kevwalt22

I recentley installed a holley hp system on my 383.

Dyno results were exactly as expected, high torque, average at best hp.

Hp 328 @4650
Tq 427@3600
Engine hp 377
Engine tq 491

Is a 50 hp and tq drop normal? Sounds like alot to me. Going to port heads and runners, bigger throttle body to hopefully increase hp. Not my concern right now tho.. my main concern is the 50 hp loss.
Anyway to decrease loss of power?

cardo0

13% loss through an automatic is kinda low to my expectation. I expect the pwr loss to increase with the more power the engine makes. 13% is quite normal for stock motors/cars. How did u get the engine peak numbers? Are they just estimates or did u dyno the engine on an engine dyno before putting it in the car?

Orr89RocZ

iTrader: (20)

Yeah usually see 17-22% loss from crank to wheels depending on trans and dyno

sofakingdom

iTrader: (1)

Not completely sure what I'm looking at; I'm going to guess that the 1st 2 guys also guessed right, and we're looking at engine dyno vs wheel dyno #s. Whether real or simulated is an open question.

Might be worthwhile to tell us the details.

If that still has TPI on top, my guess would be that it's a dyno sim engine prediction, and one of those "optimistic" "generous" "friendly" West Coast chassis dynos we all are so skeptical about. Like the one acoupla years back where somebody bragged all up one side and back down the other all about his TPI 350 making 400 HP and how he couldn't see how everybody else could hardly break 300 with better BOMs, but when he posted his ACTUAL SHEET, turned out somebody had set the "correction" factor for like 5500' AMSL, where the physical dyno itself was at like 300'. Just a minor tweeeeek, nobody'll ever notice that... it only juiced all the #s by about 25% or something. No big deal.

86LG4Bird

iTrader: (1)

What "loss" are you talking about? The ASSUMED loss that someone got by simply ratio'ing both tq & hp dyno numbers by .87 ?

kevwalt22

yea i think it was one of those weird dynos. my engine wasnt dynoed alone..it has to be an estimate. it was my first time doing the dyno i was more curious than anything..as long as its normal im good with it
TPIS runners bigmouth base by the way.

AlkyIROC

What gets to the wheels is all that matters.

The chassis dyno measures torque at the wheels and calculates HP. If it's also giving you an engine HP/TQ then that's also an estimate. The only way to know for sure what the engine puts out is to have the engine on an engine dyno. The only time that's really beneficial is to know what the best stall speed to get for the converter. However, what the engine puts out means nothing. It's always going to be what gets to the wheels.

There will always be a driveline loss. Transmissions eat up power as does the diff. Without replacing components, something simple like using synthetic oil in the trans and diff can reduce friction and slightly improve how much power gets to the wheels.

I always hate "percentage loss". Saying a 13% loss means that a higher HP/TQ engine will lose more power through an identical driveline as a lower powered engine will do. If you say you lost 50 HP through the driveline with your engine then did some changes to make more power, shouldn't you still be losing 50 HP through the same driveline?

Tibo

iTrader: (15)

As long as your posting numbers be sure to post up the engine combo as best you can. It's great for reference when people are searching for "proven" combos.

86LG4Bird

iTrader: (1)

An inertia chassis dyno such as a Dynojet measures power (determined by the rate of acceleration of the dyno rollers), and uses that power and rpm to calculate torque.

From engine to the dyno rollers, it IS in fact a percentage loss rather than a fixed loss. The more load you put through a given driveline, the higher the frictional losses through the transmission, rearend, and all bearings; and the higher the losses from the inertia of the drivetrain, ie. every single part that turns. Think of it this way: it takes more power to accelerate a drivetrain to 100 mph in 3 seconds (which is what a high hp engine would do) compared to accelerating that same drivetrain to 100 mph in 10 seconds (which is what a weak street engine would do).

sofakingdom

iTrader: (1)

That's not strictly true... there are some losses that are independent of load (a rear end takes a certain amount of power to turn at a certain speed even at 0 load for example, as does an auto trans); and then there are losses that you have correctly identified as proportional to load, including a bunch of frictional components.

As a result, a high-HP motor will often show a lower "percent loss" in a given chassis, than a lower-HP motor hooked up to all the same parts.

86LG4Bird

iTrader: (1)

You are correct, sofa. I should have said it's PRIMARILY a % loss. The losses you speak of that are there even at 0 load include windage losses of fluid inside the trans and rearend.
Thanks for keeping me honest

kevwalt22

engine:
383 forged scat piston and crank, powder metal rods
for 30# red top injectors
tpis big mouth base, siamese runners,
stock tb,(new 58mm coming)
promaxx 190cc/64cc aluminum heads..(huge ports, had to add material to tpis intake to seal properly)
1.5 rockers
holley hp efi, no a/c

transmission was rebuilt with edge 2800 converter,ls1 rear 3.23

good combo i think. will make more power after i port and polish my intake and heads. also after i switch throttle bodies. stock one chokes air flow

IROCZ1989

iTrader: (1)

Hp loss conversation aside.. are you happy with the way the car runs?

kevwalt22

yes im very happy with it. holley system is good. i personally dont need anymore power to have fun driving, but the project never stops so more hp/port&polish will be the next step...its all fun

IROCZ1989

iTrader: (1)

You know really its only a number and dynos are not consistant. If it runs well and such and most important you are happy thats really all that counts. How does it hold its own against others?