Dyno test

[dunhamfield]

I had an oppertunity to put my truck on a dyno last Sunday.
My 58 348 truck engine has 250HP at the rear wheels and 365FT LBS of torque.
I have 11-1 pistons which should have my ratio at 9.5-1.
I am running an RV hydraulic cam with every thing else stock.
I am using a 600cfm Holley carb on a 409 intake manifold.
I was a bit dissapointed in the results as I thought they would be much higher.

[Ronnie Russell]

Terry, I dont think you should be disappointed with those results. Dont know anything about your engine internals, but head mods would have been big help. You are not the first to be disappointed with chassis dyno. The chassis dyno has crushed many expectations. For the engine you built , I would say 250-365 is good. Enjoy what you have, I bet it will spin the tires real good. Just my opinion.

[petepedlar]

You have to remember that you loose a lot through the driveline. I don't know how much for sure on a car/pickup but I would guess 30- 40 HP, maybe more if it's an automatic. Also dyno's are pretty conservative. I sell Peterbilt Trucks for a living and have had lots on the dyno. I know that you can loose between 65 and 100 HP on a big Cat engine in a tandem.
If your 348 was on an engine dyno I'm sure it would be close to 300 HP. I'd say that's pretty d@#$ good for an engine that's close to stock !!!!

Dave

[dunhamfield]

I did have some work done to the set of 333 heads that I'm using.
Mainly upgrading them to todays standards.
Screw in studs. Machined for positive valve seals. Big block valves.
But mostly stock.
I have cloned my 348 to appear to be a 409. I'm using a 409 intake cause it had bigger holes at carb base. I have a 409 truck oil pan. And of course the 333 heads. 409 badging.
Most people cant tell the difference.
YES IT WILL SMOKE THE TIRES :beerbang
I think my weak link thats eating HP is the old Saginaw 4 speed that I am using.
I am using a 70's 12 bolt positrac 3.73.
It is soooooo much FUN to drive!!!!!!!!!!!!!!!!!!!!!! :brow

[fatride]

You will lose a certain amount of power through the driveline known as parasitic loss. With an automatic it can be 18 to 20%. The standard tranny would be less loss. You would still be in the neighborhood of 300 HP. Not a bad neighborhood if you ask me!

[rogersimpala]

Terry
If your interested , I have a good borg/warner super T-10 I would like to sell
p. m . me if interested
:cheers
roger

[Skip FIx]

My 2004 GTO with 280 rear wheel HP clicked off some 13 second times at 98 mph. 250 is pretty decent for a small motor.

[jim_ss409]

I've noticed that the power loss from a chassis dyno seems to really affect the top end horsepower numbers. I guess that makes sense because the driveline and fan etc. will take a lot more power to spin at higher rpm's. That's probably why an engine that peaks at 6,000rpm on an engine dyno seems to peak at a lower rpm on a chassis dyno. 250hp to the rear wheels is pretty good if you ask me... But 365ft. lbs...:deal That's outstanding!:beerbang