964 Engine rebuild questions

[ALEX P]

Okay so CHT sensor checks ot fine and the signal at the ECU plug checks out fine.

Next step was to remove the MAF and I think this is where the problem may be - The flapper is sticking with about a 1/4" gap at the bottom and when you move the flapper it makes a sort of metal brushing on metal noise. It's pretty clean in there but I sprayed a bit of cleaner in there and a little dirt came out but not enough to stop it moving. If you gently move it past the sticking zone then it snaps shut.

So if I can't see anything physically stopping it from moving and it seems quite clean does anyone have any ideas what I should do to get it moving freely?

Please don't say replace it

The last photo shows it closed and the other two where it gets stuck.

Please can someone tell me how to remove the platic cover from the MAF? It looks like a sealed unit.

[NoEardGoat]

I just cleaned mine and it snaps completely closed very quickly without any "cathching" or "rubbing" feeling. I bought some MAF cleaner and used that and an old toothbrush to scrub everywhere except on the sensor itself. I was surprised how well the MAF cleaning spray dissolved and cleaned the old oil and dirt, much better than brake cleaner (which is not approved for use on MAF sensors).

[johnsjmc]

It seems to me there is something on Steve Wongs site about the construction of the air flow meter. The resistance tracks wear and can be moved on the shaft Perhaps that is the problem.

[ALEX P]

The air flow meter turned out to be the edge of the flapper that is not shown in the photos above catching when inside the AFM (if that makes sense) so it would not fully close so as soon as that was smoothed off it snaps shut freely and runs properly again.

Finally got round to making the exhaust for it. As many people have done before on here I bought a 14" Magnaflow silencer, a couple of flanges, 4 x 90 degree bends and a length of stainless pipe and set about measuring, cutting, grinding and got a friend to do the welding as it wouldn't have looked too pretty if I had done it!!

Few poor quality pics below but it has transformed the car and feels like it can breath properly now. I'm really happy with the sound and the price of the parts was a fraction of what an off the shelf equivalent would have been.

[Spenny_b]

Well done Alex!

Sorry, I posted a couple of replies back on Page1 in January, and didn't get back or acknowledge your reply, apologies.

Back in Jan I was in the "pre-emptive research phase" whilst I was hunting down my car. I'm now in a similar position with my 964T, although not driven by a breakage, I've pulled the engine to EFI it...and whilst I'm at it, teardown and rebuild the top and bottom ends....and upgrade...

Funnily enough, because the way this project is going, am also now considering titanium retainers...which ones did you go for in the end? (like you, I noticed the ones on offer from Pelican, but they're listed for use with high performance springs....I'm just swapping in some 964 n/a cams and replacing the springs with fresh stock items).

Cheers!
Spencer.

[ALEX P]

Hey Spencer, I had a good look around at the different springs & titanium retainers etc and in the end I bought them from Don at EBS although I did go for the race springs as well.

I didn't set out with the intention of replacing so many parts but when tearing the engine down the more I looked the more worn parts I found so took the opportunity to upgrade on some parts.

[Spenny_b]

Hi Alex,

Yeah I've just been doing a bit more research this evening....thinking that because mine isn't N/A and therefore not revving as high, it won't be as prone to valve float...and it's a street engine, not intending to track, plus running "only" the stock 964 cams; by comparison to other N/A cam grinds, they're certainly not aggressive in terms of ramp speeds, so on that basis, will probably just replace with stock fare...I've already just bought a load of stuff that was well and truly out of (original) scope! Arggh!!

Off topic: as you're now running a 964 motor, you planning on going along to one of the 964 London Owners meets @ Guildford?

Cheers
S

[Spenny_b]

Meant to ask Alex....that fibreglass replacement for the tinware...are you able to share (or PM) details please?

My L & R tins are "okay"...I spent a lot of time blasting them and got them powdercoated a few months ago, but you can see the pitting underneath.

The rear tin is absolutely shot, I've seen better metal on the Titanic.

Was wondering whether your man could/would do a set of Turbo items, from which I could then insulate the rear piece with heatproof matting to protect against the turbo, directly underneath it....I can't believe the cost of the replacement tin from Porsche, and of course it'll happen all over again.

Cheers
Spencer.

[ALEX P]

Hey Spencer,

I don't know anything about the 964 meets at Guildford but I work fairly close so could always blast over.

My tinwear was also in a fairly bad state, especially the side at tfront of the engine on cyl 1, 2, 3 side where the exhaust ran & it's silly money to replace.

The chap who made the fibreglass tinwear for me is based in the silverstone area and has always done the traditional stuff but may well be interested in doing something different (mine was his first 964). PM me the exact details of what you have and what you are after and I can always ask the question. Are the turbo ones much different at that end on the engine?

Cheers

[Spenny_b]

Originally Posted by ALEX P

Hey Spencer,

I don't know anything about the 964 meets at Guildford but I work fairly close so could always blast over.

My tinwear was also in a fairly bad state, especially the side at tfront of the engine on cyl 1, 2, 3 side where the exhaust ran & it's silly money to replace.

The chap who made the fibreglass tinwear for me is based in the silverstone area and has always done the traditional stuff but may well be interested in doing something different (mine was his first 964). PM me the exact details of what you have and what you are after and I can always ask the question. Are the turbo ones much different at that end on the engine?

Cheers

Hi Alex, here ya go, the (46 page!) thread re the London 964 meets...

London 964 Owners

For the first time in ages, the last meet on the 4th didn't coincide with me having my daughter for the weekend....and I forgot to check in and have a look for the next date! Not that I have a drivable car to get there in anyway, lol!

Re the tinware, I went to see Richard Chamberlain last week re some head porting work; I'd heard a few days prior from somebody else, that most folk don't bother replacing the rear tinware; "it's a pain when you want to get to stuff, and expensive"....however, Richard was saying that for the intercooler to work, the top half of the engine bay MUST be enclosed...good rubber seals at the back, tinware in place around the sides and back and the I/C sealed as well as possible to the rear lid....interesting contrast in views!

[ALEX P]

I've just realised that I never really finished this thread off so:

Engine has now done coming up to 3500 miles & is running sweet. It wouldn't idle or run properly (running rich) up until I had it custom remapped at the tail end of last year and swapped to a MAF unit replacing the stock AFM. I tried a later AFM from a friends later model 964 but it still wouldn't idle. Whether the MAF made any increase in power I'll never know but the car now drives really well and is currently on a bit of a diet!

Couple of shots below of the engine, finished exhaust & dyno curve. The torque curve underneath is an estimation that someone kindly did for me as it wasn't available on the day.

Thanks for all your help & advice along the way.

[oh snap]

Great build. Post a video if you can, I'd love to hear the exhaust setup

[ALEX P]

Originally Posted by oh snap

Great build. Post a video if you can, I'd love to hear the exhaust setup

I haven't really got any clips of it apart from a couple of it on the rollers:

MOV04625.mp4 video by ALEX-P76 - Photobucket

[oh snap]

Sounds great! Congrats and enjoy

[safe]

Originally Posted by ALEX P

Picked up my long block today, really happy with the work. Time to start getting the rest together now!

What kind of headers is this?

[ALEX P]

They are similar to the ones in the link below apart from the pipe diameter.

Porsche 911 Stainless Steel Exhaust Header 1 5 8" | eBay

They're pretty heavy, the fit isn't perfect and the stainless isn't the best quality but the price was right at the time. Sorry, I can't see any for 1.750" dia pipes.

[safe]

Originally Posted by ALEX P

They are similar to the ones in the link below apart from the pipe diameter.

Porsche 911 Stainless Steel Exhaust Header 1 5 8" | eBay

They're pretty heavy, the fit isn't perfect and the stainless isn't the best quality but the price was right at the time. Sorry, I can't see any for 1.750" dia pipes.

Ok, I have seen the 1 5/8 on ebay before, but I think I want the bigger 1 3/4 that you have.

Do you know if the dimensions refer to the inner or outer diameter? Do you remember the inner diameter of yours?

[ALEX P]

Originally Posted by safe

Ok, I have seen the 1 5/8 on ebay before, but I think I want the bigger 1 3/4 that you have.

Do you know if the dimensions refer to the inner or outer diameter? Do you remember the inner diameter of yours?

Sorry, I never saw your question!

I expect it's way too late but the outside diameter is 2" so it must refer to the bore diameter. Hope you found some in the end.

[ALEX P]

I've read in another thread that stock 964 injectors max out at around 300bhp which got me thinking about the ones on my engine - The injectors themselves are in good shape as I had them cleaned & refurbed when I rebuilt the engine but if this is correct, with the engine putting out 308.2bhp they must be right on the edge of their performance envelope.

Could they even be limiting the engines performance?

I don't really know the difference between the various Porsche injectors but it looks like they change for every different model as shown in the part numbers below.

3.2 part # 930 606 120 00
944 part # 930 606 120 00
944 S & S2 # 944 606 112 01
944 Turbo # 951 606 110 00
964 part # 911 606 120 01
993 part # 993 606 120 00
VRAM part # 993 606 122 00

Is it possible to swap them for 944 turbo injectors as I have heard that these are capable of handling more bhp?

Is there an idiots guide to injectors?

Apologies if these are stupid questions or this has been covered elsewhere. I've had a search but it didn't really come up with much.

[safe]

An injector flows a certain amount of fuel per time unit at some specified fuel pressure. The ECU "knows" this fuel flow number (cc/min, lbs/h...) och calculates how long to open the injector, this would be called duty cycle. You want to have an injector that won't have to small duty cycle at low rpm/load, that would be inaccurate. On the other hand you don't want an injector that is to small, max duty cycle should be kept under 90%.

If you just put in a larger injector you will throw the ECU off, because it has no idea that the parameters has changed. The ECU will try to correct itself based on the lambda sensor, but can only do this for a limited range 10-20% maybe (guessing) and lambda correction is bypassed on full throttle.

Basically if you want bigger fuel injectors you need to update the ECU with a new chip. Perhaps a slightly larger injector will work fine, but a proper rolling road dyno run and tuning is something you should do, money well spent!

By the 308.2 number I'm guessing you have had the engine on a dyno. If the injectors were limiting the performance it would be showing on the dyno with air-to-fuel ratio running lean somewere around max torque / max power.