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Re: Birth of a rally car

Posted: Fri Jun 22, 2012 10:24 pm
by 911hillclimber
Interesting, mine had to be tight to miss the race car's chassis which is just 75mm off the deck.

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Re: Birth of a rally car

Posted: Sat Jun 23, 2012 1:08 pm
by pht9
Yes, yours is much more compact, as you found its quite hard to get the lengths equal. I think you would find better performance optimising the three into one merge, but to do it properly you would possibly lose some ground clearance, but I guess you already considered this point....

You have a very nice car there, must be amazing to drive :)

Re: Birth of a rally car

Posted: Tue Jul 10, 2012 3:07 pm
by pht9
some further updates to report

For the Tour Britannia event, I ran a 3.0SC engine with 964 cams and a set of Weber carbs, it was always planned to fit a really trick 3.0 MFI high butterfly engine using period RSR parts. This has taken sooo looong :banghead: to accumulate and source/fabricate all the specific parts, but we are now getting there

I will document the engine build a little later, but it was a moment of joy recently as I now have all the intake system parts ready to install on the engine. The parts are a real thing of beauty, cannot wait to hear this running !

You can see on the table the intake adapters, I will run a steel airbox with the adapters that raise the box and the inlet trmpets sit in the lower halves, like the SCRS had

A very expensive table of parts ;)

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Re: Birth of a rally car

Posted: Tue Jul 10, 2012 4:36 pm
by 911hillclimber
Very very nice table of parts, deep green with envy.

What are your aims fitting this over the webers considering the car's use?

When I've rebuilt my currently very 5 cylinder 911 3.2 I will have to decide on re-fitting the big 50mm PMO's or Triumph ITB. I want more torque and drivability from this change.
Those stacks are v tall which I think will improve the torque?
Did you find the 964 cams good?

Sorry for the questions, not often you have the chance to discuss these things with a racer.

Re: Birth of a rally car

Posted: Tue Jul 10, 2012 6:28 pm
by dragonfly
911hillclimber wrote:Very very nice table of parts, deep green with envy.
Wow, me too!

Re: Birth of a rally car

Posted: Tue Jul 10, 2012 11:51 pm
by Mike
Looking good. Coincidentally I've just last week finished my SCRS airbox for the high butterflies using a set of original 50mm
manifolds and short trumpets, I know how difficult it is to do, just taken the two years!

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Re: Birth of a rally car

Posted: Wed Jul 11, 2012 10:37 pm
by pht9
911hillclimber wrote:Very very nice table of parts, deep green with envy.

What are your aims fitting this over the webers considering the car's use?

When I've rebuilt my currently very 5 cylinder 911 3.2 I will have to decide on re-fitting the big 50mm PMO's or Triumph ITB. I want more torque and drivability from this change.
Those stacks are v tall which I think will improve the torque?
Did you find the 964 cams good?

Sorry for the questions, not often you have the chance to discuss these things with a racer.
The reason for the MFI over Webers is simply that it was always planned to have an MFI engine, as I want the car to feature as many special, rare, NOS and NLA parts that I can use - The Weber engine was an intermediate solution so that I could develop the Ohlins setup and Shakedown the car.

The 964 cams work well in a 3.0, and to be fair a well set-up set of Webers take some beating..

I do have some concerns about the 50mm butterflies for low end performance which is critical in a rally car, but we have done a lot of sim work with camshaft profiles, and have arrived at a profile of our own that should work well to give best mid range torque, I guess this will be confirmed in a few weeks when we get on the dyno !

Re: Birth of a rally car

Posted: Wed Jul 11, 2012 10:46 pm
by pht9
Mike wrote:Looking good. Coincidentally I've just last week finished my SCRS airbox for the high butterflies using a set of original 50mm
manifolds and short trumpets, I know how difficult it is to do, just taken the two years!

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That's it Mike !, am hoping mine comes back from the powder coaters looking like that :)

Re: Birth of a rally car

Posted: Fri Feb 08, 2013 11:16 pm
by pht9
SCR now looks a little different, the FIA insisted that for the homologation to be accepted, I had to refit the rubber trims in the bumpers

First dry day with sun for a while, so excuse to get it out of the workshop :)

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Re: Birth of a rally car

Posted: Sat Feb 09, 2013 8:17 am
by KS
Sun - please define. A word with which I am becoming increasingly unfamiliar.

Car looks great - very different with the bumper trims!

Re: Birth of a rally car

Posted: Sat Feb 09, 2013 9:28 am
by pht9
pht9 wrote:here is a close up of the rear lamp unit now installed, plus an overallview of the rear bumper now installed using the lightweight anodized aluminium bumper mountings. I was keen to create a minimalistic look to the bumpers and delete all the rubber trims and overriders.
The original mounting holes were alu welded and then the bumper refinished for the 'clean look' - would have been so much easier in fibreglass ! :banghead:


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When I think of the work we did on the bumpers to remove the trims :oops:

FIA have allowed the removal of the rear over-riders, but the trim inserts have to be fitted according to appendix J of the period

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Re: Birth of a rally car

Posted: Sat Feb 09, 2013 9:58 am
by keith fellowes
Interesting that the FIA insisted on the bumper trims. I have never seem an IB with bumper trims (that I can remember) on any event in Belgium or France. Thinking here of Ypres and Le Touquet rallies specifically.
Either the locals don't bother or the FIA are getting tougher, or are there different rules for racing?

The car looks fantastic.

Re: Birth of a rally car

Posted: Sat Feb 09, 2013 12:50 pm
by pht9
I provided the FIA with plenty of evidence that in period IB cars ran without the trims, look at pretty much any period shot of an Almeras prepared car !

They are applying strictly the app J article that only states bumper over-riders can be removed. I guess cars that were certificated a few years ago may have escaped this current level of scrutiny

Re: Birth of a rally car

Posted: Sat Feb 09, 2013 2:55 pm
by pht9
Over the winter I have been working on a few little projects on the car, this one has proved a challenge, but now its finished.

As some of you will know, rpm limiting on an MFI competition engine is not easy, especially to retain a period looking engine bay. Current method is a 7300rpm rotor arm, but my engine will rev above this figure and occasionally for circuit use, it is nice to have the capability for a few hundred extra rpm. I wanted to recreate the rpm limiters like the factory used on the RSR.

Finding these original parts is very difficult, and super expensive ! - so the challenge began.

The second part to this project was that I wanted to use the 8-pin HKZ unit, to complete the engine bay detail. My current HKZ is 6-pin*, so the challenge was to reconfigure an 8-pin unit, to interface with my current wiring loom, and incorporate the adjustable rpm limiter.
*Due to homologation restraints my engine is a single plug motor, like the SCRS

It is now completed, I will mount the second unit alongside, as a spare unit. Note the loom that acts as a 6pin to 8pin adapter, spare box and adjustable rpm limiter box. The finishing touch will be the scale decal to surround the adjuster knob

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Re: Birth of a rally car

Posted: Sun Feb 10, 2013 7:31 am
by 911hillclimber
Great details as ever Phil, a very nice build of a competition car, and imho better for the trims.
How you keep that paint looking like that considering the use of the car beats me.

I think you are kicking off the season in March?

Would love to come and see the car in action (as per pic in photo section).
Somewhere in Wales I think?

Graham.