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

[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