Engine Swap ...

[SUB-FT86]

Originally Posted by serialk11r

Again I'm really sorry but some of you guys have zero understanding about what the maximum torque figure actually means.

A high revving engine will be geared to take advantage of the maximum horsepower. The "lack of torque down low" some people complain about tends to be BS, if you just look at the max. torque curve. If you want max. power at a lower rpm, that's actually worse, because it means the engine efficiency drops faster at high rpm. Max torque means very little when the more sophisticated variable valve timing systems come into play, because the engine can more or less be optimized for multiple rpm ranges. The only thing you can read from the max. torque figure is if the engine is performance oriented, then it gives some kind of indication of how efficiently they were able to use the displacement. Even then, the difference is generally pretty small.

The moral of the story is, max horsepower means a lot more than max torque, because max horsepower (with weight considered) is what gives the manufacturer the ability to make a faster accelerating car.

The problem that you don't understand is a 2.0 liter engine has shit for torque regardless of how good it's geared. The ''REAL" problem is weight. A high revving 2.0 liter is better suited to something like 1700 lbs. Let me explain why I say so.

A BMW M3 has a 4.0 liter 414hp/300 tq V8 with terrific gearing and it weighs 3600 lbs. Through the whole powerband the M3's engine is sufficient just about all over. You don't need to rev past 6k for it to feel lively like a Si/Type S/S2k.

Now if you split the M3's engine in half and split its weight and power the same way then it would be like this. I4 with 207hp@8000/150 tq@5000 with a curb weight of 1800 lbs. My point?

150 lb ft geared well will feel sporty in 1800 lbs across the rev range vs feeling like a ford focus with 2800+ lbs. 2800 lbs is to much weight for a feeble 140-150 lb ft of torque.

There's a reason these engines are called torqueless wonders by many.

[82mm 4g63]

Originally Posted by serialk11r

Again I'm really sorry but some of you guys have zero understanding about what the maximum torque figure actually means.

A high revving engine will be geared to take advantage of the maximum horsepower. The "lack of torque down low" some people complain about tends to be BS, if you just look at the max. torque curve. If you want max. power at a lower rpm, that's actually worse, because it means the engine efficiency drops faster at high rpm. Max torque means very little when the more sophisticated variable valve timing systems come into play, because the engine can more or less be optimized for multiple rpm ranges. The only thing you can read from the max. torque figure is if the engine is performance oriented, then it gives some kind of indication of how efficiently they were able to use the displacement. Even then, the difference is generally pretty small.

The moral of the story is, max horsepower means a lot more than max torque, because max horsepower (with weight considered) is what gives the manufacturer the ability to make a faster accelerating car.

I think I agree with you, but I may be misunderstanding the point you're trying to make.

No one should want max TQ or HP down low, but you should want as much TQ as you can get as soon as you can get it. Considering HP is directly related to TQ [HP= (RPM * TQ) / 5252]. The more TQ you have, the more HP you have. The sooner you get your TQ, the steeper your HP curve will be. The more TQ you have at any given RPM mark, the higher your HP curve will be at that given RPM mark.

You want your TQ to come on strong and fast, but you don't want it to climax too soon (no pun intended) or you will be left unsatisfied (had to) with the peak HP number.

The big thing for me is the redline, I am NOT a big fan of high redlines. I think it was Skinsfan who posted his S/C K20 dyno. It had a damn near flat TQ curve, which is awesome. My only beef is the redline is so damn high. I don't like having to go after my HP, I prefer having it ready and waiting for me at lower RPMs. That TQ "curve" with a powerband between 2000-6500/7500 would really turn me on.



That is nice for the GenCoupe.

[suprachica79]

Whoops, my bad. forget the post lol

[serialk11r]

If you want to avoid both revs and displacement, there's no way to win. There is only so much energy you can squeeze out of a certain quantity of fuel and air. What short gears do is give you the revs faster. If you want a bigger displacement engine, that has a negative impact on fuel efficiency, engine size, cost, etc.

In short, if you think 2.0L isn't enough, you buy a car with a bigger engine and better power to weight ratio. Or forced induction, which is what a lot of you sound like you want. There's a reason the BMW M3 is a fast car, and there's a reason why a 20k car can't be an M3

[Spaceywilly]

Originally Posted by serialk11r

If you want to avoid both revs and displacement, there's no way to win. There is only so much energy you can squeeze out of a certain quantity of fuel and air. What short gears do is give you the revs faster. If you want a bigger displacement engine, that has a negative impact on fuel efficiency, engine size, cost, etc.

In short, if you think 2.0L isn't enough, you buy a car with a bigger engine and better power to weight ratio. Or forced induction, which is what a lot of you sound like you want. There's a reason the BMW M3 is a fast car, and there's a reason why a 20k car can't be an M3

This man speaks the truth! You definitely want a 2.0l engine to be high revving. You can think of torque as a quantity of acceleration (say mph/sec). Let's say two theoretical cars weigh the same and have perfectly flat torque curves. One has 200ft•lbs and one has 300. Since both have flat torque curves, the one with 300 will accelerate harder from any point in the rev range.

Horsepower can be thought of as capacity for acceleration. If two cars have the same flat torque curve, and one has a higher rev limit, both cars will accelerate at the same rate at first, but eventually one will hit the rev limit and stop accelerating. The other will continue to accelerate a while longer. The second car has more hp, even though both have the same torque.

Basically, torque enables you to accelerate at a certain rate (mph/sec). HP allows you maintain that rate of acceleration longer (hp is a function of Torque and revs). A 2.0l is going to be inherently not torquey. This can be made up for by a) making the car light (that's the lb in ft•lb), b) getting a flat torque curve (you accelerate at the same rate throughout the rev range) and c) having a high redline so you can continue accelerating while the other guy has to grab the next gear.

Hope that made sense!

[serialk11r]

The thing you're missing is gearing, which can change the torque transferred to the wheels (which have fixed diameter, and produce a force due to friction with the ground). Torque is a rotational force, it depends on the distance to the fulcrum. Precisely, it is the dot product of the force vector and the point where the force acts (with the center of rotation as the origin). If a car has 300ft-lb, there are different things the manufacturer can choose to do with that. If the car has a high rev limit and can keep producing power effectively at higher rpm, the manufacturer can fit shorter gears for greater acceleration. In theory it would be best if we had any gear ratio we wanted, and an engine that revved as high as we wanted, but there are obvious engineering limitations.

You could give a car incredibly short gearing to make it accelerate very fast, but then you max out the rev range faster and you need to shift more, which directly makes your car slower over any range of speed that spans more than 1 gear's range. You also reduce top speed and increase the excess amount of power on tap when cruising, since you can only have finitely many (and the driver can only manage so many) gears. CVT theoretically gets rid of this problem but again, engineering limitations. Mechanical CVT can only do so much due to its high friction, and "eCVT" like the Toyota HSD system is very complicated. Luckily gasoline engines can be pretty forgiving in terms of operating under different conditions, so we can get by with just a simple manual transmission just fine. Not to mention for performance applications, the torque inevitably drops near the design limit rpm because air becomes harder and harder to pull in, so you get relatively constant horsepower at high rpm, meaning it's okay if you have to drop rpm when you shift instead of holding the engine at the maximum power point.

[madfast]

Originally Posted by serialk11r

The thing you're missing is gearing, which can change the torque transferred to the wheels (which have fixed diameter, and produce a force due to friction with the ground). Torque is a rotational force, it depends on the distance to the fulcrum. Precisely, it is the dot product of the force vector and the point where the force acts (with the center of rotation as the origin). If a car has 300ft-lb, there are different things the manufacturer can choose to do with that. If the car has a high rev limit and can keep producing power effectively at higher rpm, the manufacturer can fit shorter gears for greater acceleration. In theory it would be best if we had any gear ratio we wanted, and an engine that revved as high as we wanted, but there are obvious engineering limitations.

You could give a car incredibly short gearing to make it accelerate very fast, but then you max out the rev range faster and you need to shift more, which directly makes your car slower over any range of speed that spans more than 1 gear's range. You also reduce top speed and increase the excess amount of power on tap when cruising, since you can only have finitely many (and the driver can only manage so many) gears. CVT theoretically gets rid of this problem but again, engineering limitations. Mechanical CVT can only do so much due to its high friction, and "eCVT" like the Toyota HSD system is very complicated. Luckily gasoline engines can be pretty forgiving in terms of operating under different conditions, so we can get by with just a simple manual transmission just fine. Not to mention for performance applications, the torque inevitably drops near the design limit rpm because air becomes harder and harder to pull in, so you get relatively constant horsepower at high rpm, meaning it's okay if you have to drop rpm when you shift instead of holding the engine at the maximum power point.

TLDR version: in theory gearing can fix everything, in practice engine torque rules all...

[Spencer Strayer]

Originally Posted by MiguelAE86

Mmm a nice naturally aspirated fuel injected LSx in a not-so-big size (3-4liters?) Would make the FRS go and sound perfect!

where would you even buy one? and wouldnt it be a pain in the ass to do an engine swap? or would you just take it to an after market mechanic?

I just want this thing to have about 350-400rwhp when im done with it. Im only gonna be putting about 10 grand into it so i dont even think my dream is possible

[WingsofWar]

Originally Posted by Spencer Strayer

where would you even buy one? and wouldnt it be a pain in the ass to do an engine swap? or would you just take it to an after market mechanic?

I just want this thing to have about 350-400rwhp when im done with it. Im only gonna be putting about 10 grand into it so i dont even think my dream is possible

pretty easy engines to come by, the one you really want are the all aluminum LSx engines. And swapping them in to cars like rx7, 240sx, miata, impreza, haven't been necessarily difficult for swap project guys. and have a really good success rate for even beginners.

If you want to look at local prices you can look into junkyards and try to find some corvette and pull the motor dirt cheap and build it from the ground up. Or you can google some local engine supply warehouse and see if there are used/new engines you can buy on a crate.

if you plan on dropping 10grand into the car and expect 350-400hp, you might not have a whole lot of funds left for other things, (eg, suspension, wheels.) after you achieve your power goals.

[Spencer Strayer]

Originally Posted by WingsofWar

pretty easy engines to come by, the one you really want are the all aluminum LSx engines. And swapping them in to cars like rx7, 240sx, miata, impreza, haven't been necessarily difficult for swap project guys. and have a really good success rate for even beginners.

If you want to look at local prices you can look into junkyards and try to find some corvette and pull the motor dirt cheap and build it from the ground up. Or you can google some local engine supply warehouse and see if there are used/new engines you can buy on a crate.

if you plan on dropping 10grand into the car and expect 350-400hp, you might not have a whole lot of funds left for other things, (eg, suspension, wheels.) after you achieve your power goals.

ahhh so theoretically it would be possible to get that high of power gains with 10k? I personally think im just jumping the gun a bit out of excitement. I guess ill just have to wait till its in my driveway, then figure out what im gonna do to it!

[WingsofWar]

Originally Posted by Spencer Strayer

ahhh so theoretically it would be possible to get that high of power gains with 10k? I personally think im just jumping the gun a bit out of excitement. I guess ill just have to wait till its in my driveway, then figure out what im gonna do to it!

yeah you can get pretty far on 10k if you know how to shop, budget, and do much of the tooling yourself. If you plan on buying new bolt on parts all the time and pay for labor you will find yourself out of money in no time and not even touch a fraction of your goals. but If you want those kinds of numbers your best bet is for an engine swap, i probably wouldn't recommend trying to get that kind of power on the stock n/a engine.

[SUB-FT86]

I agree with WoW's statement 100%.

[WingsofWar]

Also one of the biggest benefits of being on forums like these, are setting up vendors and group buys. So in the future when your fixing your budget and you REAALLY want a certain part, but its out of the price range of your budget. Having forums like these gives you the option of and opportunity to have discounts, while helping vendors make profit, and get others to save on money too.

[82mm 4g63]

Did I accidentally step into Bizzaro World or are we seriously talking about an LSx swap in an FRS? And for a measly 350-400hp? :reallyconfusedface: