Two Stage Dry Nitrous

[1ndecent]

Hi Justen,

I didn't get an itemised invoice, the whole kit was 490 pounds or $1239AUD. Freight and import duty was about $500 more!

The 4 way splitters were included, they are listed on Aquamist's website. They (and alot of other useful fittings) are available through local suppliers like Enzed.

Total flow capacity of the 8 jets is around 600cc/min, I am using a high speed valve controlled by one of the PWM outputs of the SM4 to map the water against fuel delivery (and another input, yet to be decided).

Water injection will not add power, but it may allow you to operate at higher boost/more advance without detonation, this is where the extra power will come from.

You have an SM2 right? Does it support dry nitrous?

I am not a big fan of single fogger wet systems, because of fuel distribution issues and the possibility of backfiring blowing the intake manifold to bits.

I doubt you would even notice an extra 75hp at the top end given the power you make now... It would help spool up though.

 

[JustenGT8]

It's just that i've had this this old NOS kit hanging around for ages. It was to help spool up a big TO4E on my RWD 3SGTE but never happened and then i sold the car.

Yeah SM2. I have 3 mappable outputs and 2 simple triggered outputs from memory. Currently the WI is just triggered at 5psi and any rpm. So you are varying water volume thru a high speed valve? interesting

WI is a bit of a black art i reckon as some fairly creditable literature and even a mate with real world data are using it to make hp...actually it improves torque but add rpm and ergo.....

Hasn't been my experience and i'm a bit stuffed as to how to test to optimise my system. Only way i can think of is to hold the car loaded at full boost on the dyno and vary the water volume by playing around with the WI pressure?

Sounds a bit harsh on the engine though as it's pretty much at the ragged edge for the stock pistons already i suspect?

I can live with what i have, just curious if there's any easy gains to be had with some simple tweaking.

Yeah gotta love EnZed...don't always love their prices but the local guys have helped me out heaps in the past with custom fuel line fittings etc.

Thanks for the feedback, if you have any more thoughts happy to hear em.

 

[1ndecent]

I am writing a thesis on water injection for knock suppression at the moment. Once I finish my testing I should be able to give you some more detailed information, but current (old) literature suggests about 10% of fuel volume is the optimum rate for water injection.

Distribution is critical, which is why I have gone with 8 nozzles. Your system could easily be modified to use a HSV for flow control, and you already have the means to drive it.

For maximum power, the ignition angle needs to be set at MBT. WI can affect the burn rate, and you may need to revise the timing map to shift peak cylinder pressure back to the point where it does most good.

Optimum A/F ratio at full load is much leaner with WI, as no extra fuel is needed for cooling.

 

[JustenGT8]

Good info cheers.

Real back of the envelope stuff but i need approx 300cc/min at max boost which is pretty much what the nozzle i have supplies. I don't get the atomisation that the aquamist nozzles give so i might swap for one of those i have kicking around.

You lost me with MBT? I assume i should be running more advance?

 

[1ndecent]

MBT is an acronym (of sorts) for 'Minimum Spark Advance for Best Torque).

For any engine there is a position in the power stroke (usually 15-20 deg ATDC) where the peak cylinder pressure should occur in order to achieve maximum torque. This position is dependent only on engine geometry, not RPM or load.

The ignition timing required to achieve peak cylinder pressure at this point is the MBT, which is dynamic, and depends on engine speed, ignition delay and burn rate. Ignition delay and burn rate can be affected by the water injection, if the effect of the WI is to cause a longer time period between ignition and peak pressure, the timing will need to be advanced to get it back to MBT.

This is what I was getting at before when I mentioned shifting peak cylinder pressure back to where it does most good.

If an engine is running high compression, high boost, nitrous, or using low octane fuel, it may not be able to acheive MBT without detonation (knock) occurring. In this case water injection can help by suppressing knock, and allowing the engine to run MBT, and develop more power.

There is heaps of information around on the internet about this stuff, here is one site that came up when I googled:

http://www.innovatemotorsports.com/resources/myths.php

This is a commercial site, and lacking in detail, if you are after more information have a look at the DIY EFI pages out there or feel free to ask more questions.

 

[JustenGT8]

Thanx once again.

Dyno for me then i think. I have no det issues at 320rwkw with the WI off and A/F at 11.5:1 from memory. I'm keen to lean things out to 12.5:1 with the WI as the det controller. Once i get that target, or close as we can, then i'll start adding ignition advance until torque peaks or i get det and then dial it back a coupla deg for safety.

I'll keep you posted. Thanks again and apologies for hijacking your thread

 

[1ndecent]

Always a pleasure to have such an interesting discussion!

How are you detecting knock on the dyno?

I have a Link Knock Block wired into the car feeding a 0-5V analog signal to the SM4, which I use to retard timing if knocking occurs. Along with the wideband O2 controller, this allows me to do all of my tuning on the road.

 

[JustenGT8]

Likewise, i never seem to be able to find the time to get right into the tech aspects like i should....too many hobbies

Dyno dude has a knock 'ear', not sure what brand though. Trusty old ear muffs do a pretty good job for my piece of mind as well.

One day maybe i'll get a wideband...in have a narrow band as a lean out warning. For the dyno rates i get though a wide band is a lot of dyno tuning time

 

[jibbby]

Sorry to bust in on this thread but it sounds like you guys really know what you are talking about..., I always thought there is problems running nitrous with a exhaust driven turbo......Am I mistaken?...

I am in the process of aquiring a GT35R single turbo to go along with a built 1uz-fe motor....I would love to keep my 100hp dry Nos system in addition to the GT35R Turbo... Is there a problem when running both together?

Any helpful info. on this would be most appreciated....

 

[1ndecent]

Hi Jibbby,

It really depends on your setup, so give us some more details!

In particular, what engine management system are you running, or intend to run with your turbo setup.

 

[JustenGT8]

Yeah more details would help provide a more complete answer but the short answer is basically 'no probs'. Nitrous is a common spool up aid for big turbo/small capacity engines....the extra exhaust gas flow NOx provides is a real help.

All the same dangers as in n/a but no extra probs i am aware of?

 

[jibbby]

Thank you fellas...I thought the NOS exhaust would effect spool up, or cause overheating... Apparently I was mistaken....As for my setup now I have just the 100hp nos dry system with the Apexi Piggy-back system which only has the ability to change the Fuel/Air ratios...

With the Garrett single turbo installed I believe I may be switching to let say an SMT6 or 7 Engine management Piggy-back unit or something that can change both fuel/air ratios and advance or retart timing....The 1uz-fe engine is built with forgies, larger injectors ,etc. to support the turbo and hp output.....That is about it, and the plans are in the works now...Currently I have plans to build up the stock auto tranny which will be sent out on Friday to boost logic to support hopefully what will be around 500whp+...That is what I have planned for my final goal with my SC4....Right around the 500whp mark with the addition of my current NOS system...

 

[1ndecent]

[FONT=&quot]I typed out a lengthy reply this morning, but the posting failed and I lost the lot, so here it is again in point form:

[/FONT]

• [FONT=&quot] Piggyback systems are dodgy.[/FONT]

• [FONT=&quot] Don't know if SMT7 can apply correction maps to fuel and timing ONLY when output (nitrous) is triggered.[/FONT]

• [FONT=&quot] SMT7 can only adjust fuelling by altering AFM signal, altering stock narrowband O2 signal, or activating extra injectors.[/FONT]

• [FONT=&quot] Altering AFM signal will cause stock ECU to change fuel AND TIMING.[/FONT]

• [FONT=&quot] Altering stock O2 signal will cause stock ECU to alter fuel ONLY if it is in closed loop mode. While in closed loop the maximum range of correction is still quite small.[/FONT]

• [FONT=&quot] The stock ECU will build up a secondary fuel correction map, based on the adjustments it has made as a result of the stock O2 signal, this correction map is always applied, closed loop or open loop.[/FONT]

• [FONT=&quot] Adding one or two extra injectors is dodgy, as you don't know if all cylinders will be delivered equal amounts of fuel. Port injection superceded throttle body injection for a very good reason![/FONT]

• [FONT=&quot] The SMT7 COULD be made to run your engine (in conjunction with the stock ECU) with turbo and nitrous. BUT there would be major compromises due to the limitations of the system. To work around the compromises and tune the setup 'safely' would result in a less than optimum power output for some operating conditions.[/FONT]

[FONT=&quot]
It sounds like you are going to get a workshop to install and tune your new ECU, you need to find a good tuner/workshop first, and then discuss your needs with them

Steer well clear of any tuner who recommends the use of piggyback control units![/FONT]

 

[jibbby]

Most likely I will begin tuning myself in the near future.....I have been studying up on this subject for some time now and hanging out with a local tuner...Unfortunately he only tunes Chevy and Fords......Anyway, from what you are saying it sounds like tuning for engine safety when running a turbo in combination with Nos may require a good Stand Alone ECU to bring out full potential of both systems...That can manage and tune everything...MAP......

I may dump the nos after all....To much trouble... Thanks a million for the reply....

Oh and I just hate when you take the time to write a really good and lengthy informative post and it doesn't send when you hit the post reply button...Then you gotta start over.....Just irritates the hell out of me and makes me want to throw the key board.......Thanks anyway....

 

[1ndecent]

Tuning yourself is good! But you also have to pay for your mistakes, so be careful!

From a tuning point of view, it makes no difference which manufacturer produced the engine, the techniques are exactly the same when tuning a standalone. (There may be minor differences between sync signals and actuator requirements though)

Saying nitrous is too much trouble is a defeatist! You just have to factor it in when you plan your system. Given that you have all the nitrous hardware already it would be a shame not to use it...

 

[jibbby]

That was my thinking, I like your attitude.....What a shame not to use it is my thinking too.....I will deal with it and make it work if it won't blow the motor or work over the turbo...Retarting the timing and changing the fuel and air mix is not a problem...That is what I expect the next engine management system I use to do....

I will deal with it when the time comes...Thanks again...The nos system stays...

 

[cribbj]

1ndecent, can you identify whose high speed valve that is in the Aquamist kit?

Hope you'll share your thesis with us!

John

 

[1ndecent]

The original part number has been obliterated, as you'd expect at the markup they must be making. I did a quick look round on the net to try and identify it, but I didn't get anywhere.

I will post the thesis online.

 

[1ndecent]

I ran both stages of nitrous concurrently today, 180hp shot triggered at 3000rpm and the 230hp shot triggered at 4500rpm. Each stage has an ignition retard of 4 deg, so from 4500rpm up it was running 8 degrees retarded from normal full load timing.

It looks like I will need some sticky drag tyres to get the power down, the 255R16 tyres I have will spin wildly in first and second with just the first stage of nitrous in use.

I was only brave enough to do one acceleration run with both stages, the logged data shows 0-100km/h in 5.2 seconds, and 0-160km/h in 10.17 seconds.

The water injection system was running 50/50 water and methanol, with the flow rate mapped to 50% of the volume of fuel delivery. However, because I sized the water jets (8x0.3mm) for a delivery rate much lower than this (20%), the system is maxed out by 4000rpm. I will have to order bigger jets to achieve the flow I need, and may need to run dual flow control valves as well.

 

[JustenGT8]

Nice. Does it hit hard? that's where you'll struggle for traction as the shock load is too much for the tyres and once they start it's hard to get it back eh. Pretty impressive numbers though...in comparison i run sub 4 sec 0-100kph and 11 sec for 0-200kph