Dissapointing Dyno Numbers. Any Ideas?
06-26-2012, 06:31 PM
#1
Dissapointing Dyno Numbers. Any Ideas? I ran my '54 Studebaker on the dyno last week and only managed to make 277 rwhp/391 rwt. This was on 7 pounds, we turned it up to 11 pounds and the thing made 450-ish foot pounds and 306 rwhp at 4000 and then one of the rear tires chucked the tread. On the dyno. Yes, it sucked.
My combination is a 5.3 with an MPT76, T56 six speed and Explorer rear with 3.08 gears. The motor has a TU1 cam and decent valve springs. Fuel is a Bosch 044 and 60 pound injectors. The whole experience was weird, everything worked like it should and IAT's even at 11 pounds were only 103 degrees. Fuel pressure is good and timing is set at 11 degrees. No boost issues, it spools nice and early with the 2" up pipes and there's full boost by 3500. I was expecting a bunch more power, it just lays down at 3800 or so.
Driveability is awesome, it runs great and it's actually pretty fun on the street with the skinny rear tires. The only thing I can think of is my exhaust is too restrictive? It's a single 3" into a Flowmaster 40 series. I think I'm about 100 horsepower down or more? Any ideas?
My combination is a 5.3 with an MPT76, T56 six speed and Explorer rear with 3.08 gears. The motor has a TU1 cam and decent valve springs. Fuel is a Bosch 044 and 60 pound injectors. The whole experience was weird, everything worked like it should and IAT's even at 11 pounds were only 103 degrees. Fuel pressure is good and timing is set at 11 degrees. No boost issues, it spools nice and early with the 2" up pipes and there's full boost by 3500. I was expecting a bunch more power, it just lays down at 3800 or so.
Driveability is awesome, it runs great and it's actually pretty fun on the street with the skinny rear tires. The only thing I can think of is my exhaust is too restrictive? It's a single 3" into a Flowmaster 40 series. I think I'm about 100 horsepower down or more? Any ideas?
06-26-2012, 07:27 PM
#4
TECH Apprentice
Something is very wrong, somewhere.
Those are N/A numbers....
First off get rid of that flowmaster, anything but a flowmaster on a turbo car.
11 degrees timing is pretty low.
What is controlling the fuel/spark?
Those are N/A numbers....
First off get rid of that flowmaster, anything but a flowmaster on a turbo car.
11 degrees timing is pretty low.
What is controlling the fuel/spark?
06-26-2012, 07:30 PM
#5
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Maybe nothing is wrong with the car. Maybe there is something wrong with the dyno or the settings on the dyno. Try taking it to another dyno to see if the results are near the same. If it is, there might be something hindering your set up.
06-26-2012, 07:34 PM
#6
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a turbo makes a great muffler... idk why anyone would put a muffler after that.. but anyway, it seems like your timing is alittle low... are you running e85? or 93?
06-26-2012, 07:54 PM
#7
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Check for the obvious stuff like the air filter being sucked closed, condition of the engine. What gear are you doing the pull in? Most are done in 4th (1-1)
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06-26-2012, 07:54 PM
#8
Engine management is stock GM ECU. Compression is 180 across the board. Valve springs are 130 on the seat 340 open. Pulls were made in third gear but when the tire blew it was in fourth. I'm in California so our best pump gas is 91. What I thought was fucked was when we added 4 pounds of boost we only saw 40 foot pounds and about 20 rwhp at 4000.
I wondered about the dyno readings, I was running a vintage style Hurst cheater slick, they are 6.5" wide and retreaded on a radial carcass. They are supposed to be a race tire with a vintage look but one of them came apart on the dyno, it was pretty violent. I wondered if maybe there was tire slip or a false reading because the tires were doing weird ****.
I wondered about the dyno readings, I was running a vintage style Hurst cheater slick, they are 6.5" wide and retreaded on a radial carcass. They are supposed to be a race tire with a vintage look but one of them came apart on the dyno, it was pretty violent. I wondered if maybe there was tire slip or a false reading because the tires were doing weird ****.
06-26-2012, 08:46 PM
#9
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Change out the muffler for a straight through muffler. Chambered mufflers are a big no no with turbos as they are restrictive and all your doing is chocking the engine. How far back does the exhaust go?
06-26-2012, 09:49 PM
#10
yeah crank that bitch.
i ran 14lbs and 14deg on non methanol motors without problems and 4.8s making 500rwhp with 68-75mm turbos intercooled. on automatics!
06-26-2012, 10:54 PM
#15
damn that is awesome and yeah i bet that flowmaster is killing power, i used a chambered muffler on 10lbs of boost on the dyno with my fairmont killed 50rwhp on my 4.8 cammed gt45 car, cut the muffler off and it went strait back up
06-26-2012, 11:28 PM
#17
That's what I thought too. I ran the Flowmaster thinking it might kill 50-60 rwhp and that might not be so bad considering the chassis it's in. Which is why I'm wondering if the tires had something to do with the dyno reading wrong. What motor makes 390 foot pounds and only 277 horsepower? And it peaks at 3900?
06-27-2012, 01:36 AM
#18
Do a compression check, I got a brand new EPP cam that was ground wrong once, didn't dyno, but the car was obviously a huge turd, pulled compression check and numbers were horrible. Threw in my old cam and bam, compression check looked good and went out on the street and pulled good again.
06-27-2012, 02:09 AM
#20
Do a compression check, I got a brand new EPP cam that was ground wrong once, didn't dyno, but the car was obviously a huge turd, pulled compression check and numbers were horrible. Threw in my old cam and bam, compression check looked good and went out on the street and pulled good again.