Special getting closer...

911hillclimber · Post by **911hillclimber** » Thu Jul 14, 2011 6:16 am

Thanks for the thoughts Bruce.

Before my custome made (DIY) manifolds i has 2.4 early headers cut and shut beyond recognition, no even lengths no nothing and 40mm webers on this same engine.Same filters too, new K&N filters.

Car gave very similar feel to power as the engine does today!

The primary lengths and diameter are from various test books etc before i started the build of the headers, and the filters have done about 30 miles of track driving.
When we took the filteres off last race meeting I took 0.9 sec of the run, but that could readily just be me driving harder.

I now have 500mm extensions to the open pipes ready to try. This increases the manifold length by about 30%.

Many race cars have manifolds to 'my style' headers but the 906/908 etc had megaphones too.

I'm looking at straight Jetex headers now. Circular, re-packable and very stright through, 400mm long.

911hillclimber · Post by **911hillclimber** » Sun Jul 17, 2011 4:01 pm

So! This is how the car will possibly race next. I have however been advised the silencers that ran on this engine just might come my way and they certainly will be modified and fitted.

Next race is Shelsley Walsh in late August!
Soon be Xmas and I'll be wondering what to do next.

could be my classic Lambretta..

MikeB · Post by **MikeB** » Sun Jul 17, 2011 5:14 pm

So off the the rolling road now, Graham?

Hope you get your silencers sorted, can't see your current pipes passing the sound check, though I'm sure the spectators would love it

911hillclimber · Post by **911hillclimber** » Sun Jul 17, 2011 5:48 pm

110dB!
Sounds great, scared the paddock when it started up...

Looks/sounds even more like a Targa Florio now.

Yes, down to Bobs soon. Mike Bainbridge has loaned me an SC dizzy and a Permatune black box/coil which will be interesting if Bob gets as far as the dist.

911hillclimber · Post by **911hillclimber** » Fri Jul 29, 2011 6:22 pm

Couldn't risk getting to Shelsley Walsh on open pipes and be banned, so found the original silencers off this engine when it passed at Prescott about 10 years ago!

After some skuduggary it is done.

Sounds so different, very deep and low, snappy throttle and settles to a steady idle very quickly.

Interestingly, the engine is still hotter on one side so down to Bob's soon.

Alex Postan · Post by **Alex Postan** » Sun Jul 31, 2011 3:38 pm

It looks better as well.
A silly question...how do you hold up the rear body when you fiddle about at the back? Straps? props? or is it an old broom handle?

911hillclimber · Post by **911hillclimber** » Sun Jul 31, 2011 4:39 pm

I've used all three, but favour the VERY hi-tech method of an old bit of Axminster across the floor at the back and swing the rear clam body over centre till the tail rests on the carpet. Massive access.
For big jobs I remove the rear and rest it on the front.

HiTech indeedy!

I have damaged this rear body nearly as much taking it on and off a godzillion times than when i crash the thing...
I want to pivot the front section this Xmas, but toying with a new body in Porsche Burnt Orange as a 3 piece, rear as is, centre section and a much smaller front nose.

This will make scrutineering so much easier.

Anyway:

'Drove' the car on the tight driveway this morning to check the box is ok. It wasn't at first till i did the final tweek on the selector position and now all seems fine.

Next task is to check the jets are the same both sides to try to explain why one side runs hotter than the other.

The plugs are all the same black colour.....

Alex Postan · Post by **Alex Postan** » Sun Jul 31, 2011 7:20 pm

Tin ware inside the cooling ducts? Airflow different from side to side as a result of the spin imparted by the horizontal fan?

911hillclimber · Post by **911hillclimber** » Sun Jul 31, 2011 7:58 pm

Engine has the stock 3.2 cylinder vanes, but the custom top fan housing is without any vanes.

the difference in temperature after say 5 mins running on the new silencers is one side you can hold the silencer body (aluminium,) and the other you can just touch it without risk of pain

I would say 40 deg C difference.

The exhaust gases are also noticably different with your palms up close to each outlet of the silencers.

Alex Postan · Post by **Alex Postan** » Sun Jul 31, 2011 9:44 pm

That does seem to indicate different combustion side to side.

Captain Ahab Jr · Post by **Captain Ahab Jr** » Tue Aug 02, 2011 9:30 pm

cooling fan distribution sounds like a good cause of temperature differences to me. Why not buy a few packs of temp. stickers and dot them around our engine or borrow a infrared temp. sensor gun thingy.

At least that way you can narrow down where the difference in exhaust temp is coming from.

Out of interest what size and capacity is your dry sump tank and do you know who made it?

911hillclimber · Post by **911hillclimber** » Tue Aug 02, 2011 10:23 pm

Bob has a thermal 'gun' with a laser pin-point position sensor so will 'look' everywhere.
This temp difference is all after ticking over. It is much the same after a full blooded run.

I think it is the jets on one side to the other. will look this week.

iirc the dry sump tank is 10 litres made by Think automotive in the UK.
It splits in half for cleaning.

Stock size but custom fittings, -16 at the top and a huge -20 outlet.
All other parts of the system are from Smart Racing or elephant in the USA.
Found any UK supplier worse than useless.
Smart were brilliant, ordered and on my doorstep in 56 hours.

IanMcLeod · Post by **IanMcLeod** » Wed Aug 03, 2011 8:37 am

As you are running an independant exhaust on each bank then you can stick an exhaust gas analyser in each one and see if one is running lean.

Ian.

MikeB · Post by **MikeB** » Wed Aug 03, 2011 8:47 am

Hey Graham

You've been talking about these jets for weeks. Must take a whole two minutes to pull out the idles in a set of PMOs !!

I think you're starting to show a lack of commitment here

Now get out there with a stubby screwdriver and tell us what's in each bank !!!

haasad · Post by **haasad** » Wed Aug 03, 2011 1:10 pm

I too wonder whether the flat fan and shroud are causing the temp difference which is so evident at idle.

When she's all revved up the air velocity and volume being shifted will be so much higher that any areas recieving less than ideal cooling at idle will not matter.

I'll bet the idle jets are the same ( but happy to be proved wrong)

andy