NITROUS OXIDE ( nos / n2o ) advice forum

Hello. This is my first post here on what appears to be a fantastic site filled with brain food. I hope to gain some new knowledge from my participation here.

I'm running a turbocharged Buick V6 all custom build on methanol. The displacement is 224 with a stroke of 3.06". Rather small in the Buick V6 world. I chose to build a revver. Redline is 7800 rpm. The cam is relatively large in duration and overlap for a turbo engine. The manifolding has been configured to take advantage of pulse tuning. The turbo presently is a 76 mm compressor and I'll be stepping up to an 80 mm soon. The small cubes, stroke and cam specs make spool up very difficult. That is really of no consequence, since that was expected and the engine configuration plan included the use of a port injected nitrous system to help spool up. The system I'm presently using is a mix of components, some of my own design. It's been working well, providing 16 psi of boost pressure in a matter of .4 seconds from activation. I use a pressure switch to shut down the system at 16 psi. I feel I have a good basic knowledge of how nitrous systems work and I'm ready to take it to the next level. When I came across this site, I couldn't hold the drool back. This site is fantastic. I'm looking to further understand the scientific side of nitrous injection and find out what the latest equipment and controls have been made available. My system is very basic and I would like to equip myself with a system that has a much broader control capability.
What I basically am looking for at this point in time is a system which will control the amount of initial injection rate, maybe with a slight ramping up to a specific manifold pressure, then being throttled back to a lower level through the engines peak torque range and then ramping up again slowly to redline, then ramping back down after the gearshift, again ramping back up to redline. Is this idea sound or do you see any problems with my thinking? The T76 will only give me about 22 psi boost without nitrous and the max boost limit that I've established for the engine is 28 psi. So there is a window in case the use of nitrous did force boost to rise a little. With the 80 mm that may not be the case. Maybe stick with the 76?
The static CR of the engine is 9.24 to one. Low for a methanol engine, but very safe. I've been at 11.4 and the tune up is too on the edge with that CR. I can't afford to go through another major failure.

Another more basic question that I've always wondered about. I've read that using nitrous with methanol does not net the same HP potential as when using nitrous with gasoline. Can you shed some light on that and explain why that is? I'm presently using nitrous jet sizes that would normally net 200 HP when used with gasoline. My sims that I have used to try and match the actual track performance tells me I'm netting maybe 80 HP from the system. Not that I'm looking for a true 200 HP to spool the turbo. It's spooling up just fine. I just want to understand more the scientific side of what's happening. Thank you gentlemen for putting up with this long post.

I should probably warn you now. I can be long winded sometimes. Sorry.

The cam specs are 248/258 .050" with a 110 lobe separation.
Intake centerline installed at 106 degrees.
For a turbocharged purpose built racing engine it's not out of the ball park, but in the Buick community, I'm nuts.

The whole engine configuration was built around some limitations of the heads. That's why the small cubes and stroke. Small valves, low flow numbers. At the time there really wasn't many options for heads for this engine and the intention was to do the best with what I had. They are aluminum heads. Not stock. Stock port configuration though.
With the head situation it was decided to rev the engine to get the HP numbers I was targeting. 950 to 1100 HP. The duration reflects the rpm target. I know some people would say lower the revs and get boost up quicker and higher in the midrange. To do that would call for some wild cylinder pressures in the midrange to get my target HP out of just 224 cid with a 3.06" stroke. A dangerous level.

There are conflicting theories as to whether pulse tuning happens in a turbocharged application. The people that have chose to design their manifolding to take advantage of any pulse tuning in a turbocharged application have always given the thumbs up. Including the elite racing classes. Formula and Indy. My personal experience also gives credence to the idea that pulse tuning does happen in a turbo application, just at much higher pressures throughout the entire system. From after turbo compressor to after the turbine housing. That's the only explanation for the type of performance I've been able to milk from this engine. I don't have any dyno figures, but look at the track results.

3337 lb. car with driver and fuel
235 cid (previous build) with 3.06 stroke
1.835" intake valve, 1.5" exhaust
T76 turbo with an approximate HP flow capability of 900 HP.
Redline limit 7800 rpm
Fuel methanol
Density altitude of over 4000 ft.
Temp 79
9.28 ET 1/4 mile
147 mph 1/4 mile
with a 5.94 1/8 split time

Certainly this was much better performance than I had imagined I would get from my combination with severly limited head flow.

And that run was with 21 to 22 psi boost. Most people claim this is impossible.

The estimated HP figures that I mentioned that I think I'm getting from my system may not be accurate. Engine sims are like anything else when relating to computers. Trash in, trash out. So I really should expect to get the full HP level from the system regardless of type of fuel. OK.

The jet sizes are NOS jets at 24 on the nitrous and 24 on the fuel with 45 psi rail pressure on the fuel.

Regardless of the HP level I'm getting from the system, I think I'm getting an adequate performance from it. Should I be expecting better than 16 psi in .4 seconds? At what point is the system being too aggressive? My rim screws are getting a pretty mean tweak to them.

Donnie, This is Ricky Dyer with O2-Technology. You have an interesting combination and one that is performing rather well. The times that you are posting at your current weight indicate 814 rwhp which would equate to approximately 980 crankshaft at 4000 density altitude and an automatic transmission. With an 11.4 A/F on C-16 or better gasoline I would not worry. I ran a similar combination with a small chevy V8 and ran at 11.4 and went very fast. The .024 jets will only make around 125-130hp, because you only have 6 jets. By the time you allow for converter slippage, etc you will not see anymore than 100hp. At 45 psi fuel pressure on gasoline, I would run a slightly smaller jet (maybe .014-.016). Your fuel injection system is making the corrections for you anyway.

On motor without the nitrous you could probably pick up 100hp by switching to a 114-115 lobe seperation. This will kill some overlap and build more cylinder pressure.

If you make the switch to methanol it will be a good one! The motor will love it. Leave the nitrous alone and run the system like you have it, but make sure that your fuel injectors are large enough to handle the extra volume of methanol. It takes approximately 2.1 times as much fuel when making the switch so you will also need to move more fuel with the pump.

You did not mention an intercooler, but I will assure you that the methanol will drop the inlet air temp. drastically and this makes room for additional ignition lead which leads to more power. With no nitrous, shoot for an A/F of 5.6-5.7 and work from there and with nitrous start at 5.3-5.4. Remember, methanol does not mind being rich. The switch to methanol alone will pick you up 100hp. Change the cam and you will have another 100hp with the same boost you've been running. At this point, you are building a considerable amount of hp per cubic inch. The only other thing that may come into play is ignition strength. An msd 8 or 10 box are what most turbo/methanol guys are running. When running methanol, pull your plug gap down to .020-.022. Hope all goes well. Sincerely, Ricky

Ricky I think you've got the fuel situation mixed up on this post, unless I'm the one mixed up over your post.

From what I've read of the above posts, the car is already on methanol.

I look forward to reading your revised post.

BTW I hope all is well in your life.

Regards

Hi Ricky,
Thanks for the interest in my project. I don't believe you caught that I'm already running methanol as my main fuel and have been since the start of the project (late 1990s). The 11.4 I mentioned in an earlier post was for static compression ratio.

The cam lobe separation is a good recommendation. The only thing that worries me is, cylinder pressure is what bit me with the last engine config. That's the one that performed as noted in the earlier post. The fuel auto ignited and I folded two rods. Of course, there were more circumstances involved in the mishap. I may get into those details if people are interested. That was at a fuel strength of 5.02 (.77 lambda).
I am also running a liquid intercooler, though most feel it's not necessary with the methanol, I choose to be safe than sorry. Plus, it was just lying around anyway, might as well use it.

Thanks for the a/f targets. That has always been a grey area for me. I just tuned until she liked it. I'm in the habit of using gasoline a/f numbers when relating to this engine so forgive me if I confuse some of you in later posts. Is he running alcohol or not?

The engine likes 5.06 to 5.37, I've been running more towards the 5.06, and no more than 4.98 a/f ratio. Power drops off fast after 4.98. That is off the nitrous. I will try leaning on it a little to see if there's anything there. Thanks.

The spark plugs are gapped at .028" with no ignition breakdown to this point in time. I'm running the Electromotive Tec3r system. It uses a waste spark system that is known for being rather potent. No problem so far.

Thanks for clearing up that I am only using 6 jets rather than 8. Slipped my mind. Gives me a little more faith in my sim program.

I'm really interested in running the controller with the Pulsoids. I'm hesitant about changing nozzles. My intake runners are very short and I had to design my own nozzles to fit them into the intake manifold flange margin. I'll try to figure out how to post some pics. I suppose I could mount them in the plenum. I already have an auxiliary fuel rail mounted in there.

To explain my fuel system a little, I run one 160 lb/hr injector per runner and constant flow inject an additional amount through regular mechanical injection nozzles that I have mounted on an auxiliary fuel rail inside the plenum. The aux fuel comes on at 16 psi and the electronic injectors are throttled back a bit and used to trim the mixture from that point on.

Here's a link to a how to post pics thread;

http://www.forum.nitrous-advice.com/how ... t1147.html

To get the best from my forum, you'll need to forget any preconceptions you may have when you're here and keep an open mind to alternatives that you almost certainly will not have seen or considered before you dropped by.

If you can post some pics I'll see what we can come up with to achieve optimum results for you.

If I haven't already pointed out the following thread to you before, it might be wise to check it out now, to prevent any temptation you may have of pulsing the kit you currently use.

http://www.forum.nitrous-advice.com/why ... t2811.html

Regards

Hi Donnie, I finally made it here. I think i will be able to get the equipment and information i need from here to accomplish my spool up issue. I'm sure i don't need much but i'm totaly new to N20.

Thanks!
Scot w

Hey Scott. I had no doubt these gentlemen could help you out. I'm sure you will enjoy the results. Later.

I understand completely. I picked up your book recently and have been slowly working through it. This is before visiting this site. Imagine how I felt when I discovered the site. It has so far made absolutely perfect sense. It is very refreshing read compared to other nitrous books I've read. It's obvious that other companies have stopped in their R&D years ago, while you have systematically attacked and revised each component of the complete system. You are my kind of man.





I'll do that.



I am well aware of the dangers of pulsing non-purpose built solenoids. I have heard the warnings from other sources also. Just how dependable are the Pulsoids? Zero failure rate? Would it not be wise to run a safety solenoid no matter how dependable the solenoid?

I should also note that my previous build that acheived the mentioned performance level was done with a cam spec of;
256/260 @ .050"
108 lobe separation
Intake centerline installed at 103

Here is a try on that picture.

Thanks for that, can you post a few more pics showing different sections of the nitrous system and the turbo, as well as the whole thing please?

Regards

Sorry about that! I took the post as though you were at 11.4/1 fuel curve and automatically assumed gasoline. My fault!!! Your numbers looked great for gas, but realizing now that you are already on methanol, you have some room for improvement. I like the way you have plumbed the system and you are definately a touch fat at 5.06. You might try working back toward 5.25-5.30 and pull out 1 more degree of timing. At 80% duty cycle, which is the max that I like to work an injector, you are probably maxing out with 6 injectors on methanol. Without nitrous 800hp would put you there. You may want to raise the pressure on the nitrous fuel from 16 to maybe 24-30 in order to help that situation if need be. The Electromotive ignition should fire everything fine, but if you raise boost any at all and can't get a tune, drop the plug gap down. Under boost with methanol, this stuff is really hard to light off! Trevor can fix you up in what ever manner you may want to run your nitrous, but with what little you are using I would just simply turn it on and use my wastegates to tailor in the boost where I want it. Just a thought. Looks like you have this thing figured out very well! Please re-consider the cam L/S, you are giving up a bunch of hp! Sincerely, Ricky Hey Trevor, Thanks for pointing out the over-sight!

Thanks Brent for the advise. I agree that the fuel is on the rich side. After I have the last part of the fuel map dialed in, I'll start leaning on the fuel a bit to see what's there. The fuel map is dialed in up to 16 psi and around 4500 rpm. From that point on, it is definitely too rich and I'm picking away at it slowly to bring it inline. The fuel map (VE table) from 2200 to 4500 rpm and 78 to 200 kPa was absolutely wild with hills and valleys. One hill was extremely high at 3200 rpm, around 105 kPa. Further evidence that some tract pulsing is taking place or maybe it's just reversion from the cam specs. It took awhile too get that part figured out (adjusting the VE table). After I did get that section carved away correctly, the engine ended up reving up very cleanly. Very happy with it. The last section appears much more linear in fuel delivery, but still needs that last bit of loving attention.

The fuel pressure that's being used for the nitrous system is the same pressure that I'm using for the rest of the fuel system. 45 psi at idle, referenced to boost.

I will post further pictures that will show the internal fuel rail that has one Kinsler aerated mechanical injection nozzle for each intake runner. This fuel rail is mounted through the center of the intake plenum. The nozzles pointing into and just past the entrance of the runner. The internal fuel rail is controlled by a solenoid via a pressure switch and GPO of the ECM.

It's a rather large plenum. The idea was to make the plenum large enough to cancel as much pulsing that may occur on the intake side and let the manifold work more like an IR intake system.

The internal fuel rail is delivering approximately 120 lb/hr at constant flow. This is in addition to the 160 lb/hr electronic injectors at a max of 80% duty cycle, by max rpm (7800).

I have had a lot of other people give me the same advise on the lobe separation. The next cam will be tighter. Thank you. At this stage of my racing hobby, the idea is to stay reliable and not blow things up. I'm not trying to blow the record books away. There's always someone with more HP money than you. Don't get me wrong. If I had the money to play with, I would build me a killer.

I just finished re-configuring my fuel system. I won't even go over what it was configured like before. What a nightmare. Delivering the extra fuel through the nitrous nozzles without the extra internal fuel rail. It worked, but was way to hard to manage, control wise. The internal fuel rail is a new addition and I have some fresh pictures that are still in the camera. I'll post some pictures of the whole engine too, to give you a better idea of the work put into this monster.

Here's an overview of the engine.


More to come.

That looks a very neat arrangement and it's obvious you've put a great deal of effort in to the system. Unfortunately it's very difficult to achieve a neat looking system that also meets the optimum design criteria, especially on any engine that has 3 or multiple of 3 cylinders.

With that difficulty in mind you've certainly done the best possible job using the components you have available to you.

However there are a number of changes that would need to be carried out with one of my system designs and if you decide to make the switch to progressive delivery, these changes would be essential as your current arrangement (even if you replaced the solenoid with Pulsoids) would not be suitable for the following reasons;

1) Pipe lengths are too long
2) Pipe bore is too big
3) Metering jets are in the wrong location

At first glance it doesn't look like there is a way of designing the optimum direct port system for your engine layout but I'm going to take another look to see if I can work something out for you.

Regards

Donnie, I guess I'm having real brain fade. I should have read the post more closely. I was assuming again that you had a dedicated fuel pump and boost regulated regulator set at 16 psi. My fault!!! All looks well!

If you have not thought of this, I'll give you a little tip. At idle, the engine is not making any boost and needs considerable rpm to do so. It will not hurt anything to run 40-44 degrees of timing with no boost and throttle response will be unbelievable. When the engine starts to make low boost then continue with your current ignition lead. This greatly helps to spool the turbo and come up on the convertor. Ricky

This is a top view pic.



I think you have a pretty good idea from the previous pictures what I'm facing.
Your 3 faults with the system are right on.
When I was designing the system, another thought I had was to T at the top of the manifold to 'one to three' distribution blocks on each side to cut down pipe volume, but couldn't come up with a design that would look right, along with a 1 to 3 block that would distribute evenly and not look goddy.

From the examples I've seen so far on this site, I must admit, your design ideas are way beyond my ability and I'm hoping you can come up with something revolutionary to help me out. I'll post a pic of the inside of the plenum. Maybe an internal system of some sort? You're the master.

The inside of the plenum. Yes, fluid does collect at the bottom of the plenum when the engine is not fully warmed up. There is a drain hose off the bottom, rear of the plenum that leads to a collection container for periodic draining. I'm trying to figure out a system to make the draining automatic somehow, looping it back somehow to the intake to be burned or allowing the vacuum pump to somehow take care of the buildup. Anyway, back to the problem at hand. Here is the pic.

Hi Ricky. Thanks for the confirmation. I do believe I've tried more advance at the points your suggesting, although I'm not using that now. I'm presently using 30 degrees at 2440 rpm and 100 kPa (converter stall speed). I've tried so many things over the years, I could be wrong. I will certainly give it a try. Thanks.

You know what? I do remember playing with the timing at T/C stall trying to see what a/f and timing numbers would give me the highest stall speed and 36 didn't net me anymore stall than 30. I must admit that I didn't try 40 to 44. I will give it a try.

I am using a pretty low stall torque converter (2440 rpm @ 0 boost, off nitrous), but as you know the nitrous does wonders to take care of that problem. The present nitrous system calibration raises the stall speed of the T/C to somewhere around 3400 rpm almost instantly and soon after that, .4 seconds after activation, 16 psi of boost where the nitrous is shut off and the auxiliary fuel rail comes on.

If it helps, I do have a video of the car making a run. You may be able to judge how effective the present nitrous system is and spot any other problems.