Horsepower

Mark,
Thanks for your comments.
The gearbox is a 4 speed, semi-auto sequential driven by a torque converter.
The whole transaxle is manufactured here in Perth and the casings are C.N.C. machined from billet aluminium. The 4 speed box bolts onto the back of the diff housing. This enables the removal of the box without removing the diff, half shafts etc.
The gear box runs Indy car type straight cut gears.
The diff housing and gears are much the same as sprint cars run.
With the aid of the computer and the W.O.T. shift full throttle gear changes are possible, giving consistant gear changes.
The intercooler, which sits above the transaxle has air directed through it by vents directly above.
A fan between the intercooler and transaxle sucks a water spray through the intercooler dropping the intake temperatures considerably on hot days.
The turbos I'm currently running (ballbearing GT25's) are good for about 700h.p. With these I have managed to eliminate all lag.
Regards Cos

 

[Pete McCluskey.]

Cos, a terrific bit of engineering. Congratulations.

 

[Jason Lycett]

I think some of you guys are just are crazy about horsepower, but i dont think it makes a quick car. Im pretty sure a well set up light weight 350hp car would be quicker round a track than some wild race motored one. We dont use tyres that could control 500-600 hp and the supercars that do, have sophisticated traction control systems to reduce the power to stop the car doing a donut on the spot!
Plus what about cooling, gearbox ,clutch etc.etc. The fastest cars are able to use all there power, get it down properley and be useable. Low weight and good balance, thats a quick car.

 

[James]

[ QUOTE ]
I think some of you guys are just are crazy about horsepower, but i dont think it makes a quick car. Im pretty sure a well set up light weight 350hp car would be quicker round a track than some wild race motored one. We dont use tyres that could control 500-600 hp and the supercars that do, have sophisticated traction control systems to reduce the power to stop the car doing a donut on the spot!
Plus what about cooling, gearbox ,clutch etc.etc. The fastest cars are able to use all there power, get it down properley and be useable. Low weight and good balance, thats a quick car.

[/ QUOTE ]

True, but what about a car with sophisticated suspension, incredible brakes, light weight chasis, modern tyres, LSD diff etc. Then you have a car that will simply destroy a 350HP car around a track!! So more power in the right car is just plain superior! No question.

Regards,

J.P

 

[Julian West]

I agree with Jason. Light weight & a properly sorted chassis will make for better lap times than something with 500 bhp & poor dynamics.

Hence the Lotus seven was invented & with less than 200 bhp will still beat almost any road car on a track/sprint/hillclimb.

/ubbthreads/images/graemlins/smirk.gif

 

[Lee]

So how many times did a Lotus 7 win at LeMans?
I think cos's approach is different but not wrong. It fits the car, and probably does not add a huge amount of weight, so as long as the handling is good, brilliant. As a long distance racer sounds brilliant.

 

[Jason Lycett]

Le-mans is a not your typical track! with huge straights it will suit horsepower, but 9/10 tracks and sprint courses a lotus/caterham 7 will trounce any 40, thats a fact. I was able to lap Mallory park in a Rover 1600 engined clubmans car 3 seconds a lap faster than a 450hp GTD 40 at a recent test day, that car had only 125BHP! I love my Gt40 replica , but dynamically it will never be really fast round a track, over weight, poor aero-dynamically, no down force etc.The Gt40 was never that quick in it's day, but it was a great endurance racer. Love to see someone try to do something different with the dynamics instead of attacking it with horsepower which will just makes things worse.

 

[Gary Gibbs]

No question one can debate the fact that some cars out perform others on the track. An F1 car can out perform a winston cup car, etc. However for a fixed car (e.g. Lotus 7) set up identically the one with the higher useable HP band will outlap the one with less power. This is assuming the two cars benefit from having well sorted suspensions.

F1 cars, for example, have way to much HP for the low speed corners and thus use the traction control system to modulate. However, every team would give their right arm for more HP (reliably).

As far as GT40's are concerned I think each person should do what he wants.

 

Since I built my car 12 years ago I've had webbers, standard exhaust, crossover exhaust, fuel injection etc. I found that a GT40 can't be an everyday car so I decided to have fun with mine.
Over the years as new technology became available I made the modifications hoping to come up with something I was happy with.
I must say the feel of that torque pushing you back into the seat as you open the throttle is a great feeling. Who cares if a go-cart can overtake you on a tight track. In my opinion that's not what GT40's were built for.
I think you should do what gives you the most fun.
Regards Cos

 

[Clayton]

Hi Cos

Welcome to the forum, I still talk about the time you took the misses and I for a Sunday drive!!!! Not only does it push you back into the seat but up the incline as well. Just plain awesome in my books. /ubbthreads/images/graemlins/shocked.gif
regards

Clayton

 

[Scott]

Seems to me that the only thing thats missing on this car is a shot of nitrous!! /ubbthreads/images/graemlins/shocked.gif
Those intake manifolds are a work of art. You should be very proud of your accomplishments with the car.
One question thou, what are the fittings with the vaccum hoses connected leading into the intercooler in front of the throttle bodies?
Scott

 

[Paul Thompson 'Hooligan']

Hi there,

Those items are bypass valves - commonly referred to as 'dump valves'.

When the throttles close, the vacuum developed is used to open a valve dumping excess pressure in the intercooler to atmosphere. Without them the air will stall, backup to the turbo and attempt to stall the turbine. It is not unheard of for the turbines / shafts to shatter on cars generating high boost without dumo valves fitted.

It also helps keep turbines spinning, to help reduce lag. /ubbthreads/images/graemlins/grin.gif

 

[Pete McCluskey.]

Good debate about horsepower guys, when you boil the fat out of it it comes down to "different strokes for different folks". My GT when completed will be 90% road use with the odd day at the track, so I am aiming for about 400HP.
But if I was going racing I would look for around 600HP.
Remember the control is under your right foot.

 

Couldn't have explained it better myself,Paul.
Give Roy my regards.

I remember that day Clayton.
How's that build of yours going?

Regards Cos.

 

[Clayton]

Hi Cos

Never as quick as you want it to be, but at least its heading in the right direction.
You must be due for an upgrade soon……cant wait for that one !!! /ubbthreads/images/graemlins/grin.gif

Clayton

 

[Scott]

Thanks Paul, I thought as such but wasn't sure. Just looked a little different to the usual way I have seen them. Used to seeing the blow off valves on 4 and 6 cylinder set ups.
Scott.

 

[Howard Jones]

I remember hearing the first Renault F1 Turbos back in the 80's at the end of shoreline (Long Beach GP). This was the really long track back then and the renaults were up to about 210 before braking to around 50mph for the Queens hairpin. Anyway the noise that little V6 made when the car went from full power to full braking can be best be discribed as opening the valve on a 2000psi welding tank. Then several huge BANG BANG BANG's of very overly rich fuel mixture backfiring out the exaust along with about six feet of flame. About a second later the car launched off the corner back in the other direction. I believe those first F1 turbos made about 600hp. In the end, a few short years later the BMWs were making about 1800hp from a 1500cc 4 banger in qualifing trim and NOBODY racing against them ever wanted less hp. As far as that goes anybody who has ever raced anything wanted more HP!