NOS with Supercharger Questions!

General Chat About Nitrous Oxide.

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topcatcustom
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Post by topcatcustom »

Ok, am I right in thinking I might get a couple of horses back from putting a new standard cam in with new followers etc? There are pistons on ebay that may be good or overkill?
http://cgi.ebay.co.uk/TVR-ROVER-V8-POWE ... dZViewItem

I am really doing this for a fun project not everyday or all out racing and primary concern is to keep costs as low as poss but have a bit of reliability there and a great toy! Would I gain much my Megajolting the ignition or will that end up costing a bomb too?! Thanks



mgbv8
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Post by mgbv8 »

These pistons are quite weak in the crown due to the amount of metal thats been removed for the valve relief.
I used this type on my last build and kept to the normal ring gaps for nitrous, but they still failed in the root of the cut out. I threw them out and fitted standard 4.6 pistons. And they have been much better for gas use.

Have you not got the original pistons??
Have you checked bore wear?

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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topcatcustom
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Post by topcatcustom »

Back to the original Q- fitting nos to blown lump- I am now definately using an offy 360 manifold which is going to be mod'd for the blower and I will definately not be able to fit a plate system in as far too small.

Can I use a couple of the 'bars' like you get in plates to go across the SC opening in the top of the manifold and custom fit them?

Reason being that if I use direct port it will only be cooling what goes into the cylinder just before it does and I'd have thought that if the gas entered the manifold higher up (ie straight after the SC) it would have a better cooling effect and more even boost across the whole manifold. If this isnt an option what is going to be best? I only want a small shot (75?) as I dont want to be melting things and I'm honestly not aiming for top bhp as I want to keep the motor reliable!

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topcatcustom
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Post by topcatcustom »

ps... Sorry didnt realise that things had changed a bit since I started this post! I AM using:

GMC 4-71 blower
Offy 360 manifold

and only going to be running about 6psi boost (again for reliability vs cost :lol: )

so due to my rushing into it I have the Edelbrock manifold AND eaton M112 spare (not the cheapest mistakes- never learn!) Bbut just means I will have to use them on another project after this one!

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Post by CastleMGBV8 »

Just a thought, you mentioned in your original post that the engine is a 4.0 and you were then looking at 3.9 pistons althought the capacitys are the same there a lot of differences in the two engines and the pistons for the earlier engine will not fit the rods of the later engine.

Kevin.

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topcatcustom
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Post by topcatcustom »

No sorry, it is def a 4.0 (the original was a 3.9 (when I started the post I wasn't aware of how much difference between them!) but the lump was so worn out I just got a 4.0 instead) !

Any ideas on what the best way of getting the nitrous in is going to be?! Maybe 4 foggers spraying into the middle of the offy under the blower?- will cool the whole charge then not just the mix in the heads (like direct port) but may cause the middle cylinders to run rich

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Post by topcatcustom »

Or I could use a plate under the carb on top of the blower- just wasnt sure about filling the blower with nos too though

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Post by mgbv8 »

From what I can see here, you are trying to use the nitrous as a charge cooler. And it seems you are thinking about using it dry. I may be wrong, but thats how I read the above. This wont yeild much power and has its own complications.

Using it dry as a charge cooler will have two effects.
1, it will cool the charge a bit.
2, it could make you run dangerously lean.
How would you intend to keep the fuel /nitrous mix correct when spraying?

If you want to avoid costly mistakes I would strongly suggest that you fit a "wet" kit, ie, spray nitrous and petrol together. This way you can set up and run the car with the charger, and you wont have to make any adjustments when you activate the gas apart from retarding the timing a tad.
There are many other considerations for using nitrous with a charger, especially as you are intending to use stock pistons.

Why cant you fit a normal NOS plate between the blower and manifold? is it a room issue? I have a complete Holley/NOS system in a box which will be going on ebay soon as I am now on my 3rd system upgrade.

Pardon me if I'm wrong. But you are new to Nitrous yes?
Forget trying to spray vapour as a charge cooler for your application. Its far more efficient to inject liquid nitrous as close as possible to the inlet valve. And also spray the matching amount of petrol to suit the nitrous shot.
You may alrady know this, but from what I'm reading it sounds like you are intending to use a dry system which will do you no good at all.

Perry

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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topcatcustom
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Post by topcatcustom »

No I definately want a wet system- for all your reasons! I have done some reading up on it but never fitted a system before- the reason I can't fit a plate between the blower and the manifold is because the blower outlet is twice the size of a standard 4bbl footprint!

It is mainly for the cooling yes- which of course is mostly in the name of more power, and of course the nitrous gives more power as well due to its own properties so its like a double bonus in a blown application.

mgbv8
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Post by mgbv8 »

I havent done any work with blowers. But if I were doing my own, I would fit a spider plate or go direct port in this instance.
I'd be concerned about controlling detonation though.
You cant beat the sound of a blower eh? I'd fit one just for the look and sound if I had the spare dosh.

Perry

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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