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**1980c10** · 10-07-2009, 08:49 PM

I get what your saying on this, But bigger is not always better. Also if you have a giant intake and throttle body set up that flows 1000cfm or sum bs number just for example and your heads flow 185 cfm on the intake and even less on the exhaust it really does do you any good, your engine can only flow as much as the biggest restriction in it. If you have 1000cfm intake set up sitting on top of 800cfm heads only 800cfm is getting into your motor and that other 200cfm is potentially moving you power band up to an unreasonable level.
Anyway most of us around here are street driven cars that weigh over 4000lbs and we need alot of low end tourqe to motivate them properly, thats why we go for the more low end power producing parts. you dont see a diesel truck making power over 4000 rpm they are heavy as balls and need lots of tourqe to do the job.

**merc91** · 10-07-2009, 08:50 PM

those engines you listed also top out at much higher rpm's than a lopo which means the air it needs isn't directly related to displacement because the maximum potential of a 2005 Suzuki Aerio 2.3L DOHC engine doesn't also occur at around 3000 rpm like a lopo so those calculations you made for a 302 are a little off. These other motors you listed are pulling in about 50% more air than you calculated for compared proportionally to a LOPO 5.0... hense the larger CID proportional size TB's on them.

I have also wondered why it's said you can go to big on the intake and TB's so if someone could explain this it would be appreciated because there's lots of guys one here that really know their 5.0's and I don't think they put on smaller TB's just because its a cool fad on here.

I also know that a LOPO 5.0 makes gobs more torque than a Dodge Caravan so the ford boys must be onto something, but if you had some numbers on a 5.0 comparing a stock GT40 intake VS a 75mm high flow unit would be very interesting to me.

So for example. 2005 Suzuki Aerio 2.3L DOHC engine = 65mm bore/60mm blade
60mm/140 C.I.D. = .4286mm per cid = 129.4mm for a 302, 150.4mm for a 351

...max power around 6000 rpm vs approx 3000rpm for a LOPO. Basically 2X the rpm would make one expect at the same rpms as a lopo, 2.3X2 would equal about 4.6L equivelant air consumption.

So thats actually comparable to a 280 CID engine air consumption at 3000rpms... 60mm/280 C.I.D=.2143 mm per cid= 64.7mm for a 302... this is shockingly close to the recommended 65mm TB.

A professional engine builder I am not, but this stuff is easy for an 18 year old engine "beginner" like myself to see, and these guys on here are very good at what they do with their passion for cars and specifically fords... so questions and reading their advice usually is the way to go.

**Outlaw440** · 10-07-2009, 08:54 PM

Originally posted by 1980c10 View Post

Anyway most of us around here are street driven cars that weigh over 4000lbs and we need alot of low end tourqe to motivate them properly, thats why we go for the more low end power producing parts. you dont see a diesel truck making power over 4000 rpm they are heavy as balls and need lots of tourqe to do the job.

A larger TB will not reduce Low end torque, as a matter of fact it will do the opposite.

Diesel trucks have nothing to do with this, the majority of them don't even have throttle bodies.

Define "low end torque" producing parts. Don't tell me your another one of those guys that thinks smaller heads, smaller intakes, and smaller exhausts make more low end tq, because they do not.

An engine makes torque, HP is a calculation, if there are restrictions that don't allow an engine to breath, you are giving up TQ and HP. Why would you build an engine with restrictions?

Originally posted by 1980c10 View Post

street driven cars .

I hear this thrown around all the time and honestly it's the stupidest thing i've ever heard. Dan millen's 6 Second outlaw 10.5 mustang is street driven too.

**1987cp** · 10-07-2009, 09:03 PM

Originally posted by Outlaw440 View Post

I hear this thrown around all the time and honestly it's the stupidest thing i've ever heard. Dan millen's 6 Second outlaw 10.5 mustang is street driven too.

Well, there is a difference in a race car you can drive on the street and something that you would actually make your wife and mother in law ride to church in.

But all this is beside the point. You were making some interesting points about what one can do with better parts that don't come from the boneyard .... we've already addressed the fact that most GMN buildups are severely budget-limited and address the goal of improving on a 150 horsepower snoozebox that makes my homebuilt junk seem quick, so how about most of the rest of us shut up and try to learn something about making actual power.

I have read before about the concept that a 1000cfm or so throttle body isn't a big problem on an injected street engine, as long as the rest of the system is suitable for the intended application. I keep ranting at guys not to install 750cfm *carburetors* on their stock-cammed street crap, but that's a whole different ballgame.

**Outlaw440** · 10-07-2009, 09:04 PM

Originally posted by merc91 View Post

I have also wondered why it's said you can go to big on the intake and TB's so if someone could explain this it would be appreciated because there's lots of guys one here that really know their 5.0's and I don't think they put on smaller TB's just because its a cool fad on here.

There is no such thing as "too big" of an intake when it comes to EFI. The only reason people use small factory intakes like GT40s and 65mm TB's is because they are cheap and budget improvements over the stock stuff.

Originally posted by merc91 View Post

So for example. 2005 Suzuki Aerio 2.3L DOHC engine = 65mm bore/60mm blade
60mm/140 C.I.D. = .4286mm per cid = 129.4mm for a 302, 150.4mm for a 351

...max power around 6000 rpm vs approx 3000rpm for a LOPO. Basically 2X the rpm would make one expect at the same rpms as a lopo, 2.3X2 would equal about 4.6L equivelant air consumption.

So thats actually comparable to a 280 CID engine air consumption at 3000rpms... 60mm/280 C.I.D=.2143 mm per cid= 64.7mm for a 302... this is shockingly close to the recommended 65mm TB.
.

So you mention one engine. What about the heavy ass lincoln i posted? The nissan pathfinder SUV? The mercedes benz? All of which are heavy vehicles. Don't tell me they don't make low end torque.

How do you know where a suzuki aerio makes max power @ 6000rpm ? did you look it up? Do you own one? How does it get to 6000rpm if it has no low end torque? Your logic is very elementary and i've seen it millions of times.

**1980c10** · 10-07-2009, 09:09 PM

first off I never said a larger throttle body will kill TQ, and no im not one of those guys who thinks small stuff makes TQ I plan on using a very large turbo to make mine haha, diesel trucks do have something to do with this as I am trying to get it through your head that are cars are heavy, and make peak HP and TQ at a somewhat low rpm. And need alot of TQ to move them - ''like a diesel'' They are not a 2000lb honda that spins to 9500rpm. The stock H.O. ecu rev limit is 6250rpm most guys on here run a stock ecu with the stock rev limit. So an intake setup with a power band from 4000-8000 doesnt do us much good, 2000rpm of usable power would be wasted. You have it in your head that bigger is better and money is unlimited for everyone and we can all build an engine that revs 9000rpm and use a giant intake and throttle body, this is REAL WORLD street cars as in daily drivers back and forth to work everyday, and I for one know its not much fun to drive something on the street with a giant cam, and a dog at any kind of rpm you will see with daily use. anyway just my 2 cents.

**Outlaw440** · 10-07-2009, 09:11 PM

Originally posted by 1987cp View Post

I have read before about the concept that a 1000cfm or so throttle body isn't a big problem on an injected street engine, as long as the rest of the system is suitable for the intended application. I keep ranting at guys not to install 750cfm *carburetors* on their stock-cammed street crap, but that's a whole different ballgame.

YES! exactly.

I think the whole "intake too big" myth comes from people trying to use carburetor logic on EFI engines, yes, carb'd engines are much more sensitive to big intakes/carbs that are too large. Carb'd engines need restriction due to their design, which is to pull in fuel and air, whereas efi motors are just pulling air through the intake.

Originally posted by 1987cp View Post

But all this is beside the point. You were making some interesting points about what one can do with better parts that don't come from the boneyard .... we've already addressed the fact that most GMN buildups are severely budget-limited and address the goal of improving on a 150 horsepower snoozebox that makes my homebuilt junk seem quick, so how about most of the rest of us shut up and try to learn something about making actual power.

I am only posting this information in hopes of teaching people what i have learned through trials and tribulations, and thousands of dollars i have wasted on garbage i should have never bought in hopes that other people don't have to go through that.

**1980c10** · 10-07-2009, 09:34 PM

also your heavy cars dont make what i would call low end TQ sure they make some amount of TQ but ehh
lincoln ls
-
Power: 209 kW , 280 HP SAE @ 6,000 rpm; 286 ft lb , 388 Nm @ 4,000 rpm

pathfinder '' not to bad ''
-
Power: SAE and 127 kW , 170 HP @ 4,800 rpm; 200 ft lb , 270 Nm @ 2,800 rpm

and the mercedes benz
-
Power: SAE and 145 kW , 194 HP @ 5,500 rpm; 199 ft lb , 270 Nm @ 3,750 rpm

For comparision sake

1991 grand marquis
-
Horsepower: 150 hp
Max Horsepower: 3200 rpm Torque: 270 ft-lbs.
Max Torque: 2000 rpm

1991 mustang
-
225 horsepower at 4200 RPM and 300 ft-lbs torque at 3200 RPM

1998 explorer 5.0
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215 H.P. at 4200 RPM and 288 LB/FT torque at 3300 rpm

**gadget73** · 10-07-2009, 09:36 PM

I have a bit of a wrench to throw in here. A huge throttle body is not useful unless you're actually moving air through it. 90mm on a stock lopo is a total waste of money. Also, a very large throttle body when the rest of the engine isn't up to the task is a waste. Also, I'm not convinced that bigger is always better. Air velocity is an important factor for determining an engine's power band. Huge intake runners, large valves, huge throttle bodies all make for excellent total airflow numbers, but it also makes for bad velocity. True, its less critical than in the carb days where you had to be concerned with the fuel dropping out of the air/fuel charge coming through the carb, but very slow moving air through the intake can slightly reduce your volumetric efficiency. A fast air charge can actually "ram" a little more air into the cylinder at lower speeds than would get there with a huge intake tract. Thats where the "loss of low end torque" statements come from.

Another thing to consider is the speed density ECM's basic programming. It knows that with the TPS at a given voltage, you have the throttle open a certain percent of the way. Lets just say its 25% for example. At 25%, it expects x amount of airflow. Now increase the throttle body size until what used to be x at 25% throttle is now 2x at 25% throttle. The ECM doesn't know what you did, so its assuming you're still feeding it the same amount of air, and as a result you get a lean fuel mix. This is far less a concern with mass air, since it meters actual airflow instead of using the educated guess method SD operates on but its important to be aware of what you're doing before hanging parts on an engine.

**Outlaw440** · 10-07-2009, 09:36 PM

Merc91 i took the liberty of looking up where the Suzuki aerio makes its peak power, and while it is irrelevant to the topic at hand.

155 HP SAE @ 5,400 rpm; 152 ft lb , @ 3,000 rpm. Peak TQ at 3000rpm, there goes your abscence of power down low arguement, because first of all peak numbers dont mean shit in reality, its the what i call column average, where the motor will actually be operating once you are moving. Who gives a flying fuck what the motor does at below 1500rpm.

Originally posted by 1980c10 View Post

diesel trucks do have something to do with this as I am trying to get it through your head that are cars are heavy, and make peak HP and TQ at a somewhat low rpm. .

They make Peak HP and TQ at low rpm because of the intake/cam/head combo they were dogged with from the factory to comply with emissions laws.

Originally posted by 1980c10 View Post

You have it in your head that bigger is better and money is unlimited for everyone and we can all build an engine that revs 9000rpm and use a giant intake and throttle body, this is REAL WORLD street cars as in daily drivers back and forth to work everyday, and I for one know its not much fun to drive something on the street with a giant cam, and a dog at any kind of rpm you will see with daily use. anyway just my 2 cents.

Who said you have to rev it to 9k rpm to take advantage of a larger TB? Because anyone who says that does not know what they are talking about.

I get it that your talking about real world street cars, all my cars are street driven too. Just because it has a giant cam doesn't mean it will be a dog at usable rpms. All my cams are custom with the exception of the truck, and they aren't "dogs". Its amazing what you can do when you buy a proper camshaft/head/intake combo.

Boy, all this when i just break the ice about throttle bodies, wait till i start discussing cylinder heads.

**Outlaw440** · 10-07-2009, 09:43 PM

Originally posted by gadget73 View Post

Air velocity is an important factor for determining an engine's power band. Huge intake runners, large valves, huge throttle bodies all make for excellent total airflow numbers, but it also makes for bad velocity.
.

Velocity, oh boy, the V word came out, this is hillarious. In the REAL WORLD, what does velocity mean? How do you measure it on a running engine? what happens if its too low? what happens if its too high?

The sooner you realize that Velocity means nothing in the real world the better.

With the proper camshaft and what some would consider "huge" heads and intake, it'll make all the power in the world down low-middle-and up top. You need FLOW to make power.

I was not reffering to lopo engines, a bigger TB won't mean anything until you get up to at least E7/GT40 heads (which are focking tiny even for a 302) and change the cam/and obviously an intake with an inlet big enough to support the TB.

Originally posted by gadget73 View Post

Another thing to consider is the speed density ECM's basic programming. It knows that with the TPS at a given voltage, you have the throttle open a certain percent of the way. Lets just say its 25% for example. At 25%, it expects x amount of airflow. Now increase the throttle body size until what used to be x at 25% throttle is now 2x at 25% throttle. The ECM doesn't know what you did, so its assuming you're still feeding it the same amount of air, and as a result you get a lean fuel mix. This is far less a concern with mass air, since it meters actual airflow instead of using the educated guess method SD operates on but its important to be aware of what you're doing before hanging parts on an engine.

Thank you for making an obvious arguement that you should tune the damn thing when you step up up to a larger intake/TB.

**grandpaslincoln** · 10-07-2009, 09:56 PM

I don't see the reason to be a prick.

**Brown_Muscle** · 10-07-2009, 10:07 PM

our dodge caravan make 260 ft/lb of torque.... 180 HP.... its a beast

**1987cp** · 10-07-2009, 10:41 PM

Originally posted by Brown_Muscle View Post

our dodge caravan make 260 ft/lb of torque.... 180 HP.... its a beast

Compared to a 140hp/280 lb-ft 351W ... yup!

It hasn't helped that everyone has jumped in with the "stock stuff is always better" routine. Lots of GMNers like factory-based upgrades a) because secondhand factory stuff is cheap, and b) because it's adequate for what most people are doing, especially those who will never upgrade their 4000rpm shift governor. Truth is, even the fabled 5.0 HO stuff was only really impressive compared to the 110hp "performance" cars from 1980-81, which is why folks are able to make big improvements without spending a huge amount of money (like Scott's and Thain's cars that both use OE Ford cams and intakes).

BTW, I find it hilarious that a Suzuki Aerio engine is rated at 155hp. I've spent some rather decent seat time in one (5-speed, too), and if nothing else, I learned that it made a 140hp Crappalier (automatic model, even) feel like a rocket by comparsion.

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