What compression are you running? Your current fuel upgrades aren't going to cut it. You will need bigger injectors (which means a MAF re-cal) and a bigger probably a 255 fuel pump too.
I don't see any problem with you hitting your 400 whp goal. I make 313 whp after adding a Vortech (seeing 9-10 psi) on the stock longblock with a full exhaust (long tubes).
yikes!!! yes get the cobra intake ported or go with a aftermarket one......
And a vortech would be someone ur current combo.....it probably wont be running the stock 8 lbs of boost the s trims come with because ur engine is more efficient and flows better, thus there isn't as much restriction (pressure) to cause boost...u can always put a different sized pulley on it to make it put out more boost if u want, but no doubt u will be over 400 rwhp with that and a better intake
And a vortech would be someone ur current combo.....it probably wont be running the stock 8 lbs of boost the s trims come with because ur engine is more efficient and flows better, thus there isn't as much restriction (pressure) to cause boost...u can always put a different sized pulley on it to make it put out more boost if u want, but no doubt u will be over 400 rwhp with that and a better intake
With a halfway decent tune, the blower will put you well over 400rwhp. 450-500rwhp would be my guess.
The Cobra intake isn't as bad as you are led to believe, especially not on a boosted car. Get TMOSS to port your lower, I did and he did excellent work.
What RPM did your HP and TQ peak at on the dyno?
Your tuner will want/suggest at least a 255HP in tank pump and 42lb injectors. Adding the inline TREX pump could be come a necessity depending on how close you are to 500RWHP.
Once you get blown, you'll wonder why you even messed with N/A.
Wes
The Cobra intake isn't as bad as you are led to believe, especially not on a boosted car. Get TMOSS to port your lower, I did and he did excellent work.
What RPM did your HP and TQ peak at on the dyno?
Your tuner will want/suggest at least a 255HP in tank pump and 42lb injectors. Adding the inline TREX pump could be come a necessity depending on how close you are to 500RWHP.
Once you get blown, you'll wonder why you even messed with N/A.
Wes
s-trim will do wonders.
1. find out your compression ratio. anything below 9.5:1 is okay.
2. cobra intake will restrict the flow, but since your boosting it and your goal is only 400, you should be okay without even porting it.
3. e-cam isn't the best cam, but its not the worst either. you'd be better off with something else.
4. 30# injectors are pushing it, but you might be able to work it with them. I'd go with 42#s since you have the chip/tune.
5. 190lph fuel pump isn't enough. vortech kits come with a 255lph pump so you'll want to put that in. also a t-rex inline pump as well.
6. as long as you have the stock accessory brackets you'll be fine for the install. when they stock engine they just more or less mean stock mounting hardware.
7. dyno tune it when you have it installed.
8. i'd get a boost gauge at the very least.
9. have fun
1. find out your compression ratio. anything below 9.5:1 is okay.
2. cobra intake will restrict the flow, but since your boosting it and your goal is only 400, you should be okay without even porting it.
3. e-cam isn't the best cam, but its not the worst either. you'd be better off with something else.
4. 30# injectors are pushing it, but you might be able to work it with them. I'd go with 42#s since you have the chip/tune.
5. 190lph fuel pump isn't enough. vortech kits come with a 255lph pump so you'll want to put that in. also a t-rex inline pump as well.
6. as long as you have the stock accessory brackets you'll be fine for the install. when they stock engine they just more or less mean stock mounting hardware.
7. dyno tune it when you have it installed.
8. i'd get a boost gauge at the very least.
9. have fun
if you are going to a 331 shortblock and getting new heads, i'd get 185s instead of 165s.
it's not as big a deal (air flow wise) as it would be if you were staying n/a, but since you are planning on new heads anyway, i think the 185s are a better fit for you.
*edit* looking at your sig, i'm guessing you already have the 331 and 165s? if so feel free to ignore my statement above.
but, i'm not sure how good an e-cam is for boosted apps, someone else will probably chime in about that.
it's not as big a deal (air flow wise) as it would be if you were staying n/a, but since you are planning on new heads anyway, i think the 185s are a better fit for you.
*edit* looking at your sig, i'm guessing you already have the 331 and 165s? if so feel free to ignore my statement above.
but, i'm not sure how good an e-cam is for boosted apps, someone else will probably chime in about that.
Man I heard on the Internet the Cobra intake sucks.
Sounds like Jay set you up good, nice #s.
Are those 60s or larger?
Wes
horsepower (HP) = lb/hr (fuel) / BSFC
BSFC is the brake specific fuel consumption of an engine and depends on many factors including thermal efficiency, mechanical efficiency and air to fuel ratios. Most piston engines have a BSFC of between 0.5 and 0.55 lbs. of fuel per hp per hour at maximum power, set fairly rich with AFRs between 12 and 13 to 1. For our formula we will assume a BSFC of .5
If we assume BSFC of .5, then HP = 2 * lb/hr. Then, if we round the weight of a pound of fuel to 6 pounds HP = 12 * gal/hr. So, if we assume .5 BSFC, then you can actually multiply the numbers in the flow charts by 12 to compute supported horsepower.
Stad wants 400 whp, which puts us at almost 470 engine horsepower, so let's make it 500 just in case he goes over a bit.
The HP 255 Walbro pump chart is this:
PSI --- gal/hr
0 ---- 76
10 -- 73
20 -- 68
30 -- 63
40 -- 59
50 -- 54
Most of us run anywhere between 31 and 43 psi, so for the sake of the lowest flow amount, we'll choose 40 psi, which is 59 gal/hr.
If we put the numbers in:
59*12 = 708 horsepower that the fuel pump can support at 40 psi. His current injectors will starve that combo long before that single fuel pump will.
Even at 50 psi with 54 gal/hr we still have 54*12 = 648 horsepower.
Let's make sure we point him in the right direction. When I really got into messing with my fuel system and talking with others, I really learned a lot. I also learned that a lot of what I thought I knew was only half right. Maybe what I learned can help a bit...
Let's go over some additional things to consider in your numbers that might make you increase your estimate.
First off, assuming he has no mechanical problems and the car is tuned even mostly right, his combo is going to make well over 470 engine hp with an S-trim. I don't think there can be much argument on this.
When doing these type of estimates on fuel, it is always better to have slightly more than you need rather than just enough. A 20% safety margin on fuel components is also wise - some even use a 30% margin on the pumps.
Your BSFC is quite low for a centri blower - .65 is a good number. Look around on Google or ask around and see what you come up with.
When boost is applied to a fuel pressure regulator, the fuel pressure is raised in a 1:1 ratio to compensate for the pressure trying to push fuel back in the injector. So if you run 10# of boost your fuel rail will be running about 50psi of pressure assuming a stock initial setting of 39psi.
Now we get to the meat of where I'm coming from with him needing more pump.
If he keeps the 30s he has to run a FMU. The FMU works by raising the fuel pressure by the ratio of the disc you are running. If you have a 10:1 disc in, for every 1PSI of boost, you'll see an additional 10PSI of pressure behind the injector.
Here is where he absolutely has to have the 255 pump and TREX.
In your flow chart for the 255 you note that as the PSI increases, the flow tapers off. It is quite dramatic past 50PSI. So using what you now know you can see how a single in-tank 255lph just won't cut it.
Now if he steps up to a 42 or 60lb injector and can get rid of the FMU he will still be at or past the limit on his single 255 pump.
Now all these numbers going around are fun and assume everything is working to its best. How do we really find out what a fuel system will really flow?
There are a couple simple methods...
A fuel pressure sender can be datalogged along with the boost pressure. Now that we know boost and rail pressure increases at 1:1, you can make a run and watch the relationship of the two numbers.
Another way is to figure out what your max boost will be - let's call it 10PSI. Using what you know of fuel pressure under boost, set your regulator at 50PSI. Now with the car on a battery charger, jump the fuel pump to run (you can do this at the test port). Run the fuel into a graduated container that can measure out one gallon. With a stopwatch, time how long it takes to fill up one gallon and then do the math to convert this into gallons/hr.
This will also work with the FMU, just set your fuel pressure to what it will be with the disc you are running.
Here's some more excellent reading:
http://www.kennebell.net/media/articles/FUELFLOWFORENSICS.pdf
http://www.autoperformanceengineering.com/html/fpspecs.html
http://www.eecanalyzer.net/ - Has a great fuel deliver calculator
That's my 2c, hope it helps you make your decision, Stad. Boost is fun, I highly recommend it.
Wes
Let's go over some additional things to consider in your numbers that might make you increase your estimate.
First off, assuming he has no mechanical problems and the car is tuned even mostly right, his combo is going to make well over 470 engine hp with an S-trim. I don't think there can be much argument on this.
When doing these type of estimates on fuel, it is always better to have slightly more than you need rather than just enough. A 20% safety margin on fuel components is also wise - some even use a 30% margin on the pumps.
Your BSFC is quite low for a centri blower - .65 is a good number. Look around on Google or ask around and see what you come up with.
When boost is applied to a fuel pressure regulator, the fuel pressure is raised in a 1:1 ratio to compensate for the pressure trying to push fuel back in the injector. So if you run 10# of boost your fuel rail will be running about 50psi of pressure assuming a stock initial setting of 39psi.
Now we get to the meat of where I'm coming from with him needing more pump.
If he keeps the 30s he has to run a FMU. The FMU works by raising the fuel pressure by the ratio of the disc you are running. If you have a 10:1 disc in, for every 1PSI of boost, you'll see an additional 10PSI of pressure behind the injector.
Here is where he absolutely has to have the 255 pump and TREX.
In your flow chart for the 255 you note that as the PSI increases, the flow tapers off. It is quite dramatic past 50PSI. So using what you now know you can see how a single in-tank 255lph just won't cut it.
Now if he steps up to a 42 or 60lb injector and can get rid of the FMU he will still be at or past the limit on his single 255 pump.
Now all these numbers going around are fun and assume everything is working to its best. How do we really find out what a fuel system will really flow?
There are a couple simple methods...
A fuel pressure sender can be datalogged along with the boost pressure. Now that we know boost and rail pressure increases at 1:1, you can make a run and watch the relationship of the two numbers.
Another way is to figure out what your max boost will be - let's call it 10PSI. Using what you know of fuel pressure under boost, set your regulator at 50PSI. Now with the car on a battery charger, jump the fuel pump to run (you can do this at the test port). Run the fuel into a graduated container that can measure out one gallon. With a stopwatch, time how long it takes to fill up one gallon and then do the math to convert this into gallons/hr.
This will also work with the FMU, just set your fuel pressure to what it will be with the disc you are running.
Here's some more excellent reading:
http://www.kennebell.net/media/articles/FUELFLOWFORENSICS.pdf
http://www.autoperformanceengineering.com/html/fpspecs.html
http://www.eecanalyzer.net/ - Has a great fuel deliver calculator
That's my 2c, hope it helps you make your decision, Stad. Boost is fun, I highly recommend it.
Wes
Well said, very good.
My argument was strictly with him upgrading to larger injectors. I feel that using a FMU here instead of going larger on injectors is foolish.
So, we pretty much agree
Although, at 10 psi of boost my fuel pressure gauge shows approximately 40 psi, so I'm not sure where you got the 50 from?
My argument was strictly with him upgrading to larger injectors. I feel that using a FMU here instead of going larger on injectors is foolish.
So, we pretty much agree
Although, at 10 psi of boost my fuel pressure gauge shows approximately 40 psi, so I'm not sure where you got the 50 from?
No way 30's are going to cut it on 331 with HCI. Your going to need to 42's (I would just get 60s and be done) The Gss307 255 pump drops like a $10 whore at 55 to 60 PSI were a boosted car will run. And these flow numbers are at the pump not at the rail their is a 5 to 10 psi difference between the two. So with a base FP of 40 and 12 lb of boost then add the presser difference your talking 57 to 62 psi at the pump.
I have flow tested both the 255 alone and the 255 and the Trex and the Trex kicks the **** out of the 255 in tank
With a stock 302 with a HCI, strim with the stock 3.33 Vortech pulleys and a power pipe I see 14to 15 PSI. I pushed my 42s to the max 90 to 95%
A GSS 340 HP 255 in tank and 42's will be closer or he can use his 190 and the trex and be done. The trex is in the kit
I have flow tested both the 255 alone and the 255 and the Trex and the Trex kicks the **** out of the 255 in tank
With a stock 302 with a HCI, strim with the stock 3.33 Vortech pulleys and a power pipe I see 14to 15 PSI. I pushed my 42s to the max 90 to 95%
A GSS 340 HP 255 in tank and 42's will be closer or he can use his 190 and the trex and be done. The trex is in the kit
If you have 40 psi base FP and 10 lb boost and still have 40 psi fuel presser something is ****ed up
Your fuel presser should go up the same amount as boost 40+10=50. Your injectors are fight the intake presser so this evens this out
If your regulator is working properly and is tapped into the manifold at the right place, you will see boost and fuel pressure increase in a 1:1 ratio.
If your base fuel pressure is at the stock setting (39psi), you will see 49psi at the rail under 10psi of boost. All this is doing is keeping the same pressure at the injector tip. If there is 10PSI of air pushing air INTO the injector, you also need 10PSI more pressure pushing fuel out to keep it equal so that the PCM can calculate the required fuel.
Wes