V MAX - How fast?

[luckyp]

Next challenge.

Box G50 03 1 (also says L04461) 5 speed

Engine 383 550bhp. have the 7000rpm 'pill' in at the mo.

I've asked Amerspeed to tell me how high I can go (I have an 8000rpm 'pill' yummy!!!)

Any number crunchers tell me what I can expect at say 6500,7000, 7500 and 8000?

Ta

Pete

[yiihaa]

I have an Amerspeed 383 550bhp and Gail told me to limit it to 6300 for reliability. May have different internals to yours.

I also have a G50/03,

In fifth you'll get 25.8mph/1000RPM

So:
6000 - 155
6500 - 167
7000 - 180
8000 - 206

So with a sensible limiter in place you should hit the limiter at Bruntingthorpe.

[luckyp]

yiihaa said:

I have an Amerspeed 383 550bhp and Gail told me to limit it to 6300 for reliability. May have different internals to yours.

I also have a G50/03,

In fifth you'll get 25.8mph/1000RPM

So:
6000 - 155
6500 - 167
7000 - 180
8000 - 206

So with a sensible limiter in place you should hit the limiter at Bruntingthorpe.

6300!!! Opps - sent the vid link to Gail and it shows bouncing of the 7000 pill. Think 180 could be the target then.

Cheers

Pete

[luckyp]

Do you think taking the wing off would make much difference in getting to V Max.

BTW it's not 'the' V Max but an event at RAF Honnington.

Pete

[peterpsg]

Rip the 5 speed out and stick in a 6 speed, I've got a G50/21 and it's about 30 mph/1000rpm in 6th.

I comfortably hit 185 (speedo) down the runway at Marham, at just over 6000 rpm in 6th, with a 7k chip.

Note that the MSD chip will soft limit a few hundred rpm before the chipped redline.

Make sure you have shaft needle roller rockers or a stud girdle fitted if you're reving that high often.

[luckyp]

peterpsg said:

Make sure you have shaft needle roller rockers or a stud girdle fitted if you're reving that high often.

I was just thinking of wearing boxers - will that be OK?

Don't think I have the time or the will power to get and change the box. Just gonna make do.

What do these things above do?

Pete

[steve_d]

Needle roller valve rockers are much stronger than the standard pressed steel version.
A stud girdle fits along the top of all the studs the valve rockers pivot on. This strengthens them and prevents them bending under heavy loads.


Steve

[peterpsg]

Nice pics Steve, you snuck in while I was typing!!!

They help your engine rev high with out the rocker studs ripping out or otherwise comming adrift.

Needle roller rockers have a little wheel where the rocker meets the top of the valve, so there's less friction...

Shaft mounted rockers have a more solid mounting than the more common stud (bolt) type, thus the rocker is less likely to move around.

A stud girdle, despite the silly name, is what I had fitted, as I have needle rollers, but they were simple stud types, so the girdle is a lump of suitably carved metal that holds all of them together. This provides rigidity, as well as damping vibration, and helps the valve train track the cam profile more accurately at high revs, which is probably worth a few BHP as a side benefit.

Also rememer, that the SBC has a lot more weight in the valve train than an OHC engine as it has the pushrod, rocker, caps, retainers etc etc, to offset this they have very high spring pressure (rate), this all acts to help restrict the upper rate at which these operate.

Then there is the cooling aspect of the springs as well, if they get too hot, they lose their 'temper', literally, and things go pear shaped pretty rapidly after that.

Anyway, I'm sure you won't have a problem, just make sure your oil's nice and fresh and topped up plus all the usuals!

Edited by peterpsg on Friday 15th September 23:29

[luckyp]

Thanks guys, I'm in danger of learning something here, and that is what I didn't want to do!! When you understand things you wanna change them for the good - and that sounds expensive!! I'm just gonna bury my head...la-la-la-la-la...I'm not listening....I don't wanna go 200mph...la-la-la-la. Damn. Doesn't work.

Now I'm gonna be dreaming of rockers, girdles and bent valves!!

Night

[peterpsg]

Just watching your Santa Pod vid... guess the wing aint the best place for a camera...

Getting a stud girdle fitted should only cost a couple hundred quid, and it's a good bit of engine insurance...

[GTWayne]

P, I have a stud girdle that is brand new and never been fitted (upgraded to Jessle shaft mounted rocker set up after I had already bought and stock pilled them!) and you are welcome to 'borrow' them for your event, let me know and I will bring them up with me on Sunday

[luckyp]

peterpsg said:

Just watching your Santa Pod vid... guess the wing aint the best place for a camera...

Getting a stud girdle fitted should only cost a couple hundred quid, and it's a good bit of engine insurance...

I'm sure you spotted the (not) so clever editing, all the wing mount was done before any runs - although they allowed me to run with 'wingcam' if I wanted to. I though?.....naaaaaaaa.

P

[luckyp]

GTWayne said:

P, I have a stud girdle that is brand new and never been fitted (upgraded to Jessle shaft mounted rocker set up after I had already bought and stock pilled them!) and you are welcome to 'borrow' them for your event, let me know and I will bring them up with me on Sunday

Wow please do Wayne - serious question, is it one size fits all - you know my spec don't you?

P

Edited by luckyp on Saturday 16th September 07:29

[bluesatin]

I used to do 162mph everytime at bruntingthorpe on the rev limit (6,400). Problem was it was 1/2 way down the runway so had to back off. Last time with new gearbox I did 175 without trying so I think it will do just over 180 at 6,400. Unfortunatly Ultima are not that welcome at Bruntingthorpe these days due to local noise limits.

[gtr-gaz]

180 mph at RAF Marham last year. Bouncing off the 6,500 limiter all the way down the runway
(535 AS engine)

I think mines also an 03 box.



ETA video www.pistonheads.tv/clip561

Edited by gtr-gaz on Saturday 16th September 12:07

[GTWayne]

luckyp said:

Wow please do Wayne - serious question, is it one size fits all - you know my spec don't you?

P

Edited by luckyp on Saturday 16th September 07:29

Depends which type of rockers you have fitted but as far as I am aware there are only two types so you have a 50/50 chance. I will bring them along tomorrow and you are welcome to take them and see.

[luckyp]

Cheers

Pete.

Back to polishing...........

[steve_d]

luckyp said:

Cheers

Pete.

Back to polishing...........

That was a waste of time.

Steve

[luckyp]

Black is cr&p!!!...........for dust!!

[cortina1]

BTW, what speed does it go is the most frequently asked question I get, purely on what the car looks like and at sea level conditions I usually answer "somewhere around 190 mph" ....haha, never had anyone question me yet.