Thread: anyone have a "desk top" dyno?

Tweet

Was hoping someone with a computer dyno (or just experience) would have fun running some numbers and come up with an approximation of hp.

I have some of the specs on the engine, probably not everything needed but maybe enough to be in the ball-park.

(In deference to Donny who built this thing up, he was making do with my already purchased (but removed from a POS build courtesy of a LA "stroker" builder ) good quality/unrun parts...some really don't match...but it is very streetable and more power than I can use at the track.)

1965 289" block bored to 0.040"
steel crank is for a 347" stroker...so I guess that is 3.4" ?
rods are 5.40" h-beams

Ross pistons, flat top. Moly rings

Compression was calculated to be at 10.7/1. I assume the squish is where it should be, the guy seemed to be quite organized. ( he builds/crews sprint car engines )

Trick-Flow heads, circa 1999...2.02 intakes, 1.9 exhaust
Weiand Stealth double-plane intake, port matched to the intake.

750 Holley double-pumper, #71 primary, #80 jets

Hydraulic roller with 222 intake, 230 exhaust, 112 between lobe centers
Lift, with 1.72 roller rockers, is .538 intake and .569 exhaust

Headers are smaller than I would have liked at 1 1/2" for the initial tubes into collectors ( side pipes, straight through glass packs, about 30 inches long )
(To get larger header tubes I would have to have gone to custom build.)

MSD 6AL box and centrifugal only distributor...I am running it at 32 degrees...probably not as much as it could take, but I "open track" the car in "pretend" road-racing and figured if it was detonating I would never hear it till it was toast. Ain't really a race anyway.

I have always guestimated, er, approx-a-mavat-a-dated...somewhere from 375 to 400 hp, but really have no accurate idea.

As to rear wheel hp estimate a Tremec 5-sp and 3:54 Dana/Jag rear center.

At 13,500 miles, 5 years and the engine runs great. About 10 open-track weekends on it in 5 years and oil runs 70/60 psi warm, 30+ at idle...all well so far...knock on wood!

I try to keep the RPM to 6000, although the engine is still pulling...are the
1 1/2" headers the biggest bottle-neck in this combo?

How much advance can probably, or would normally, be safely run, assuming 91 on the street and 100 un-leaded race gas mixed in at the track?

I have been very impressed at the quality of the posts on this forum form several of the guys..."Tech guy" sounds to have a extensive back ground in this stuff.

Thanks for a great forum

Desktop Dyno says 503HP @ 6500 and 464 ft lbs @4500!!

Sounds like a winner

That may be a Good engine for the Strip . But you will need Larger Tube Headers and a Bigger Gear 3.73-3.90 is ok with that 5-Speed. You will need to run it every bit of 6500 RPM to E.T With it . Some 289 blocks can not be made into stroker Builds .

Geezer and Tango,

Thank for your input.

500 hp sounds great...a bit too good to be true...but for now, I'll take it! I had assumed closer to 400.

The car ( ERA 289 Cobra replica ) hasn't been to a drag strip, just to road race tracks...would like to try a drag strip. It has lots of torque, hard to get it on the ground without spin or wheel hop...have to "roll" into the pedal to hook up. Original set of Hoosiers were great at the track, but the current Dunlop GT radials just aren't a real performance tire. (ok on the street)

Wish I had had bigger tube headers made, but at the time ERA only had the 1 1/2 available, and I didn't know any custom header builders.

Have heard up to 1 3/4 is reasonable with this combo and a 2300lb car. Would like to trade a little torque for some HP.

Pete

IMO that's a real generous virtual dyno, the numbers are plenty high.... I've had similar sbf's with better heads and a roller cam, the "real" dyno numbers were around 430hp and 460 torque.... 503 & 464 would be great, but I think the simulator is a bit on the high side....

1 5/8" headers would be better, and tri-y's would be better yet. The tri-y's on the dyno always seemed to bring a bit more bottom end to the party.... Timing is probably about right for street and cheap gas. On track days and 100 octane, you could bump it a couple degrees.... With the 5 speed and 3.54's must be a long winded thing on the straightaways!!!!

I've run desktop dyno against actual dyno numbers dozens of times and they're usually 5-8% "optimistic".

He asked for dd numbers and that's what I gave him. I would expect real world, with a solid tuneup, of about 450-460HP and 415-430 ft lbs.

Originally Posted by Geezer2

I've run desktop dyno against actual dyno numbers dozens of times and they're usually 5-8% "optimistic".

He asked for dd numbers and that's what I gave him. I would expect real world, with a solid tuneup, of about 450-460HP and 415-430 ft lbs.

hey geezer would you be able to desktop dyno my combo on my 'first 496 build a running success' post please? its not a very extreme build but i wouldnt mind a rough idea where im at for power and there arent any reputable chassis dyno operators in my area. all the specs you need should be there, need any more just ask. cheers man

Originally Posted by Geezer2

I've run desktop dyno against actual dyno numbers dozens of times and they're usually 5-8% "optimistic".

He asked for dd numbers and that's what I gave him. I would expect real world, with a solid tuneup, of about 450-460HP and 415-430 ft lbs.

5-8% is a reasonable descrepancy ..................

Kitz

Your 496 comes up with 480HP @ 5000 and 547 ft lbs at 3500.

So figure a real world 440-450 and 500 ft lbs, a real "stump puller".

It should be stout in a heavy car like your Impala (or my cad!).

hahaha awseome! cheers man