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Engine build progress

A very important part of my cars spec aswell is the suspension,rebuilt LSD and bigger callipers with Pagid pads,no point building a quick car without paying attention to the components that put the power down and bring it to a halt..
 
Quick update. No progress on Sly's new engine, it's still apart. Holidays, hot Summer, not warming at the idea of spending hours in a very hot garage, etc. You get the picture. Things may get back on track as days will get colder. On my engine I eventually have the settings for the closed loop boost control pretty much sorted. Running a solid 1.2 bar of boost with no knock at all even in the unpleasant heat we had last week, and with the current ignition map I see 1 bar no sooner than 3400 rpm with the new GTX30 turbo. The SPS turbo definitely offered a more frantic spool and a more exhilirating power delivery as it would reach 1 bar of boost at as low as 3000 rpm and offer epic performance up until 6000 rpm, but now with the GTX turbo the torque kicks in at 3500 rpm and really begins to push from 4000 rpm to whatever RPM I feel like revving it. The engine feels less stressed, probably just as fast but without feeling it. So the GTX turbo may have shifted the power band about 500 rpm higher, which I can't really exploit at the moment, as even though it seems to blow more air in upper revs, confirmed through datalogging by a very slightly leaner AFR, and especially at "very high" rpm such as 7000, where the engine feels happier presumably thanks to less exhaust back pressure, the standard 951 camshaft certainly prevents the engine to deliver as much power as it could. The plan now is therefore to try a more aggressive camshaft to maximise top end performance. I could try advancing ignition timing but it feels counter-productive to me with a camshaft that remains the limiting factor. To give a rough of idea how all this techy stuff translates in how the car drives and feels, with the new turbo it's now deceivingly fast, a bit like the clinical efficiency of a standard turbo 250 with of course the power and torque curves much scaled up, while with the SPS turbo it had the urgency of a chipped turbo 220.
 
Not even. I am thinking the new intake with the standard cam would be a total nonesense, so will replace the camshaft first.
 
Yep, just scrolled back a few pages to check and came to that conclusion too. I did briefly run a bigger cam in a previous 3L build and while admitting to a fair amount of inexperience back then, my recollection was that the motor just wanted to keep revving. It had a worked head and lighter flywheel too. My take is that a bigger cam will bring more uniformity of your overall engine, it will definitely 'need' to be driven in a somewhat more 'race' manner. I would think that the extra .500cc should help redress the balance, but you've been driving a 3L so it's not as if you've come from a 2.5L and stepped into this build. You will feel the extra lag a bit for sure...but you will also get used to it without thinking about it and really enjoy your new top end....at the expense of the extra fuel you'll be using! [;)]
 
Patrick, now that I have less exhaust backpressure to work against, I suppose I can advance timing a fair bit in the spool up area, which may help the turbo reach 1 bar a bit sooner. Tom, this is a standard GTX3076R with a Tial turbine housing. Had to grind the engine mount, use an adapter, cut and weld exhaust tubes. It's not a big deal for someone who can weld with either a MIG or a TIG welding unit, just have to have some spare exhaust tubes of the right sizes... but then I will admit this is easy to say once it's all done! [:D]
 
Took no picture that shows any more information than what was posted elsewhere on the web already. See this thread for comprehensive pictures.
 
Nothing much to say except it's good to be able to sit in the car, turn the key, go for a drive and drive the hell out of it without even needing to keep an eye on the gauges... Running 1.2 bar with an AFR of 12.5 and it doesn't even detonate, along with very reasonable EGT and IAT levels - gotta love a properly powerful spark and globally desrestricted engine... la la la ... Oh happy days... [:D]
 
That's great news Thom... sounds like your having fun... As to George's question I'd also be interested in seeing some times although I'd be more interested in your 1/4 mile terminal speed rather than the time. 944's are not that quick off the mark, they tend to bog down but once they are moving not much can match them let alone beat them. As an example some years back with less mods than I have now I did a 14 secs 1/4 mile.. not much quicker than standard, so pretty slow although my rear shocks were completely shot as confirmed by a picture taken during take off. It looked like the space shuttle, it had sat back so far on it's haunches ..lol... The point is though that it covered the first 1/8 of a mile very slowly, due in part to my bad start (I never rag it off the line) and also the bad suspension, however the next 1/8 was a different situation altogether and although it crossed the line at 14 secs it was travelling at over 110mph. The point to all this rambling is that the 996T does the 1/4 in 12.5 secs so 1.5 seconds faster yet is only doing 112 mph terminal speed meaning that soon after covering a 1/4 mile distance my car would fly past a standard 996T... interesting don't you think... just imagine what it would do with 450 bhp....:) regards Pete
 
George, a steady cruise on the motorway (130kph) returns 28mpg, and driving on B roads at reasonably enthusiastic speeds with the occasional full throttle stab seems to return between 20 and 25 mpg. I tend to avoid smaller country roads these days because the car is fast enough off boost already to become somewhat of an uncomfortable drive on roads with little frontwards visibility, at least considering my limited driving skills. Pete, under full load the rear end brakes loose in 1st and 2nd gear even before I hit full boost, and I occasionally get wheel spin in 3rd too, so it looks like it would take a lot of practice to perform clean standing starts. I am not really interested in installing some traction control system either, as I want to retain some "fear factor" to avoid having to recover the car should I lose it at excessively high speeds. This is one of the reasons why I stick with standard tyre sizes too. It may not be the most scientific approach to making both a very fast & efficient car, but I am not interested in turning it too far into a boringly/effortlessly fast car like a modern one. That said, a figure I can give you now is that with the SPS turbo I measured 100-200kph (62-124mph) at 9.0s flat, at least through ECU logging. It may not be as precise as a GPS but for now I have no other way to measure acceleration. Since I have been advancing ignition timing with the new GTX turbo I suppose I could trim a couple of 1/10s off, but I would have to measure it again to make sure. I'm not aiming at properly measuring the car yet as the engine runs out of breath above 5500 rpm, certainly because of the standard camshaft. While the turbo seems to be in its sweet spot up there and blowing a lot of air, the engine seems unable to turn all that air into power and revving it beyond 5500 rpm is just useless. Ultimately If I can get around 8.0s for 100-200kph I will be happy. For the past month I have been trying to spec a camshaft profile with Jon Milledge but the guy is not the easiest to communicate with. That is the missing part of the puzzle before I commit to take the car on the dyno.
 
Pete - (great to hear the Spirit in your answer [;)]-keep it up pal) , TTM thanks for the comments, we have similar objectives for our 951's I think. The difficulty off the line is unavoidable, good traction combined with initial low torque, then rapid high torque delivery, not easy to modulate, with just a LSD to help. I have a Motorsport Clutch which I like but the heavy 500hp tuners would probably laugh at it, they could be right. Anyway - for daily use the 0-20mph is not important. But for Quarter mile times ....its VITAL [:)] CRITICAL[:D] 28mpg is good. the 100 to 200 time is not familiar to me, but 8 seconds - thats locked into my memory....[8|] I dont know if you would recognise an iphone app dyno results [8|] ...but I'm seeing around 14.5sec and 114mph on track following a less than ideal off the line. 60 comes up in 5.8 sec's. I intend to go back and and try a few more runs. There is a great satisfaction in having a good general use car that is quick, economical, tractable, that must be the goal for a daily driver. TTM, the cam subject facinates me, Milledge seem to be highly regarded, I am aware of similar tailing off of the power development above 5000rpm. My quarter runs involve a change-up at about 5700rpm. If I knew what to ask for, I would be interested in a cam to fix this. ( did you ever drive a 996TT with variable cam timing - incredible ) I suspect my head has been skimmed, and the cam timing is out, my old 944t was slightly better in this regard from memory. Barks showed me a vernier adjuster on his 951, good idea I think. George 944t
 
Hi Thom You seem to be very much in my camp of thought for how cars should be, I also loath traction control, I prefer standard rim sizes and the tyres that fit them. although I will buy the best tyres that I can find, currently IMHO Goodyear F1's as they have so much grip in the wet. I'm also anti ABS, if it comes on your already taking longer to stop than you would do if braking properly. I have used an app that records the cars speed using GPS, I know some will say they are useless but I disagree, some are surprisingly accurate and who can argue with a GPS log? What I'm not so keen on is the bhp predictions that some apps have, there's to many variables which are mainly unknown to take them seriously, however the acceleration times and speeds achieved are very accurate if based on GPS. On one such test I recorded 0-100 of 10 secs and 1/4 mile in 13.16 secs, although I had backed off before reaching the line... it er.. wasn't on a drag strip hence why backing off.. say no more sir..:) this was after fixing my suspension issues which had been slowing my launch down more than one might think. regards Pete
 
Just thought I would bump this thread for a little update. My engine has had a loud valve train since the beginning. It has munched several camshafts and a bag of lifters, and if odd-shaped Ti valve spring retainers were diagnosed faulty because they kept hitting the lifters and destroying them thus the cams, now with std retainers the valve train is still a bit noisy, more than it should. I preloaded valve springs as through the (relatively dubious) method described in the service manual and rechecked installed heights as I last had the camshaft housing off, which are all correct. At this point the only possible reason left I can think of is that these valve springs purchased then new from Porsche may actually be a fair bit stiffer than they should, causing that hammering lifter noise. Does that make sense?
 
ORIGINAL: TTM Just thought I would bump this thread for a little update. My engine has had a loud valve train since the beginning. It has munched several camshafts and a bag of lifters, and if odd-shaped Ti valve spring retainers were diagnosed faulty because they kept hitting the lifters and destroying them thus the cams, now with std retainers the valve train is still a bit noisy, more than it should. I preloaded valve springs as through the (relatively dubious) method described in the service manual and rechecked installed heights as I last had the camshaft housing off, which are all correct. At this point the only possible reason left I can think of is that these valve springs purchased then new from Porsche may actually be a fair bit stiffer than they should, causing that hammering lifter noise. Does that make sense?
Click to expand...
Have you replaced the cam and lifters since the new springs were fitted?
 
Hello, As my engine is always undergoing some kind of evolution, here is about the latest addition : an aftermarket intake manifold. On a local flow bench, it returned flow values about 20% higher than a standard intake manifold. On the road, this increased flow is verified at upper rpm as the engine runs a little bit leaner, and apparently breathes better as the engine has never felt as happy to be revved - makes you wonder if this is still a 944T engine [:)]
B2700F8008B843CAAD01F9096312E8B5.jpg
 
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