Harrison Mk5 EVO II

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hcd
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Joined: June 23rd, 2006, 12:25 pm
Location: Hertford, UK
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Harrison Mk5 EVO II

Post by hcd »

Hi All,

Here are the details of my 750mc 750 formula car running a GC built 1108 FIRE engine‚¦

The car was originally built in the early 70¢ž¢s. The only part that is still original is the basic chassis outline. I bought the car as a write-off in 2002, hoping to rebuild it and compete in the 2003 season. The car came with a modified Reliant 850cc engine, I was warned these engines were fragile ¢‚¬Å“ it lasted five laps testing at Snetterton.

After numerous other failures at other circuits and never actually making it to a single race, I decided it was time to ditch the Reliant lump in favour of the newly introduced (in the 750 formula) Fiat 1108.

After phoning around a few tuners I decided to go for Guy as I liked his no-nonsense …œI¢ž¢m not going to quote anything until I¢ž¢ve seen the engine‚ approach. More on the engine here http://guy-croft.com/viewtopic.php?t=21

Turns out, he was probably the best choice, as the engine feels great to drive, and I regularly, get comments on how nice it sounds, compared with some of the other competitors.

As for the rest of the car, it was my first attempt at anything like this, the most I¢ž¢d done before was change shocks etc‚¦ It¢ž¢s taken me three years to complete, it has amazing high-speed grip, due to the fact I spent a lot of time designing the undertray and rear wing, but also has a lot of work that still needs doing.

I¢ž¢ve got some gearbox and cooling issues at the moment, but I¢ž¢m sure I¢ž¢ll get them sorted by next season.

Have a look at my website http://www.racingaspirations.com/ for more info and pictures.

Huw
Attachments
Silverstone - August 06 - understeer at Luffield corner - not perfect yet
Silverstone - August 06 - understeer at Luffield corner - not perfect yet
silverstone.jpg (98.59 KiB) Viewed 8156 times
In the workshop - early 06
In the workshop - early 06
workshop2.jpg (268.3 KiB) Viewed 8162 times
In the workshop - early 06
In the workshop - early 06
workshop.jpg (246.7 KiB) Viewed 8161 times
1108cc FIRE engine - it's quite a tight fit! I've taken the labels of the ignition leads now.
1108cc FIRE engine - it's quite a tight fit! I've taken the labels of the ignition leads now.
1108.jpg (75.71 KiB) Viewed 8162 times
hcd
Posts: 21
Joined: June 23rd, 2006, 12:25 pm
Location: Hertford, UK
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Post by hcd »

Thanks

There are 26 cars entered this year, 22 started at Silverstone, averages out about 20. Apparantly the formula used to be so popular that the races had to be split.

Almost all the cars are self built - some of them are a bit ropey, but there are some stunning cars as well - got some pictures here.

http://www.freezeframe-photography.co.u ... /index.htm

The 750 formulas start on the 8th row, 2nd picture in.

Huw
Testament
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Joined: June 22nd, 2006, 7:47 pm
Location: Taupo, New Zealand
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Post by Testament »

Whats the reasoning behind using just a single barrell of a weber DCOE? the little 1108cc just cannot flow enough for more carburation? or is it due to class rules?
Guy Croft
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Post by Guy Croft »

What's the reasoning behind using just a single barrel of a Weber DCOE? The little 1108cc just can't flow enough for more carburation?

Good question, but no, the reverse is true, the use of single barrel is to keep the power down and is stipulated as you indicated, by the race regs.

GC
hcd
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Joined: June 23rd, 2006, 12:25 pm
Location: Hertford, UK
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Post by hcd »

Excuse the pictures, they were taken using my phone.

A remote oil filter has been added (sits just in front of the engine), the exhaust on just cleared the filter in it's original position, so it seemed wise to move it.

You can also see that the original ignition system is being utilised, some competitors are using Polestar mappable ignition. I may have a look at changing this once the cooling system is sorted.
Attachments
cockpit.jpg
cockpit.jpg (292.04 KiB) Viewed 7985 times
A good view of my homemade airbox, you can aslo see that the #1 cylinder ignition lead needs shortening.
A good view of my homemade airbox, you can aslo see that the #1 cylinder ignition lead needs shortening.
enginebay2.jpg (365.94 KiB) Viewed 7993 times
Engine bay from overhead - you can clearly see that only 1 choke is being used. You can also see that the exhaust headers only just fit in the engine bay.
Engine bay from overhead - you can clearly see that only 1 choke is being used. You can also see that the exhaust headers only just fit in the engine bay.
enginebay1.jpg (353.58 KiB) Viewed 7996 times
You can just about see the Mocal oil cooler, which transfers heat to the water cooling system.
You can just about see the Mocal oil cooler, which transfers heat to the water cooling system.
oilcooler.jpg (353.85 KiB) Viewed 7971 times
Radiator exhaust. This was only added a month ago, you can see the original exhausts in between the upper wishbones.
Radiator exhaust. This was only added a month ago, you can see the original exhausts in between the upper wishbones.
radiator.jpg (276.98 KiB) Viewed 7974 times
My homemade dashboard using SPA-Design instruments.
My homemade dashboard using SPA-Design instruments.
dashboard.jpg (349.79 KiB) Viewed 7977 times
Testament
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Joined: June 22nd, 2006, 7:47 pm
Location: Taupo, New Zealand
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Post by Testament »

Guy Croft wrote:What's the reasoning behind using just a single barrel of a Weber DCOE? The little 1108cc just can't flow enough for more carburation?

Good question, but no, the reverse is true, the use of single barrel is to keep the power down and is stipulated as you indicated, by the race regs.

GC
Just out of interest, did you flow the head? in your view how does it compare to the Fiat sohc motor?
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