is it just me, or does Desktop dyno seem a little optomistic about TPI intakes?

I know its just a program, but it is often preety close.


I plugged my engine specs in and was a little suprised at the numbers it generated.

355
Ported L98 heads with 2.02/1.60 valves
10.29:1 compression
Comp 08-501-8 cam with 1.52 rockers
Small tube headers and open exhaust

It said 369hp@4300 rpm and tons of torque.

Now, DD does not have an option for ported or bigger runners.

I am running a stock base ported to 1205 on the head size and 1/75" round ports on the runner side, with ported SLP runners.

I think the number is high, but am curious what others think?

 

Your combination isn't much more radical than mine, your intake is ported and your intake valve is larger, but over all our engines are similar. Same cam, heads etc. I can't recall what DD2000 claimed my engine put out but I can look it up tonight. I do remember that the program liked to rev the engine where the TPI intake won't typically run. The program is fun to play with but my actual dyno session made the pretend numbers useless.

 

Ok I found my desktop dyno file. I undershot the compression and airflow file a bit just to make sure I wasn't being overly optimistic, but my numbers still came out to be huge. 365HP @5000 and 453 TQ @3500. So I changed to HP manifolds since I'm running shorties, and that dropped them down more reasonably. 328HP @4500 And 434TQ @3000. My actual numbers to the wheels thru a T5 and a 9 bolt are 249HP @4400 and 350TQ @2850. So considering drivetrain loss, does that mean the desktop dyno made a reasonable guess? Or does it still shoot too high?

 

Havent tried the latest version but the early ones along with Camquest were a little optimistic. I wouldnt sweat it too much really doesnt sound that far off.

 

Not sweating it all, just curious what others have seen with their tpi builds.

 

Well GMHPT made nearly 416 HP and 486 ft/lbs of torque from a ~10:1 355 with stock vortecs, out of the box Vortec TPI base, accell runners, and a ported plenum with a mild comp cam 08-304-8

 

You got a link to that article? Over 400 HP from stock Vortecs w/a TPI intake? I wanna' see what I did wrong.

 

My issue with most magazine engine dynos is they inflate the numbers by not running any accessories and exhaust that doesn't portray a system any car could have, unless it's a van. Not picking on your rides Fast355..I had one myself with engine dyno exhaust on it. Not that they fudge the numbers but they're optimized to advertise bigger numbers on the cover. How does that compare to Desktop dyno..I guess thats a tough call. Maybe DD is supposed to predict SAE Gross and not Net like most of us think of now.

 

The DD2000 results times 80% for drive train loss came out pretty close to what I got on a Mustang Dyno pull. I used actual head flow numbers I got off one of the magazine web sites. I used it to compare heads and cams. I figured if the calculations were wrong, at least they were wrong the same way every time. So comparing head to head should give me an idea of how much change there would be.

 

Something Old, Something New
http://www.gmhightechperformance.com...es/tpi_engine/

 

Impressive but I'm willing to bet that those heads/intake were "stock" like magazine test cars of the 60's were "stock".