eric1h

iTrader: (7)

I have an 04+ LS1

H-beam rods, diamond -2cc pistons
edelbrock performer carb intake
proform 750 race carb
MSD 6LS
ATI super dampener, no underdrive
no accesories other than waterpump and alt.
stock 241 heads
PRC dual springs with chromoly 7.425 Push rods, LS7 lifters
Pat G spec'd cam: 226/230 .598”/.600” 111LSA +4 advance
TKO500 5 spd
3.50 ford 9" rear end


Block was build by texas Speed so i dont think there is anything wrong with that.

Valvetrain was installed per standard installation instructions, should I have done anything different for PR install?

here is the potential weak link
crappy ebay shorty headers...., no cats


I was expecting somewhere @ 400whp

The A/F was @ 12.45

Best run once it was all tuned was 338hp/331tq

It was on a dynojet dyno

that seems low.. thoughts?

could the crappy headers really be losing THAT much?

What could be wrong? cam timing? could the lower compression of -2cc pistons lose THAT much power?

smok'nZ

iTrader: (160)

Stock manifolds? Cats?

86MonteSS

iTrader: (3)

what kind of dyno? you should be making WAY more than that.

98z8uup

iTrader: (7)

Why did you go with shorty headers. Something does seem wrong.

eric1h

iTrader: (7)

not stock manifolds, short headers per above, dynojet dyno.

Went with shorty headers because the car has side exhaust and noone makes a long tube header. the shortys are temporary, I wanted to get the swap done first and then I'll work on a set of custom long tubes...

The last LS1 I had on the dyno, same year, but with stock internals and same carb/intake manifold setup made 326whp with NO oil pressure(don't ask)

eric1h

iTrader: (7)

Only things I can think would be wrong...

1. for some reason the cam timing is off(but i did install the cam per the timing dots and instructions, spun the crank a few times to verify they were till lined up)

2. too much preload on the valves? maybe holding them open a little? but i would think the car would rough like crap and not pull any vacuum

3. could have been WAYY to much oil?

I have 13Qts of oil in the car, 7 for pan, 1 for filter, 2 for oil lines and cooler, and 3 for accusump.

When i arrived at the dyno shop the valve was closed so I dont know if all the oil from the accusump was in the pan or where it should be.

eric1h

iTrader: (7)

oh and no cats, just high flow mufflers on the side pipes

a crappy pic of the side exhaust

Patrick G

iTrader: (14)

A printout of the dyno sheet would show if it was funky cam timing or not.

Your problem is more likely carb not opening up all the way at WOT (vacuum secondaries?) or your motor is losing spark in one cylinder. Pull every plug wire and verify continuity and proper resistance. Use a timing light to verify spark at each plug or use an infrared temp sensor to see if you have a dead hole. This is more common than you might think, especially if you're running MSD coils or wires.

eric1h

iTrader: (7)

Thanks I'll check that out. it is a vacuum secondary carb, so it is possible.

Also a good idea to check the wires, but we did pull all the plugs and check them I would think a dead wire/coil would show up as way rich on that plug.

johnLs1camaro

iTrader: (28)

^ I would think you'd be making every bit of 400rwhp was the car tuned?

eric1h

iTrader: (7)

Thats what I expected! 400-420whp

Yes car was dyno tuned by a local reputable chevy tuner.

Patrick G

iTrader: (14)

If it's a vacuum secondary carb, then that's the most likely reason for the soft numbers. You may need to subsitute a lighter spring for the secondaries so they open up all the way at WOT. You may only be operating on 2 bbls (plus a little bit of your rear 2).

eric1h

iTrader: (7)

I have an open track/testn tune on Monday I am going to do the paperclip trick to see if the secondaries are opening all the way or how much, so hopefully that will tell us!


I am also looking to see if I can convert the carb to a mechanical secondary

DREAMZ28

iTrader: (1)

Dont LS1's use 6 quarts of oil?
I may be wrong but that's what I've seen..

JonCR96Z

iTrader: (33)

Well with a different pan and whatnot, its' probably different, but using the dipstick is always a good way to check the oil level. It also probably isn't helping that you exhaust appears to be crimped down to the same size at you header primaries where it turns for the side exhaust.

eric1h

iTrader: (7)

The Oil pan is a moroso 7qt pan, the exhaust is mandrel bent where it exits the shorty headers, not crimped.

I think Patrick may be on to something with the vacuum secondaries, going to test this Monday

JonCR96Z

iTrader: (33)

It's obviously crimped at the other bend.

02LS6

iTrader: (18)

even if its a 7 quart, that is still an awful lot of oil...definitely not a full quart for the filter, it takes MAYBE 1/4 of a quart...like john said...use the dipstick

eric1h

iTrader: (7)

like said, 7qts for pan, 3 qts for accusump, I have 10+ feet of Oil lines, Plus the oil cooler is good for a quart... Also, I don't have a standard LS1 oil filter, its a MUCH larger oil filter.... the oil level is right when the accusump has filled with oil, the problem is when you leave the valve open and shut off the car, and then later shut the switch off leavng all the oil in the pan

All that aside, I know how to use a dipstick, the problem was, I wasnt there when they ran the dyno, and when i start the car i flip the switch for the accusump, so I dont know what the oil level was when they dyno'd the car...

02LS6

iTrader: (18)

ah i see what you mean, and sorry I wasn't saying you didn't know how to use a dipstick, but yes 13 quarts still sounds like a little much just because while its circulating you know that there is still going to be more than 7 quarts in the engine at once, so i would bump it down maybe just a little, and definitely try to re-dyno and be there when its done so you know for sure next time...

for an example, my 98 z28 is sts outfitted, but sts only calls for an extra 1/2 a quart, = to 6 and 1/2 quarts because its a stock ls1, and i know damn well the oil lines going all the way back to the rear of the car and then back up plus whats in the turbo are way more than 1/2 a quart. hope this helps!!