Top speeds on track (atmo engines)

I'm interested to know what maximum speeds a Mk1/Mk2 with an NA engine can achieve on UK circuits, to gauge how my possible gearing will fair.

I've only done Donington a couple of times and can get upto about 110-115mph before braking for the chicane at the end of the lap. New gearing will make this my maximum speed(!), so I might have to avoid certain tracks (Combe, Rockingham, Silverstone, Snetteron, at a guess)

With brief engine (power/torque) and gearbox/rpm info, what top speeds do you get upto at these tracks and at what section of the circuit?

Brands Hatch
Cadwell Park
Castle Combe
Croft
Donington Park
Goodwood
Mallory Park
Oulton Park
Rockingham
Silverstone
Snetterton

 

combe, 120mph in me old 16v jetta many moons ago, up avon rise

 

I do Brands, Cadwell, Oulton, Croft, Donnington, my car is very low geared 4.4CWP & i never get over 130mph.
If i keep the car one of my next mods is to use a lower 4.7CWP & closer 5th gear.
I would use 5.1 but they dont do one for my box.
Ray

 

I'm just buying a GPS sytem as I'm of the 120 clock at Goodwood and Combe

 

was that speed reading or GPS reading?

 

speedo reading, that's why I'm after a Snooper or the equivelent to get some idea.

 

Combe just under 130
About the same at Donny
130 at Snett
125 ish at Brands

Takes a long time to get from 125 - 130 in a MkI

2Y Rod change box 4.2FD 20v motor 235 bhp approx

Just to add when i did the PVW sprint the Stack speedo was out by 2 mph at 140 mph.

 

Just been looking at the VW Cup speed trap speeds, and Donington was 110mph, quickest Mk1 was 107mph.

Snetterton was 123mph, quickest mk1 was 119.8mph

 

I have seen 127 at Combe.
Donny was a guess but it would hit the limiter in 4th around Dunlop bridge.
8500 rpm 4th gear was 120
As data logging is not allowed at track days i only had the speedo to go by and may be it wasn’t 2 mhp out like it was at Bruntingthorpe.

 

ibiza touches 150mph up the rise @ Combe as a comparison to my old jetta.
scarey as!

 

the speedos are usually out by a bit anyway

 

123mph through speedtrap halfway down straight at Aintree (external gun measurement) near top of 4th gear with a 02A box with 4.2 FD and 598mm dia front tyres

crap ratios I know, when I win the lottery I'll fix it

Unusual to go over 130mph with an atmo car on a UK circuit I would think although mine will pull more than this given a long enough run

 

If you gear it to do 120-125mph at peak rpm you wont be far away.

 

A couple of quick graphs, the first showing the current and possible gearing with the standard 3.89 and 4.47 final drives and the second with the same 4.47 final drive and standard close ratio gears, for different rpm limits/gear change rpm.





I seem to recall infinity's Mk1 being geared for around 110-112mph with the setup he has and, video link of G's car at Donington. Seems to be hitting a limiter down Starkeys.

Granted it's a bit of a paperweight (660kgs?) compared to my Mk1, which still has full dash, front seats and a couple of other bits and still with a stock KR engine, the only exception being the Ashley manifold and exhaust system.

It does take a fair distance to achieve 120mph, judging by the replies so far and given the current weight and power, it seems I might be alright. I dont think I've seen many KR engines running up big rpms apart from when using throttle bodies?

Standard ECU's are limited to either 6800rpm or 7200rpm iirc? Would it be safe to run the engine up this high on a straight lap after lap, or should I perhaps look at upgrading something?

 

7200 and yes given good health, upgrade your b...s

 

With 100mm cabby/rocco driveshafts being tricky to come by, would I be alright to change the 100mm flanges on the 'box to 90mm so I can stick with my current GTI driveshafts?

The 'box has a Kaaz differential fitted. Is it going to be beneficial to use the slightly larger CV's from cabby/rocco driveshafts due to the diff?

It's going to be bolted to a pretty much standard engine for the time being...

 

Thruxton?

 

Thruxton is not as quick as you think on top speed....its just fast everywhere!

Not for something with a relatively low power to drag ratio anyway. The speed trap was just before Church when VW Cup went there and it was about 123mph

 

Would think Silverstone would be quite high......

 

My car is geared for 111mph with road tyres & 127mph with track rubber (as in the video link above)

Top speeds

donington - 127mph
Snett - 127mph
combe - 120 ish mph
mallory 120mph