Banks Newsletter

[GiesJ]

I received an email version of the Banks newsletter :



We calculated that we would need a minimum of 600 hp to reach our goal of 200-plus mph at Bonneville in our Project Sidewinder Dodge Dakota sport truck this summer. After baselining an unmodified engine at 396 hp and 580 lb. -ft. of torque, we put our first-iteration race engine on our dyno, modified with a ported and polished cylinder head, our Big Hoss intake and exhaust manifolds, a Holset HY 55 variable geometry turbocharger, larger injectors, and a modified fuel curve, and made 700 hp and 1100 lb. -ft. of torque in the first week of testing. Those are huge numbers, and there's more to come.



I then went on to read on their website:

When we baselined this engine (tested it in it's stock—or "before"—form), we got 396 horsepower and 580 lb. -ft. of torque at 3600 rpm. And this was an engine that was already hopped-up a bit by the people at Cummins.



Two distinct questions -

Can one of you turbo guys explain or show me where to find more about this Variable geometry turbo theory?

and

Does anyone know what the "unmodified" engine is all about? That's almost half again of what a 'stock' engine is. What can Cummins do?

Sorry, one last question - I've seen many people post dyno numbers of around 300 horse and around 800 ft/lbs of torque, any idea why the Cummins numbers have such a different hp/tq ratio?



Just trying to understand...

thanks,

J

PS - I don't have a problem with Banks so please don't think I'm trying to rip 'em one.

 

[Extreme1]

My guess on the HP discrepency is that most of the dyno folks (myself included) talk about rear wheel numbers, the Banks numbers are most likely flywheel HP.



Also, recall that there is a 370 HP 12 valve (marine version I think) available from Cummins.



For turbo theory stuff try holset.com

 

[WKener]

If they are getting 396hp and only 580 lb-ft torque, sounds to me like they are revving the crap out of the motor.

Also, recall that there is a 370 HP 12 valve (marine version I think) available from Cummins.

Hmmm, I would think that the lower compression marine engine would have a higher torque-to-hp ratio... Can anybody explain to me why that would not be the case?

 

[SlyBones]

There is a mathimatical formula for hp and torque, based on RPM.



HP= Torque X RPM divided by 5252.

H. P X 5252 Divided by RPM = Torque



two engines could both have 370 hp. One with a lot of torque and one with much less. The one with lots of torque would have a wide powerband with good hp at low rpms, throughout the rpms, up to its peak. The one with less torque would have a narrow powerband, one that has less power at low rpms and rises sharply as the rpms increase.



370hp @ 2750 rpms and 800ftlb @ 1800 rpms = 274hp @ 1800 rpms



370hp @ 2750 rpms and 650ftlb @ 1800 rpms = 222hp @ 1800 rpms



Of course this is a made up example, not sure how realistic this is for our diesels.

 

[rspinks]

I don't think they are starting with a standard issue ISB or 6BTA engine, not with the HP peak at 3600rpm anyways. Sounds to me like maybe they're starting with a specail engine designed for high RPM power rather than typical diesel stump pulling torque. At what RPM does the 370 have it's power peak?