Engine build progress

[George Elliott]

Thom, I have e-mailed you images of the 3" Downpipe. Hope you receive them. I measured the 3" unit and compared to the O.E downpipe. Volume measurements were taken using water as per images. According to my calculations, the results are as follows: O.E D/P Inlet Dia:58mm Outlet Dia:58mm Volume of D/P:7290ml (729g) Calculated Length based on above:276mm Measured Length (+/- 5mm):302mm Average Dia, considering Measured Length & Volume: Dia 55.4mm 3 Inch D/P Inlet Dia:60mm - (matching Turbo Outlet) Outlet Dia:73mm Volume of D/P:10550ml (1055g) Calculated Length based on above:n/a as the calculated length is clearly incorrect when measured with string. This indicates that within the component there are restrictions highlighted in the results below. Measured Length (+/- 5mm):302mm (as above) Average Dia, considering Measured Length and Volume: Dia 66.7mm Conclusions: (Pls check the calculations and feel free to challenge them.) Diameter of the component is increased by 20% Volume of the component is increased by 44% (this is what counts for performance) Comments: The 3" D/P is 76.2mm Stainless with 1.5mm wall thickness, therefore 73.2mm max inside bore Dia. The 3" D/P has a 60mm Inlet matching the KKK Hotside, leading immediately to a flared adapter, and the first bend before reaching the 3" section. This provides a progressive bore increase over the first 5cm of pipe. The average diameter is 66.7mm due to the wall thickness and need to increase as smoothly as possible from 60mm to 73.2mm. The effect of the progressive increase is that gas velocity is assisted at the bend, and backpressure is less likely to arise as the pipe diameter increases. I dont have the 3" Exhaust (yet) but give me 6 or 8 weeks and it should be made / fitted I just received a message to say the e-mail has failed. (images are 5mb) - will resend one at a time. Feel free to post the images if/when you get them. regards George

 

[TTM]

Hi George, Thanks, I received the pictures. This looks like a nice piece of brazing indeed! [] The pipe diameter increasing will help reducing exhaust back pressure, but I'm not sure about velocity, as I had always understood they were reciprocal physical quantities? Could you calculate the difference with my early downpipe, which is 61mm inner diameter all the way? I'm still not in a hurry about receiving it as I don't even know what kind of 3" exhaust I could install behind it and I also have to sort out the headgasket first, which won't be before at least 3 weeks [&:]

 

[George Elliott]

Thom, thats actually TIG welding (tungsten inert gas as you may be aware). Very common with stainless fabrication. If you measure the volume of water which the D/P will contain when sealed off flush with tape at the inlet end and filled to the brim on the outlet end, then we can make the average bore calculation. No problem with the time, wanted to let you see what it looks like, and let you know its here. Good luck with H/G George 944t

 

[barks944]

I like the idea of increasing the diameter as the pipe leaves the turbo, the outlet is small on the K26/6 not sure of the size on the K26/8. I though you might get wierd turbulance etc if you just stuck a 3" pipe straight onto the turbo.

 

[os951]

Get rid of that plastic jar [] Our old version's proto here; improved version on it's way.

 

[GPF]

Hi Olli, Is this from a full kit? What does the filler look like? I have my AOS off at the moment.....

 

[os951]

We are working on it at the moment. Filler will be added to lower nipple.We also have changed shape a bit for better fitment on 951 applications. Old version worked great on n/a models.

 

[TTM]

The old girl crossed the 300,000 km mark today, or 186k miles in old money

 

[GPF]

ORIGINAL: DivineE Thom (or anyone else who has one) I am moving house in 8 days to a one room nothing and having to pay to put the rest of my stuff in storage. I chucked an awful lot out but in the process I came across some shiny hard pipe extensions I had made for the SFR intercooler. They are the same shape as the ones SFR supply but better made (the SFR ones are the ones with the visible weld in the photo). Its only a pointless fancy thing but if you want some more shiny bits I'll cut you a very aggressive deal  ..say £10 plus postage? Cost me £100 to get made. See below. p.s. do I get another golden star for suggesting a boost leak ..it's ALWAYS a boost leak.

Ben, did you get rid of all these?

 

[DivineE]

ORIGINAL: GPF

ORIGINAL: DivineE Thom (or anyone else who has one) I am moving house in 8 days to a one room nothing and having to pay to put the rest of my stuff in storage. I chucked an awful lot out but in the process I came across some shiny hard pipe extensions I had made for the SFR intercooler. They are the same shape as the ones SFR supply but better made (the SFR ones are the ones with the visible weld in the photo). Its only a pointless fancy thing but if you want some more shiny bits I'll cut you a very aggressive deal ..say £10 plus postage? Cost me £100 to get made. See below. p.s. do I get another golden star for suggesting a boost leak ..it's ALWAYS a boost leak.

Ben, did you get rid of all these?

Erm. To tell the truth I got rid of none of them as I got very distracted by my change of life and location and forgot all about it. (Very sorry I didn't get back to those who asked me for them) I'll get myself sorted out and re-post about it when I'm settled somewhere and all my stuff is unpacked. p.s. as this is the thread of shiny parts now, how much were those clutches I saw selling for? I've got myself a daily now as the 944t never really was a practical every day car so I'd consider a 4 puk clutch if it saves money over the extortionate factory item!

 

[TTM]

The head is currently off, with no apparent sign of failure on the headgasket. Raceware studs are out, new 2.7 studs are in. Lifter #4 is shot and damaged the cam lobe to the point the camshaft cannot be reused. By chance we found a late NA camshaft (9R) in my spares, so we will use this. New lifters really are c**p. I am wondering if I shouldn't install a complete series of old ones instead of a new one. On the positive side cylinder bores still look as new and there is no sign of detonation on the pistons.[]

 

[TTM]

The standard headgasket seems to be holding fine so far, and the late 944 NA camshaft seems to make the engine breathe slightly more freely up top without losing much if any low down. Migh be a placebo effect though as it's been more than a month since I last really pushed it. It's become a bit of strange drive though, far more binary than it initially was, it does require some effort to drive slowly and becomes quite mad when generously opening the throttle and unleashing the power. If it was a dog it would probably be a Sighthound - almost useless for shopping around, and running away a lot more quickly than you would want it to as soon as you throw sticks. I suppose the large intercooler is vastly responsible for the change of character. With it seems to have come some "power delivery threshold" below which the engine will drive more or less reasonably like a fast 944S2/968 and above which like a possessed animal. Transition in power was smoother with the original intercooler (and also perhaps, but to a lesser extent, with the original turbo camshaft). This rather abrupt transition in power delivery might be smoothed out a bit with an exhaust.less restrictive than the original's... and that should make it even less enjoyable to drive slowly

 

[DivineE]

ORIGINAL: TTM Might be a placebo effect though as it's been more than a month since I last really pushed it.

Excellent news that its back on the road and all running well[] I'm pretty sure the early lux camshaft is the same as the turbo and the post 86 lux has a different cam. What year is it?

 

[barks944]

I've got a couple of lux cams I could use on my turbo. Are there any identifying marks on the cam that you can use to distinguish between early and late lux camshafts?

 

[TTM]

Early Lux/turbo camshaft part number ends with 5R, late Lux camshaft ends with 9R.

 

[barks944]

Thanks thom!

 

[TTM]

You are welcome. When a headgasket is excessively torqued, shouldn't the rings suffer, when the engine is fully warmed up, from a certain "lack of room" that would prevent them to expand evenly, thus leading to improper sealing of the combustion chambers? Trying to understand why the headgasket initially failed...

 

[DivineE]

ORIGINAL: TTM Early Lux/turbo camshaft part number ends with 5R, late Lux camshaft ends with 9R.

Ahh I see you're somewhat ahead of me[] ..carry on carry on. Do you know what the difference is? We speculated that it was a longer duration with more overlap but that was a guess.

 

[TTM]

The 9R camshaft has 1mm more lift and 3° more duration on the exhaust side than the 5R, turbo camshaft.

 

[944 man]

Thom, are you still looking for a good 2.7l cylinder head? Simon