Bob Watson Rolling Road Session

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hot66
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Bob Watson Rolling Road Session

Post by hot66 »

I've not been that happy with the way my car has been running for the past 12 months. It had been pulling pretty well but then the chain tensioners started to collapse :roll:

As part of the recent work Mike Bainbridge sorted out the tensioners & re timed the cams. At the same time we had the throttle bodies rebuilt and fitted new injectors and a new rear stainless box.

This was all set up approximatly and I bedded everything in on the DDK Scottish trip 8) The car was much better and was running smoother & less rich. At the top end it pulled well & it now had some reasonable bottom end and it still had quite a marked 'coming on cam' point. I know barry will testify it wasn't a slouch ;) :lol:

The plan had always been to finally get my car set up properly on a rolling road, so after a huge number of recommendation I booked the car into Bob Watsons for the Thursday before Silverstone Classic.

After a truly horrendous trip down from Yorkshire we arrived at Bobs mid afternoon.

We got the car onto the rolling road and strapped her down

Image

Bob started the 1st power run to get a starting point. Now if you have never been stood at the rear of your car whilst it is ran up the box then steadilly loaded up through the rev range you are in for a shock :shock: The noise & energy is tremendous and all the time you are scared shittless the engine is about to go bang :shock: :lol:

Anyway the 1st power run was started but Bob wasn't happy. He took it to 6400 rpm and then stopped. He got out of the car muttering about the engine feeling flat etc which didn't exactly make me feel happy :roll: .... the numbers from the 1st run ?

168 bhp @ 6400rpm :shock: :(

That number was very shocking as the car pulled really well.

Bob was not worried though and got tinkering

Image

The timing was re-set ( timing needs to be set when the engine is hot ) as it had been initially set whilst cold , the linkages were all checked and the position of the throttle butterflies adjusted slightly.

Some more power runs were done and graphs started to look a lot better :)

The main problem that was showing up was some really poor fuel delivery. The car was going from rich to lean & back to VERY rich through the rev range. Bob did a lot of tweeking of the MFI pump to try & even out the fuel ing. Bob admitted this one was a bit of a challenge as the MFI pump was VERY sensitive ( ideally needing a rebuild soon ). Bob set up the pump as best he could , although it is not perfect at very low rpms

After about 5 power runs Bob was ready for our 6th & final run 8)

After all the adjustments the final numbers were :


198 bhp @ 7210 rpm
204Nm @ 5840 rpm


8) 8)

I was really pleased with those numbers as a stock 2.4S is 190 bhp :)


You'll notice the power come in very late ..... only 90 rpms off the limiter
:shock:

The numbers are great but its how much more drivable the car now is. The engine pulls from lowish revs all the way through to the red line and the obvious 'on cam' moment has now been smoothed out. Additionally the engine much quieter & the fuel consumption appears to have improved dramitcally

8)

All in all I was at Bobs for 2.5 hours and it was well worth its money. Well recommended.

Image
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by Nige »

excellent results, its pretty hairy standing next to rear wheels when the engine is at full tilt. I kept thinking I hope I've fastened those wheel nuts properly.
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Post by johnM »

Great pics James, hope to have mine down to bobs soon, so at least I have a figure to aim for :wink:

Best get the engine fairies into gear.
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Post by hot66 »

look forward to it John :)
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by johndglynn »

7210rpm! 8)

Great stuff James, have you weighed your car?
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Post by 58A - 71E »

I was wondering how you'd gone on James, good stuff 8)

Think this has convinced me to pay Bob a visit too.... :wink:
James

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Post by Derek »

James

Thanks for updating everyone, sounds well worth the effort :) .

Did Bob expect max power so high in the range?

I know what you mean about being so close to your engine on the rollers.

I used to run a 125cc GP race bike in the GB championships and wrecked a motor on the dyno :cry: followed by the spare engine on the next run :cry: :cry:
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Post by hot66 »

johndglynn wrote:7210rpm! 8)

Great stuff James, have you weighed your car?
not yet, but my car is all stock so not a lightweight ;) Mind you if I removed the recaros It'd make a difference ... they weigh loads. In fact I struggle to actually lift a single recaro & base :shock:
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by hot66 »

Derek wrote:James

Thanks for updating everyone, sounds well worth the effort :) .

Did Bob expect max power so high in the range?
Bob reckoned it was still pulling :shock: . He didn't seem that surprised. I'll have to check with Mike on where the cam timing was set :)
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by tanick »

James, why the new injectors and how much were they (if you don'tmind me asking)?

I've had a couple of rolling road sessions and as proven by the backfires at the end of the straights on Monday, it is running too rich, but its been necessary to set it like that to keep it smooth at lower revs. All this points to injectors. Did Bob test the spray pattern on them? Did you change them all?

Thanks and nice to meet you at the weekend.
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Post by Michael Birch »

James,

Bob had mine 2 weeks ago, I haven't seen the graphs as I'm in SE Asia although he did tell me that it was 215 BHP.

We can now have a race to the Black Sheep Brewery in God's country!
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Post by hot66 »

tanick wrote:James, why the new injectors and how much were they (if you don'tmind me asking)?

I've had a couple of rolling road sessions and as proven by the backfires at the end of the straights on Monday, it is running too rich, but its been necessary to set it like that to keep it smooth at lower revs. All this points to injectors. Did Bob test the spray pattern on them? Did you change them all?

Thanks and nice to meet you at the weekend.
When I had the car at Mike Bainbridges we put the injectors on the test rig as I thought they might be bad. The result was the injectors were shagged as fuel poured out like a tap rather than a fine spray :shock:

Can't remember the exact price but they were approx £65 each from type911.
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by hot66 »

Michael Birch wrote:James,

Bob had mine 2 weeks ago, I haven't seen the graphs as I'm in SE Asia although he did tell me that it was 215 BHP.

We can now have a race to the Black Sheep Brewery in God's country!
sounds like a plan 8) Let me know when your back in Yorkshire :)
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder

1963 Honda C100 Supercub

Its not how fast you go, but how you go fast ;)
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Post by MdR »

hot66 wrote: I struggle to actually lift a single recaro & base
Wuss :lol:
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Post by Gary71 »

198 bhp @ 7210 rpm
204Nm @ 5840 rpm
All the best engines generate maximum power just before they let go :lol:

Lovely figures, it must really fly :)
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