Miatapower List Archive

This read-only message was archived from a public mail list.
Mail From: Toby Weir-Jones <(email redacted)>


So I'm considering a small upgrade.

I want to add a direct-port nitrous/methanol system to the car. This will
require the addition of a second fuel tank and associated pump & plumbing,
along with all the nitrous bits. Which is fine.

The question is: how do I calculate the effective incremental cylinder
pressures under nitrous? If I assume the motor can run safely at say 16psi
effective pressure increase, can I safely divide that 16psi between turbo
and N2O+methanol?

Variables I'm aware of:

--flow rate of nitrous jets
--flow rate of methanol jets
--pressure of nitrous
--pressure of methanol
--possibility of a boost-sensitive methanol pressure regulator
--temperature issues
--existing MAP issues related to turbo

the NitrousExpress kit model #80045 (4-cylinder, EFI, direct port &
methanol) claims standard jetting at 125 hp. Ultimately the question boils
down to: how much (if at all) would I need to reduce the boost to run those
jets, and is my incremental power gain worth it after the boost reduction?

I'm more inclined to jet the whole system for ~75 hp and the NX tech assures
me appropriate nozzles could be supplied. But we'll see.

Anybody have a '94-'97 intake manifold they want to sell?

twj

This read-only message was archived from a public mail list.
Mail From: Brad Franks <(email redacted)>


Hi Toby,

I'm kind of new to NO2 but am learning as I go during my prep/ build up for
the install of a similar system from NOS. As I understand it cylinder
pressures don't play as much a part in the system as do cylinder
temperatures. The intake charge is reduced as a function of NO2 injection,
but because of the larger amounts of combustibles the cylinder temps tend to
rise dramatically. Similar in theory to a boosted engine.

Personally I would think about ignition timing as a function of NO2
separately from the ignition timing while under boost. For obvious reasons
you want to reduce timing under boost, and you will probably want to reduce
timing under NO2 separately. You may be under boost quite a bit more often
than under NO2 depending on how you set the system up so setting timing
curves according to both happening simultaneously may lead to less than
desired results when one system is functioning independently of the other.
(whew, that was a long one...) For instance: When you run out of NO2 and are
waiting for the bottle to be refilled you will be under boost only, but your
timing curve would be set up for boost+NO2.

That is of course assuming you can and choose to f* with timing for optimal
performance from your NO2 kit. OTOH, in my lack of knowledge on the subject
matter I am only applying logic and not any first hand experience.

Usual disclaimers of sheer and total ignorance apply to the above
statements.

Brad

-----Original Message-----
From: (email redacted)
[mailto:(email redacted)]On Behalf Of Toby Weir-Jones
Sent: Thursday, April 27, 2000 12:11 PM
To: '(email redacted)'
Subject: cylinder pressure calculations w/nitrous?



So I'm considering a small upgrade.

I want to add a direct-port nitrous/methanol system to the car. This will
require the addition of a second fuel tank and associated pump & plumbing,
along with all the nitrous bits. Which is fine.

The question is: how do I calculate the effective incremental cylinder
pressures under nitrous? If I assume the motor can run safely at say 16psi
effective pressure increase, can I safely divide that 16psi between turbo
and N2O+methanol?

Variables I'm aware of:

--flow rate of nitrous jets
--flow rate of methanol jets
--pressure of nitrous
--pressure of methanol
--possibility of a boost-sensitive methanol pressure regulator
--temperature issues
--existing MAP issues related to turbo

the NitrousExpress kit model #80045 (4-cylinder, EFI, direct port &
methanol) claims standard jetting at 125 hp. Ultimately the question boils
down to: how much (if at all) would I need to reduce the boost to run those
jets, and is my incremental power gain worth it after the boost reduction?

I'm more inclined to jet the whole system for ~75 hp and the NX tech assures
me appropriate nozzles could be supplied. But we'll see.

Anybody have a '94-'97 intake manifold they want to sell?

twj

This read-only message was archived from a public mail list.
Mail From: "Ashton Smith" <(email redacted)>


I run a direct port wet system on my car. It is the NOS #5030FI kit. I
have .018 jets for NOS and .014 jets for fuel. The fuel is T'ed off of my
fuel line in the engine compartment. With those jets and 40psi or so on
fuel pressure it equates to aprox 12 hp/cyl or 48 hp total. This is run on
top of 16 psi from the turbo. I have the FMII with the Link computer using
pre-set timing values. Also I have the motor set to stock ignition timing.
It works well.

My motor recently blew up. It wasn't due to the NOS. It was a stupid
friend of mine messing with stuff he wasn't suposed too. Anyway, it ran
with turbo and NOS for 15,000 miles with no problem.

Ashton Smith

-----Original Message-----
From: (email redacted)
[mailto:(email redacted)]On Behalf Of Brad Franks
Sent: Thursday, April 27, 2000 1:06 PM
To: 'Toby Weir-Jones'; '(email redacted)'
Subject: RE: cylinder pressure calculations w/nitrous?



Hi Toby,

I'm kind of new to NO2 but am learning as I go during my prep/ build up for
the install of a similar system from NOS. As I understand it cylinder
pressures don't play as much a part in the system as do cylinder
temperatures. The intake charge is reduced as a function of NO2 injection,
but because of the larger amounts of combustibles the cylinder temps tend to
rise dramatically. Similar in theory to a boosted engine.

Personally I would think about ignition timing as a function of NO2
separately from the ignition timing while under boost. For obvious reasons
you want to reduce timing under boost, and you will probably want to reduce
timing under NO2 separately. You may be under boost quite a bit more often
than under NO2 depending on how you set the system up so setting timing
curves according to both happening simultaneously may lead to less than
desired results when one system is functioning independently of the other.
(whew, that was a long one...) For instance: When you run out of NO2 and are
waiting for the bottle to be refilled you will be under boost only, but your
timing curve would be set up for boost+NO2.

That is of course assuming you can and choose to f* with timing for optimal
performance from your NO2 kit. OTOH, in my lack of knowledge on the subject
matter I am only applying logic and not any first hand experience.

Usual disclaimers of sheer and total ignorance apply to the above
statements.

Brad

-----Original Message-----
From: (email redacted)
[mailto:(email redacted)]On Behalf Of Toby Weir-Jones
Sent: Thursday, April 27, 2000 12:11 PM
To: '(email redacted)'
Subject: cylinder pressure calculations w/nitrous?



So I'm considering a small upgrade.

I want to add a direct-port nitrous/methanol system to the car. This will
require the addition of a second fuel tank and associated pump & plumbing,
along with all the nitrous bits. Which is fine.

The question is: how do I calculate the effective incremental cylinder
pressures under nitrous? If I assume the motor can run safely at say 16psi
effective pressure increase, can I safely divide that 16psi between turbo
and N2O+methanol?

Variables I'm aware of:

--flow rate of nitrous jets
--flow rate of methanol jets
--pressure of nitrous
--pressure of methanol
--possibility of a boost-sensitive methanol pressure regulator
--temperature issues
--existing MAP issues related to turbo

the NitrousExpress kit model #80045 (4-cylinder, EFI, direct port &
methanol) claims standard jetting at 125 hp. Ultimately the question boils
down to: how much (if at all) would I need to reduce the boost to run those
jets, and is my incremental power gain worth it after the boost reduction?

I'm more inclined to jet the whole system for ~75 hp and the NX tech assures
me appropriate nozzles could be supplied. But we'll see.

Anybody have a '94-'97 intake manifold they want to sell?

twj