displacement and the torque curve

[bleh]

as most of you have noticed we had developed an interesting tangent in the bugatti thread. i think it would be good for all of us to explore this.

i had posted a dyno graph of another new jersey honda enthusiast that had roughly 125 foot pounds to the wheels from 2500rpm to 8212rpm. this is a naturally aspirated 1.8 liter engine and the torque values match.

there is no argument that more displacement or compression creates more torque, however more displacement does not effect where in the rpm range the engine makes power. that is mainly dictated by how the rod/stroke ratio, piston shape and cam, head, header, and intake manifold design work together. i know this is redundant but, the placement of the torque curve in the rpms is independant of displacement.

there is a lot more to talk about so ill let you guys continue to fill in. this should be a good thread

[Anzeige eBay]

Hallo bleh,

 

kennst du schon displacement and the torque curve (Anzeige)? Dort ist vieles zu finden.

 

Verschiedenes über Autos Ersatzteile (Anzeige) | Verschiedenes über Autos Zubehör (Anzeige)

[iroc-z89]

now whats the question? I can answer it but I dont understand what you want

[bleh]

no question. discussion. that smaller sized engine had a pretty level torque curve for almost 6000 rpm.

[iroc-z89]

The dyno graph is hard to read but:

Camaro Iroc Engine TPI350

This should make you drool, very similiar to my car on the first test

[bleh]

what is the significance between tests? also what are the specs of the motor. i can see its a 350. also it only what about the rest of the graph? the redline isnt under 6000rpm is it?

[iroc-z89]

Thats the same exact engine as whats under my hood, except he has 45 cubes on me and he is running vortec cylinder heads.. The redline is the same as mine at 5500rpm...

The first test is a stock tpi, then modified tpi, then a camshaft with the modded tpi

[iroc-z89]

Okay bleh, Ill appease the gods. I find it interesting that a small displacement engine can put out a decent level of torque. Obviously though, I do not know the stroke of this engine which would create that level of torque. I am going to guess and say that the stroke would be around 3" with a slightly larger bore. Any inforemation on this bleh? I know your on

[bleh]

which motor the b18c?

stroke of 87.2mm and a rod ratio of 1.58

which is why it is able to make fairly consistant power all the way up. a higher ratio would help it rev higher. the motors that are tuned for high revving and suck with daily driving usually have a ration closer to 2.

my point wasnt that the motor made a large amount of torque, just that it remained farily consistant and wasnt tunes strictly for high reving. it is still a very decent daily driving motor. the purpose of this thread is the placement of the torque across the rpm band. part of my point is also in asking: what are the torque numbers in the 350 bellow 3000rpm? considering that less than half of the rpm range is listed

those are some pretty decent bump sticks btw

[bleh]

another interesting tangent:

when tuning, if you were to maintain a torque curve producing the same output but shifted this output further up on the rpms, the car would most definitely be faster. while still producing the same amount of torque. simple theory. but it kinda funny thinking about it...

[iroc-z89]

What with the 350? TPI cars idle with about 250ftlbs. or better depending on idle speed. The intake runners that produce that torque limit the engine. Thats why the LT1 replaced the TPI, it has short runner but it is a peaky engine unlike the TPI.. Tuned port injection was designed to make consistent power, and tons of torque. Notice how there are no spikes in the curve......... Yeah the engine im building is gonna make lots of torque just crap for hp just short of a 1:1 ratio

[Anzeige eBay]

Hallo bleh,

 

schau doch mal hier zum Thema Zubehör für Verschiedenes über Autos (Anzeige)? Eventuell gibt es dort etwas Passendes.

[LateNightCable]

This is cool, we've got some blood in these veins again! An actual discussion. it feels good.

I could learn from this too! I'll just sit back and listen for a while.

[bleh]

wow yea that defines a low revver. everything with that motor just works well with the sub 5000rpm. fat runners, lower rod stroke ration and as you said the tpi.

its interesting that the cam does shift the power band up the rpms as well as increasing it. hense the new peak power being 400rpm higher than the old peak power, as well as the majority of the gains above the first test are well towards the redline. an increase between 50-60ftlbs looks pretty constant after 4000rpm.

im convinced if you could some how let the motor rev to at least 6500 and get a spacer for the runners as well as getting headers with longer primaries and secondaries that with that cam you the car would be so much more intensely faster.

but the motor is limited because of its rod stroke ratio.... are you catching my point?

[iroc-z89]

Im catching your point but what I posted is my little useless engine project

My garabage: 3.736, bored .060 over, make it a total bore of 3.796

3.48, stroked out to 3.75.. Making a 340cid engine, thats capable of nothing but massive burnouts

350engine = 4" bore, 3.48" stroke.

So its not so bad after all.. Though most american engines have a hard time going over 7000 rpm. Usually 7500, is the point that you see connecting rods fly.

This is cool, we've got some blood in these veins again! An actual discussion. it feels good.

I could learn from this too! I'll just sit back and listen for a while.

Miss me, LNC?

[Speedster25]

Would the car be faster, becuase the higher the torque is in the rpms, the horsepower can add on after that torque is produced?

Jason

[iroc-z89]

Torque is how much power the engine actually puts down, like how much resistance it can put against something. Horsepower is how quickly it moves that resistance

[bleh]

havent you guys ever heard that hp is really just a pretty number?

iroc, of course we miss you. what is a forum like with a 2 sided conversation? man we have got to be multifaceted. we need people from every crowd to keep our conversations as neutral as possible. if you werent here it would just be me talking about jap makes and lnc stayin pretty balanced. we need domestic enthusiasts too

i dont think you should stroke the motor, granted it will be nice for your really low rpm torque, i think your car would perform much better just boring it out and getting a cam that helps it in the higher rpms... also while your popping the heads you might as well get some slightly higher compression numbers. well i could be wrong... i know nothing about tuning those beasts. i dont know how easy it is to do that.

[iroc-z89]

Its quite easy just a 305 is quite expensive... The pistons I want for that stroker are almost $900. Then you have to get a valve job on the heads and then ported.. So your choices are pay 1500 for new aluminum heads or 1500 for your old ones..Then you have to have either machined for lift, which means have the valve guides/boss cut up. Camshafts are around 300.. Self Aligning Roller Rockers are around 300. The roller lifter conversion is around 500. Then you need screw in studs, guide plates, retainers, pushrods, locks, tons of lube.. And that just a basic heads and cam job.

Which is not worth doing to a 305... Maybe a 409 bbc.

[bleh]

hmm interesting. i understand why all the low revvers are kept low revvers. although making the engine rev higher would be faster, it requires a lot more work and $ to get it done right. and also looses a some of its daily driving ability.

[iroc-z89]

remeber how I said that my Iroc revs to 5500..and it has seen 7000. Thats extremely high for a 305 they are only designed to see 4500...

Keep in mind that stroke makes alot more torque than bore.. But bore is the horsepower maker

[LateNightCable]

I always loved massive under-square engine's with big bore. But let's not forget the importance of valvetrain. This probaby has greater effect on performance than even bore or stroke. Any motor that is allowed to breath, even the slowest turning lunk of an engine, will benefit from more power across the board, and certainly can't hurt responsivness.

Iroc was refering to a PM I hadn't yet responded to. By the way, I seem to recall a project 502(?) on your agenda. How goes it?

[bleh]

iroc, i know what your saying. but to say one makes torque and the other makes horsepower is a generic statement and isnt always true.

lnc, while you are right that the head is important in making power as well, the bottom end is much less flexible with todays modern technology. where as some heads now have, variable cam, ingnition, and fuel timing and also self adjusting intake manifolds and even exhaust manifolds.

the real key in any car is the combination of everything in making an efficient useable power band. and for tuners like us, that usually means picking an engine that has a bottom end with potential then tuning the head. i think its easier working with the head at least.

[iroc-z89]

true it is a very general statement, but it is somewhat true, most engines such as small stroke hondas make very little torque, though they are capable of horsepower.

Must be nice to have variable timing, im stuck with the same stuff since 1955, hell they put fuel limitations/NOX I have to figure out.

I never brought up a 502 did I? I have that crappy 305 thats bored over buts thats about it

[bleh]

the low torque isnt on account of the small stroke. its the small displacement.

observe the breif comparison

motor bore stroke displacement hp tq

d16z6 75mm 90mm 1.6liters 125 106

b16a3 81mm 77mm 1.6liters 160 111

same years of availability, same manufacturor and in one country or another both motors were available in the same chasis. now there are many reasons for the b16 to have more hp but it begins with a higher rod stroke ratio. note the difference in torque is nearly negligible.

[iroc-z89]

Yes but bleh is there any difference in intake runner length, and cylinder head comparison between the 2 engines.. same goes for the exhaust

[bleh]

everything is different between the motors. they are different motors. my point was that it started with creating the optimum bore/stroke/rodlength. like any good manufacturer they catered all other variables to what the engine is good for. however they both still have very similar torque, the d16's torque just cuts off 1000-2000 rpm sooner giving it less hp.

the d16 bottom end is usually good for 8000rpm, but the factory redline is 7200. where the b16 bottom end is good for close for well over 9000rpm. and the factory redline for ALL b16s is well over 8000rpm. the head just plays tag along, and is designed accordingly.