Fox Hp Estimate Help. Supercharged 331

Kpblownfox

Member
Jun 8, 2016
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Over the winter I had a 331 built from the ground up and just had it on the Dyno. It made 490 rwhp and 531 rwtq at 4900 rpm on 8 pounds of boost from a novi 2000 before it ran out of fuel I'm have a all new fuel system installed now. But I was wondering if anyone could give a educated guess based on those numbers of what it will make once I can run it all the way to 6500 like I plan. Thanks!
 
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mikestang63

SN Certified Technician
Aug 27, 2012
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when you say it ran out of fuel- injectors? fuel pump? Most guys can easily get near 550-600 rwhp simply with a 340 in tank and 60# injectors. Maybe upgrrade the stock fuel rails if you see it leaning out on the top end? What rpm was it fading out at. What is your AFR/ FP?

Are you running a stock block? Be careful about turning that wick to 10 brother. Once you start going over 400rwhp it's rolling the dice on these blocks. Spinning them to 6500 regularly won't help. There are plenty of desktop dyno calculators you can play with to see what projected HP would be.
 
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Kpblownfox

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Jun 8, 2016
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It has a dart block and scat rotating assembly the fuel system was still from the original 302 set up so it was a 255 pump and 38# injectors with all stock rails and lines. As we speak I'm having the aeromotive A1000 kit Installed. Every thing in the car is good to 1000 hp so I'm just getting everything right before I turn the boost up.
 
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Kpblownfox

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Jun 8, 2016
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At 4000 rpm the afr was getting into the high 11's he shut it down when it hit like 12.5 it just didn't have enough injector but I figured I might as well do the whole system. I also switch it over to mega squirt
 
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mikestang63

SN Certified Technician
Aug 27, 2012
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sounds like a plan. That should be a nice setup once it is all together. Definitely not enough injector. I would go with at least 75# if not higher injectors
 
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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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At 4000 rpm the afr was getting into the high 11's he shut it down when it hit like 12.5 it just didn't have enough injector but I figured I might as well do the whole system. I also switch it over to mega squirt
Let me know if you need any help, I run the megasquirt thread here.


Fwiw.... my 52lb injectors are at a 65% duty cycle at 5800rpm 5psi.

But I only have a 306 with iron heads. You WILL need at least 60#ers
 

Kpblownfox

Member
Jun 8, 2016
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Maryland/Delaware
Let me know if you need any help, I run the megasquirt thread here.

Ok cool I'm having it professionally tuned so I have a solid base and I know I won't melt it down. But I will definitely be wanting to learn how to tune myself and do so tweaking


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a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
10,427
6,533
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Hillsborough county
Ok cool I'm having it professionally tuned so I have a solid base and I know I won't melt it down. But I will definitely be wanting to learn how to tune myself and do so tweaking
Sweet. Get some data log files from him, he can log them during the dyno pulls directly from Tuner Studio. I would like to look them over if you don't mind. There are a few things a "correctly" tuned street motor should have on a scatterplot. Same way the oem do it....

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A5literMan

At least it is lumpy...
5 Year Member
Jul 30, 2011
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I just want to play the "guess my hp number" game....ill say [email protected] But that's just an utterly wild guess. What's the rest of your motor's specs? Heads,cam,intake,etc? With the right parts and 4-7# more boost...you could get into the mid 600's
 

Kpblownfox

Member
Jun 8, 2016
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Maryland/Delaware
Ok let me see if I can rattle this off the top of my head lol dart block .30 over 331 rotating assembly forged position 9:1 compression victor jr heads with a lot of port work trick flow R intake 75mm throttle body no maf novi 2000 8 pounds with full aeromotive fuel system and 60# injectors and I'll be running the Anderson power pipe and msd ignition and distributer


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A5literMan

At least it is lumpy...
5 Year Member
Jul 30, 2011
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Your inj and tb are going to limit you...but should/could break the 600 mark. Make sure to post the sheet when it gets tuned with the fuel system upgrades. :nice: Oh and post some pics of the car!!