I'm only running stock right now but I'm planning on adding soon. My main question is about our cars and the imports. My friend just got a Honda Prelude and it's putting out 170 horsepower... same as ours stock How can a little 4 banger put out the same horsepower as our 8s? Does the horsepower matter as much as the torque? I don't know how much torque his car has but would that be mroe of a deciding point than the horsepower?

Also, what keeps our cars from putting out 300+ horsepower? people get the 4 bangers up there, and it seems we tend to struggle.

 

Well, this topic will be closed, seeing it is not TGO Tech. Also, it has been covered many times. But I'll put my IBTL in right here anyway...

Torque is a measure of force put out.
Horsepower is more of a measure of power put out over a time.

http://auto.howstuffworks.com/question622.htm




Basically, torque wins races, and horsepower sells cars. Torque gets you off the line, and horsepower gets you going faster. Their engines are rated in peak torque and horsepower (just as ours), but their curves are much sharper. This means they put out far less horsepower (and torque) before 5000 rpm than after (obviously). Our cars (as most V8s) have a broad torque curve which carries us off the line much faster.


I dont think im 100% correct though.

 

The heads and cam
300 horsepower is a VERY simple point, even with a 305, to get to.
400 horsepower is a little more tricky, and at 500 you start losing streetability (remaining n/a that is).

if you want 300 horsepower, instead of the L03's 170, try a new cam and set of heads. For $500 and some good old fashoned labor, you can be there in a weekend if you know what you're doing.

 

Oh boy everyone get your boots on because it is going to get deep. There are thousands of factors that determine the power output of an engine. Torque is what makes cars fast. The faster you make it the faster your car is. The LO3 only has 170 and is one of the weakest small blocks ever made. 300hp out of a v8 is a piece of cake (more so for higher displacment engines although it can be done with a 305). Cylinder head design, cam size, fuel injection style are all factors that make and limit power. The important thing is to look at the power curve as a whole. The 170 v8 will a ton faster than a 170 4 cylinder in a vehicle of equal weight. Why is that? The v8 has a flat power curve and for the most part makes its advertised power levels at most points in its rpm curve. It is vary flat and you make your 170hp from low rpm to high rpm. This is not true for smaller displacment engines and they have peaky power curves that tend to make their peak numbers over a small rpm span. This is only a minor thing to help you understand the power differences but there is far more involved.

The Gen 1 small block design is great but leaves a lot to be desired when it comes to engine technology of today. Engineers are starting to make engines efficient based on volume, gas expansion and the work it does, all based on overall displacement. I will not go into detail because there are text books out there and not enough space here to give a lesson.
Just remeber that torque rules and that is what produces low ET's.

Do you have a specific TBI related question. If not this will get locked. I suggest you go to a library and check out some books on IC engines and apply some of the pricipals to the vehicles you have in question.

 

People bring up the fact that trucks with diesels have 500 tq and only 250 hp, yet are still slow. Why is this? Simple; the truck is twice as heavy. When you double the weight, you need to quadrouple the horsepower to remain the same speed. Plus trucks are usually geared lower for towing instead of racing. Also, diesels take longer to spool up, which may also affect the speeds of acceleration.

 

what it really all comes down to is the area under the torque curve. peak HP really means nothing, the area under the power curve in the RPM range you use, is what counts. that is if all things are equal. wieght is a factor, gearing is a factor, heck the areo-dynims figure into all of this.

good example, i have an audi and a camaro (i really do )

the audi has 194hp @ 7500rpm, but only a peak of about 150tq at around 4k, but the tq curve is flat there. this is a quattro car, so it can launch descently.

the camaro kills it iniitaly, but by the end of the 1/4 the audi has just about caught back up, and is pulling hard on the camaro. if the race was 1500ft instead of 1320, the audi wins. point HP is something to think about, from a roll the camaro wouldn't have a chance, even though it twice the torque.

stop light to stop light, the torque wins everytime. but think if you are talking a full 1/4 or from a roll, the HP is going ot equalize things.

 

I hear all this things about torque this, torque that. Torque is good. That's right and all, but explain to me this.

My car makes NO power under 3,000 RPMs. POS cars make more power under 3K RPMs then I do. There's no torque down there, yet I bet I pull a better quarter mile number then yall guys.

Yeah this is true and all but you are kinda making it sound like the torque has to be made low in the RPM range. That's not true, I have raced many vehicles that make much much more power then I do (in the idle - 3000 RPM range) and I still win.

So, it takes me a while to make my torque, does that mean my car would be faster (in the quarter mile) with more torque off-idle?


I'm not arguing that torque is bad or that torque will cause you to lose races. But, keep in mind that it does NOT have to be made at low RPMs.

First link in the sig is my combo...


Brady

 

You're gonna make more HP than torque at 5252 rpm regardless. If you have a high-revving race motor, then you're going to rev to 7, 8, even 9 thousand RPMs. But anything under 5252 rpm is going to have more torque than HP. Since the majority of your time is spent below 5252 rpm, in your torque band, this is where you want the majority of your power to come from.

 

That is because you will still have a larger area under the curve. You just make up for it up top where you do have torque. It may not come in till 3000rpm but I bet it stays flat from there on up to 6500 or so doesn't it.

No it doesn't have to come into the power curve fast but it has to stay there for awhile. Hence the 3000rpm to 6XXX rpm for your car.

If you could flatten your torque curve under 3000 rpm so that it models the curve past 3000rpm than YES. You car would be hella faster. However you have built your motor for high end. I bet you still make good torque down low but you don't notice it as much because of your wicked high end. LS1's don't feel like they have any low end either and we all know they are solid right off the line. Say your car makes 400 lb ft from 3000 rpm till 6000 rpm but only 150 from 1000 to 3000. Now if you extened that so that you made 400lb ft from 1000 to 6000 your car would be a lot faster. If you mainaitna that toruqe over a longer RPM span you will be considerably faster. Large displacment engines are good at this and little ones aren't.


You are absolutely correct here and toruqe does not have to be made down low but instead just over a large rpm span. Most V8's have a flatter torque curve than what you are describing for your car. You however still have amazing numbers under the curve but it is just higher up. and makes up for what it lacks down low.

 

Relating this to TBI, what mods would give me the biggest jump in power (and as i understand it the power is torque, not horsepower). I was thinking a new intake and exhaust just to get the engine breathing but i'm wanting to do something big after that. probably a limit of $800 though on the next mod. Where would my money be best spent?

 

this topic has been covered several times.
Get a cam, and a pair of heads, and an intake manifold if possible.

 

For $800 you should do some research on a nice exhaust set-up from the headers back. Do a little research on the exhaust board and you will find your answer with a bit of searching. Good luck.

 

Actually, the exhaust and intake aren't included in the next mod. I'm getting the exhaust from a friend for $100 -> hedman headers and the muffler from a 99 SS, no cat (who needs it) and I'm getting an open element and harwood hood. But could i do heads for under 800? it seemed like that was a $1500 job. I'm going to have to do a search on it now that it doesn't seem to be.

Sorry to ask questions already covered, I'm going to go do some research on this all and come back with any questions if i have them. No point in trying to get the general information when it's already been post a million times before. Thanks for the help!

 

people often confuse "air cleaner" with "intake"


we're talking about the manifold...

 

I knew you were all talking about the manifold but does "intake" usually refer to manifold?

 

For small block chevy's it does but for other cars it mean air intake. You could get a nice set of used 305 TPI heads for 100 and put some money into them with a little port work abd some good springs. That will leave you enough money to get a used Lt1 or L98 cam and tuning equiptment to make it all work in harmony.

 

Correct, it seems like it still pulls nice at that RPM, but I don't have a dyno graph to prove it.
Correct, thats why there are some turbo cars out there that make high HP numbers for a short amout of "time", and their cars are still not that fast during a 1/4 mile race. Correct again, but that is theoretical. On a NA SBC 350 I (I'm no expert) don't know of a way to have the best of both worlds (huge torque down low, lots of power till 7,000 RPMs). I am pretty sure we're on the same page here....

 

Yea I meant to add that you have to sacrifice a little of one to gain another. That is the nature of the beast for a NA IC engine. The best combos are the ones that make the most power under the curve. You give up low end in favor of monster top end. Other guys go the other route and start off down low and fall flat on top. Both cars can be eqaully as fast though just depends who makes the power longer. I bet you would amaze yourself at the torque you do make down low. Even hgih reving strip terros make prett good low end. It may be only 200-250 lb ft but that is more than your average car is gonna have. It is just that extreme high rpm power surge that you feel that makes it seem as if you have zero low end. You get punched by de la hoya and then tyson. Both put a whoopin on you but the other makes the other look like a pansy.

 

As said a few times in this post, stuff like this has been covered MANY times on TGO. Do a search for "HP/TQ" or "More power from TBI" and you'll be clicking for days...

And PLEASE remember, this is the TBI board...

Bruce (90RS305)