Time to go Stage II!

[norbs]

Donnie, we are building 2 different engines mine is for daily street use and yours is full out race. You do not need to go that high rpm, just turn up the boost? Redo your sim with 40 psi boost target, and overlay 30 psi, Mike runs up to 60 psi!

 

[Alky V6]

Donnie, we are building 2 different engines mine is for daily street use and yours is full out race.

That's correct.

You do not need to go that high rpm, just turn up the boost? Redo your sim with 40 psi boost target, and overlay 30 psi, Mike runs up to 60 psi!

The sims I've been doing have been with a boost target of 45 psi. There is no extra exhaust capacity being dumped overboard. Besides, if that wasn't the case and I could have the boost ramp up quicker in relation to engine rpm, cylinder pressures would exceed my limit.
If I could get the boost to ramp quicker with the small displacement, I would need to drop some CR to get cylinder pressures below limits. The lower CR would add to spool up difficulty.

 

[norbs]

That's correct.
The sims I've been doing have been with a boost target of 45 psi. There is no extra exhaust capacity being dumped overside. Besides, if that wasn't the case and I could have the boost ramp up quicker in relation to engine rpm, cylinder pressures would exceed my limit.
If I could get the boost to ramp quicker with the small displacement, I would need to drop some CR to get cylinder pressures below limits. The lower CR would add to spool up difficulty.

Sorry for the confusion, I thought you were targeting 30 psi on your new build. I think lower CR is a good idea and safer. Could you just not use more NOS to spool the turbo quicker?

 

[Squid4life]

You are right, Mike. The longer stroke does move the torque curve left. I was a little surprised to see how drastically, though. It also tops out the compressor capacity and head flow capacity sooner.
The redline of the stroker motor would end up being about 1,000 rpm lower, as you eluded to in your post.
Maybe a 3.4" stroke wouldn't be a bad compromise.

Donnie, RyanGraves is selling a billet Sonny Bryant in the for sale section. It's a 3.50" stroke.

 

[Squid4life]

I am starting to think the free trial of the sim only gives a small portion of what you are using. I tried it, but it won't really give any intelligible data because I can't plug in everything required. I'd be curious what my junker should be turning out, and see if I need to change any variables before it is too late...

 

[Alky V6]

Sorry for the confusion, I thought you were targeting 30 psi on your new build. I think lower CR is a good idea and safer. Could you just not use more NOS to spool the turbo quicker?

I'm already using the maximum shot size I can use for a nitrous/methanol mixture. And lowering the CR would make the existing nitrous shot less effective. With the cam specs I'm going to use with this new combination, I don't need anything making the spool up less effective.

 

[Alky V6]

I am starting to think the free trial of the sim only gives a small portion of what you are using. I tried it, but it won't really give any intelligible data because I can't plug in everything required. I'd be curious what my junker should be turning out, and see if I need to change any variables before it is too late...

What sort of parameters are you not sure of? Let's see if we can't straighten those out.

 

[Alky V6]

Norbs, you obviously have a different idea of what makes a racing engine. To each their own.
You build your engine the way you want to, and I'll build mine the way I want to.
View attachment 155054
The light blue and red trace lines are using a 3.625 stroke with a 218/218 dur, 115 l/s camshaft. It was installed somewhere between 3-5 degrees advanced.
The green and dark blue trace lines are using a 3.06 stroke and my crazy cam specs.
Both are using my manifolding specs, although the manifolding specs are having far less effect with the smaller camshaft.
Both are using the same turbo. FI91X.

I edited this post (#119) to include some descriptions of what specs were used in this comparison sim.

 

[Squid4life]

What sort of parameters are you not sure of? Let's see if we can't straighten those out.

Well, without all the parameters in there, the results are pretty blah to say the least and will pretty much tell you your stuff is going to end up in a bucket for scrap. I am still learning the software, but it really takes looking at a required parameter, running out to the garage to take some measurements, and plugging them in. I am at work right now, so don't have access to it, but I am sure I can take measurements to come up with port sizes, intake tract sizes, header tube diameters, etc, but I am unsure of nozzle size for one thing; that is about the only thing I can come up with off the top of my head... The software is crazy detailed, which is good, but let's say you don't have the entire cam card in front of you. It is difficult if not impossible to get any good info out of the software. Seems it is the same situation with regards to cylinder head flow, or backpressure, or backflow ratios, etc. There are some terms I have never even heard of, but luckily some of those are grayed out and don't need filled in. I will have to play with it some more and see what all I am lacking to be able to get good data...

 

[Alky V6]

Well, without all the parameters in there, the results are pretty blah to say the least and will pretty much tell you your stuff is going to end up in a bucket for scrap. I am still learning the software, but it really takes looking at a required parameter, running out to the garage to take some measurements, and plugging them in. I am at work right now, so don't have access to it, but I am sure I can take measurements to come up with port sizes, intake tract sizes, header tube diameters, etc, but I am unsure of nozzle size for one thing; that is about the only thing I can come up with off the top of my head... The software is crazy detailed, which is good, but let's say you don't have the entire cam card in front of you. It is difficult if not impossible to get any good info out of the software. Seems it is the same situation with regards to cylinder head flow, or backpressure, or backflow ratios, etc. There are some terms I have never even heard of, but luckily some of those are grayed out and don't need filled in. I will have to play with it some more and see what all I am lacking to be able to get good data...

If you're having problems with a parameter, the meaning, or what number to plug in, I can help with that. If there's more than one that is giving you problems, we can simply go over them one at a time. I admit the turbine nozzle is a grey area without some real world data to compare against the sim, but even without real world data to compare against, you can play with a realistic range and still get useful output. I can help you with measuring your turbine housing to get you close.

 

[Alky V6]

Preliminary guess for a spring from the cam manufacturer is 300 on the seat and 750 over the nose. He wanted some other specs, so those numbers might change.
He knows it's a turbo application, but doesn't have the target max boost level yet.

 

[norbs]

Donnie, I am sorry but i don;t believe going to a smaller cubic inch with a bigger cam is not going to make 500 hp more than a 4,1 engine , with a 3.625 stroke, with the same boost, you have made some errors somewhere in your calcs.

 

[Alky V6]

Donnie, I am sorry but i don;t believe going to a smaller cubic inch with a bigger cam is not going to make 500 hp more than a 4,1 engine , with a 3.625 stroke, with the same boost, you have made some errors somewhere in your calcs.

If you're talking about the last comparison, I did note that I used the FI91X for both engines. The 4.1L engine, with the small cam that was used, did not develop enough exhaust energy to push the FI91X to the same boost that the smaller engine was able to push the 91mm to. That is why you are seeing the large HP difference.
Though the 4.1L had displacement over the smaller engine and was able to spool the turbo a little sooner, the cam used in the 4.1L simply choked the engine down at a certain rpm, the exhaust energy fell flat, and the turbo could not be pushed to a higher boost level.

 

[Alky V6]

That's the sort of balancing act you must go through when you're running such a large turbine side. Some engine configurations don't give you the luxury of having a lot of extra exhaust energy on call (wastegate) to tap into when you feel like it. And, displacement alone is not always the cure all.
The answer to the latest comparison would be to run a larger cam to create more exhaust energy to drive that monster turbo, and slightly increase the powerband. The result being, having the ability to produce more boost and a higher peak hp level.

 

[Alky V6]

Imagine having no wastegate and your only way of controlling the boost rise rate in relation to engine rpm was matching the right size turbine housing/wheel combination to the engine.
The engine would need to produce the right amount of exhaust energy at the right rpm, matched with the right turbine housing/wheel combination to produce the right amount of boost for that particular rpm. If too much boost is created too early, excessive cylinder pressures could cause a problem with the fuel, or high mechanical stresses could be too much for the equipment. If too little boost is created, then power at that particular rpm is not being optimized. That scenario continues at every step up in rpm until full boost and/or max rpm is realized.
If one finds an 'engine to hot side' combination that is very closely matched, then engine rpm becomes a very important factor in continuing to supply a rising rate of exhaust energy to the hot side inorder to keep boost on a rising curve. If the exhaust energy being supplied falls flat for whatever reason, the closely matched hot side cannot continue to create a rising rate of boost, and the boost will level off and begin to fall as rpm is attempted to be pushed higher. Soon those factors that hindered the rising rate of exhaust energy will also stop the rise in engine rpm.
Displacement can help in getting the closely matched turbo to spool sooner in the rpm powerband, but if other factors begin to choke the engine down, the fall off in the rising level of exhaust energy will show up as a slow down in boost rise and even a fall in boost as rpm is pushed higher. Those other factors can be anything that begins to hinder the performance of the engine as rpm rises. Small heads, small cam, small manifolding, small exhaust system.

 

[Alky V6]

I was checking the flow numbers for the heads I'm going to use for James and his sim thread, and I found that I got some numbers mixed around. The 312.4 cfm intake port flow number at .600" (actually .580") lift was from a set of square port Indy heads I had flowed at the same time I had a standard intake port set flowed. I was curious about the differences between the two.
The flow numbers to the set of Stage II heads with the standard intake port, that I plan to use are below.
Used set.
Flowed @ 28", 4.00" bore.
45cc chamber
245cc intake port volume

2.08" intake valve, manley # 11844 used in test
.1 68?
.2 127.6
.3 185.6
.4 241
.5 281
.6 304.3
.65 306.5?
.7 308.7

1.60" exhaust valve, manley # 11539 used in test
No tube
.1 53?
.2 96
.3 132.2
.4 185
.5 223
.6 236.3
.7 236.3?

The numbers with question marks after them were not supplied by my head man. They are guesses on my part to complete the flow chart for the sim.

 

[Alky V6]

Here are the specs of the turbo I use.​

Model - FI91X by Forced Inductions. This is a 91mm turbo, a modified version of the Borg Warner Airwerks S510 which comes standard with a 95mm compressor wheel.​

Island CFM: 1300​

Island pressure ratio: 2.6​

Island efficiency: 78%​

Surge CFM: 374​

Exh turbine efficiency: 80% good pulse turbo​

Turbine nozzle diameter: 2.2-2.37? I'll be able to narrow this one down better when I have some real world results with the new combination.​

Max flow, CFM: 2404 assuming 1650hp comp capacity. 2258 assuming 1550hp comp capacity.​

Throttle location: blow through​

Max boost limit, PSI: 45​

# turbo: 1 single turbo​

Intercooler efficiency %: 45 -65? I'll be able to narrow this one down better when I have some real world results with the new combination.​

Intercooler CFM rating: 2000​

Wastegate is: before intercooler​

​

Here are my notes on the FI91X.​

Forced Inductions FI91X. (Airwerks S510)​

91/123mm compressor wheel.​

110/101mm turbine wheel. .918 trim.​

Original turbine housing is a Borg Warner T6 S510 1.15 a/r.​

Turbine side efficiency is 79 percent.​

T6 tubine housing radius is 4.79" measured (5.93" calculated).​

Use 2.95" nozzle diameter for 1.15 a/r.​

Use 2.40-2.92" nozzle diameter for 1.15 a/r, split housing. Middle ground is 2.63". Realize that the a/r ratio on a split housing is typically less than the noted number. For instance, a split housing stamped as 1.15 may in reality act like a 1.0 a/r ratio housing. The divider wall takes up some of the area in the scroll.​

Max PR for a 224 cid engine is 5.5 @ 125 lbs/min.​

Max compressor flow occurs at 3.7 PR @ 165 lbs/min for 95mm. For 91mm 155 lbs/min? Wheel speed is 88,000 rpm.​

Max turbine side flow is 70 lbs/min.​

Turbine nozzle area (1.15 a/r measured): 2.486"x2.179"=5.417 square inches area=2.6269" dia.​

Compressor flow in lbs/min @ 2.0 PR = 40.​

Maximum compressor efficiency is at 2.6 PR @ 116 lbs/min (78%) for 95mm. For 91mm 2.6 PR @ 99 lbs/min.​

Liquid intercooler dimensions: 9"x4.5"x10".​

Exhaust back pressure to boost pressure measures to be .85-.95:1. A turbine nozzle size of 2.37 with 80% Good Pulse Turbo Exh Turbine Eff% picked gives a good exhaust pressure to boost ratio match for the Stage I build.​

2.92 a/r simulates initial spoolup characteristics well. Exh/map ratio doesn't match well, though.​

2.37 a/r simulates real world exh/map ratio well. Used in Stage I calcs.​

Stage II calcs will use turbine nozzle specs of 2.20-2.37, and intercooler specs of 45-65% eff.​

 

[norbs]

Air to water IC's are about 65-70% eff and water at least 80%+ but real world data is best.

 

[Alky V6]

Air to water IC's are about 65-70% eff and water at least 80%+ but real world data is best.

I am using an air to liquid intercooler that is running dry and blocked off. I am just guessing at 45-55% eff. Basically, it just acts as a heat sink that quickly heat soaks.

 

[Alky V6]

Air to water IC's are about 65-70% eff and water at least 80%+ but real world data is best.

Norbs, could you clarify the above quote. Do you mean air to air at the beginning of the sentence and then air to water for the 80% eff?