Horizontal fan on a 911? LOLA PORSCHE
- Thread starter bones
- Start date
Yes: More tubes More welding...[:-]
Still welding tubes of all sorts all over this car! Techie question for some of you: Just how 'sensitive' is the 3.2 to a header system which has unequal length primary tubes? My only experience of this topic was with my hot Impreza. The Subaru has an unequal length header system which gives the uneven exhaust not of the boxer flat four. For better (marginal) performance you fit equal length and the engine looses the beat, but adds a touch more power. This is with a high revving turbo engine, not a big lazy N/A motor like the 3.2. Any thoughts? Personally I think it will change the exhaust notes, but little else, but the factory and the after market players spend a lot of effort to get the pipes much the same length from what I've seen on google etc.
bones
New member
All the info I've read on this matter points towards all tuners being in agreement that the headers on a 911 engine should be of equal length, based on my own experience of changing from a stock system with later heat exchangers with unequal length headers to a stock set of early heat exchangers with equal length headers, I'd say the improvement in performance was very noticeably better.
I think you are right as so many strive to get the lengths into the space available (which is very tight). Exceptions seem to be the turbo engines. On ebay there are some real RSR headers which are close to a 'log' manifold but the very unequal length primaries flow gracefully to the turbo collector. Several works shaped 914-6 racing headers use really long primaries which are not equal, but the length difference as a % of the overall length is probably 10 or 20% difference. The ones I've butchered are radically different, ie the shortest to the longest must be about 1:5 respectivly.... Still: could be ok for the season opener while I learn to drive the car, and then in Xmas 2009 have a custom set made. Such a pity I can't use the custom made headers that came with the engine, but simply just 70mm too deep.
All the top quality headers for the 911 turbos are equal length. It's just that the run of the mill aftermarket ones are simply as short as possible.
Significant progress today. I must have simply been in the right frame of mind. After ages yesterday looking ar the bunch-of-bananas I have resigned myself to some DIY/butchery of the stock 2.4 headers off Gary. Absolutly none of the aftermarket headers will fit. The only real course would be some custom made headers, and I've been quoted £1400 for those. I need to spend that money on other things, so a whole bunch of welding and pipe cutting and endless filing I have an exaust system that fits, lets the engine sit as low as possible and the gearchange rod(s) even stand a chance of fitting/aligning. Certainly not equal length! Plan is to silence it (what a shame) with 2 short silencer boxes either side of the gearbox. I can now press-on with the front and rear drivetrain mountings and then the gear shifter. Graham. These are ones I cannot use! Now for sale if someone is interested-cheap too. An appeal to the Site's moderators: Can we have 3 pics/post please????
How it looks 15 mins ago![&:] All that effort to get that bloody tube to appear in that spot!
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 will appear in the post. [IMG]http://img.photobucket.com/albums/v228/gary71/test2.jpg)
OK: I'll try that next time, but I've tried my usual host Tinypic and this Forum always comes back as 'too large'. Your old headers don't look too bad under the engine!
Test picture! I wish I could remember how I did the big one... There are times I hate computors...
God, these pics are a bit big! Gary:
This might be better, the camera angle can kid the eye. The angle is quite acute and a bit of a worry, but I think they will be ok. I'm using Ford sierra driveshafts/CV's (smaller than 911's) and all clears (just) even on full compression/droop. The shafts themslves are much larger in diameter than my 911 shafts, so will be tough enough. The 'modified' (butchered) manifold will do for next year. Next year will be a shake-down for car and driver, and I expect will be a bit tail heavy, so I hope it will be a bit '911' to drive as those don't scare me too much! Made the front engine mount last night using modified 911 parts. Front mounts are 911 with poly bushes (as my hillclimb Bitza) and the gearbox mounting is a choice of 2 ways. The chosen way will be determined by the gear change linkage. Just thought about using a cable to change gear instead of solid rods. That just might solve a few other issues too..... Rear uprights soon. Must get my MIG welder sorted out. Graham.
I'm not sure about norm aspirated but with turbo's the best collectors do not merge flat.
I think I know what you mean. The pipes are nearly how Porsche did the early pipes, I've had to cut the loops from them that ensure equal lengths as I couldn't get them into the space as they originally were. The 3-into-1 collectors are stock system. I am sure these are not the best way, but must do for now. The £1400 is needed elsewhere on the car rather on new pipes. Incidentally; there are some RSR 3 litre headers on ebay and certainly they are not equal length. Infact they look cruder than mine! (stock Boxter ones are much the same; 3 unequal pipes into a log type collector and off to the silencer..
Thanks for the info. These are optimal for a 911 turbo engine, but as you say they will hang lower. B&B have collectors like this and people have said they hang lower than stock and have scraped them... My GHL's are flat like yours. Even the SSI's have collectors like the stock ones [&:]
Thanks Nathan. The ground clearance is everything on this little car. The tub is flat bottomed for some 'gound effect', but will be about 40mm when set-up for the track. Not much room under there when the going gets tough (ie grassy off track!) On the Lola there are 2 main chassis rails, delicate in themselves, and the engine/headers are 20mm above them. I'm trying to get the CofG as low as possible, hence all this effort on the headers. Found details of a 70's sport racer in the States that raced/reaces with a 2.8 RSR spec. You should see the headers on that one! After 2 hours of chain drilling, filing and welding I made just one front engine mount last night.....[:'(] Same again tonight. These bespoke projects test you in several ways. Hope it all works in March 2009.[]
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Graham Looks fun, do you have the chassis number, if so you should update the Lola Heritage website, they are keen to keep track of all thier cars. I've just purchased a T492 to run in the S2000 Historic class next year, even has a full FIA passport. Regards Kevin
I wish mine looked like that! I used to post on the Sports 2000 site (where I found my car) but got 'insulted' due to me butchering the car. (true). My car came with no chassis number, has been modified in the tub area during it's very colourful history in the 80's (to say the least). Little of the suspension was Lola T492 either... Above all, they are great cars, made beautifully (till a butcher comes along), and although mine is a Lola T492, without a number godness knows about it. It might have been repaired in the past so lost the number? Graham
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