Torque/HP graphs

[DocDirk]

I've looked all over the web and called a few engine manufacturers but have yet to discover a source for actual torque/hp curves for the engines promoted for use in a cobra. Anyone know of a good source for this kind of information for different builds/displacements? Thanks !

[ByronRACE]

Originally Posted by DocDirk

I've looked all over the web and called a few engine manufacturers but have yet to discover a source for actual torque/hp curves for the engines promoted for use in a cobra. Anyone know of a good source for this kind of information for different builds/displacements? Thanks !

All but a very few engine manufacturers wouldn't dream of handing you a dyno and configuration sheet to go with the engine, for fear that it would open up discussion/controversy/litigation surrounding why the engine doesn't hit the advertised number.

There's quite a large gap between advertised and reality, and quite a few less than satisfied owners who go and verify power on a chassis dyno and find a discrepency that can't be explained away by "drivetrain losses". This happens all the time.

If you want a high performance engine that truly hits the number, can be dyno'd a the manufacturer to prove it, and can be sold to you with a dyno sheet and/or video of the actual dyno work, I'd recommend shopping with one of the Engine Masters Challenge participants.

http://www.popularhotrodding.com/enginemasters/

Or, one of the builders/businesses that frequent 460ford.com and have a proven track record.

Otherwise, I wouldn't buy it unless it was well known/common (like the 514 FMS crate motors), or I'd seen it run and/or had an opportunity to measure one just like it. A lot of these guys are throwing numbers around that have little basis on reality.

[RodgerH]

Single point HP and torque values from an engine or chassis dyno are practically meaningless...except for unverified bragging. The dyno operator should furnish a spreadsheet or graph showing the pull from 3000 RPM to the maximum RPM, usually 200-300 RPM past the peak HP RPM.

To verify the accuracy of the dyno, look at the HP and torque values at 5250 RPM. Ideally they will be equal. If they were not reasonably close, I would question the calibration of the dyno and the accuracy of the numbers.

If your operator can't (or won't) supply a spreadsheet or graph for your particular engine (and this doesn't mean an engine built "exactly like" one that was on a dyno) so that you can see the numbers at 5250 RPM, all bets are off concerning your true and accurate HP and torque values.

Rodger

[xlr8or]

You mean one like this:

This is my friends engine built by Keith Craft. 514 with TWM injection. Notice where they cross.

[ByronRACE]

And good rods with 4-bolt mains on 2,3,4 I hope. That must be a real short runner, large cross-section intake if it's doing that NA. Looks good.

[JustOne]

Why is 5250 important?

[Bob In Ct]

They always cross at 5,252! They have to.

HP = (Torque X RPM) / 5252

Bob

[RodgerH]

Originally Posted by JustOne

Why is 5250 important?

HP=(torque x RPM) /5250, therefore,

(HP x 5250)=(torque x RPM).

Insert 5250 RPM into that equation and HP must equal torque.

Look at any correct graph for HP and torque and they cross at 5250 RPM.

(Bob is right, it's actually 5252 RPM.)

Rodger

[xlr8or]

Originally Posted by ByronRACE

And good rods with 4-bolt mains on 2,3,4 I hope. That must be a real short runner, large cross-section intake if it's doing that NA. Looks good.

It's the TWM Stack Injection system. 58mm throttle bodies and ported heads. Solid roller cam etc. The intake ports are about as big as a tennis ball. Pushes his SPF around pretty well.

[Power Surge]

Originally Posted by RodgerH

HP=(torque x RPM) /5250, therefore,

(HP x 5250)=(torque x RPM).

Insert 5250 RPM into that equation and HP must equal torque.

Look at any correct graph for HP and torque and they cross at 5250 RPM.

(Bob is right, it's actually 5252 RPM.)

Rodger

They will always cross at 5252. On graphs where that doesn't happen, it's because the scaling is different on the hp and toque axis', not because something is wrong with the dyno.

[RodgerH]

Originally Posted by Power Surge

They will always cross at 5252. On graphs where that doesn't happen, it's because the scaling is different on the hp and toque axis', not because something is wrong with the dyno.

True. The graph's HP and torque curves must use the same scale for the crossing point to be an indicator of dyno accuracy.

If the graph's HP and torque scales are different, you'll have to determine the numeric values for HP and torque at 5252 from the graph, or get them from the spreadsheet. The numbers will be nearly the same if the dyno is accurate.

Rodger