stock lq4, 4l80e trans. 72/68 snail on 11psi. when i say stock i mean stock. all i have done is gapped the rings. had it run on the dyno at street machines on saturday and it made 385hp. i didnt get a torque reading because they were too scared to put the rpm pick up on my wire as it was so close to the flipped manifold.... all i know is it made 385hp on 11psi. should i be happy with that considering my timing is at 13* and im running 91 pump gas with no cooler or spray?
"drive fast, take chances"
"never let small minds convince you that your dreams are too big"
Sounds a little low.
No intercooler if that is what you mean by no cooler, surely didn't help your intake temps. Woulda said 400-415hp on 11psi but air temps and fueling could be the cause or you have exhaust problems too. Lack of flow etc etc.
Any logs or what was the fueling like?
Last edited by 5FDP; 07-23-2018 at 07:01 PM.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Stock, Lq4 is 300 crank hp stock. Through an auto trans would see like 250sh rwhp. Assuming about 10-15 hp per pound of boost (+135 avg), 385 rwhp would be a conservative estimate. Sounds reasonable without an intercooler.
Ed M
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I guess it would depend of what year LQ4 it is as they do make 300-325hp depending on year and application per the wiki.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
I think its good for a stock cam. The cam really opens up the potential of these engines, you could gain 80-100 horsepower with a cam swap.
It usually takes about 17-19psi to double an engines hp. Exactly 1bar of boost would do it if turbos had 100% adiabatic efficiency. Assuming 69-75% Adb.Eff., 11psi is 75% of 1bar or .75bar of 75% efficient boost pressure.
75% of 300 is 225, 75% of that is 168,
168 + 300 = 468
468 * .8333(4l80e drivetrain loss) = 389rwhp
Are you on the stock valve springs? You're probably blowing the valves open in boost lol.
2010 Camaro SS 6spd
1979 Mustang - 5.3, 243 heads, Sloppy stg 2 Cam, On3 78/75 turbo, 4l80e, built 8.8
Thats low. I know a few guys who Dyno'd Saturday and they were close to other dyno numbers they got so I doubt the dyno reads low.
Whats your AFR at? You say that its stock, is that also stock injectors?
are you sure its making that much boost?
What where the IATS?
What was the ECT?
They were too scared to hook up the truck correctly? I would have asked for my money back. They might not have even got a correct reading.
Have you raced anything to compare it to?
Last edited by podium; 07-24-2018 at 10:59 PM.
My buddies 2006 LQ4/4L80E made 345 rwhp/315 RWTQ unlocked 2nd gear pull recently. Has about 2,600 rpm stall speed 9.5" converter. It is a bit of a mismatch build. Has a Little Johns stage 2 turbo cam (keep trying to get him to swap to a custom grind for N/A since his turbo plans have switched to future positive displacement blower) ported/milled 317s, TBSS intake, and long tubes in a 1997 C1500. Was conservatively street tuned by me and has never had a wideband on it even though I have suggested multiple times he add one.Originally Posted by ksauto
should do better, 5.3L 10-12 PSI easy 400rwhp, maybe high iats? 13 is safe
maths
with perfect intercooling and 75%VE at 10psi of boost:
323cidx6000/3456= 560cfm * .069 = 38lb/min *.75(75%VE) = 285brake horsepower @ 0psi, 10/14.5psi is .6896 pressure ratio, 285*1.6896 = 481 brake horsepower * .825 (17.5% drivetrain loss) = 397rwhp
with perfect intercooling and 75%VE at 12psi of boost:
323cidx6000/3456= 560cfm * .069 = 38lb/min *.75(75%VE) = 285brake horsepower @ 0psi, 12/14.5psi is .8275 pressure ratio, 285*1.8275 = 520 brake horsepower * .825 (17.5% drivetrain loss) = 429rwhp
maths agree, but we are splitting hairs at 385 vs 400, myriad factors can account for 15hp. Good lord the # of things i could list here that have influence.... The point is I would say he is within 15hp of what it should be producing. I dont think the engine is hurt or the exhaust system is holding it back or anything. If there is a hidden parasite, it isn't gorging itself.
put some synthetic oil, open the plug gap, run it with a cold intercooler with a bag of ice on top, use the lightest wheels you can find, add a degree of timing, find more than 15hp I bet lol
Last edited by kingtal0n; 08-03-2018 at 12:17 AM.
I’m really interested in the intake air temps. I just finished a non intercooled setup on my ls1 that was about 400rwhp as it was before boost. I hoping for around 100hp more with about 6lbs. Am I being too optimistic?
How does one determine horsepower without torque? Last I checked, you cannot do that as HP= (RPM*Torque)/5252 .Something isnt adding up here.
Do you mean how does a Dyno do it?
A dynojet for example, uses the known mass of a roller in the ground which is accelerated vs time to generate a horsepower output figure. It does not compute torque directly; instead, once it generates a horsepower graph, it works backwards through the math you posted to find torque based on RPM. 5252 is equal to 33,000/2pi
This is why you can unplug the RPM monitor from the dyno, and it will still generate a horsepower curve (vs MPH) but will not provide a torque curve.
A turbo with no intercooler running through the center of its map is typically 70-75% efficient
so if 1bar of 100% efficient boost doubles the output of a motor (minus a couple minor losses say 10% for various friction and physics) then 7psi is worth half of that. Minus the 30% you are missing from not having an intercooler (70% of 7 = 4.9psi) So it would be like running 5psi~ of boost on the engine, which is 5/14.5 or 34% increase in output. your original figure of 400rwhp * 0.34 = an extra 137 horsepower, minus 5-10% for various losses as above is an easy 100 extra horsepower. Just watchout for IAT/EGT rise which can be fatal to an engine regardless of output.
The dyno calculates torque. ONLY. If you can can calculate HP, then you can calculate Tq. He could definitely get a Tq curve vs roller RPM, hell, you could get a HP curve vs roller RPM, but you cant have HP and no TQ it doesnt work that way.
Lets put it another way, tell me how you can measure HP without measuring TQ? Simple equation is all thats neccessary.
If the HP curve is correct, you can do simple algebra and fiqure TQ from it.
Last edited by matty b; 08-27-2018 at 11:47 PM.
Its impossible to get a torque curve if you don't have an RPM signal because the dyno has no idea what gear you are in, and how tall the tires are, stuff like that. therefore it cannot plot RPM without tach signal. which means it cannot find torque vs rpm in any particular gear. so you will never get a torque curve from a dynojet with no clamp-tach pickup, but it can still generate a horsepower curve because it knows the mass of the roller in the floor and can count seconds.
Torque is Newtons times meters, force (kg*m/s^2) times some length (meters). To go from torque to power you divide by time (seconds). So N*m/s which is really Mass*meters^2/seconds^3 is equal to power.
horsepower is only one kind of unit of power. Power is a rate of doing work. Work can be expressed in Joules which is kg*m^2/s^2 or Newtons times meters as above. To get power divide Joules by seconds, N*m/s giving us Watts, a unit of power or Joules/second. A more common unit of work in America is the foot-pound or ft-lbf (pounds in terms of force like newtons). To get power again you simply divide by seconds, ft-lbf/s. One horsepower is 550 ft-lbf/s. One horsepower is also equivalent to 746 Watts, or 746 Joules/second.
Power is calculated in engineering systems, such as pump power Watts requirements which provide fluid head/pressure. Compressor flow is an example where we determine pump mass flow rate by using volume flow rate and converting to density/time rate by taking pressure and temperature into account. The mass flow of air molecules available to an engine is the factor concerning power, since it determines how much energy can be extracted from a fuel based on an air fuel ratio. Some fuels with different properties allow different operating gas expansion rate ranges for safe combustion to take place so it varies with fuel but always within a specific range.
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