Exhaust size for nitrous motor

[Paul Bahnstormerz]

Engine is 1776, 110 cam with 1.25 rockers, ported 40x35.5 heads, 9:3:1 CR, 44idfs. I've always ran it with a 1 5/8" merged header with a Magnaflow turbo muffler.
Current plans are to run a progressive 100 bhp nitrous shot, which raises the question what size header do I need on this engine? Do I size the exhaust on NA horsepower or size it for nitrous horsepower?

[BeetleBug]

Engine is 1776, 110 cam with 1.25 rockers, ported 40x35.5 heads, 9:3:1 CR, 44idfs. I've always ran it with a 1 5/8" merged header with a Magnaflow turbo muffler.
Current plans are to run a progressive 100 bhp nitrous shot, which raises the question what size header do I need on this engine? Do I size the exhaust on NA horsepower or size it for nitrous horsepower?

My guess:

Your cylinders will crack long before you reach the power limit for your exhaust. That is unless you have a nitrous controller that is able to gradually deliver the nitrous. Your cam build compress very early and that in combination with thin cylinders and 100hp shot is why I believe your cylinders will not be up to the task. But please try and do not take my word for it.

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[Paul Bahnstormerz]

It's being controlled with pulsed solenoids from the digital controller, I can control every aspect of fuel and nitrous delivery, including ignition retard. The nitrous starts at 15% of maximum and I can build up to a % of maximum over a timed period, I can also delay the nitrous flow and flow fuel first to ensure I don't get a lean period. So getting it in no problem.

[Bernard Newbury]

It's being controlled with pulsed solenoids from the digital controller, I can control every aspect of fuel and nitrous delivery, including ignition retard. The nitrous starts at 15% of maximum and I can build up to a % of maximum over a timed period, I can also delay the nitrous flow and flow fuel first to ensure I don't get a lean period. So getting it in no problem.

Sorry, nothing to do with the exhaust but what progressive controller are you using?

[K-Roc]

Sounds like a Maximiser from Wizards of Nos,  I have a brand new on for sale if anyone is interested.

http://www.noswizard.com/catalog/product/gallery/id/1011/image/1152/

[Paul Bahnstormerz]

Sorry, nothing to do with the exhaust but what progressive controller are you using?
[/quote]

Hi

Using the Wizard of Nos setup for everything, the controller is their Maximiser

http://www.noswizard.com/nitrous-control/nitrous-controllers/maximiser-nitrous-controller.html

[modnrod]

No-ones really answered yet. 

I haven't used NO2 on ACVW, but plenty of other stuff. On my bikes I have tried to optimise the pipe diameter for the overall new HP, but it made it sort of "fluffy" and I lost a whole tenth just on the 60ft.
I went back to the normal sized pipes, and got it all back. Also, I have never overheated or melted anything on my aircooled bikes I've run it on, it's only on for 8 or 9 seconds anyway, so perhaps not enough time to heat load the system up perhaps?

[BeetleBug]

I have used nitrous on my 2221ccm and 2332ccm engine and I did not optimize the pipes for the total HP on nitrous. The jetting was always spot on the theory so I reckoned that it was OK. A 40hp shot gave 40-42hp on the dyno etc. It was not before I started playing with nitrous on a turbo engine that the actual output greatly exceeded the jet size. A 18hp dry shot produced close to 50hp on the dyno with a 4 degree ignition retard. A great surprise to us then but logical when you think about it.

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[Bernard Newbury]

When you are a putting nitrous engine together you should base everything around the nitrous. Cam, gearbox, compression and so on. If you think about it,  what goes in has to come out so you need to take into consideration the exhaust, as you do not want that to be the restricting point.  Just my view.  

[Bernard Newbury]

When you are putting a nitrous engine together you should base everything around the nitrous. Cam, gearbox, compression and so on. If you think about it,  what goes in has to come out so you need to take into consideration the exhaust, as you do not want that to be the restricting point.  Just my view.     Oops, don't know what happened here, posting twice!!