Top speed!!!!

[redkarla]

Hi

I had the chance of a nice blat yesterday evening. On route got the devil in me open dual carriage way and opened her up. Got to 4500 revs in 5th which equalled about 125 – 130 mph ish and just didn’t want to pull much more.

She’s been great and what I don’t understand is that she pulls every gear right through the revs and I’ve even hit the limiter twice (by accident) in third. So if its ok in 1st, 2nd 3rd and ok for 5000 rpm in 4th why she wont give more in top.

It was very noisy with the roof down so couldn’t hear the engine to well but she never got hot, oil pressure was great and didn’t feel that she was baulking just wouldn’t rev more.

Tried again on the way home lovely cool evening and got 5000 out of her = 135 mph but no more.

I know the obvious one would be to get to a rolling road and try and map the problem. It’s not that I ever go that fast usually and for the last 4 moths I’ve never doubted the performance but now I’m niggled. Advice welcomed.

[TimmyArt]

I'd write that in a differnet language and edit it if I were you before saying that on a forum...IMO

[Nicholas Blair]

Private road

[thenick]

Yeah I'd change the mph reference! Anyway I'm sure there are lots of things that can cause this but as something to check first, how many miles has your cam done? If its worn then you will be losing out on the top end, which would cause the car to run out of puff at high revs, especially in 5th when you've got a fair amount of wind resistance I'd imagine!

To confirm, you could always take it to a rolling road and have your power curve checked out. It should be fairly obvious if you've got a problem. In fact I believe they're doing discounted RR sessions at Roar this weekend so might be a good chance to check out your car's health for 30 quid.

[redkarla]

Off course it was a "private road" !!!! Did not think. it was cam would this not show up when on full chat through the rev range and gears?

Thanks for the advice so far. Can't get to roar this weekend I was already booked (by the girlfriend) before I brought the car.

Any body suggest a good rolling road set up in the south? I'm in dorset but don't mind a hundred miles or so>

[Dave 500]

i've had 156 out of mine at an event a few years back... had the roof down to...

[thenick]

Well its not always that noticable. When my original was a bit rounded off I couldn't really tell the difference as the power had just sliped away very quietly, and its a very even drop off from what I've seen so its hard to notice unless you drive two cars back to back, one good one bad. In this case it may have run out of puff in all gears at the top end, but theres lots of noise and you're still going pretty fast so you don't notice, but your top speed comes down due to the lack of power at the top. On the rolling road this would be easy to spot as your power curve would drop off early.

I'm no expert though so I'm sure someone will be along soon to give some better advice!

Edit: When my 450 was standard I had 155 leptons out of it with a another 5-600 revs in reserve but I thought things were getting a bit silly having already destroyed the tuned Nissan 200 that started the initial race! - On a private road in the early hours of course!

Edited by thenick on Thursday 26th June 12:17

[tvrbob]

On a nice section of private duel carriageway driving my Chim 400 early one morning I found myself in a contest with a 'sorted' Golf. We got up to 145 leptons according to my speedo. I then decided to pull in and let the Golf go but unfortunately for him he had nothing left. The challenge then set I eased it up to 150 leptons and showed him who was boss.

[pwd95]

What's the mph/1000 rpm then? if its 25 mph/1000 rpm then you only got 125 mph at 5000 rpm.

[Chequred Demon]

You should be able to get 150 parsecs (indicated) out of a 400. Mine revs quickly to 6000 in the gears except 5th where she struggles, which I am working on. My backing off point is governed by the bonnet lifting, and so I will be purchasing a front splitter over the winter, which will hopefully sort things.

[Konrod]

pwd95 said:

What's the mph/1000 rpm then? if its 25 mph/1000 rpm then you only got 125 mph at 5000 rpm.

Mine is at about 32mph/1000 in 5th - 90 mph on private airstrip is just under 3000rpm. If you can pull max revs (6250 on mine) in 5th that equates to..... er......b***y calculator.....+VAT.........divided by ....er.....

Quite fast.


4th is about 25mph/1000, which at 1:1 should pull to max revs which is 155mph (ish).

editted to add the key bit: most cars have overdriven 5th gears - this means that they can't achieve max revs in that gear, hence 4th is a higher max speed than 5th. Doubtless some engineerey type will be along who can explain why (something to do with wind resitance vs power if I recall)

Edited by Konrod on Thursday 26th June 18:22

[Ubernoober]

I managed 140 warp factors before the closing speed on the hedgehogs in front became too great. I think there was some left but on the RR my 400, despite having 250bhp, peaks at 5000 rpm then falls off quite rapidly so I doubt there was too much left.

[f@-pots]

With the roof down your ability to increase the afore mentioned 'lepton' count is severely restricted due to aerodynamic drag, try it with the roof up and I'm sure you will see an improvement!!

[Jasandjules]

In my 4.0 I got her to 140 but I bottled out as the front was going light. I have no idea what the revs were because I was looking for a braking point.

I've not had the 5.0 on a runway at all yet so no idea what she'll do.

[aerospoke]

I have seen 258 kmh on my speedo which equals 160 mph. This was with the targaroof of in my 400 which supposedly had a blueprinted standard engine with polished heads.

Cheers Jens

[Colin L]

Autobann, 163mph on the clock with roof up and 152 with the roof down.

Also on a rolling road had the wheels going at 171. But that was with me standing beside her, hands covering my ears.............

Colin L

[jsr]

On an airfield day, i've have 150 out of my standard, but very healthy, 400. It was still pulling rather strong. Reckon the speedo was 10-20 mph optimistic though. Still, on a longer runway with GPS, i reckon an actual 150 should be achievable, maybe a bit more.

[Big Ashy]

On a private dual carriageway/runway thingy, I lent my Griff to an absolute stranger who assured me had her up to a indicated 173 Lepton`s on the standard Lepton indicator supplied with the car?

I am sure there is an element of discrepancy here, but the perfect stranger told me it was BY fast as the FN front end went very light and he couldn`t here a thing because the wind noise was incredible, even with the roof on and the windows up, alledgedly!! 6000 Warp Speed Factors in the 5th Centinel, again, alledgedly!

[timshap]

With my 500 have seen 165 indicated on the autobahn with roof down. Still with reserves.
Roof up against big mercs and porsche's 155/160 easy as they were on the limiter at 155 and just couldnt get past as I could still noticeably pull away . Quite an enjoyable experience. It does however take quite a lot of braking to get back down to 90 quickley though.

At that sort of speed you do think more about blow outs and diff failures etc..

Tim

[Overhere]

I'm hitting 122 at the end of Caslte Combe straight just befor Avon Rise in 4th! Never been in a palce to try more (legally) but trying to sort a trip to the Ring before the summer is over... There's a clip on YouTube of a Griff hitting 170 on the last 2 mile straight on the Ring. Sounds like fun!