Head flow question, anyone have examples?
Head flow question, anyone have examples? I'm looking for anyone that has gone from stockish heads to higher flowing heads and the the gains that you saw. Heads/cam examples are applicable as long as you ran the same boost level. I'm interested in either dyno numbers or MPH results from the track.
Right now i'm on stock 6.0 heads and a 03 Z06 cam. I'm trying to decide if I should spend the money on an L92 head setup with a bigger cam or if I should spend the money on upgrading the turbo to an ST80. Cost probably ends up being about the same in the end. I'm not really looking for a whole lot more power on the street, but I won't shy away from it. I'm trapping 130-131 mph in my street trim setup @ 15psi in 100 degree temps and 7000' DA's @ 3850 race weight.
Right now i'm on stock 6.0 heads and a 03 Z06 cam. I'm trying to decide if I should spend the money on an L92 head setup with a bigger cam or if I should spend the money on upgrading the turbo to an ST80. Cost probably ends up being about the same in the end. I'm not really looking for a whole lot more power on the street, but I won't shy away from it. I'm trapping 130-131 mph in my street trim setup @ 15psi in 100 degree temps and 7000' DA's @ 3850 race weight.
this is something i was going to do pretty soon... right now i have stock heads with a small cam, and i just got some stock 6.0 heads that i want to put on.
The one thing that i am debating is whether or not i should have them ported or not.... is porting even worth it, or should i just put the 6.0's on as they are?
The one thing that i am debating is whether or not i should have them ported or not.... is porting even worth it, or should i just put the 6.0's on as they are?
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Joined: Nov 2003
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From: Norn Iron
a head/cam package should give you good gains everywhere.
A bigger turbo might only offer gains at the top end. Although the term bigger turbo can be quite general given todays turbo technology.
A bigger ( or better ) turbo might give gains everywhere, and spool earlier.
A bigger turbo might only offer gains at the top end. Although the term bigger turbo can be quite general given todays turbo technology.
A bigger ( or better ) turbo might give gains everywhere, and spool earlier.
my philosophy is if u can make the same hp figures on the least amount of boost possible then thats the goal.less heat and more reliable.ive heard it said that ideally u want infinite boost out of the turbo and zero boost at the intake since the motor will consume all the air.
Designing the build for Big HP at the lowest boost will be more efficient for sure.
I am hoping the setup in my sig will put me close to 800+RWHP
at only 16psi. I will be finishing the build in the weeks to come and
post up the results.
I am hoping the setup in my sig will put me close to 800+RWHP
at only 16psi. I will be finishing the build in the weeks to come and
post up the results.
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Well we sure have discussed a lot of theory on why it's better to have good flowing heads, but I haven't seen a single real life before/after comparison.
Anyone ever made a comparison?
Anyone ever made a comparison?
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Verdad Gallardo ive heard of a few people ask why their car made the same hp or 20whp more on 2-3psi difference after they swapped heads or why their car gained a lot of hp with heads/cam but lost boost but not a direct comparision
Don't have an exact comparison on the same car with just a head/cam swap or anything, but every turbo car I have seen and tuned that has heads/cam vs stock stuff always makes 80-100 or more rwhp at the same boost level. For example, last APS C5 kit on a stock C5 running 8 psi made 500 rwhp. That same kit and same boost on a heads/cam C5 made 600 rwhp. My car made 670 rwhp on 10 psi with crappy 91 octane, haven't ever seen or heard of a stock heads/cam setup make that much power on 10 psi with 91 octane. The motor made 410 rwhp before boost so mathmatically it's just about right for a very efficient combo. It's just efficiency and turbo motors follow the same basic principles that N/A motors do. You get more air in and out with big heads and a bigger cam and it will make more power at the same boost level since boost is just a measurement of restriction.
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Joined: Jul 2005
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Zombie, last year, we dyno tested a single turbo 377 at 7 different boost levels, ranging from 3.5 psi all the way up to 18 psi. No, we didn't swap heads, but I did learn something valuable.
When you plot "peak hp VS boost level", and put boost level on an absolute scale, you see that it's nearly a straight line. The line points to zero hp at about -11 psig "boost" (manifold pressure). -11 psig = about 22"Hg. This makes sense, because at 22"Hg vacuum, the engine is making no power at all. At 14.7 psia (atmospheric pressure), the line crosses 400 hp, which is about what I would expect from this engine naturally aspirated (377, 8.5/1, Fastburn heads, 230 cam).
The point of all this is. . . that the power an engine produces is roughly proportional to the density of the air in the intake manifold. Density if proportional to pressure. The baseline is the amount of power the engine makes NA. So, if an engine makes 400 hp NA (14.7 psia), then it will make around 800 hp at 29.4 psi (14.7 psi boost).
Our 377 made 490 hp at 3.5 psi boost (18.2 psia) and 860 hp at 15 psi boost (29.7 psia), which follows the line very well.
The disclaimer here is that the slope of the line will vary depending on the turbo used. Also, as you reach the limit of a turbocharger, the line will flatten at when you try to raise the boost higher.
What I'm getting at is that the more power you make NA, the more you'll make on boost. In fact, if heads pick you up 20 hp NA, then they could pick you up 40 hp at 15 psi boost, assuming you're not running out of turbo. Remember, turbo's max out on airflow (hp), not boost.
When you plot "peak hp VS boost level", and put boost level on an absolute scale, you see that it's nearly a straight line. The line points to zero hp at about -11 psig "boost" (manifold pressure). -11 psig = about 22"Hg. This makes sense, because at 22"Hg vacuum, the engine is making no power at all. At 14.7 psia (atmospheric pressure), the line crosses 400 hp, which is about what I would expect from this engine naturally aspirated (377, 8.5/1, Fastburn heads, 230 cam).
The point of all this is. . . that the power an engine produces is roughly proportional to the density of the air in the intake manifold. Density if proportional to pressure. The baseline is the amount of power the engine makes NA. So, if an engine makes 400 hp NA (14.7 psia), then it will make around 800 hp at 29.4 psi (14.7 psi boost).
Our 377 made 490 hp at 3.5 psi boost (18.2 psia) and 860 hp at 15 psi boost (29.7 psia), which follows the line very well.
The disclaimer here is that the slope of the line will vary depending on the turbo used. Also, as you reach the limit of a turbocharger, the line will flatten at when you try to raise the boost higher.
What I'm getting at is that the more power you make NA, the more you'll make on boost. In fact, if heads pick you up 20 hp NA, then they could pick you up 40 hp at 15 psi boost, assuming you're not running out of turbo. Remember, turbo's max out on airflow (hp), not boost.
Originally Posted by engineermike
What I'm getting at is that the more power you make NA, the more you'll make on boost. In fact, if heads pick you up 20 hp NA, then they could pick you up 40 hp at 15 psi boost, assuming you're not running out of turbo. Remember, turbo's max out on airflow (hp), not boost.
If you made 450rwhp on motor, @ 15psi, you could make 900rwhp. That's in theory and assuming that other parts like the blower, turbo, and intercoolers don't become a restriction, and can keep up with the air flow.