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Rolling road plot from a 2 stage system

 
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dbv8
Knows His Stuff
Knows His Stuff


Joined: 21 Jul 2008
Posts: 477
Location: Barrow-in-Furness

1998 TVR Chimaera

PostPosted: Tue Apr 03, 2012 6:30 am    Post subject: Rolling road plot from a 2 stage system Reply with quote

A few changes have been made to the nitrous system on the TVR.
Bottles relocated, bigger lines etc.
The car was taken back to Bailey performance where the megasquirt was initially wired in and mapped for 308 bhp.

On Friday the mapping was tweaked and gave 312 @5900 on 95 ron petrol because no V-power was available.

The MS switches maps automatically when the nitrous is activated and ignition is retarded 6 degrees.
Stage 1 is from a bottle in the boot which was fully heated to 950psi and jetted for a 75 shot and wired for a fixed hit at WOT.
Stage 2 from a bottle on the rear shelf. This bottle hadnt been heated and was at 650 psi and jetted for a 65 shot on a pushbutton on the steering wheel.
The car was driven up to 4th gear but held off full throttle tilll about 3300 rpm then floored for the satge 1 to kick in, then the button was pressed from about 4500 rpm to 6000.



The next day the car was tested at Shakey. Note a poor launch to 60 foot of 2 seconds, I am normally at 1.85 so pleased with the results....


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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Sat Apr 07, 2012 8:19 pm    Post subject: Reply with quote

I would activate nitrous at 3000 rpm and then 2nd stage at 3700rpm.

Perry
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Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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dbv8
Knows His Stuff
Knows His Stuff


Joined: 21 Jul 2008
Posts: 477
Location: Barrow-in-Furness

1998 TVR Chimaera

PostPosted: Wed Apr 18, 2012 10:03 am    Post subject: Reply with quote

I dont think a great deal can be learned from that rolling road plot. The second bottle was too cold really for starters.

I do agree that there is no need to push for high revs. I can have maximum amounts of torque around 4000-4500 rpm and my gears only drop between 1800 and 1400 rpm so if i shift aroung 5800 then i am hitting full torque in the next gear.

Obviously more track time and experimantation is needed to find the sweet spots. Just need to sort my brakes for the burnout and replace my clutch asap Rolling Eyes
Theres always something needs doing isnt there? Laughing
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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Wed Apr 18, 2012 7:56 pm    Post subject: Reply with quote

Its a never ending story Del Smile

But each year there seems to be a better ending eh ??

This year I'm going to be experimenting with adding timing back in at high rpm on nitrous.

Or go the other way and drop timing way way back for bigger shots at the top end. On Jasons scrapper 4.6 in the Escort of course Laughing
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Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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dbv8
Knows His Stuff
Knows His Stuff


Joined: 21 Jul 2008
Posts: 477
Location: Barrow-in-Furness

1998 TVR Chimaera

PostPosted: Thu Apr 19, 2012 6:53 am    Post subject: Reply with quote

mgbv8 wrote:
Its a never ending story Del Smile

But each year there seems to be a better ending eh ??

This year I'm going to be experimenting with adding timing back in at high rpm on nitrous.

Or go the other way and drop timing way way back for bigger shots at the top end. On Jasons scrapper 4.6 in the Escort of course Laughing


Adding the timing back to compensate for the pressure drop? Makes sense to me.
Do you run 2 bottles Pel? My second stage is completely independant with its own bottle. As i am only running 100 shot stage 1 and 65 stage 2 I think pressure drop isnt a big issue for me. I must be producing good power top end to be hitting 127+. According to a better online calculator i would need that 165 bhp to add the 16 mph to my NA terminal.
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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Thu Apr 19, 2012 6:37 pm    Post subject: Reply with quote

I only ever used a single bottle mate. Even when running the 300 shot. But I did need to have a few spare full ones for a weekend as with 11lbs in the bottle it was using around 3lbs per pass. So after 2 runs the level in the bottle wasnt enough to keep pressure good enough for a third run, even at 900psi.

So it was 2 passes from each of the 5 bottles and then do a transfer by heating one bottle and running the other bottle under the tap if I had to do it trackside. I could normally get 4lbs topped up.

FYI
full 11lb bottle at 850-900 psi saw a touch over 100psi drop on a 10 second pass. Second pass on the same bottle pretty much the same. But a third pass on that bottle would drop by 150psi or more.
_________________
Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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mgbv8
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Gold Member


Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Wed Jun 06, 2012 9:42 pm    Post subject: Reply with quote

dbv8 wrote:
mgbv8 wrote:
Its a never ending story Del Smile

But each year there seems to be a better ending eh ??

This year I'm going to be experimenting with adding timing back in at high rpm on nitrous.

Or go the other way and drop timing way way back for bigger shots at the top end. On Jasons scrapper 4.6 in the Escort of course Laughing


Adding the timing back to compensate for the pressure drop? Makes sense to me.
Do you run 2 bottles Pel? My second stage is completely independant with its own bottle. As i am only running 100 shot stage 1 and 65 stage 2 I think pressure drop isnt a big issue for me. I must be producing good power top end to be hitting 127+. According to a better online calculator i would need that 165 bhp to add the 16 mph to my NA terminal.


Adding timing back in is not for pressure drop!!
Its for higher engine rpm ?? Smile
_________________
Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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