How do I "move" my horsepower?

[KLS]

I'd like to have more horsepower in the midrange, 2000-3500 rpm, and I'm willing to take it away from the top end.

What really works? Anything?

I've seen JBA's dyno chart, and it looks too good to be true, so I don't believe it.

I haven't seen a dyno chart on the TRD headers.

Downey tells me that they haven't dyno'd their headers (well, how do they develop them???)

I don't want to increase the exhaust noise much, and I'm not at all sure a cat-back system adds much of anything except noise.

Ideas anybody?
Ken

[v8Toilet]

I've been researching this myself. The JBA headers do increase your low-end torque considerably but like you I don't trust that graph on their website. I don’t trust any graph from the manufacturer themselves. I would only trust third party dyno numbers. I have dyno charts for both the TRD and JBA headers from members here who have brought their trucks to a dynamometer.

The JBA headers seem to have the clear torque advantage. With just JBA headers and a Borla exhaust system this member got 217.6 horsepower and 293-ft. lbs. of torque to the rear wheels.

Compare this to a stock dyno run from a California emissions equipped truck, which stock put down 265-ft. lbs. of torque and 205 horsepower to the rear wheels.

The guy with the TRD headers, Borla dual exhaust, JET ECU upgrade, and air box modification got 236 horsepower and 279.2-ft. lbs. of torque to the rear wheels.

If you figure the 15% driveline loss than here is what you get.

STOCK 241.1 horsepower (California trucks have 240 horsepower) Torque 311-ft. lbs. of torque.
Using the Drag program I get 0-60 in 7.98 seconds and the quarter mile in 16.07 seconds @ 85 mph.

JBA and Borla give you 255 horsepower and 344.7-ft. lbs. of torque at the crank. Your 0-60 comes in 7.35 seconds and the quarter mile in 15.61 seconds @ 87.4 mph.

TRD dual Borla, Jet ECU, and Air box mod gives you 277 horsepower and 328.5-ft. lbs. of torque at the crank. Your 0-60 comes in 7.58 seconds and the quarter mile in 15.738 seconds @ 87 mph.

Looks like the JBA headers with a single Borla exhaust system have the clear advantage because that setup make more torque down low where you need it in a heavy truck with an automatic transmission.

Remember this! Horsepower sells cars but torque moves them.

See Dyno Run

[Agent WD-40]

According to that info the JBA does appear to have more torque but what do you think that the JET chip did to the HP and torque? Do you think that that could have moved it up some in the power band? I have not looked at the graphs, but what do the HP and torque curves look like for those 2 trucks? Is one a lot flatter than the other?

[KLS]

Thanks for all the very interesting info.

One point. Power does work, and horsepower is the unit of power we use. Torque is force. Torque is just used to compute hp. (In case anyone forgot, hp = torque x rpm / 5252.)

What sells cars is indeed high horsepower numbers, often at nearly unusable rpms. What moves cars is horsepower at useful rpms.

I had a very unenlightening chat with a Downey sales rep. The only thing I gleaned from that conversation is that a friend of his has 35" tires on his Tundra, and he feels that with the Downey headers he regained most of his acceleration back that he used to have with the stock tires. Too bad your Drag program can't work with this data....

You big tire guys...how good would those results be?

Ken

[v8Toilet]

Actually I can put in any tire size and width I want to and see what it does to acceleration. I don't have any dyno numbers on Downey headers though. The program I have is Drag2000 made by Mr. gasket.

There is a thread where a guy tested his Tundra before and after with a G-tech below. The Downey headers like almost any header make a difference but like you said at what RPM? With 1-5/8 primaries compared to 1-1/2 for the TRD and JBA headers your torque curve might be moved up the RPM band more than the others might. Without and Dyno numbers I won’t take a chance cutting my exhaust system and spending $400 to find out that my low-end torque would be hurt.

I also checked into their history with the V6 and L4 guys and it's a mixed bag as far as product workmanship and customer service goes.

I talked to a representative at Downey and all he did was give me his opinion on how great Downey headers are. Smoke in a mirror as far as I'm concerned!

[RagerXS]

Originally posted by KLS
One point. Power does work, and horsepower is the unit of power we use. Torque is force. Torque is just used to compute hp. (In case anyone forgot, hp = torque x rpm / 5252.)

What sells cars is indeed high horsepower numbers, often at nearly unusable rpms. What moves cars is horsepower at useful rpms.

Ken, you are partially correct. Notice that with your formula HP and Torque are always equivalent at 5252 rpm. Torque will always be greater than HP below 5252 rpm, and HP will always be greater than torque above 5252 rpm.

Torque is what generates your acceleration (like off the line), HP is what allows you to sustain speed (like up an incline without down-shifting).

It's semantics in a lot of ways since torque and HP are directly proportional to each other. But the convention is to speak of torque at low - mid rpm and HP at mid - high rpm.

Also, let's dispel another myth: drivetrain loss is a constant value, not a percentage. Sure, friction increases as rpm increase, thus the drivetrain loss varies slightly with rpm. But a 200 cHP engine and a 300 cHP engine dropped in the same chassis will show the identical drivetrain loss when measuring power output at the wheels. This has been extensively tested in the Miata community. 115 cHP stock engines and 280 chp turbo engines all show 25-26 HP loss (e.g., 90 rwhp and 255 rwhp, respectively). The only debate left there is whether it is 25 or 26, and the consensus seems to be a combination mfg tolerance differences and the fact that actual dyno accuracy, which is typically not good enough to consistently differentiate a single HP.

~ Fred

[charlie]

Ken,nothing reasonable will increase your mid RPM HP.The only data that would mean anything would be before and after runs on the same dyno,same operator,same day,or at least same time of day with same general weather.
The stock manifolds aren't just thrown together,they work well.Headers might give you a bit more high rpm hp,but not much.I really doubt that they can increase midrange hp and high rpm hp.They would have to have some sort of active exhaust like Yamaha,and Honda have on their motorcycles to do that.
You would have to do the typical hotrod stuff we have all been doing forever to get any noticeable increase in power anywhere.
Increase compression-8 pistons,plus a lot of workfigure $500+labor maybe $1500 more.93 plus octane gas,and it will still ping.
Cam(cams really 4).Figure $700+labor,a lot of labor.This would be the best normally aspirated way to get more power.The V8 peaks at 4800,and redlines at 5400.It should be safe to rev the 84mm stroke to 7000.With the right cam you should be able to make peak power at 6500 rpms,and pick up maybe 25-30 % more power-high RPM power,but more power.You would have to modify the fuel injection,and ignition programs.You would also get your money's worth out of good headers now.
Supercharger driven off the crank.Best way to go if your motor can take it.It will certainly decrease the longevity of your motor,but it would be a kick.I don't think TRD will claim you will get stock reliability from a supercharged motor,just isn't possible.If I needed more midrange power,I would supercharge it.None of the exhaust mods will give a noticeable increase in midrange power-noisier,yes,but you won't really "feel" more power-you will "feel" more noise!
Well,save your money,and get a supercharger.Don't waste $1800 on exhausts systems that give almost no power increase.Spend $4000,and get a real increase.If you keep your foot out of it,the motor will probably take it.Just use it for short runs.Luck,Charlie
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