top speed

Post by **superchargedfool** » Tue Jul 08, 2008 11:31 pm

I was wondering at what sort of speed do other people with quick minors hit the brick wall where they just seem to stop accelerating.

Mine goes like the clappers up to 4th gear @ 100mph but after that it accelerates really slowly.

I know the aerodynamics are not good but was just wondering if I am alone with the brick wall at 100, don't get me wrong my top speed is higher than this its just thats where it stops feeling impressive.

Post by **polo2k** » Tue Jul 08, 2008 11:33 pm

you might be able to hold it off a little longer by lifting the power band a little, somthing like a cam or slightley bigger pully (although I think you tried this before)

Post by **polo2k** » Tue Jul 08, 2008 11:35 pm

ps if it helps I think the 1000 has a drag coefficent of somewhere around 0.3 (iirc 0.01 less than a maclaren F1, whetever that is ;) )

Post by **turbominor** » Wed Jul 09, 2008 1:30 pm

i saw just over 110 on my roadangel in my last minor running 4psi and exactly the same with a 1293 a+ and no turbo

That was with a 1098 ribbed minor box and 3.7:1 midget diff on 15" wheels

Post by **jonathon** » Wed Jul 09, 2008 2:03 pm

All minors will hit problems at around 95-100mph, due to the massive build up of air under the bonnet . We had this problem at Milbrook proving ground when testing over there. We fitted our front spoiler and , what a difference, the air was directed from under the car, bringing back the rather vague steering and almost having the effect of sucking the car to the track. We managed just under 130mph on the bowl and did 3 laps 'no handed' at 120mph, with the car nice and stable.
At Bruntingthorpe on Sunday we were achieving three figures easily enough, but then we did have a very torquey motor. I suppose that as the torque/power increases the barrier will move upwards on the mph scale.

Post by **Redmoggy** » Wed Jul 09, 2008 6:36 pm

Im just curious. I understand the build up of air,but could you relieve this by venting the bonnet?

Post by **MoggyTech** » Wed Jul 09, 2008 6:47 pm

Redmoggy wrote:Im just curious. I understand the build up of air,but could you relieve this by venting the bonnet?

Not really as you then have an air dam, which still offers massive resistance. Spoiler/splitter is the way to go. It's easier to split air and create down force, than channel it through ducting.

Spoiler/splitter also has the added advantage of increasing nose weight at high speed, thus giving you the ability to go round corners, rather than into a tyre wall.

Post by **motherofgod** » Wed Jul 09, 2008 9:31 pm

I do like threads like this

I've had just under 140mph out of my minor, I have considered putting airvents in the wings to allow air to flow to be increased. As you may know I intend to do 200mph in my car but am saving for a new engine!

James

Post by **Mogwai** » Wed Jul 09, 2008 10:26 pm

would some sort of undertray to smooth the floor help. for example the crossmember must cause a resistance to airflow

Post by **MoggyTech** » Wed Jul 09, 2008 10:35 pm

Mogwai wrote:would some sort of undertray to smooth the floor help. for example the crossmember must cause a resistance to airflow

Absolutely, but you are getting into F1 development territory, so a wind tunnel session or two wouldn't hurt

You may also succeed in getting the Minor airborne, but that would look good anyway.

Post by **Mogwai** » Wed Jul 09, 2008 11:02 pm

maybe not that far

but a lot of modern cars have at least something under the front end & not just for catching oil leaks

Post by **Redmoggy** » Wed Jul 09, 2008 11:40 pm

Nice lakes style alloy belly pan be cool!

Post by **jonathon** » Thu Jul 10, 2008 9:30 am

James , give John Webster a ring, I'm sure you know that he is a drag car builder. He has the MG supercar

hah! and is attempting to break 200mph, only he already has over 600bhp and figures on needing a few hundred more to break through the air. The Minor would be quite a handful over 140-150 as its very short and narrow so I think some severe aero packages would be needed to achieve your desired 200bhp. I wish you well though, and would love to see your attempts, Maybe a Bruntingthorpe day out then ?

Post by **superchargedfool** » Thu Jul 10, 2008 1:12 pm

I have not been near my computer since posting this thread but I am pleased now I have got back to find that it isn't just that my engine isn't as good as I hoped.

Thanks for the input guys. I would love to fit a front splitter but it would loose the car the surprise aspect that it has at the mo.

I went to Ashby Follville show tuesday evening and on the way back did give it some and quite surprised my friends that were in convoy with me. The moggy aquitted itself to perfection. My friend was driving an E30 325I estate and in the end he gave up trying to loose me. The moggy went really well.

I think I will have to go for more power, my mojo is still only half in the car at the mo but I can feel an engine build coming on for more boost.

I'm thinking another 20 or 30 bhp and more midrange torque should move the brick wall effect up the scale a bit further.

I know at the mo the car would do 115 to 120mph, I have never done it but I know by how it is still going at 110 there is more but not that much. I am not looking for more top speed, just more acceleration at around the ton.

I might play with an engine bay undertray as well.

Cheers for input guys.

Post by **MartinB** » Fri Jul 11, 2008 12:26 pm

My hillclimb and sprint minor (streel legal) has shown 135mph on the data logging at a sprint and was still accelerating hard, with over 400BHP I suppose it should do. Does tend to weave a bit under braking at these sort of speeds though as the back end gets quite light with the weight transfer, aero etc.

Martin

Post by dp » Sat Jul 12, 2008 6:18 pm

I've been up to IGN mph when I run out of clock. No sense of running out of steam up there but also no idea what speed I'm really doing.

Post by **Innovator** » Sun Jul 13, 2008 8:50 pm

Re...... Build up of air under the bonnet.

I did some relative pressure testing by using a U tube manometer, one pipe below the bonnet and one above in the same place. I found a maxium of 0.25 psi difference........ doesnt sound much but think of the area this is over.

I cut vents at the place of max pressure difference and the front had so much more grip in the faster bends. Wool on the openings showed that above 30mph there was substantial airflow out of the vents.

I was running a sump gaurd under the engine with this set up though that effectively sealed the space between the chassis rails.

Post by **Redmoggy** » Sun Jul 13, 2008 10:45 pm

Where did you find it was best to put the vents?

Post by **motherofgod** » Thu Jul 17, 2008 7:31 pm

Yes I'd be interested too, also while on the way to the dorset rally I took a vid not going top speed(would need both hands on the steering wheel for that!!) but a bit of fun.
http://www.youtube.com/watch?v=9DRQcyllbIo&feature=user

James