4-2-1 or 4-1 header? any difference in HP?

[gthompson97]

Originally Posted by hellah fresh

Yes it does help out a bit. It helps out on the mid-hi range rpm. I can feel a little pull. When i take off my car pulls a little but after it hits the 5-6k rpm you can really feel it. Also what i heard that helps and get high gains was the 60mm throttle by www.modernperformence.com But yes that 54mm helps. I got mine done from ebay for $40 dollars. You have take your old one out and send it in to them go get it bore out. The ebay id was conceptillusions. They did the work for me and also free powder coat form 6 different colors to choose from. But about that modern performence throttle... i heard alot of great reviews in dsmtuners.com. Everyone that bought the throttle said it pulls and it cost around $220 and for a better gain bore out your intake manifold to match the 60mm.

yeah....the reason I asked is because my head is ported and polished along with the intake and exhaust manifolds being gasket matched and ported to the same port size of the head. if i got a bigger throttle body, it should drastically improve airflow.

[drewh4386]

I just thought I would copy and paste this. It depends on what you want. Lower or higher tq.

Originally Posted by 95 GSXracer

Alright, enough BS, time to get into it. You guys that answered chose the wrong car. But you thought about it, and gave a reason, and thats all that maters

In my example above the car that makes the torque at 6k rpm will beat the car that makes tq at the 3k rpm. Here is why. As I said above it is HP, not torque, that moves you down the track in a given period of time. Torque is a static force, and HP is that torque appied over time and distance. You need time to be moving. MILES per HOUR, METERS per SECOND, etc. Distance and time.

Lets take a look at the formula for HP.

Torque x RPM
------------- = HP
5252

That 5252 is the constant used in the equation, and I could go on for a good bit about where it came from. But its not necessary. Ashah000, chances are when your physics class discusses HP, you may go over where that number comes from.

Using that example, lets firgure out the HP for the 2 cars that I used in my above example. We will use 300 ft-lbs for the example, but you can pick any number and run the math for yourself and see what happens. We will also assume that they both have the same torque curve.

Car #1 makes peak torque at 3k rpm. So 300 times 3000, divided by 5252. It makes 171 HP.

Car #2 makes peak torque at 6k rpm. So 300 times 6000, divided by 5252. It makes 342 HP.

See what happens? Double the rpm, double the HP. Since HP is what moves you down the track, the car that goes to 6k rpm will beat the car that only goes to 3k rpm. The higher the rpm you can make a given torque, the higher your HP will be. Imagine if we could have a flat torque curve of 300 ftlbs from 0 to 15000 rpm. We would have 856 HP, and could probably finish the quarter mile without ever shifting

Now why couldnt we just up the torque on the 3k car to equal the 342 HP of the 6k car? Well you could. But you would still have to gear it up in order to get to the same speeds as the 6k car. Which brings me to my next point. Gearing

The car will accelerate the hardest at the peak of the torque curve. That is what you will feel from in the car. You cant measure or feel HP, only torque. Both cars making the 300 ftlbs will "feel" the same to the passengers. (The car making 856 HP at 15000 rpm wont feel any faster than the other two examples) If the car accelerates hardest at its peak torque, in what gear will it accelerate the hardest? The one that has the most torque AT THE WHEELS. First gear. So we will say that the car will accelerate hardest at the peak WHEEL torque. And we can all agree that gearing will determine wheel torque. That being said, lets look at out two examples again. Both cars come off the line. The 3k car is pulling hard at its peak torque while the 6k car is still coming up to its peak torque. But then what happens! The 3k car has to shift into second, while the 6k car is making the same peak torque, but with the wheel torque of first gear. The 3k car is in second with less wheel torque, so the 6k car starts to pull away. This repeats itself gear after gear. If you havent figured it out yet, the key to all this is torque mulitplication. Gear reduction. The 3k rpm car may get to its torque peak earlier, but it also has to shift earlier, to a gear that will put it at a wheel torque dissadvantage to the 6k rpm car. This is the key guys.

So now not only is the 6k car making more HP, but its spending more time in the lower gears making more wheel torque, accelerating the car harder for a larger period of time. This is the key poeple. Torque is a good thing, but it is better to make that torque at higher rpm so you can take advantage of lower gearing for a greater length of time. And force applied (wheel torque) over time/distance equals your results on the track.

To finish our examples of the 2 cars, lets use the calc at www.dsm.org to see what each one would run in the quarter. The trap speeds are VERY accurate on this calc based on my own experience with many cars. The ET is only accurate with very good traction, so assume AWD if you want to go by the ETs. So if you enter your timeslip into that calc, the nember given for "speed method" is most accurate. I only pay attention to the trap speed results. I will use the numbers we came up with above as wheel HP (what this calc and all other gives you) to avoid getting into a debate about what our drivetrain loss is

The 3k rpm car with 171 WHP will run 15.5 at 88 mph. And 88 mph is about what stock DSMs do with 170 wheel HP. Pretty accurate. Though an AWD will do better than a 15.5

The 6k rpm car with the same torque but 342 WHP will run 12.4 at 110 mph. Thats a 22 MPH improvement! So you can see how extreme this example was And again, an AWD DSM driven perfectly will trap about 12.1-12.2 at that 110 mph. And this is what you would expect to run at this power level in a DSM.

Our fantasy 15000 rpm car (856 hp) would trap about 150 mph, all with 300 ft/lbs of torque.

So to get back to the real world where tq peaks are fairly close to each other, all cars are geared appropriately, etc, making the same torque at higher rpm gives you the advantage. This is why the 9 second DSMs all shift at 10k rpm. Every part of the car is chosen for its ability to move the torque curve higher in the rpm range. Intake manifolds with short runners, big cams, etc. They start making power late in the rpm range, and they have no trouble getting the car off the line with no low end torque. Look at Curt Brown and John Shepperd, pulling 1.2-1.3 60 foot times if you dont believe me. Look at those nasty rotary motors that have to idle at 4k rpm and dont start to make power until 6k and up. They pull equally fast 60 foots. It may not be fun to drive on the street, but you can always get the car off the line. Launch rpm, flywheel weights, etc, can be adjusted. How is it that these tiny little 4 bangers with hardly any torque are running 7s and better? They rev to the moon, yeilding lots of HP for that amount of torque. The results speak for themselves.

I hope this helps to clear some of this up. If there are any more specific questions, by all means, ask away

[hellah fresh]

Originally Posted by l_eclipse_l

Just look at any of the old muscle cars, a good majority of them have more torque than hp, and they are fast as hell. Just need a few more gears....

Well as of American muscle cars they hve hi end HP. My Friend raced a 69 Camero with his 90 Teg basic mods. He took the camero off line... but after awhile the camero caught up and that was it. But now im 50/50 with the headers now. I looked at some Greddy headers on Nopi.com and they made a 4-1 design. So that got me thinking... And Greddy do have a pretty good reputation behind all thier products. So Im thinking Greddy over DC Sports.??? Greddy 4-1 Vs DC Sports 4-2-1. So now i dont know. Im not going to buy those brands but im back to 50/50 now =\

[hellah fresh]

Hey drewh4386 Thats a good way of putting it! Good Job now i know what i want 100% for sure. So 4-1 it is. I always knew cars that shift later then other cars will eventually catch up with the car with more torque. So now i have my mind set. 4-1 it is Baby! Thanks alot man for the good infomation.

[drewh4386]

lol! yeah I just thought I'd let everybody know (who didn't know that hp is measured off of tq*rpm / 5252. SOme people in here were saying it like they were 2 different tweakers that can be seperately be gained and lost. BUt like I said it all depends on what you want to do.

[hellah fresh]

Hey one last question!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Ok im changing up my piping to 2.5 SOooo what i want to know is should i get 4-2-1 to make up for my loss torque scince im going 2.5 with no CAT? Basically its going to be down pipe to Straight 2.5 with no cat.

[drewh4386]

I would guess so because you lose a little back pressure with everything straight through.
which equals loss of power in a N/A.

[hellah fresh]

Originally Posted by drewh4386

I would guess so because you lose a little back pressure with everything straight through.
which equals loss of power in a N/A.

Ok so still 4-1 or 4-2-1? let me know because im going to buy it off ebay today which is sunday.

[drewh4386]

if you are look for lower torque/hp get the 4-2-1 because with a bigger straight thru pipe you will lose alot with the same set-up with 4-1. But not enough to lose stock hp/tq. or at least that is what i felt racing.
After experimenting.....
I had a 4-1 with no cat.
It was a bit noticeable with stock piping.
The exhaust pressure is not going to have much to pressure against. Thus creating power loss. Too much pressure will create power loss also. I'll put it like this....when I'm (dangerously) speeding down the high with a friends, (160hp. all his is in the low end) when i'm in the upper rpms, he is no match. Makes me wish I had a turbo.

[hellah fresh]

i see that you have a 4-1 header on yours. What is i get a 2.5 magna flow cat? should that help out or no CAT is better? haha ok if you where me and is going to do 2.5 a 4-1 is the way to go for that set up?

[drewh4386]

Me i have 2.25. I'm saving 2.5 for the turbo.

[hellah fresh]

Originally Posted by drewh4386

Me i have 2.25. I'm saving 2.5 for the turbo.

Soo your saying 2.25 is the way to go if your a n/t?? I didnt do my piping yet because im waiting for my headers to come in this week. Some people in dsmtuners.com said to go with 2.5, so im confused??? Which is the better gain in hp 2.25" or 2.5??

[drewh4386]

2.5 is better.

[hellah fresh]

haha cool my nizzle thats what im doing. 2.5 DP with 2.5 piping with no cat. But i hope i dont lose hp tho =\

[jackoo]

I have been reading about headers for awhile and noticed that 4-1 headers give u a little extra tork during take off which can help u during drag races. Well on the other hand 4-2-1 headers help u during speeding in other words its good for long distance races.