To get more takes some real talent and some blue sky thinking. In my experience there is a justified price to pay.

StanUK951

In Strega's defence I think he's making a fair point...

I make the math 18 hours total labour time, worst case. If the flat rate of £1000 is used that is £55/hr, which to be fair is a very competitive garage labour rate for any marque, let alone Porsche.

However, when I get my garage bill it is based on time and materials. The only costs on my invoice are the labour time charges and the prices charged for parts. No overhead costs, so one has to assume these costs are included in the labour charge, as labour does not cost anything near £50/hour...

Am I missing something?? I don't know what 9M charge for Motec but I'm interested as I would like to do this on my car one day. I think they are entitled to charge what the market stands and Colin makes a fair point with respect to development time. Expertise should and rightly does cost more than someone who doesn't put as much emphasis on quality.

If the cost is £4500 I'm sure Colin will justify, even if it is just to say that's what he charges and therefore that's what it costs... Although I did think the Motec kit costs more than £1k...

NineMeister

For the record Stan, our dyno rate is £75 per hour and workshop rate £60. Each motec job takes us at least 20 hours total.

StanUK951

Apologies - my above post was mis-timed, somehow pages 2 and 3 of this thread were not visible so I was really replying to KaiB's first post. Sorry!

I think the above still stands but Colin has justified his pricing (although I agree he shouldnt have to as such, though I certainly have to in my line of work and take no offence from it - and neither has Colin).

Colin - hopefully I will be able to get my car to you one day for this upgrade. What power output do you expect from a standard fresh 964 engine.

NineMeister

Thanks Stan, we would look forward to seeing you. The results below show two typical Motec upgrades vs remapped stock Motronic, no further mods other than the 9m Motec package.

As for the obvious digs at our pricing, whilst I'm not offended it does sadden me that these points are raised on a public forum without the thought to what constitutes the full scope of a professional conversion and how difficult doing that job actually is.

StanUK951

Hi Colin - sorry I hope you didn't think I was having a dig at your pricing, I tried to be at pains to say the opposite.

KaiB made the point that the £1000 for labour didn't include overheads. I suppose my only point was if it doesn't include overheads, where are they?! The labour rates in my business include, the employees time, overheads such as insurance, business rates, taxes, etc. and of course profit, which is not a dirty word.

I think you are entitled to charge what you like and by making the comment that I hope to bring my car to you one day I was kind of saying I think you're charging a fair price for your vast experience in this product.

Hope that clarifies. Thanks!