modding for torque or hp

specops_SC

Registered User
ive been trying to find a good answer by searching but im either not putting in the right search parameters or something. what i wasn to know is what mods increase torque as opposed to hp. i want my car to run 270-290 hp, but i want to get about 410-420 lbft of torque all at the wheels. is this combination possible? i only have a small understanding of how an engine produces torque and horsepower, other than gas explodes in the cylinder and the more gas/air in there the bigger the explosion and more of everything. i've been confused when i hear people say they increase torque but only a few hp or the other way around. any info would be appreciated. thanks.
 
specops_SC said:
ive been trying to find a good answer by searching but im either not putting in the right search parameters or something. what i wasn to know is what mods increase torque as opposed to hp. i want my car to run 270-290 hp, but i want to get about 410-420 lbft of torque all at the wheels. is this combination possible? i only have a small understanding of how an engine produces torque and horsepower, other than gas explodes in the cylinder and the more gas/air in there the bigger the explosion and more of everything. i've been confused when i hear people say they increase torque but only a few hp or the other way around. any info would be appreciated. thanks.

I had started a thread that got good answers...

http://www.sccoa.com/forums/showthread.php?t=49217

Also, someone pointed me to Apten Performance's website...

http://www.apten-us.com/vehicles/sc/

The Apten one should be stickied in the FAQ section, IMO.
 
yea. i followed that thread. im not looking for need info on what to do for numbers. i have a pretty good idea of what im gonna start off with. but people always talk about hp increases. what about torque increases? is that just not as critical or something? if im wasting my time chasing after lots n lots of torque, id like to know. hehe :rolleyes: im asking because i see g=people mod their cars to make 50 or 60 hp more, but only get a part of that in torque. its just kind of confusing. one example is that a 5% od pulley will give you so much hp and torque. but a 10% od pulley will give you way more torque, but not as much hp as youd think. :confused:
 
:confused: yet..? this is a belt driven supercharger..and it eats HP numbers from the overall rating ..... with a 5 vrs 10% pulley.. this is easy too see ..5%...uses less HP ...than a 10% needs... the gains [hp/torque] become
better flow and more volume into the motor ...and the ability to remove it from the motor..which in most cases is done in pieces ..from changing things like exhaust.. aftermarket cold air intake .. bigger MAF.. bigger Thottle body SC porting ..raised top....bigger injectors..head porting ..bigger valves ... cam changes..lighterpulleys ...different...intercoolingsystems ..bore/stroke.flywheel weight ...and so on ..all will effect HP/torque #'s in different ways ..some good some not so good ...but the supercharger will still take 70 or so HP to drive ....dave
 
the the 5% benefits both torque and HP because it lets more air in and moves it faster the 10% does the same thing but the SC consumes the extra HP but by letting more air in it produces more torque.
 
Not sure why you would only worry about torque unless you are planning on running 1/8ths... and besides that, keep in mind that these things are tough enough to get the wheel spin under control....
 
Torque is rotational force. Horsepower is torque times rpm. Torque is mainly good for take-offs and spinning tires. Horsepower is good after you get well into the rpm's. I could understand focusing on torque, but wanting to limit your hp? That's mad talk. I'm more focused on hp myself but I certainly won't cry if I get a little extra low-end torque to go with it.
 
Look at it this way...

You will need to generate big torque down low, thru the mids, and up high. This is the REAL goal of every person on this board who has an SC. And this is the philosophy that pretty much everyone else with a potentially fast street car is trying to achieve. Torque is king- if it can be effectively controlled in a lightweight car, and with the right setup- practically no one would be able to outrun you (in a perfect world :). The problem with the SC is that the current hardware setups we are using are not allowing the engine to produce enough of the good stuff (torque) to overcome the SC's shortcomings. There are physical limitations with the 3.8 v6- then there is a weight issue with the car itself. Someday the SC community will overcome these problems.

Horsepower is simply a measurement of how much work is being produced by that engine at any given rpm.

People don't think in terms of torque at higher rpms, but it is a fact that you need high end torque as well. That is what's so great about cars like the Dodge Viper- it has a very wide, even, power bandwidth which happens to produce high horsepower numbers up high as well as high torque numbers down low and high. And unfortunately, the honda VTEC engines use the same wide bandwidth philosophy- but at a much lower power level (for gas mileage and efficiency).

Forgive me for saying this, but look at the turbo Supra. that car was built for massive power at high rpms, but does not create alot of torque down low. AND, it's just about as heavy as an SC. But it has a very narrow but massive torque output (especially when modded) at high rpms- so much up high that this car can rip a viper on the top end. The Supra produces torque in such a way that it allows you to get a decent launch off the line, and more than makes up for that turbo lag down low by pulling extremely hard on the top end. In general, a stock SC will beat a stock or modded supra off the line, but above 50 mph or so look out- he's about to own you.

So what you want is the same as i want- a wide powerband like a viper. Torque is the force that is turning the wheels, not horsepower. It's just that if you have big torque up high, you will have a big horsepower number. When we are adding mods to open up the airflow capacity of the 3.8 v6, we are actually increasing the max amount of air that engine can process which in turn increases torque and hp. Some mods just accentuate torque in certain areas of the rpm band.

Anyway, this is why those projects like the whipple and the turbo are being heavily pursued here- the end results of these will put our cars very close to the big leagues.

hope that helps.
 
Last edited:
Torque and HP go hand in hand. Torque is measurable and HP is calculated from torque. HP=TQ x RPMS divided by 5250, so the higher your torque is in the rpm range the higher your HP will be.

David
 
You're right David. HP is actually calculated rather than measured. And the higher you go up in rpms, the more HP you will need to achieve a flat torque curve.

A 900hp F1 race car will only produce 263 ft lbs of torque at 18,000 rpms, but if you wanted 900 ft lbs of torque at that same 18k rpms you will need to generate 3,085hp.

Yet a 900hp freight car puller in a train yard will produce 2,626 ft lbs of torque at 1,800 rpms (much more than this at the wheels because of fluid or electromagnetic coupling)- slow as molasses, but can pull a big house.

very interesting...

263 ft lbs doesn't seem like much for a race car, but factor in the extreme gear ratios they must be using... the extremely high rpms is allowing them to use very aggressive gear ratios- it's gonna put down some seriously extreme leverage (torque multiplication) to the ground at the rear wheels. That's one of the main reasons why an F1 car can rocket from 0 to 140 mph in 5 seconds. And that is also one of the reasons why Ferrari has been dominating that circuit power-wise. it's all about the torque baby...
 
Last edited:
This seems like a good thread to jump in on with something that's been bugging me... What would cause lower torque numbers (relatively speaking) vs. HP numbers on a modded SC engine? On my recent rebuild I added p&p'd heads, .520 cam, roller rockers, in addition to the MPII setup, 42# inj., DIC, 5% pulley, 75 tb, 76 maf, etc. that I'd already had. Dyno tune (using EEC tuner) yielded only 311 rw torque against 256 rw hp.

Seems a little low, no?

Thanks for any input...
 
I installed a MPII Blower and plenum.I gain 29.7 RWHP, 0 RWTQ.

If you make the IC,IC tubes,plenum,intake manifold,Larger you will see the torque raise.And add between 500 to 1000 RPM to your power band.

RANDY
 
Last edited:
joenintiesc said:
This seems like a good thread to jump in on with something that's been bugging me... What would cause lower torque numbers (relatively speaking) vs. HP numbers on a modded SC engine? On my recent rebuild I added p&p'd heads, .520 cam, roller rockers, in addition to the MPII setup, 42# inj., DIC, 5% pulley, 75 tb, 76 maf, etc. that I'd already had. Dyno tune (using EEC tuner) yielded only 311 rw torque against 256 rw hp.

Seems a little low, no?

Thanks for any input...

1) submit your dyno chart to the club so it can be posted. Maybe you aren't that proud, but it you did that we could help you out a little and it would also be a source of encouragement for others. :)

2) Because your car is an auto and you don't show any transmission mods, more than likely your pull was started after your torque peak had already occurred.

3) Most of the guys who have really high torque numbers on an AOD also have tranny mods like a higher stall converter. A torque converter will boost your initial torque readings significantly. Take a close look at some of the "higher" torque generating cars at your HP level and you will see a trend. ;)


As for the initial question on this thread, concentrate on HP and don't worry where the torque falls. Sure you "drive torque" and "race HP" but for us with boost torque is really nothing other than a function of how much boost you throw at the motor.

Simply put, increasing the output of the blower will increase torque. Increasing the efficiency of the motor will create HP. Concentrate on HP, and do what mods are necessary to keep boost where you need it.

On a stock IC, boost should not exceed 14psi. For an Eaton powered car with a good IC, boost can be increased to about 16-17psi. If you have an AR on the car, boost can climb higher in either case without over running the IC.

Many folks here have way over-run their IC which has been a continual source of blown headgaskets, bent connecting rods, and other engine damage. If you keep the IC and boost in line your motor can eventually make over 400rwhp without hurting the stock bottom end.

:)
 
Thanks for the feedback, Dave. I will get that dyno sheet posted soon...

As far as transmission mods, all I have is a shift kit, added when the AOD was rebuilt a few years ago. Would a Lentech valve body make any difference, my guess would be probably not, as far as real torque numbers are concerened... But that was going to be my next trans upgrade.

I just wish I could experience some of that "tire spin" that everyone seems to both enjoy and complain about! :rolleyes: (Guess I'll have to put on the 10% pulley I have and see what it adds...)

thanks again,
joe
 
hytorksc said:
A 900hp F1 race car will only produce 263 ft lbs of torque at 18,000 rpms, but if you wanted 900 ft lbs of torque at that same 18k rpms you will need to generate 3,085hp.

ok. now this makes a lot more sense to me. so in a nutshell. at x rpm's you need to generate x amount of hp for x amount of torque.


Randy N Connie said:
I installed a MPII Blower and plenum.I gain 29.7 RWHP, 0 RWTQ.


RANDY

so in this example, even though peak numbers didnt move, the torque curve was flattened because you are now making more hp at higher rpms. which would be a good thing too because now you have x amount of torque from lets say for example 2500-3000 rpm instead of 2500-2800 rpm. those numbers are probably off for our engine, but you guys can see what i mean. and if i got anything wrong please correct me.
 
XR7 Dave said:
On a stock IC, boost should not exceed 14psi. For an Eaton powered car with a good IC, boost can be increased to about 16-17psi. If you have an AR on the car, boost can climb higher in either case without over running the IC.

Right now, I can hit 13-15psi and the only blower related mod is 5% OD pulley. Over the winter, I'm planning to port my blower and plenum. Should I think about doing something with the IC as well? And is a DoubleIC enough or should I consider spending the extra money for a front mount?

Thanks
-Andy "Melon"
 
Melon said:
Right now, I can hit 13-15psi and the only blower related mod is 5% OD pulley. Over the winter, I'm planning to port my blower and plenum. Should I think about doing something with the IC as well? And is a DoubleIC enough or should I consider spending the extra money for a front mount?

Thanks
-Andy "Melon"

You have to keep things in perspective. If all you plan to do are external mods to the motor then yes, I would say that a double IC will work well for you. Keep in mind that a double IC is just about useless without an IC fan and a shortened AC condensor. Now that the core is that much thicker, you are going to have to take steps to get the air through it.

If you plan to do internal mods at some point, then the double IC is not going to keep up. It might work with the AR and internal mods due to lower charge temps, but that is yet to be determined.

David
 
The only internal mods I'm planning on are heads and cam. Probably a few other small things while I'm there, but those are the big ones. I'm only looking for low to mid 13's.

-Andy "Melon"
 
Back
Top