What could be wrong? Only 248HP LS1?
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From: Denton, Texas
What could be wrong? Only 248HP LS1? Here's the story. I have a refreshed 1998 LS1 short block with ARP rod bolts and LS2 oil pump, 2005 GTO 243 casting LS2 heads with dual springs and titanium retainers on stock valves, LS1 intake, polished TB, Comp cam (its a turbo grind) 232/228 .610/.595 113LSA, LS2 timing set, long tube headers, performance tune by a very reputable tuner, 58 lbs of fuel pressure at the rail under full throttle. I am only getting 248 HP at the rear wheel on the dyno with 3.42 gears through a 4L60E. I have degreed the camshaft and it's installed correctly. I know my C1500 is heavy but I would sure think I'd get better than 9.23 in an 1/8 mile pass. Guys running almost stock engines are hitting 8.5s and putting down almost 400 HP to the ground.
Any ideas where I'm leaving HP on the table?
Any ideas where I'm leaving HP on the table?
get better intake TB combo, better maf , good plugs, good wires * msd* and why a turbo grind if yours isnt usiing a turbo? make sure you have got good pushrods* not power..just insurance*
It is probably getting some blow by on top of that. I would start with a leakdown test. Sounds like you have an LS1 running on 5 cylinders with the power it is making currently.
Originally Posted by GOaT Cheese
Maybe it is a REAL dyno with a REAL opperator and not someone blowing smoke up your A**.
think its been proven many times that a stock LS1 doesn't make 305hp, more like 350hp. Heavy car or not (which makes no difference BTW), bone stock 98 LS1 with 243 heads should be putting near 300hp to the tires in an auto. Hell my old LT1 with a Dynomax muffler put 230 to the ground on a Mustang dyno, again in an auto...
But believe what you want
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Is it tuned properly, what is your AFR?
When I had my old motor (98' LS1) in the truck, I gain around 40hp just by getting the AFR setup correctly. It was going real rich due to COT still being enabled.
When I had my old motor (98' LS1) in the truck, I gain around 40hp just by getting the AFR setup correctly. It was going real rich due to COT still being enabled.
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Transmission slipping sounds like a very good possibility, I'd also have the tune looksed at by another shop to make sure it's o.k. Leakdown test, plug inspection, and an autotaap might also be a really good idea too. There's definately something wrong.
I agree with the compression check and leak down. It is hard to troubleshoot how it is running without some type of scan tool. You are definately down on power for some reason. Any smoke on hard acceleration?
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I'm going to swap a factory cam back into it and see what it does. It's hard to believe the numbers. The tune was looked at hard for about 8 hours. There is no miss at all, runs like a champ but not as hard as it should. I can't tell if it smokes black when I accelerate, I'm usually looking frontwards. :LOL: The plugs have gone from stock factory plugs to TR55s to TR6s and no change in ET. Runs like a scalded ape with a 150 shot from the bottle. It's amazing that it doesn't run any better than this. I had about the same engine in another vehicle and it was a little better but the other truck had 4.10s and 2" shorter tires. A set of 4.56s would probably help get it motivated off of the line if only I could get traction. On the dyno they said it was lean, according to their POS wideband that kept falling apart. Also, they said detonation was heard and was causing black smoke out the tailpipes. That was before the 243s went on. I haven't re-dyno'd since then.
Compression testing showed 190-195 in all cylinders. The heads are fresh stock 2005 units with dual manley springs. The valves are tight. It's a bitch to roll it through a compression stroke by a 1/2 ratchet on the pulley bolt.
Compression testing showed 190-195 in all cylinders. The heads are fresh stock 2005 units with dual manley springs. The valves are tight. It's a bitch to roll it through a compression stroke by a 1/2 ratchet on the pulley bolt.
Teching In
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From: Colorado
It is not the cam, that one is not that diffrent from mti's x1 or other reverse split cams that have been making good power. Tranny slipping, maybe. I would look deeper in the tune-up. o2's that are not reading correctly? Bad info from a sensor or wide band will screwup the best tuners out there. Look at the plugs, look at the tune up the old school way. The power your missing should show in the plugs.
Teching In
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From: Colorado
Another cam tid bit, Heavy vehicles do not like big cams nor do they like wide lobe seps. Has nothing to do with dyno numbers but if you do a cam swap, keep that in mind for decent time slips. Been there and done that.
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Oh, forgot to say it's got a 3600 RPM Vigilante convertor in it to get up in the high rpm sweet spot. This thing is a blast to drive but it's embarrassing at the track once they bottle runs dry. It eats the pre-2005 Mustangs for lunch, except the S/C ones. Maybe their dyno sucks but other cars with about the same mods as mine were putting over 350 hp to the ground that day.