Boosted 4V cobra motor vs Ls1
01-30-2007, 01:20 PM
#41
Originally Posted by black98ws6ta
As stated before if the restrictions call for pump gas boost then I think you will have the advantage. You have heads that flow more, and more ci.
Aren't you the guy who had Bob @ EPP tune your ride? You made a shitload of power!!! Congrats! Also remember he is running a 4:10 gear which won't help his spooling time compared to my 3:42's.
01-30-2007, 04:55 PM
#43
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If your brother runs stock cubes for a 98 Cobra and you both run stock compression, you will make more power than him on 91 pump gas. Compression is similar (You are 10.1:1 stock and he's 9.85:1) but you have a bunch more cubes than him. And you will have a stronger power curve too.
01-30-2007, 05:13 PM
#44
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Originally Posted by Pro Stock John
If your brother runs stock cubes for a 98 Cobra and you both run stock compression, you will make more power than him on 91 pump gas. Compression is similar (You are 10.1:1 stock and he's 9.85:1) but you have a bunch more cubes than him. And you will have a stronger power curve too.
Not necessarily! Cubes do not determine power under the curve. If they use the same size turbo and the camaro redlines at 6300, but full boost comes in at 3200,there's only a a 3100 rpm to take full advantage of. The larger you go in motor, decreases your rpm capabilites. If a civic uses the same size turbo, but doesnt get full boost until 4500rpm, but makes power to 9-9500 rpm, thats a 5000rpm curve.
Take another example. The new Z06 is faster than the 06 viper, despite haveing less power, smaller motor and a smaller displacement. But it does have more power under the curve, due to its higher redline capabilites. On another note.
01-30-2007, 05:53 PM
#45
Originally Posted by 52172
Just wanted to ask if people know which motor would make more power and have the better curve given the ls1 has a forged shortblock and also the cobra motor. My brother is building his cobra with a single turbo to compete with me. We both would be trying to get the most power out of 91octane fuel. My heads are ported and am running a 222/224 .581 114 cam with 9.8:1 compression. Who do you guys guess will be able to lay down more power?
01-30-2007, 06:01 PM
#46
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Originally Posted by lcvette
Smearin,
I am 100% completely aware of the difference of boost pressure and actual flow as I do alot of work in the field
, however I think alot of people here also overlook the fact thjat even though boost gauge pressure is a measure of restriction, it is also the pressure at the back of the intake valve and while in alot of cases boost pressure may not be viewed as ideal.. on smaller cube motors with good flowing heads and intake, it may not always be a restriction in the intake tract but the top of the piston and the pressure differential across the cylinder and the intake port... after all the more pressure the higher velocity and the greate amount of airflow will be forced through a restrcitive port albeit at a higher temperature because nothing escaped physics and the laws of compressed gas and the direct relation to pressure and heat.
if you look at a supra, its a 187 cubic inch engine and it may show upwards of 35 pounds of boost in extensive builds.... does that mean that just because it pushes 35psi that it won't make the power? NO, in fact power per pound of boost may not be as efficient at higher level but it will STILL show a gain in power, so do not underestimate the power of pressure just because it is not the most IDEAL setup.
and I am in no way trying to compare your car to another but I think your turbo is small for your motor.. but then again I like the feel of a larger turbo and more top end rather then instantaneous throttle response.. so turbo sizing is kinda like clothes.. different sized turbos will created two very different types of power band.. it just is what you wanna drive. I have ridden in a few 76mm 03-04 cobra cars and gotta say that I think the 76mm unit is Sized spot on for the power range and rpm band they have with the 4 valves per cylinder and and DOHC's. hell they jump straight into the F1A blower in most cases and the blowers work very well on them. if you look at the compressor map of a 76mm unit, you will see that those efficiency islands rise upwards against the pressure ratio on the left hand side so they stay efficient when pushing up in the high boost range, some may even tell you that they find their 'happy spot" where they really begin producing airflow efficiently at their max pressure ratio and max airflow which on the cobra motors happens pretty high up in the rev range where they are capable of moving airflow like an bigger motor at lower rpm.
in no way am I trying to pick a fight, but I see too many people go straight to the "boost pressure is a bad thing" and while the restriction is clearly just that.. more pressure does not mean you get less gain, just that you are having to push harder for that gain. in the end.. 20+ pounds of boost is gonna make air get where it needs to be.. on top of the piston in the intake stroke!
Chris
I am 100% completely aware of the difference of boost pressure and actual flow as I do alot of work in the field
, however I think alot of people here also overlook the fact thjat even though boost gauge pressure is a measure of restriction, it is also the pressure at the back of the intake valve and while in alot of cases boost pressure may not be viewed as ideal.. on smaller cube motors with good flowing heads and intake, it may not always be a restriction in the intake tract but the top of the piston and the pressure differential across the cylinder and the intake port... after all the more pressure the higher velocity and the greate amount of airflow will be forced through a restrcitive port albeit at a higher temperature because nothing escaped physics and the laws of compressed gas and the direct relation to pressure and heat.if you look at a supra, its a 187 cubic inch engine and it may show upwards of 35 pounds of boost in extensive builds.... does that mean that just because it pushes 35psi that it won't make the power? NO, in fact power per pound of boost may not be as efficient at higher level but it will STILL show a gain in power, so do not underestimate the power of pressure just because it is not the most IDEAL setup.
and I am in no way trying to compare your car to another but I think your turbo is small for your motor.. but then again I like the feel of a larger turbo and more top end rather then instantaneous throttle response.. so turbo sizing is kinda like clothes.. different sized turbos will created two very different types of power band.. it just is what you wanna drive. I have ridden in a few 76mm 03-04 cobra cars and gotta say that I think the 76mm unit is Sized spot on for the power range and rpm band they have with the 4 valves per cylinder and and DOHC's. hell they jump straight into the F1A blower in most cases and the blowers work very well on them. if you look at the compressor map of a 76mm unit, you will see that those efficiency islands rise upwards against the pressure ratio on the left hand side so they stay efficient when pushing up in the high boost range, some may even tell you that they find their 'happy spot" where they really begin producing airflow efficiently at their max pressure ratio and max airflow which on the cobra motors happens pretty high up in the rev range where they are capable of moving airflow like an bigger motor at lower rpm.
in no way am I trying to pick a fight, but I see too many people go straight to the "boost pressure is a bad thing" and while the restriction is clearly just that.. more pressure does not mean you get less gain, just that you are having to push harder for that gain. in the end.. 20+ pounds of boost is gonna make air get where it needs to be.. on top of the piston in the intake stroke!
Chris
Theres another guy on here with a pts kit and a 67 tubro making more hp than me.. so.... yup
01-31-2007, 01:54 PM
#48
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Originally Posted by 25psi
Not necessarily! Cubes do not determine power under the curve. If they use the same size turbo and the camaro redlines at 6300, but full boost comes in at 3200,there's only a a 3100 rpm to take full advantage of. The larger you go in motor, decreases your rpm capabilites. If a civic uses the same size turbo, but doesnt get full boost until 4500rpm, but makes power to 9-9500 rpm, thats a 5000rpm curve.
Take another example. The new Z06 is faster than the 06 viper, despite haveing less power, smaller motor and a smaller displacement. But it does have more power under the curve, due to its higher redline capabilites. On another note.
Take another example. The new Z06 is faster than the 06 viper, despite haveing less power, smaller motor and a smaller displacement. But it does have more power under the curve, due to its higher redline capabilites. On another note.
It all REALLY comes down to how efficent you put the power down and how well your gears to maximize that power produced. Also, tires and luck have their role in things. I understand your a v-8 hater, me too!!! But more cubes will yield a more torque or is capable of producing more, from lower in the rpm range, thus it doesn't need to turn 10k rpms to get it moving like a 4cly. high compression turbo motor.
12-13-2008, 06:45 PM
#50
Update... This is Al--52172 Brother. Just got my car back pending a dyno tune. Car is built by MMR-modular mustang racing, builders of the fastest 1/4 must in the world. I have the stock B heads with stage 3 porting. Stage 2 turbo cams, and the motor is a MMR 950 stroker so that puts the cubes at 302. My heads flow way over 300 but I haven't put them on the flow bench. I'm running 355's with a trutrac and 31 spline shafts to compliment the the 8.8 rear. As my brother has mentioned we both have the same turbo--A TC 76 non BB. Mark Leduc feels my car will pull his on the top side. He thinks my car is at least 200 pounds lighter as well (lots of contraversy here).
Stay tuned for dyno results and head to head action with video.
Let's hear some biased opinions--
Stay tuned for dyno results and head to head action with video.
Let's hear some biased opinions--
12-14-2008, 10:13 AM
#55
I didnt read all the pages, but if you had the same compression you would whip him. What compression is he running? Your 9.8:1 is gonna limit you with 91 octane.
If you guys run the same boost with the same turbo... you will lay it on him pretty good. I suspect it will take ~4-5psi more for him to make the same power as you.
If you guys run the same boost with the same turbo... you will lay it on him pretty good. I suspect it will take ~4-5psi more for him to make the same power as you.
