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Horizontal fan on a 911? LOLA PORSCHE

I've just read the entire thread. Yours is truly a fantastic journey and I'm so sorry I have only just found it! You have done a really amazing job to create a very special car and should be extremly proud of your achievments> I will be looking out for updates! Mike
 
Wow, that's a bit of determined action! Thanks for the kind words, but there is an even (much much) longer thread on 10-10ths with very nearly 20,000 hits. We all need to get a life! I've always wanted an Old Skool racer and had cars like these and GT40's etc on my TD folder at school an awful long time ago.
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I quite fancy a big engined 914-6 at the moment, but I do get distracted easy..[&:]
 
Ran the Lola at Loton Park hillclimb again over the weekend, and finished up taking a very early bath. On the second practice run I actually got 3rd straight after second right on the fastest part of the hill. God, for 200 bhp it sure does go in 3rd! Bit too well as on the crest of the rise the car left the track at about 70 mph, into the weeds, grass and caterpillers and into a brick wall built in WW2! Crunch comes to mind, and the Lola is a bit crumpled. took it all apart at the front and all seems ok, but damaged one of my wheels (maybe repairable) and the front of the body, now bodged back together. No other damage can be found. The Great Escape I think. Very lurid, and it snapped in a nanosecond. Not a skid mark on the track. Marshals close to by fight path said I came over the rise broadside. Time to get the suspension properly set-up I think. Shelsley Walsh this weekend with a leisure drive of competition planned. [:mad:]
 
Graham, Glad that you did not do too much damage to that lovely car or yourself! Pity that you were unable to take full advantage of the brilliant Loton Park sunshine. It was as always a great event. Regards Ian
 
Thanks Ian. I think I've found the problem this evening why the Lola is so nervous to drive. The rear bump steer was horrendous. I have got one corner now close to ideal after 4 hours of trying to understand the path of all the links. Toe-in change from full droop to full compression is now 20 mins; it was 3.2 degrees! Full steam ahead for Shelsley which is going to be wet I understand.... Loton was great, I marshalled at the top of Cedar Straight (where i came off) and watching the Porsche lads in Fallow was just so entertaining. And to think my Bitza is just sitting here waiting....[;)]
 
Great to hear you were relatively unscathed and not too much damage to the wonderful car-I can't imagine how dismayed you must have been or was it angry-but to bounce back(no pun intended ) so eagerly shows great resolve. I remember reading a fantastic book about sports car & racing car suspension set up & design some years ago but can't remember the title now-I seem to remember it was a challenge getting my head round all the theories & calculations-anyway-more power to your elbow-carry on the great work. Regards, Colin.
 
Years ago when i built American style Hot Rods I bought a book called 'How to make your car Handle' Bit of a period piece now, but pertinent to my Lola's system. After 4 hours friggin' about last night climbing my very steep learning curve I read chapter 3 in bed.[&o] And there was a little diagram and one paragraph about bump steer on racing cars with trailing link suspension.... Fortunatly, I had done exactly what it says to do! [8D] I should know better at my age and just go down the pub![:(] No chance! Got to beat these issues although at 6.00pm last night I delared it was over for 2009! Had a terrible day at work so that infuences things.[:mad:]
 
With your exhaust manifolds I would 'Guess' that the SSI's from the earlier cars were designed for performance and that the later headers as use on the 3.2 were purely for emmissions. My 'Guess' is that the ones you have are just too small a diameter, primary and secondary. IIRC you had to alter them anyway. I'm looking forward to you hopefully posting your calculations.
 
Calculations?! No, I did no calc except those to squeeze them into the slender gap I have. I have lost all the primary lengths and the pipe Dia's are those for a 2.4. I have the same headers (before my surgery) on my stock 3.2 in my 911, and the engine is perfect, vice free and fab. I have sever backfire on the car and this nearly had me banned from racing this weekend gone! Fed-up with Webers atm...
 
I mean't that I would like to see the calcs you do this time for your headers. My car does pop (bang[:mad:]) once on the over-run, usually in 3rd. Does it at Brands and Snetterton. Are you gettiing flames? [8D]
 
OK, misunderstood! I've searched Google for 3 cylinder exhaust calcs for primary length but to no avail. My plan is to base the headers on a 914-6 Turbo Thomas system if i can get it in. I will have to cut it somewhere but he has offered to loan me his prototype to try first and I can take it from there on virgin pipes. For sure the tubes will be 38mm ID! Popular theory is it is the step of the '2.4' system at the manifold/head of the 3.2 engine that is causing all the problems. There are no flames (now) but the stainless silencers are very yellow showing the heat they are getting to. The mixture is quite rich, and the unspent fuel is causing manifold explosions at anything below 4500 rpm. I have just Prescott hill to go in early Sept and then it all comes apart for checking and more work. No rest with this car for sure.
 
I thought this had the data so you could calculate? [link=http://www.bgideas.demon.co.uk/tmanual/Tm_Ch4.pdf]http://www.bgideas.demon.co.uk/tmanual/Tm_Ch4.pdf[/link] It does make sense though that the 3.2 headers/exchangers would be the optimum diameters.
 
Thank you very much indeed for this. I had found some of that article a while back but not all of it! The headers are the first job on the list that starts after the last hillclimb in early Sept (Prescott). The car now has 4 gears and reverse so that pain is out of my mind now and i can focus on 6 V important tasks for the winter and one cosmetic (the body repair/colour/scheme) Turbo Thomas has offered to help in the header dept using stainless 1.625'' od tube which matches the 3.2's port dia of 38mm assuming 1mm or so wall thickness. I do wonder how important (realy) the primary legnth is and their equality? I know there are firing pulses coming down the tubes and they should follow each other without any 'bumping' but I wonder if this is pure theory when you consider thottle openings, engine loads etc. Is the gas fow that precise? I have even thought about opening the ports to the 38mm to match the heads, but to taper these to the '2.4' engine/ssi diameter and exit to a 2'' secondary?(as ssi) There is more to the pipe dia than meets the eye as in the states most of the headers are sized for the engine capacity (which means port diameter) and if the system runs open or silenced. The pipes are larger on an open engine. I will have to think a lot more before taking up Turbo Thomas' offers or even start a diy header project again using a mass of 1.625 U bends and hours of fun fabricating tubes. When Terry ran this engine he ran it on open headers (lucky man) and the headers he hhad made were 1.75'' dia in very thin stainless and all beautifully equal length. Such a shame I could not get them to fit at the time, but I bet I could now. I doubt the new owner will sell them back to me (I swapped them for a racing oil filter assembly). Thank you very much again, Graham.
 
Graham, I only pasted a link that someone else posted for you earlier in this thread [:)] I think having equal length primaries is very important on a NA car (I didn't bother with my 930). I also think having the correct primary and secondary diameters is very important and could be based on a bhp figure. What I have no idea about is if you are better to have two silencers or whether it's beneficial to merge the two secondaries. I'm guessing it's better to have two silencers but I have never read anything about this. Twin turbos don't merge AFAIK. I have no idea about lengths of primaries, but that document has lots of info. I can't see that tapering down to the 2.4's would work, but it could be a phenomenon! I'm a plumber and that just doesn't seem right to me [:D]
 
Most racers with V6/V8/ flat engines seem to have separate silencers/bank. My particular problem is simply space available, especially the 'ground clearance' which is particularly tight. This will show itself if the primaries sit on top of each other instead of running alongside each other. This makes getting the primaries equal near impossible, and it was this that forced me to cut n shut the 2.4 headers. With a turbo driven engine it seems to matter little. My Impreza 's headers were very un-equal, maybe 4:1 difference in length. This gives the Impreza the engine beat that is so unique to that car. 400+ bhp is easy out of a 2 litre Impreza engine. The carb engined motors depend on natural flows and balance, and I seem to have disturbed this on my 3.2 big time. Sorry to have forgotten the link in my own thread! There are so many threads on this car, it is easy to miss the obvious.... Tonight I've lengthened the gear lever and the change feels so much better with the extra leverage now. This might improve things for Prescott soon. Just the rear brakes to fix and a bit of cosmetics and the car is ready for it's last run.[8D]
 
Just looked at some 993 stock headers on eb@y. Am I right to think that the 993 pipes are a match for the 3.2 heads? The primary pipe lengths are certainly not equal, but at best could be multiples of the shortest, but that is a guess from the pictures that I cannot copy across. Any thoughts?
 
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