Dyno Results-comments welcome
Thread Starter
Drifting
Joined: Oct 2000
Posts: 1,526
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From: Harrison Township, Mi
Dyno Results-comments welcome
I took my car to the Dyno yesterday. Results after tuning.....
291 RWHP @ 4800
343 RWTQ @ 3700.
I was hoping for 300-325 horsepower. The dyno guys said that the Factory LT1 intake is hurting me up top and suggested a Wieand single plane. It's kind of a moot point because I want this thing to look bone stock, but I thought my cam was way to mild for a single plane (508/529 222/230 hydraulic roller). I also thought this intake would pull to 6,000. The power is pretty flat from 4700-5300 (around 280-290), then just falls off like somebody pulled the plug. The cam is rated 2,000-6,000. I know I could pick up some top end with headers, but that' also not an option. I'm running a Pertronix in the stock distributor with Accel rotor and cap and a Pertronix flamethtrower coil. Could this be hurting me up top?
You should have seen the torque curve....300 ft. lbs. + from the start of the pull at 2500 RPM to about 4900 RPM!!!!!
I'm going to Norwalk tommorrow....Are the 12's in sight?
291 RWHP @ 4800
343 RWTQ @ 3700.
I was hoping for 300-325 horsepower. The dyno guys said that the Factory LT1 intake is hurting me up top and suggested a Wieand single plane. It's kind of a moot point because I want this thing to look bone stock, but I thought my cam was way to mild for a single plane (508/529 222/230 hydraulic roller). I also thought this intake would pull to 6,000. The power is pretty flat from 4700-5300 (around 280-290), then just falls off like somebody pulled the plug. The cam is rated 2,000-6,000. I know I could pick up some top end with headers, but that' also not an option. I'm running a Pertronix in the stock distributor with Accel rotor and cap and a Pertronix flamethtrower coil. Could this be hurting me up top?
You should have seen the torque curve....300 ft. lbs. + from the start of the pull at 2500 RPM to about 4900 RPM!!!!!
I'm going to Norwalk tommorrow....Are the 12's in sight?
Thread Starter
Drifting
Joined: Oct 2000
Posts: 1,526
Likes: 1
From: Harrison Township, Mi
Re: Dyno Results-comments welcome (drives61)
They had an 02 sensor hooked up. Final a/f ratio was 12.9:1-13.0:1, which yielded the numbers at the top of the thread. Prior to tuning, the secondaries were pretty fat (not sure how much, I wasn't there when they tested it).
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Dyno Results-comments welcome (randy72)
Is porting/gasket matching an option or have you done it? If possible and not done, you might pick up 10 or 20 horses. What carb you running?
Race Director
Joined: Aug 1999
Posts: 10,073
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From: Toronto
Re: Dyno Results-comments welcome (68shark)
Are you staying away from headers b/c you want the factory look? If not, DAMN you need them. :yesnod:
Those are some VERY fine dyno numbers indeed. :cheers:
Those are some VERY fine dyno numbers indeed. :cheers:
Former Vendor
Joined: Apr 1999
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From: ECS Sales & Service Advisor
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Re: Dyno Results-comments welcome (randy72)
Those look like pretty damn good #'s to me! And they should be enought to help you get into the 12's I would think!! :cheers:
I hope to get some Dyno #'s for my car by the end of the week! :cheers:
I hope to get some Dyno #'s for my car by the end of the week! :cheers:
Race Director
Joined: Oct 2000
Posts: 15,048
Likes: 79
From: central FL, near the beach.
Re: Dyno Results-comments welcome (randy72)
randy
i'm not sure you can get more with a stock exhaust.
but it should not plummet past 5300.
not knowing what tuning they did, for the drags i would gap plugs .030".
and set valves 1/8 turn past 0 lash warmed up and running. i would attempt to estimate spring seat pressure/were springs changed?
if 1181 pertronix, should be great if the resistance wire was bypassed and with a ballast resistor. could also wire a temporary lever switch for 12v to coil at WOT.
i'm not sure you can get more with a stock exhaust.
but it should not plummet past 5300.
not knowing what tuning they did, for the drags i would gap plugs .030".
and set valves 1/8 turn past 0 lash warmed up and running. i would attempt to estimate spring seat pressure/were springs changed?
if 1181 pertronix, should be great if the resistance wire was bypassed and with a ballast resistor. could also wire a temporary lever switch for 12v to coil at WOT.
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Team Owner
Joined: Jul 1999
Posts: 26,545
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From: Huntersville NC
Re: Dyno Results-comments welcome (drives61)
Randy, do you have an LT1? You should compare notes with Gordonm. He does have headers, otherwise looks bone stock (to me :) ) . Not sure what mods he has. What rear gear do you have? MJ
Oh, and the Pertronix detractors say that they can get screwy at higher rpm, so I guess it is possible that the pertronix is part of your problem above 5000 rpm.
[Modified by MNJack, 12:04 PM 6/12/2002]
Oh, and the Pertronix detractors say that they can get screwy at higher rpm, so I guess it is possible that the pertronix is part of your problem above 5000 rpm.
[Modified by MNJack, 12:04 PM 6/12/2002]
Thread Starter
Drifting
Joined: Oct 2000
Posts: 1,526
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From: Harrison Township, Mi
Re: Dyno Results-comments welcome (MNJack)
let's see if I can get all of these.
Here' the total combo-383, 70 LT1 heads, full port and gasket matched, LT1 intake bone stock, 780 Holley vac. sec., 3.70 gears, 4 speed. Cam specs already given. 10:1 comp.
Not sure on the springs. I bought a matched set for the cam and the machine shop replaced them with a different set because of inadequate seat pressure. Not sure what they are, but the shop checked the seat pressure. I'm sure that the valves are not floating.
The resistance wire was by-passed so that the Pertronix sees 12V full time.
Here' the total combo-383, 70 LT1 heads, full port and gasket matched, LT1 intake bone stock, 780 Holley vac. sec., 3.70 gears, 4 speed. Cam specs already given. 10:1 comp.
Not sure on the springs. I bought a matched set for the cam and the machine shop replaced them with a different set because of inadequate seat pressure. Not sure what they are, but the shop checked the seat pressure. I'm sure that the valves are not floating.
The resistance wire was by-passed so that the Pertronix sees 12V full time.
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: Dyno Results-comments welcome (randy72)
Randy
If you don't want to do headers maybe an h or x-pipe might give you a little extra. Sounds like you have a pretty good combo all things considered
If you don't want to do headers maybe an h or x-pipe might give you a little extra. Sounds like you have a pretty good combo all things considered
Race Director
Joined: Oct 2000
Posts: 15,048
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From: central FL, near the beach.
Re: Dyno Results-comments welcome (randy72)
randy
key factor- what do the heads flow?
L82 or better fuel pump? mine could not keep up; had to upgrade.
stock mufflers could be a real problem with 383
what is the plug gap? always looking for easy stuff :D
key factor- what do the heads flow?
L82 or better fuel pump? mine could not keep up; had to upgrade.
stock mufflers could be a real problem with 383
what is the plug gap? always looking for easy stuff :D
Melting Slicks
Joined: Apr 2000
Posts: 3,286
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From: San Jose California
Re: Dyno Results-comments welcome (randy72)
Randy,
I had a very similar result to yours with my L88. I too was hoping for much higher readings (411hp), but the engine seemed to run out of breath above about 5000 rpm. The hp peak was about 1200-1500 rpm short of expected. Restrictive mufflers could cause this, yet not in my case because I also ran with open headers. Did you make the runs with the hood closed? Hot underhood temps will cost you 1% loss of power for every 7.5 degrees F. The corrected net Horse Power is in part determined by air temp, but the temp is measured at the machine, not under your hood.
It was suggested that I install the cam 4 degrees advanced instead of straight up for improved drivability. NOT! When I put the cam back to designed timing specs, the rpm curve improved as did all 'round drivability. This may not be the case for all cams, but advancing the factory L88 is certainly a mistake.
I also changed my plugs to projected nose Champions. This seemed to make a big difference too. I have to go back and re-dyno to see what the improvements are.
Chuck
p.s. Are you sure your carb was opening all the way?
I had a very similar result to yours with my L88. I too was hoping for much higher readings (411hp), but the engine seemed to run out of breath above about 5000 rpm. The hp peak was about 1200-1500 rpm short of expected. Restrictive mufflers could cause this, yet not in my case because I also ran with open headers. Did you make the runs with the hood closed? Hot underhood temps will cost you 1% loss of power for every 7.5 degrees F. The corrected net Horse Power is in part determined by air temp, but the temp is measured at the machine, not under your hood.
It was suggested that I install the cam 4 degrees advanced instead of straight up for improved drivability. NOT! When I put the cam back to designed timing specs, the rpm curve improved as did all 'round drivability. This may not be the case for all cams, but advancing the factory L88 is certainly a mistake.
I also changed my plugs to projected nose Champions. This seemed to make a big difference too. I have to go back and re-dyno to see what the improvements are.
Chuck
p.s. Are you sure your carb was opening all the way?
Instructor
Joined: Feb 2002
Posts: 152
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From: margate florida
Re: Dyno Results-comments welcome (randy72)
nice for stock LT1, run my stock 454 LS6 last sat. max rwhp 351.4 max rwtq 435.3 i seemed to peek at 5500rpm on the hp and the torque was at 330 from the start of the graft and peeked at 3700rpm i do have headers and under car chamberd ex. and a 308 rear the motor is bone stock with 1500 miles on it not rebuilt . i also been to the track 1/4 mile time was 13.8 at 104 mph i took it easy hit my rev limiter 2 times only was able to make one pass before the track closed for the night. jim
Pro
Joined: Jun 2001
Posts: 683
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From: Calgary
Re: Dyno Results-comments welcome (randy72)
Randy, I tried the pertronix in my stock distributor too. In my case it didn't work too well because the distributor was virtually worn out. My timing was erratic, and the car didn't like to rev past 5k. You might want to try an MDS tach drive distributor. I did and it made all the differance in the world.
Sounds like you are using the same hydraulic roller that I am (Crane?). I'm running it in my 406 with a weiand 7530 single plane intake. It is one of the very few single planes that gives up little lowend torque to a dual plane. :cheers:
Sounds like you are using the same hydraulic roller that I am (Crane?). I'm running it in my 406 with a weiand 7530 single plane intake. It is one of the very few single planes that gives up little lowend torque to a dual plane. :cheers:
Thread Starter
Drifting
Joined: Oct 2000
Posts: 1,526
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From: Harrison Township, Mi
Re: Dyno Results-comments welcome (74vetteman)
I'm running the Crane Powermax cam. I have to look stock for Factory Appearing drag racing. The car alreadyhas an h-pipe. The wieand is what the dyno guys suggested. I don't know if the hood was opened or cloesd. I was at work when the dyno work was done.
Race Director
Joined: Oct 2000
Posts: 15,048
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From: central FL, near the beach.
Re: Dyno Results-comments welcome (randy72)
randy
unless you spent big bucks for someone like Joe Sherman to port the heads, you are getting good power, about as good as stock.
Myself i would rather blueprint a stock LT-1 and shift at 6500-7000, it's just more fun(to win without cheating) than an airflow challenged 383. But, nobody else will know you are shifting near 5300, so enjoy yourself :cheers:
unless you spent big bucks for someone like Joe Sherman to port the heads, you are getting good power, about as good as stock.
Myself i would rather blueprint a stock LT-1 and shift at 6500-7000, it's just more fun(to win without cheating) than an airflow challenged 383. But, nobody else will know you are shifting near 5300, so enjoy yourself :cheers: