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Todays result for the MGB

 
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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Sat Jul 25, 2009 2:40 pm    Post subject: Todays result for the MGB Reply with quote

Well!!
It took 7 passes to get the AFR thingy right. As I thought. She was running mentally rich.
I've now settled on a ratio of 2 nitrous to 1 fuel, and she runs just a tad rich still.

She made 378bhp with 602 ft/lbs of torque. Tranny losses are high, so I got 297bhp at the wheels.
But as I suspected. I'm making too much power, too low in the rev range. I guess a new cam will help sort this eh??
And my pipes need to extend a touch as the flames were quite big out the sides. Smile


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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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Darkspeed
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Joined: 02 Sep 2007
Posts: 897
Location: Shropshire

1994 Ginetta G Series

PostPosted: Sat Jul 25, 2009 4:00 pm    Post subject: Reply with quote

Perry,

Interesting results - hope you dont mind a few questions

What value of Nitrous was being injected?
Was that all done in top gear and what box you running?
What was the overall gain in power from the first run?
What AFR did you achieve?

Cheers

Andrew
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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Sat Jul 25, 2009 8:49 pm    Post subject: Reply with quote

Andrew!
I have a few issues that dont add up for this lot of testing. The main one being that I may have a restriction in my nitrous system?? Which is why I had to drop the fuel delivery in the nitrous system.

She ran 220 nasp on the last dyno day. But oly 198 today. But the car has been hammered for 2 years since then.

I was using a theoretical 300 shot of gas. But this only gave a tad under 200hp increase.

The runs are done in 3rd (top) gear. I run a Chevy TH350 streetfighter autobox.

I cant remember the actual AFR we settled on as the numbers were confusing me. My mate was rambling on about Lambda and stoic etc. So I asked for it in simple terms. He showed me the plot on the screen and pointed to a line on the grid that read 1.0 and said that was something important. He said he would want me to be running down near 0.8 or something.
Anyroad up! The final nitrous run was apparently 1 notch on the rich side of ideal!! Which he was happy with.

But I know I need to get that power band further up the rpm scale eh?
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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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CastleMGBV8
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Joined: 18 Aug 2007
Posts: 2334
Location: Sidcup, Kent, UK

1975 MG MGB GT V8

PostPosted: Mon Jul 27, 2009 9:08 am    Post subject: Reply with quote

Perry,

I did try posting a long reply on friday but in the attempt to link some additional information, the page of text disappeared!

As there are as many questions as answers it would be easier to talk, if you like give me a ring on 0208 309 6154 we can probably make more sense of it.

I have some suggestions re the cam but need more information.

Kevin.
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mgbv8
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Joined: 18 Nov 2006
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1975 MG MGB GT V8

PostPosted: Mon Jul 27, 2009 9:15 am    Post subject: Reply with quote

Cheers Kev
Will do mate. I'm also convincing myself that the carb is too small to keep up with the nitrous I'm using. I think that is one reason I'm having to add more oxygen chemically afer the carb.
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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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CastleMGBV8
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Joined: 18 Aug 2007
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Location: Sidcup, Kent, UK

1975 MG MGB GT V8

PostPosted: Mon Jul 27, 2009 9:39 am    Post subject: Reply with quote

Perry,

Before we speak can you get your existing cam specs from R/S?

Don't think it's a carb problem as a 500 will flow enough for 300+ BHP without gas and when the gas is on the draw on the carb is substancially reduced.

Kevin.
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mgbv8
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Joined: 18 Nov 2006
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1975 MG MGB GT V8

PostPosted: Mon Jul 27, 2009 12:43 pm    Post subject: Reply with quote

The cam spec just says
rpm range:
idle to 6000rpm

Inlet 212
Exhaust 218

lift:
inlet 0.465"
exhaust 0.480"
Lob sep 114 degree's

Thats is really.
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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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mgbv8
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Joined: 18 Nov 2006
Posts: 5326


1975 MG MGB GT V8

PostPosted: Mon Jul 27, 2009 12:43 pm    Post subject: Reply with quote

The cam spec just says
rpm range:
idle to 6000rpm

Inlet 212
Exhaust 218

lift:
inlet 0.465"
exhaust 0.480"
Lob sep 114 degree's

Thats is really.
_________________
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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CastleMGBV8
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Joined: 18 Aug 2007
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Location: Sidcup, Kent, UK

1975 MG MGB GT V8

PostPosted: Wed Jul 29, 2009 8:45 am    Post subject: Reply with quote

Perry,

Did you get the e-mail I sent you?

In addition to try and make some sense of where the power drop between the N/A power curves from last year and this year is from, it might be a good idea to do a compression and possibly a leak down test to see if that massive amount of torque and the resultant extreme cylinder pressures have had an effect on the rings and possibly the exhaust valves and seats.

Kevin.
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mgbv8
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Joined: 18 Nov 2006
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1975 MG MGB GT V8

PostPosted: Wed Jul 29, 2009 4:46 pm    Post subject: Reply with quote

Yes Kev!
I got the email. And I'll do some testing after I've raced on Sunday.

Pel
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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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mgbv8
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Joined: 18 Nov 2006
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1975 MG MGB GT V8

PostPosted: Thu Jul 30, 2009 8:06 pm    Post subject: Reply with quote

I've just been given Des Hamills book.

Camshafts for the thick twat!!!

Its good reading. It has pictures. And the words are nice and big too Smile
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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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Coops
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Joined: 17 Nov 2006
Posts: 6057
Location: Newbury, Berks

1986 Ford Capri

PostPosted: Thu Jul 30, 2009 8:11 pm    Post subject: Reply with quote

mgbv8 wrote:
I've just been given Des Hamills book.

Camshafts for the thick twat!!!

Its good reading. It has pictures. And the words are nice and big too Smile


fooking hell Pel you do make me larf mate Laughing Laughing
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stevieturbo
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1980 Ford Granada

PostPosted: Thu Jul 30, 2009 9:30 pm    Post subject: Reply with quote

600 lbft ???
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