Help Checking my numbers, and a bit of Direction...

I'm curious what you're using to calculate your airflow numbers. Do you have hard numbers for volumetric efficiency and BSFC or are you guessing? Even if you went with a VE of 0.70 and a BSFC of 0.38 (and assuming the peak hp specs you quoted earlier, standard conditions, and a 25 percent parasitic drivetrain loss), you should only need about 82 lb/min of air. Plotting that on a S472 and keeping it at a PR of between 2.8 to 3.0 or so is the sweet spot and wouldn't be too hard to spool, especially with a diverter valve.
 
0 Xero 0 said:
I'm curious what you're using to calculate your airflow numbers. Do you have hard numbers for volumetric efficiency and BSFC or are you guessing? Even if you went with a VE of 0.70 and a BSFC of 0.38 (and assuming the peak hp specs you quoted earlier, standard conditions, and a 25 percent parasitic drivetrain loss), you should only need about 82 lb/min of air. Plotting that on a S472 and keeping it at a PR of between 2.8 to 3.0 or so is the sweet spot and wouldn't be too hard to spool, especially with a diverter valve.
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I was simply using (L x VE% x RPM x PR)/5600.. VE being a constant between any of the setups, I was using 80%. Back calculating it from numbers we have experienced and applying it to what im doing is how I came to current numbers. I didn't go deeper into any of the calc's besides that. That being said, 82lb's is exactly what I got when I factored my own numbers in my post above. Which I agree, puts me right in the range of a 471/2 or FMW468. I think AFR tells the whole story here, unless you got a better explanation...
 
I would agree with you. I guessed a VE of 70 percent. I can only infer that because 12 valves have around 65% stock, but these engines were designed to be n/a originally, so they likely flow better. Anyhow, my calculator changes required airflow based on AFR in addition to all the other inputs necessary. I guess a 22:1 ratio, which is smokeless. I was just trying to figure out how you got the 113 lb/min you mentioned earlier! You might consider a pro hx52 or hx55 as well. They're inexpensive and have a 67 mm compressor inducer. They flow the same as a s471 too, but it's hard to find smaller turbine housings for them than the Schwitzers. You could go through a holset dealer unless it's easier to go through the channels you've already established.
 
I think the difference in flow comes from the lack of swirl needed, so they could get away with a more traditional port. It still has a neck in it, but no dam's are needed or anything of that sort.

Im not brand loyal to any turbo, I think the big three all have their merits, I just like the fact that I can get a new BW for the price of a rebuilt Holset or Garrett of equal performance.
 
I'm just a numbers guy, so I wanted to know where you got your numbers from for the calculation.

I understand. I'm slightly biased towards Holset but for good reason. They're extremely durable and a 67 mm HX50 flows 0.75 kg/s or 99 lb/min compared to a S471, which flows 95 or so. The HX50 will spool more quickly too...
 
In regards to the 113lbs/min earlier?

I took boost numbers at HP peak for two different trucks (Above) and calculated airflow based off of that. NMB2 was seeing 35psi on his 365whp run, and I was seeing 17-18psi on my 235whp run. If you Back-calculate using the formula above, both runs come out to 5.2 and 5.3 lbs/min per HP of airflow respectively. The HP per CC or fuel was also fairly high at 2.61 and 2.81 hp/cc on those runs. If you Calculate for 600whp, you would need 113lb/min to achieve 600whp at those numbers. However, I ran my other dyno numbers through the same process, just using the HP peak and boost numbers from that, as well as my hp/cc number, and I came out at 7.3lb/min per HP, but the AFR was much more rich with a 2.1hp/cc number.

More fuel makes it utilize the air more efficiently was basically the conclusion I came to.
 
I wish I could find an engine data sheet for these engines like you can for the B-series Cummins. If I could get the true BSFC, it would help a lot. I can only hazard a guess that it's around 0.4 after thinking about it more. This fuel system isn't the most efficient due to the low atomization and inherent nature of IDI combustion. A 12-valve is 0.33, which is pretty amazing. I think the HEUI powerstrokes are around 0.36 or so and common rails are in the low 0.30s. If you ported the head like you did with your last one and got the VE around 90 percent or better, it would pay massive dividends in the airflow requirements. For example, if the VE is changed from 70 percent to 90 using the specs you mentioned previously, the air requirement is 64 lb/min; however, porting and gasket matching come at a price. By increasing the size of the intercooler inlet and outlets, the intercooler piping, and the exhaust along with porting, you lose a lot of low-end response. Perhaps that wouldn't matter as much with these engines since they have a stronger low-end than most diesels...
 
0 Xero 0 said:
I wish I could find an engine data sheet for these engines like you can for the B-series Cummins. If I could get the true BSFC, it would help a lot. I can only hazard a guess that it's around 0.4 after thinking about it more. This fuel system isn't the most efficient due to the low atomization and inherent nature of IDI combustion. A 12-valve is 0.33, which is pretty amazing. I think the HEUI powerstrokes are around 0.36 or so and common rails are in the low 0.30s. If you ported the head like you did with your last one and got the VE around 90 percent or better, it would pay massive dividends in the airflow requirements. For example, if the VE is changed from 70 percent to 90 using the specs you mentioned previously, the air requirement is 64 lb/min; however, porting and gasket matching come at a price. By increasing the size of the intercooler inlet and outlets, the intercooler piping, and the exhaust along with porting, you lose a lot of low-end response. Perhaps that wouldn't matter as much with these engines since they have a stronger low-end than most diesels...
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Im going with 4" Charge piping and Water-to-Air intercooling, so Im not too worried about external Airflow, its really a matter of Getting the air though the ports. Whats nice about the IDI head, is the dependence of chamber swirl isn't as crucial as DI because the atomization of the fuel exiting the Pre-cup and swirling on the piston top. So it gives me a bit of room to work the port.
 
Any progress on this setup? Interested to see the pump mounted up on this bugger.
 
AFR of 22:1 is way too high for idi-engine, use something like 16:1, bsfc 0.4 is about right, VE 80% should be quite close also with negative overlap, with better cam that has overlap that makes engine breath it can be over 90. HX 50 has made over 600 hp with 3 liter idi Mercedes engines.
 
gman99 said:
Any progress on this setup? Interested to see the pump mounted up on this bugger.
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Yeah, finally found a cam for the pump, its a "D" profile cam like a 160/170 pump, but it will work for the amount of fuel Im running. The shop has just been backed up, and its been one of those "side" projects that they are cutting me a deal on and working on it when some time free's up. Its getting an RQV gov. I told them to bench it for 350cc all the way to 4K, I don't care where it defuels or drops off, as long as I have that volume til 4K, I think it should be enough. I think the pump should be done soon, they had told me that it would be done about a week ago.

Only thing holding me up from starting fab is the pump.
 
Leiffi said:
AFR of 22:1 is way too high for idi-engine, use something like 16:1, bsfc 0.4 is about right, VE 80% should be quite close also with negative overlap, with better cam that has overlap that makes engine breath it can be over 90. HX 50 has made over 600 hp with 3 liter idi Mercedes engines.
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That's what I have noticed as well. Im really interested to see how the top end is with this setup. Im so used to the rotary pumps limiting our HP's curve's to about 2800 peak (Then flattening or dropping off after, depending on the fuel curve of the pump)...

Ill check the cam card again and see the total degree of overlap, but im pretty sure its more than any cam we have run... I was originally going to run a Supercharger/Turbo compound setup, so I wasn't as concerned with BP/DP ratio.
 
Im just going to drop my pictures in here as I progress with this build as so much of the information in already here...

Got my heads drilled out for the bigger studs, and got one cylinder drilled and tapped for 9/16" Studs with the Mag-drill. Im going to finish the rest of the holes with a drill bushing jig Im making right now.

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Also did a bunch of measurements and 4.550" diameter fire rings are going to work perfect for me, so I am going that route. I also am working with another machinist on possibly doing some 4340 Billet Rods, but my mind isn't set on it yet.

As far as the Turbo's go, I am just going to run an externally gated 60/68/.91 over a 75/96/1.32. If the engine lives, I can always tune the turbo selection later.

The pump is almost done at the shop, last time I was down there it just needed the Gov. Housing installed and ran on the bench, so hopefully Ill have some pics and specs soon.
 
The cam above is experimental, I had it ground up to test. The cam that is coming out of the engine is 111ICL, 180*/195*@.050, same lift... The specs above I came up with from knowing how the "bigger" cam that NMB2 and I ran (The cam from the dyno numbers above) acted, and how my current cam acts, and what I wanted out of the new grind.
 
Raylocker said:
The cam above is experimental, I had it ground up to test. The cam that is coming out of the engine is 111ICL, 180*/195*@.050, same lift... The specs above I came up with from knowing how the "bigger" cam that NMB2 and I ran (The cam from the dyno numbers above) acted, and how my current cam acts, and what I wanted out of the new grind.
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???.......
 
Got the one side done, and I am waiting to do the other side until I strap a head down on this side and get everything torqued to make sure it holds up. I ran into a Hitch with the counterbores for the head bolts on the heads though. I got most of them opened up with my cutter, but the interrupted cut on the top row is wreaking havoc on my cutter, so I have to mull it over a little bit.

Pump is supposed to be done today or tomorrow as well.

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Here are a couple pics of the pump from Saturday, its ready to run.

Im building two saddles so the shop can mount the pump on the stand, they didn't have the appropriate sized ones for this particular pump, so I am trading them the saddles in exchange for a little cost off the pump. I should be done with them tomorrow afternoon, so if Im lucky the pump will get ran on Tuesday.

I am only about $1200 total into the pump at this point, so I am getting off very easy so far...

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