Engine homework, Is my math right?

[Shaolin Crane]

Ok ive been doing alot of research regarding what supercharger to run how much horsepower and what boost and compression ratios i want to run my goal is 800-850rwhp so according to static compression ratio, effective compression ratio relative to boost and a moderate engine compression for an effective street driven beast am i to assume my math so far is correct...
Effective compression for a moderate to heavily modded street motor is 18:1
assuming i have a 347 that makes 430rwhp (mods to do so are not important at this time) with 9.5:1 static compression(18.5 effective compression) will make the 8XXrwhp at 14psi of boost with 91 octane an a suitable aftercooler? Any more knowledge on the subject will greatly help me

[94cobra69ss396]

I really doubt you will be able to get 800+rwhp with a 347 on pump gas, even with an aftercooler. You also will not double you rwhp at 14 psi. You are going to have to either run more boost or make more power N/A to reach 800rwhp.

[enkeivette]

We had a big thread debate on this already. Technically 14.7 lbs will double your hp, but that doesn't include loss. Like added heat or the 20%? loss from the motor having to drive the blower. If you want 800hp, calculate what you need for at least 1,000.

Better idea if you want to run pump gas, something I decided was a must for me, call the blower company, give them your specs and ask them how much boost you can run on 91. Then ask what pulley you'll need to get close to that much boost.

[enkeivette]

PS. My H&C 383 is supposed to be good for 500hp with high compression, it's only 9:1 so it would never make that NA. With 13lbs of boost I'm only hoping for 600-700 flywheel hp intercooled.

[Shaolin Crane]

ok but my math was correct though right? i didnt mean this as set in stone, just trying to further my understanding when it comes to boost my goal was already to shoot for the 1000hp mark and if i walked away with 800hp i would be happy, my blower choice was already the F1c as it has he stepped ratio that would spool at a lower RPM than a normal F1r

[Vettezuki]

. . . assuming i have a 347 that makes 430rwhp (mods to do so are not important at this time) with 9.5:1 static compression . .

I've never heard of an NA 347 with 9.5:1 CR making 430WHP on 91. My 346 LSx made 432 WHP in the vette it came out of. It's north of 11:1 and needs about 93 octane. Good for the spray, not for boost.

(18.5 effective compression) will make the 8XXrwhp at 14psi of boost with 91 octane an a suitable aftercooler? Any more knowledge on the subject will greatly help me

In a vacuum (i.e., pure theory, no modifying factors, yeah approximately). HOWEVER, it never works that way and there are a lot of reasons, maybe enkei will find the post where we harassed him. I think a boosted 347 making 800WHP on pump gas is a Unicorn. I've never heard of one and can't imagine the combo necessary, save for much lower static compression and higher turbo (not SC) boost. It wouldn't be a friendly street driver though, it'd have big lag that would come out of no where and kick you in the face, more like a drag car you'd spool and launch.

Ron whattaya think?

[Shaolin Crane]

I've never heard of an NA 347 with 9.5:1 CR making 430WHP on 91. My 346 LSx made 432 WHP in the vette it came out of. It's north of 11:1 and needs about 93 octane. Good for the spray, not for boost.



In a vacuum (i.e., pure theory, no modifying factors, yeah approximately). HOWEVER, it never works that way and there are a lot of reasons, maybe enkei will find the post where we harassed him. I think a boosted 347 making 800WHP on pump gas is a Unicorn. I've never heard of one and can't imagine the combo necessary, save for much lower static compression and higher turbo (not SC) boost. It wouldn't be a friendly street driver though, it'd have big lag that would come out of no where and kick you in the face, more like a drag car you'd spool and launch.

Ron whattaya think?
Hmmm ok, well as long as my understanding of the equation is there i can start focusing on learning the variables, but i have seen many 800rwhp motors on pump gas over at stangnet, but if need be i can always run race gas or avgas

[Vettezuki]

. . but i have seen many 800rwhp motors on pump gas over at stangnet. . .

I'd be curious to know all their variables and see their sheets. Lower static CR, more than one atmosphere of boost and heavily intercooled, on a pump gas 347, maybe. :huh:

I'd also be hesitant to call it an equation in anything other than an idealized sense. Details will always revise real output DOWN. :judge:

And finally, I've never been in an 800WHP car. I've been in enkei's Vette which is probably well into the 500s . . . it's ridiculous. At 800WHP, you're going to have to make everything on the car heavy duty and carefully dialed in or it'll be a death trap.

Keep us posted.

[Shaolin Crane]

I'd be curious to know all their variables and see their sheets. Lower static CR, more than one atmosphere of boost and heavily intercooled, on a pump gas 347, maybe. :huh:

I'd also be hesitant to call it an equation in anything other than an idealized sense. Details will always revise real output DOWN. :judge:

And finally, I've never been in an 800WHP car. I've been in enkei's Vette which is probably well into the 500s . . . it's ridiculous. At 800WHP, you're going to have to make everything on the car heavy duty and carefully dialed in or it'll be a death trap.

Keep us posted.

sorry i should have stated this will not be a traditional hydraulic roller cam engine, this will be a full mechanical roller cam, linked lifter, 0oz imbalance high rpm engine

everything on the car is heavy duty, full MM catalog, built 8.8, 10 point cage (not installed yet) and next weekend i will be gauging the bumpsteer, cornerweighting the car and carefully balancing everything to make sure the car is as predictable as possible

[94cobra69ss396]

You're building this engine for your road racing Mustang, correct? Are you going to be racing it in a series or is this just for fun? Right now you have a pretty much stock 302 that probably makes about 200rwhp or less. Even with a mildly built 347 with 9:1 compression and 10psi that will run on pump gas you should be able to make a reliable 450-500rwhp. Trust me when I say that even with that you are going to be more than happy with the available power. The 275 rear tires you have now will have a hard time holding that much power when on the throttle coming out of a corner. This is what Eric has planned for his fox body only with a 331.

Back when I decided to rebuild my 302 and add the Vortech S-trim I had my car dyno'd to see where it was at for a base line. It made 254rwhp. The only things I changed besides adding the S-trim and it's supporting mods (injectors, fuel pump, MAF, etc.) was a set of AFR 165 heads and an E303 cam. I figure if I were to have dyno'd the car after installing just those I probably would have made closer to 300rwhp. As my car sits now with 12psi it made 436rwhp on 91 and 471rwhp on VP Street Blaze 100. Now granted I'm not running an aftercooler so there is still another 50rwhp or so I could be making on pump gas but that is still far from double the power output of the N/A combo.

[Shaolin Crane]

You're building this engine for your road racing Mustang, correct? Are you going to be racing it in a series or is this just for fun? Right now you have a pretty much stock 302 that probably makes about 200rwhp or less. Even with a mildly built 347 with 9:1 compression and 10psi that will run on pump gas you should be able to make a reliable 450-500rwhp. Trust me when I say that even with that you are going to be more than happy with the available power. The 275 rear tires you have now will have a hard time holding that much power when on the throttle coming out of a corner. This is what Eric has planned for his fox body only with a 331.

Back when I decided to rebuild my 302 and add the Vortech S-trim I had my car dyno'd to see where it was at for a base line. It made 254rwhp. The only things I changed besides adding the S-trim and it's supporting mods (injectors, fuel pump, MAF, etc.) was a set of AFR 165 heads and an E303 cam. I figure if I were to have dyno'd the car after installing just those I probably would have made closer to 300rwhp. As my car sits now with 12psi it made 436rwhp on 91 and 471rwhp on VP Street Blaze 100. Now granted I'm not running an aftercooler so there is still another 50rwhp or so I could be making on pump gas but that is still far from double the power output of the N/A combo.

Just for fun, i realistically might get the car out to 3 track days a year my schedule probably wont allow more, this engine wont have any expense spared, it is currently built to handle the 1000hp mark, mechanical roller cam, forged pushrods, 1:7 rockers, cam TBA (something very aggressive)just need 185 heads, trick flow box R, injectors etc etc

[94cobra69ss396]

Just for fun, i realistically might get the car out to 3 track days a year my schedule probably wont allow more, this engine wont have any expense spared, it is currently built to handle the 1000hp mark, mechanical roller cam, forged pushrods, 1:7 rockers, cam TBA (something very aggressive)just need 185 heads, trick flow box R, injectors etc etc

You're not going to get there with AFR 185's. You need to go with the 225's or something equivalent.

[Shaolin Crane]

You're not going to get there with AFR 185's. You need to go with the 225's or something equivalent.

Well i was actually leaning towards Trick Flows, i was only hoping to do it with 185's so i could keep the power range down low and start building power around the 3-4k range, well i guess back to my research, still a long way off until that engine is done

[enkeivette]

You're not going to get there with AFR 185's. You need to go with the 225's or something equivalent.

:iagree: I run AFR 195s, have more cubes than you and only 1lb less of boost than you intend to push. I'm not even putting out 800hp.

Even with 220s and a solid cam I don't think you'll make 800hp with only 14lbs of boost out of a 347. You'll need more boost, and more octane. Otherwise more cubes.

P.S. You don't need an F1 for only 14lbs, that's a waste. You can do that easily with a D1 or maybe even a P1. My D1SC is good for I think 19lbs.

[BADDASSC6]

Hey I would like to chime in.

I'm assuming that you have not bought the blower yet. You are running a big blower which will obviously help. It will push more are at the same PSI than an S trim due to the reduced heat input. I would say the easiest blower hp estimator is:


(PSI/14.7X NA HP)-W(blower estimate 50-150hp)=SC horsepower

I will also through out that road racing gets substantially more expensive with the increase in power and weight. I sometimes debate shifting from the Corvette to a solstice just for the cost savings. May not be that big of a deal based on 3 track days per year, but if your schedule frees up and then you become funds limited that would suck. WHen you do go racing watch out for this one black Corvette. The driver is a real ass. Good luck on the build keep us posted.

[Shaolin Crane]

Hey I would like to chime in.

I'm assuming that you have not bought the blower yet. You are running a big blower which will obviously help. It will push more are at the same PSI than an S trim due to the reduced heat input. I would say the easiest blower hp estimator is:


(PSI/14.7X NA HP)-W(blower estimate 50-150hp)=SC horsepower

I will also through out that road racing gets substantially more expensive with the increase in power and weight. I sometimes debate shifting from the Corvette to a solstice just for the cost savings. May not be that big of a deal based on 3 track days per year, but if your schedule frees up and then you become funds limited that would suck. WHen you do go racing watch out for this one black Corvette. The driver is a real ass. Good luck on the build keep us posted.
I'll be a cop soon so i dont foresee my schedule freeing up for a long time but thanks for the tip, if it does happen that the motor has too much power i can always remove it and put it in my drag car then build something in the 400-500hp range for the road course car

[BADDASSC6]

Thanks for you future service. Go big or Go home!

[Shaolin Crane]

:iagree: I run AFR 195s, have more cubes than you and only 1lb less of boost than you intend to push. I'm not even putting out 800hp.

Even with 220s and a solid cam I don't think you'll make 800hp with only 14lbs of boost out of a 347. You'll need more boost, and more octane. Otherwise more cubes.

P.S. You don't need an F1 for only 14lbs, that's a waste. You can do that easily with a D1 or maybe even a P1. My D1SC is good for I think 19lbs.

Sorry i missed this post, reason i chose the F1c was room to grow for the blower

[enkeivette]

Hey I would like to chime in.

I'm assuming that you have not bought the blower yet. You are running a big blower which will obviously help. It will push more are at the same PSI than an S trim due to the reduced heat input. I would say the easiest blower hp estimator is:


(PSI/14.7X NA HP)-W(blower estimate 50-150hp)=SC horsepower

I will also through out that road racing gets substantially more expensive with the increase in power and weight. I sometimes debate shifting from the Corvette to a solstice just for the cost savings. May not be that big of a deal based on 3 track days per year, but if your schedule frees up and then you become funds limited that would suck. WHen you do go racing watch out for this one black Corvette. The driver is a real ass. Good luck on the build keep us posted.

Put that motor in a Solstice. You will be my hero.

[Shaolin Crane]

I also have to say i think there was a bit of miscommunication on my part as far as the terms of my engine,i didnt mean to come off as im going to make 800rwhp with 14psi of boost, just that i wanted to make sure i was understanding the equation for calculating boost, minus the variables set forth due to parasitic loss etc. My error and i hope this clears some stuff up

[enkeivette]

I also have to say i think there was a bit of miscommunication on my part as far as the terms of my engine,i didnt mean to come off as im going to make 800rwhp with 14psi of boost, just that i wanted to make sure i was understanding the equation for calculating boost, minus the variables set forth due to parasitic loss etc. My error and i hope this clears some stuff up

Not really. You need to calculate from gross hp, not flywheel hp with accessories and definitely not wheel hp, then you need to subtract parasitic losses.

Further, you don't have a 347 that makes 430whp with only 9.5:1 compression. A 9.5:1 347 with TF or AFR heads will make closer to 450 gross hp, with a nice tune, with the right cam, if you're lucky.

So let's play with rough math:

450 gross hp - 5% for accessories and exhaust and - 15% for a standard trans driveline and a solid diff = 360 wheel hp.

800whp/ 360 whp = 2.22. Which is 1.22 x stock whp.

1.22 x 14.7 = 17.9 lbs of boost, not including blower loss!

So my guess, you'll need closer to 20lbs of boost to get to 800whp with a 347 running Trick Flow 185s and a fatty cam.

[94cobra69ss396]

KJ, the Tech Editor for 5.0 Mustang & Super Fords magazine built a 347 (4.125 bore x 3.25 stroke) that made 800rwhp with a Novi 2000 and I believe something in the range of 18psi. He also used AFR 205 heads and a somewhat mild hydraulic roller that had .600+ lift and 230/240 duration. You can read about it on their website.

[Vettezuki]

KJ, the Tech Editor for 5.0 Mustang & Super Fords magazine built a 347 (4.125 bore x 3.25 stroke) that made 800rwhp with a Novi 2000 and I believe something in the range of 18psi. He also used AFR 205 heads and a somewhat mild hydraulic roller that had .600+ lift and 230/240 duration. You can read about it on their website.

At 18PSI were they running pump gas?

[94cobra69ss396]

At 18PSI were they running pump gas?

I don't remember. I doubt at that level he was.

[enkeivette]

With around 9:1 intercooled I'm supposed to be able to run 19lbs intercooled off 91 octane with AL heads.

18lbs sounds more like my math.

[Shaolin Crane]

Not really. You need to calculate from gross hp, not flywheel hp with accessories and definitely not wheel hp, then you need to subtract parasitic losses.

Further, you don't have a 347 that makes 430whp with only 9.5:1 compression. A 9.5:1 347 with TF or AFR heads will make closer to 450 gross hp, with a nice tune, with the right cam, if you're lucky.

So let's play with rough math:

450 gross hp - 5% for accessories and exhaust and - 15% for a standard trans driveline and a solid diff = 360 wheel hp.

800whp/ 360 whp = 2.22. Which is 1.22 x stock whp.

1.22 x 14.7 = 17.9 lbs of boost, not including blower loss!

So my guess, you'll need closer to 20lbs of boost to get to 800whp with a 347 running Trick Flow 185s and a fatty cam.
yeah i hadnt gotten to the accessories math yet, just was trying to understand the basic boost to CR, then i would move on from there, i wanted tosee if i could get a more exact rather than "should be in the ballpark..."

[joedls]

I'm assuming this is a Ford. What block do you plan to use? A stock 5.0 liter block will crack right down the middle before you make anything close to 800 WHP.

[Vettezuki]

I'm assuming this is a Ford. What block do you plan to use? A stock 5.0 liter block will crack right down the middle before you make anything close to 800 WHP.

Even with the billet main supports and valley girdle or whatever the hell it's called. (Though a hi-perf block is the right way to go at this power level.)

[94cobra69ss396]

I think I heard him say something about already having a Dart block at the cruise.

[Shaolin Crane]

Dart iron eagle, with a probe dominator 347 rotating assembly