Nine Ball

iTrader: (38)

We had the opportunity yesterday to dyno test a bone stock '02 4.8L truck and I also dynoed my bone stock '02 5.3L truck (203 miles on it!)

both trucks were dyno tested in 2nd gear due to the mph limiter in 3rd gear, so both graphs would be about ~5 rwhp higher if we could dyno in 3rd.



As you can see, the area under the curve is very different. Since both of these motors share the same bore diameter, this is basically an example of what more stroke will provide. The 5.3L motor uses the same 3.62" stroke from the LS1 motor.

Tony

[ March 03, 2002: Message edited by: Nine Ball ]</p>

oxidizr

iTrader: (4)

Seems right on par... Here's the dyno of 2nd and 3rd gear on my 01' with ~500 miles on it back in October last year.

http://home.earthlink.net/~rwaitas/_...dyno-stock.jpg

Richard, think "photo resize". You almost killed me on dial up with that huge pic. <img src="gr_grin.gif" border="0">
-Tony

I guess the 02' to 01' power increases are not as substantial as perceived to be.

Richard

[ March 03, 2002: Message edited by: Nine Ball ]</p>

really slow truck

<img src="gr_eek2.gif" border="0"> holy crap! i was thinking that swaping the cranks to go from 4.8 to 5.3 would give you about 10-15rwhp, but man.... 24! VERY NICE! <img src="gr_grin.gif" border="0">

if they are only rated 15rwhp higher how could they dyno that much higher? is chevy underrating the 5.3s or something?

Nick99Chevy

If you subtract 20% driveline loss, they're rated about right. The 4.8 comes out a little low though.
285-20%=228
270-20%=216

Nine Ball

iTrader: (38)

R.S.T., those numbers pointed out on the graph itself are just showing how much different some parts of the HP curve are. When you compare actual "peak" rwhp values between the motor, just look at the comments at the bottom of the graph. 221 rwhp vs 232 rwhp. So, only a 11 rwhp difference in "peak" HP. But, peak is not what is important for performance, we want the most area under the HP curve. The highest average rwhp is what is important.

Round Rock, both trucks were X-cab, shortbed, 2WD, 1/2 ton trucks. Mine has 3.42 gears in it, not sure what his had in it, maybe he will reply.

Tony

really slow truck

i looked at it again, and that was just the hp at 4500 rpms, the max power is still about 12rwhp higher from the 5.3, but both are above the 20% loss estimate, and both of those dynos are done in 2nd gear.

on my truck when i gained 20rwhp and 30rwtq (peak) from going from 2nd to 3rd gear on the dyno

99RedHawk

Nice comparison of the two motors, for second gear.It does show the difference in the two motors..Still don`t know why Gm made the 4.8..I think the power under the curve will be a lot different (more than 5rwhp) if you compare both in third..The engine and drivetrain will be at a 1 to 1 ratio, so to speak. I know my truck made 21RWHP more and 32 torque higher over the whole column average.Thats between second and third comparison.All under the curve..

GREGGO

iTrader: (2)

OK, I'll let my numbers out of the bag. With the 4.8, headers (ASM's) true 2.5" Magnaflo,X pipe duals, K&N FIPK, pulley and HPPIII my #'s were:
259 rwhp and 269.4 ft-lbs torque uncorrected
247 and 257 corrected. BTW that is with 373:1 and an Auburn posi.
Now today, Tony and did an A-Tap run and found out I was running rich. Someone even made that comment Saturday. All this time I thought it was lean. I could be losing as much as 5-10 rwhp there. Brook, I should get the spreadsheet Monday and I want you to take a look at it for me. I was hoping for the 260 rwhp range, guess it's on to getting electric fans and head work on my extra set next. I picked up the cutouts Saturday and will get them on Monday. <img src="gr_grin.gif" border="0">

[ March 03, 2002: Message edited by: Fast4.8 ]</p>

really slow truck

hey greg, was this done in 2nd or 3rd gear? im curious to compare to my numbers. i have the same problem as you about running rich at wot (havent checked in a while but i believe before maft they were .96 or 7ish), lean at part throttle and rich at wot. i had the maft on and it and it worked great but sold that and hopefully will have ls1 edit sometime soon

bryan

GREGGO

iTrader: (2)

[quote]Originally posted by really slow truck:
<strong>hey greg, was this done in 2nd or 3rd gear? im curious to compare to my numbers. i have the same problem as you about running rich at wot (havent checked in a while but i believe before maft they were .96 or 7ish), lean at part throttle and rich at wot. i had the maft on and it and it worked great but sold that and hopefully will have ls1 edit sometime soon

bryan</strong><hr></blockquote>

Mine was done in 3rd, the dyno that is. The A-tap was all through the gears but the #'s were similar. I don't know the exact numbers until Tony sends the spreadsheet and I don't know much about A-Tap yet. I just got a laptop and am waiting on a GP that is being put together to get the program.