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Author Topic: Ignition retard and cam centres for nitrous  (Read 4045 times)

Offline Isleofmanbusa

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Ignition retard and cam centres for nitrous
« on: January 28, 2014, 04:09:15 PM »
Motor is 1441 12.5 c/r cp h/duty pistons carillo rods ect  using VP C16 ,and MSD SB6 ignition Cams are Kent spec as follows
Applications   Race
Power Band   N/A
Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust
Duration   248 Deg Inlet / 234 Deg Exhaust
Timing   19/49 42/12
Full Lift   Inlet 105 Deg ATDC/Exh 105 Deg BTDC
VC (mm)   0.20 mm Inlet / 0.20mm Exhaust
LTDC   2.60mm Inlet / 1.66mm Exhaust
I intend to be spraying from 70 to 150 bhp .So my question is what cam timing would you recommend and how much ignition retard for 70 through 150 of spray hope some one can help
My mind is a scary place

Offline Rocketgeezer

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Re: Ignition retard and cam centres for nitrous
« Reply #1 on: January 28, 2014, 07:59:47 PM »
Motor is 1441 12.5 c/r cp h/duty pistons carillo rods ect  using VP C16 ,and MSD SB6 ignition Cams are Kent spec as follows
Applications   Race
Power Band   N/A
Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust
Duration   248 Deg Inlet / 234 Deg Exhaust
Timing   19/49 42/12
Full Lift   Inlet 105 Deg ATDC/Exh 105 Deg BTDC
VC (mm)   0.20 mm Inlet / 0.20mm Exhaust
LTDC   2.60mm Inlet / 1.66mm Exhaust
I intend to be spraying from 70 to 150 bhp .So my question is what cam timing would you recommend and how much ignition retard for 70 through 150 of spray hope some one can help
You need to give Ryan Shinitz a call he seems to have it on the ball with heavy nitrous, what I do know from my race car days with nitrous, is the cam setup was not as big a deal as ign timing, had to dial timing way back when nitrous was activated, MSD box's made it easy, but if something screwed up and the timing didn't retard when it was supposed to the pistons started spraying themselves out the exhaust  :|
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Offline Isleofmanbusa

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Re: Ignition retard and cam centres for nitrous
« Reply #2 on: January 29, 2014, 04:40:59 AM »
Thanks for reply I will try to avoide spraying molten piston out of the exhaust  :D :tu:I hope
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Online RansomT

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Re: Ignition retard and cam centres for nitrous
« Reply #3 on: January 29, 2014, 08:11:37 AM »
I've been trying to figure out your cam specs.  Over on this side of the pond, we don't commonly use specs in mm and I'm not even sure Kent measures the duration/lift in the same spot as we do.

With that said:  what type of racing are you going to be doing?  1/8 : 1/4 : Land Speed ?
Fastest 1.5-Mile Pass - 252.222
Fastest 1-Mile Pass - 244.2997
Half Mile - 211.47
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211.079 LTA. P/P 1350

Offline Isleofmanbusa

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Re: Ignition retard and cam centres for nitrous
« Reply #4 on: January 29, 2014, 08:45:57 AM »
1/4 mile will try to get in touch with Kent and ask that question  :tu:
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Online knecum

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Re: Ignition retard and cam centres for nitrous
« Reply #5 on: January 30, 2014, 05:23:24 AM »
Mm to in =.  Mm x .03937.     In to mm =.   In x 25.4.   If the duration is advertised in typical duration # like 240-257 its meas @ .040 or .;050  checking lift.   If its listed at some crazy 280 degrees. It's meas from .001 ish to the same on closing side

Offline SEJ

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Re: Ignition retard and cam centres for nitrous
« Reply #6 on: January 30, 2014, 11:11:08 AM »
Motor is 1441 12.5 c/r cp h/duty pistons carillo rods ect  using VP C16 ,and MSD SB6 ignition Cams are Kent spec as follows
Applications   Race
Power Band   N/A
Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust
Duration   248 Deg Inlet / 234 Deg Exhaust
Timing   19/49 42/12
Full Lift   Inlet 105 Deg ATDC/Exh 105 Deg BTDC
VC (mm)   0.20 mm Inlet / 0.20mm Exhaust
LTDC   2.60mm Inlet / 1.66mm Exhaust
I intend to be spraying from 70 to 150 bhp .So my question is what cam timing would you recommend and how much ignition retard for 70 through 150 of spray hope some one can help

Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust = .365"/.321"
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust = .357"/.313"


I'm pretty sure that they measure duration at 1mm of lift which is just under 0.040"  (0.03937")
« Last Edit: January 30, 2014, 11:15:36 AM by SEJ »
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Online RansomT

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Re: Ignition retard and cam centres for nitrous
« Reply #7 on: January 30, 2014, 11:49:09 AM »
Motor is 1441 12.5 c/r cp h/duty pistons carillo rods ect  using VP C16 ,and MSD SB6 ignition Cams are Kent spec as follows
Applications   Race
Power Band   N/A
Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust
Duration   248 Deg Inlet / 234 Deg Exhaust
Timing   19/49 42/12
Full Lift   Inlet 105 Deg ATDC/Exh 105 Deg BTDC
VC (mm)   0.20 mm Inlet / 0.20mm Exhaust
LTDC   2.60mm Inlet / 1.66mm Exhaust
I intend to be spraying from 70 to 150 bhp .So my question is what cam timing would you recommend and how much ignition retard for 70 through 150 of spray hope some one can help

Cam Lift(mm)   9.27mm Inlet / 8.15mm Exhaust = .365"/.321"
Valve Lift(mm)   9.07mm Inlet / 7.95mm Exhaust = .357"/.313"


I'm pretty sure that they measure duration at 1mm of lift which is just under 0.040"  (0.03937")

I was getting the same thing, but that puts those cams close to the Yosh Stage 1 cams (that's why I questioned the method of measuring)  ... which isn't enough cam especially for that size of engine.  (let alone the spread is wrong from nitrous)
Fastest 1.5-Mile Pass - 252.222
Fastest 1-Mile Pass - 244.2997
Half Mile - 211.47
Fastest Nitrous Bike
Production Bike
211.079 LTA. P/P 1350

Offline Isleofmanbusa

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Re: Ignition retard and cam centres for nitrous
« Reply #8 on: January 30, 2014, 04:01:28 PM »
So what cams would recommend
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Offline gixxre750

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Re: Ignition retard and cam centres for nitrous
« Reply #9 on: January 30, 2014, 04:07:18 PM »
It depends on who did your head and the cams he recommends. 415/395 is a pretty popular combo w a 1441

Offline Isleofmanbusa

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Re: Ignition retard and cam centres for nitrous
« Reply #10 on: February 05, 2014, 10:13:46 AM »
So with 415/395 cams what cam timing would be good for my nitrous motor ?
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Offline gixxre750

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Re: Ignition retard and cam centres for nitrous
« Reply #11 on: February 05, 2014, 12:05:51 PM »
If they are web cams, they recommend 106/108 but every head is different. But that's where I would start