Time to go Stage II!
- Thread starter Alky V6
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It looks like the actual peak hp will depend much on whether the advertised hp rating of the FI91X compressor is accurate or not. Forced Inductions advertises the hp capacity of the FI91X at 1650hp. I used 1600hp in the sim for the Stage II project. If the actual rating is any less than 1600hp, the sim power output curve I have for the Stage II project will drop accordingly. There is no extra capacity, or wastegate percentage being dropped overboard.
When I started working with the sim last night, I was in the 1,200s. By the end of last night, actually morning, I was at 1,496 bhp.
I just performed a calc using the advertised hp rating of the FI91X, 1650hp. The power curve broke over 1500 hp at 9250 rpm. Looks like I should have gone with the non-variant S510/95mm turbo.
Imagine it. I just might max out this 91mm with a 224 cid Buick V6. Unbelievable.
Imagine it. I just might max out this 91mm with a 224 cid Buick V6. Unbelievable.
One reason why I don't have any extra compressor capacity on hand is because of the size of the turbine housing and the a/r ratio. The sim is showing that the turbine is matched in such a way that the wastegate doesn't come into play throughout the rpm ramp up. I tried tightening the a/r (nozzle size) a little on the turbine housing in the sim, and all it did was cause the boost to ramp in a little quicker in relation to the rpm. As I explained earlier, my self imposed BMEP limit was being skirted closely with the a/r as it was before trying to tighten it up. With the a/r tightened up a little (.120" less nozzle diameter), the BMEP limit was being rode.
In essence, the size of the turbine housing is acting as a boost control device as the turbo spools with rpm rise, making any special attempt to control the boost rise in relationship to rpm rise with the wastegate unnecessary. This would make it difficult for my BMEP limit to be exceeded. That's a good thing.
In other words, the turbine housing seems to be a perfect, safe match for the engine.
In essence, the size of the turbine housing is acting as a boost control device as the turbo spools with rpm rise, making any special attempt to control the boost rise in relationship to rpm rise with the wastegate unnecessary. This would make it difficult for my BMEP limit to be exceeded. That's a good thing.
In other words, the turbine housing seems to be a perfect, safe match for the engine.
When this test came up on the screen, I quickly printed out every spec sheet I could on the parameters for this test. I didn't want whatever it was that changed the test to disappear before I could discover what it was.
I knew something wasn't right with the parameters. But what was it? What made the sim jump from 1,496 on one run, to 1,649 peak bhp on the next?
I knew something wasn't right with the parameters. But what was it? What made the sim jump from 1,496 on one run, to 1,649 peak bhp on the next?
In the 1650 hp power curve, you can see that the hp flattened out right at 1650 bhp. That's where the compressor ran out of air. I had the compressor capacity set to 1650 hp on that test. All future tests will use this compressor capacity setting.
BTW, the compressor hp capacity parameter was not the reason for the big hp jump in that test.
BTW, the compressor hp capacity parameter was not the reason for the big hp jump in that test.
Donnie, why is there no boost @5500 rpm? Go in and change the crank and see the effects. Why dont you use a quick spool valve and modulate it with the ams-1000 and go bigger turbine. Are you fudging the head flow numbers of the stage II heads, like you did with the stage I heads?
Regarding the 1650 hp curve. I did find the parameter that the sim changed on me, automatically.
Due to the type of parameter, and more important the setting of the parameter that caused the power curve to jump up like that, it makes that power curve completely unusable for sooo many reasons. Too bad.
Although, it may be a hint into what real world results might have in store. Hmmm. The sim has been known to underestimate before, by a wide margin.
Due to the type of parameter, and more important the setting of the parameter that caused the power curve to jump up like that, it makes that power curve completely unusable for sooo many reasons. Too bad.
Although, it may be a hint into what real world results might have in store. Hmmm. The sim has been known to underestimate before, by a wide margin.
I am not using any nitrous assist in these Stage II sim tests. That is why there isn't any boost happening until midrange. I am simply matching the turbine housing specs in the sim to real world exhaust backpressure to intake boost pressure figures I got with the Stage I project. I would imagine that may change a tiny bit with the Stage II heads, but for now, I'm just matching to past performance.
I actually did make a quick spool valve. It's on the car now. It does work, but is half as effective as the nitrous tune I discovered to spool the turbo. Both methods do not work together, so the spool valve is just along for the ride, in the open position, of course. The quick spool valve will be eliminated in the Stage II build.
I am not fudging the Stage II head flow numbers. I have no reason to. I have no real world results for the Stage II build yet. The only reason I fudged the Stage I head flow numbers was to get the sim to match attained real world numbers.
Don't forget. The sim does not simulate actual turbo spool up very well. It hangs at a very low level, then suddenly ramps up to a big boost number for the next column result. The sim has a hard time simulating a smooth ramp up of boost. Not realistic.
The plan is to do small cam changes and study trends.
Squid4life
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Very interesting stuff Donnie. Curious to see what your lobe sep you were talking about will be. From what I have been told lately is that you are somewhat limited to what you can turn a cam to run with regards to lobe sep, due to the blanks themselves. I want to say ~114 was about max. You know anything different?
The specs I've been playing around with are very different from anything anyone else is using. It has to do with the exhaust backpressure to intake boost pressure ratio of my combination.
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