I appreciate it guys.

as far as the ECM and fuel mapping, is that not part of the tune? To change that fuel map?

 

Yep valve springs need to be attended to for sure but when you said refresh I thought you were talking about tearing the engine down completely. Valve spring maintenance is one of the critical factors we use when we spec a cam.

 

YES Valve spring / train maintenance

chit bottom ends can go on just about for ever.

 

Was the 486rwhp on 15w-50 oil?

There would certainly be a difference on the dyno going from 5w-30 to a higher viscosity...how much I don't know.

Otherwise...compare track times from then to now...that's the true measure of performance!

 

the engine would, but higher HP engines need the heavy oil protection.

I run 15-w50 in my LS6 with low 400s rwhp But when I get running my oil temp is 230-250 so the oil thins out very quickly.


Over in another thread, LG mentioned is race engines last 15 hours in sprint set up or 24 hours in endurance set up.

Thread and Video - Click HERE

 

To my knowledge the 15/50 is the only oil the engine has ever known.

The car has never been tracked/raced but the orignal owner and myself both have provided the car plenty of test sessions for the sticking Toyota throttle issue - or maybe better said that we both have gassed the car some...but missing 60 rwhp is a big variance "imop".

I have pm'd the original owner and one of the builders hoping they will be able to shine a light on these 60 missing rwhp???

 

If this is an auto car, did you have tuning software hooked up the second time you dynoed the car? Because if you didnt lock the converter with the software when it was dynoed there goes your 60 hp because the converter is slipping and wont lock up.

 

In addition to feeder82's comment, I would ask what modifications are done to your car and engine? The original 486rwhp through an automatic sounds like forced induction?

Please list your engine and car's modifications so we can have an idea which dyno numbers are more plausible.

 

This is from the first owner whom had the build and install done:

The short block is a factory LS2 that was stroked out from 364cid to 402cid. It has been balanced & blueprinted, deck honed, and the entire rotating assembly is forged. As a starting point, I used the offering from A&A (refer to that sheet that was in the package I supplied you... with the Post-it notes on the back). It has flat-top (high compression) pistons, Clevite bearings, Diamond rings, ARP studs, and Comp Cams 228/232 .581/.588 114 LSA +4. In English, that means the intake/exhaust duration is 228/232, intake/exhaust lift = .581/.588, Lobe Separation Angle of 114 (lower numbers give more lope, but you can't go much lower than 114 with an automatic transmission), and 4 degrees of ground-in advance. The intake system is upgraded from 78mm (stock LS1) to 90mm, using an OEM LS2 throttle body and FAST-90 intake manifold. The cylinder heads are AFR 205's that have been ported. The valve springs are whatever AFR uses. Tony Mamo is a designer at AFR and a CF member - he could probably give you specifics. The oil pump is stock LS2 that has been ported. The oil pan is stock LS1, so it takes the amount of oil specified in the owner's manual. The transmission is an FLT Level-5, with a Setrab transmission cooler. The cooling system has a 170* thermostat, the fans have been programmed lower to take advantage of that, and the system is filled with a 60/40 concentration of distilled water and universal anti-freeze (+ a can of 40Below). I don't know the brand of the universal anti-freeze, but it can be mixed with the red (Dex Cool) or green anti-freeze -- it's what Charlie Williams uses at RPM. The headers are LG Pro long-tubes that have been thermal (ceramic) coated. The hi-flow cats are by Random Technology. I selected the LG headers because they were the only top of line units that used a slip-fit connection to the catback... meaning you don't have an exhaust flange to possibly catch on a speed bump. The brakes are stock with stock pads up front and Hawk HPS in the rear. Brake fluid is Wilwood EXP 600+ (DOT 4). The tensioner pulley (up top on the passenger side of the serpantine belt) is a stronger billet unit made by RPM Motors. The idler clutch on the serpantine is GM factory equipment - it was a unique feature of 2004s with automatic transmission. The plug wires are MSD, which are nice because they can be formed into any shape and routed away from sources of heat. The air cleaner/intake is a Halltech Stinger using a K&N filter. The fuel injectors are GM 42lb truck units that have been flow-matched (stock is 26lbs). The coilovers are Pfadt 12-way adjustables. The rear-end ratio is stock (but optional) 3.15, and the output shafts are stock. Final compression ratio is 11:1.

 

auto ....and yes he tried the convertor locked and unlocked

 

Take note of this comment, a change in the curve shape can be a real tell.

I take it the previous dyno curve was from the origional owner or the builder? It could be a case of "massaging" the dyno to get a good HP number. The bigger HP number makes the guy with the check book feel better about dropping a bunch on their engine.

Peter

 

Out of curiosity, what were the locked vs unlocked numbers, both horsepower and torque?
Ed

 

By the sound of it.. your 402 should be making 470-500 rwhp.

Run it at the track.. dynos are for bench racers.

If you trap high 110's your low on power...

Mid to high 120's your fine.

 

Leakdown or compression test will tell the story if there is anything wrong.

 

from the seller:
A&A is located in a coastal community, so the elevation is essentially the same as yours. Two things come to mind re the "missing hp."
They use an eddy-current dyno, which loads the drivetrain more (but better simulates real world driving, and helps get the AFR zeroed in). More load = less calculated rear wheel power.
The 486 pull was the 2nd or 3rd of the day, and goes back to when I had the vacuum pump installed (you can see it in my gallery pics). That probably accounts for 10-12 hp right there. The first pull is always lower. If your guy only did 1 pull, that could account for another 20-25.
I was Charlie's guinea pig on the pump idea. There was 1-2 hp parasitic loss in driving the pump, but it gave back 12-15... plus it almost always ensured that the catch can was empty. It worked great... when it worked! I originally had a 3-vane pump, which I blew up almost immediately. That original unit had vanes made of some nylon composite. Then we went with a 4-vane unit with carbon fiber vanes. It lasted a bit longer, but still went west. Since it did last longer, I decided to give it another try, in case I had just gotten a bad one. I also switched to the billet tensioner pulley (which is still installed) in case it had gone bad from side loading. No such luck. At that point, I had Charlie remove it and substitute the existing check valves (hidden under the radiator cowl). This allowed retaining the 2-stage catch can w/o reverting to the crappy stock PCV system. In a stroker motor, the PCV will route all that oil vapor and mist back into the combustion chamber. Not good!

Anyway... all told, I don't think the two items I mentioned would account for 60 hp (and I was present for the dyno run BTW). That pull was also made running 100 octane unleaded race fuel. Maybe the combination of all 3 accounts for it? The high & low octane tables still exist in the PCM, but Charlie set it up so that high is race fuel, and low is the 91 octane that passes for premium out here. Stock is 92 octane high and 88 octane (I think) low. Try it again sometime with race fuel and see how you do.

 

from the builder:
Nothing immediately comes to mind other than to do the basic analysis of the engine to try and determine cause - leak-down test, compression test, etc.

I'd like to look at the two dyno charts, if available, and maybe I can draw some keener conclusions.

 

from a neutral 3rd party:

I would have a leak down test performed.

You build the engine for a certain compression and adding race fuel doesn't do any a lot of good to be honest if the compression is built for pump gas
Compression doesn't change but you can add more timing. We did and experiment one day and kept adding timing and the most we picked up was 3hp.

Also the thing about dyno runs is correct being the 3rd one is usually the best one but its more like 2-5 hp difference not 25 hp.

With all thats been said you need to do a leak-down test to find out whats up. Guessing from a dyno graph isn't going to tell anyone anything.

from me:

 

Local tuner feels that no way on the valve springs (car pulls strong)
recommends replacing msd wires with gm performace wires and installing ngk plugs (not sure what's in it now)...inspect intake.

 

Maybe its the smoothing... Your first dyno could have been on smoothing 2 while your heat on the last run was high and smoothing was set to 5... That can explain it all. I have seen heat kill power on many dyno runs... my motor has seen a 30rwhp loss between 70f 32% humitity vs 102f 56%... Let that rattle your brain.

The best way to know is in a 1/4 mile run
observe the temps, hum, da...

 

I think you may need to rethink what you are saying about timing here. If you only saw a 3 hp change than you have something else wrong. Try Dynoing a motor with 87 octane and get your timing maximized and then change to 93 and maximize your timing and I promise you will see more than 3 horsepower gain.You will also gain going from 93 octane to 100 octane. All my dyno experience is a totally different than chasie dyno's as I have a engine dyno and mostly work on supercharged Big Block's for boat applications but I have seen to much timing kill 90 horsepower and I have seen to little timing will kill one about the same. I will admit that we face different challanges with boat motors as they do not have gear shiftable transmissions and are always under a constant load but there is more to timing and fuel than one thinks. Also I would like to add that you can not set timing correctly without the following info: Knock meter (and not the one already in your car), EGT in each cylinder and AFR in each bank or better yet in each cylinder.