Under-powered since rebuild ?
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Racer
Joined: Nov 2000
Posts: 320
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From: Warrington England
Under-powered since rebuild ?
Guy's. I have noticed since my engine rebuild that it doesn't feel as quick off the mark. When I'm Highway driving at say 70mph and hit the gas up to 100mph there is a lot more power than I used to have but from the lights if I floor it, it's like your waiting for it all to happen. I had it tuned on a rolling road yesterday and he said that although my compression readings were all pretty much the same they were lower than before I changed the cam, heads and rings etc. meaning that was why I am losing some low-end grunt. All the readings were around 130/135 psi. Is this right? :confused: VettePaul
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From: Waterford Mi
Re: Under-powered since rebuild ? (VettePaul)
What cam did you use? The cam is what controls where you engines power band is going to be. A cam that is for high rpm's won't perform at low end as well as a cam made for low end power. Cam specs will state what rpm range it will have its power. A cam rated 22000-5500rpm won't take off as well as a cam with a 1500-3000rpm. The engine, cam, trans, and rear end have to work together.
[Modified by redwingvette, 5:09 PM 7/13/2002]
[Modified by redwingvette, 5:09 PM 7/13/2002]
Team Owner
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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St. Jude Donor '06-'10, '13
Re: Under-powered since rebuild ? (redwingvette)
And the cam will change the pressure of the cylinders. Overlap will allow more or less pressure to be in the cylinder at one time.
From what I remember, and I could be totaly wrong, high torque cams build higher cylinder pressure than high HP cams do.
From what I remember, and I could be totaly wrong, high torque cams build higher cylinder pressure than high HP cams do.
Drifting
Joined: Apr 2002
Posts: 1,750
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From: Stockton Ca
Re: Under-powered since rebuild ? (BSeery)
Unless your "quench" piston to head clearance is already .040 you can get back some lost comp by thinner head gasket. This improvement will help! Redwing is right about cam bleed off. Tighter quench will decrease detonation and improve combustion!
Le Mans Master
Joined: Dec 2000
Posts: 5,245
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From: Blue Ridge Georgia
Re: Under-powered since rebuild ? (Taijutsu)
One thing that you could have done was to advance your cam 4 deg. Lot of work now that your motor is back together. First I could can that holley and get a 650 Speed Demon, get lars to recurve your dist, go with a elect cooling fan. All of that maybe you can get about 25 low end horses.
[Modified by Paul 75 L82, 1:26 PM 7/13/2002]
[Modified by Paul 75 L82, 1:26 PM 7/13/2002]
Thread Starter
Racer
Joined: Nov 2000
Posts: 320
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From: Warrington England
Re: Under-powered since rebuild ? (Paul 75 L82)
Thanks Guy's. I was told by the makers of the cam (federal mogal) that it is a marine application. I was also informed by various forum members that it is in fact an L-82 spec. Does that explain anything? :confused:
Also, at the time I was going to advance the cam but I was told I would need high duration lifters etc so I didn't bother. :cheers: VettePaul
Also, at the time I was going to advance the cam but I was told I would need high duration lifters etc so I didn't bother. :cheers: VettePaul
Racer
Joined: Feb 2000
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From: Berlin,NJ,USA
Re: Under-powered since rebuild ? (VettePaul)
VP If its a automatic you could go with a looser torque converter. Stock is around 1800 bump it up to 2200 to 2500.
Or you could get nitrous for a little off the line boost.
Enjoy.
Or you could get nitrous for a little off the line boost.
Enjoy.
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From: Waterford Mi
Re: Under-powered since rebuild ? (Rocket Ron)
From what you said about the cam being a "marine cam", I would say that the difference is in the cam. Marine engines don't see much of a load so they build rpm's quickly, a car needs to pull a lot more. I agree with changing the torque converter will help. You will run higher rpm's on the highway though.
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Thread Starter
Racer
Joined: Nov 2000
Posts: 320
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From: Warrington England
Re: Under-powered since rebuild ? (redwingvette)
I agree with changing the torque converter will help. You will run higher rpm's on the highway though.
Burning Brakes
Joined: Aug 1999
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From: Palatine IL
Re: Under-powered since rebuild ? (VettePaul)
If your signiture is correct than it may not be the cam. It might be the RPM intake. The Edelbrock RPM manifold has larger runners and is designed to provide more power at higher rpm (2500 - 6500 rpm) for the track. Therefore you lose low end power. The L-82 cam makes it's power from idle - 5500 rpm which is not matched to the RPM intake. All the pieces must work together to achieve good torque and horsepower. You need to check the rpm range of each part you plan to use. Also the RPM flows more air so you will have to make sure the carb, heads and exhaust can flow more air otherwise you will hurt performance. So you might want to try an air intake that matches the power band of the cam and heads.
I also noticed you had dual exhaust. If the exhaust is wide open, 3" pipe no cats, you will hurt low end.
Also, you could try a 3.55:1 gear ratio. This helped my low end torque.
[Modified by vettesite, 12:00 PM 7/14/2002]
I also noticed you had dual exhaust. If the exhaust is wide open, 3" pipe no cats, you will hurt low end.
Also, you could try a 3.55:1 gear ratio. This helped my low end torque.
[Modified by vettesite, 12:00 PM 7/14/2002]
Thread Starter
Racer
Joined: Nov 2000
Posts: 320
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From: Warrington England
Re: Under-powered since rebuild ? (vettesite)
That's interesting drives61. I've only covered 1800 miles so far.
vettesite, all I can say is that the performer rpm I already had on before rebuild. So basically all I have changed since is cam, heads and rings. Thanks for reply, VettePaul.
vettesite, all I can say is that the performer rpm I already had on before rebuild. So basically all I have changed since is cam, heads and rings. Thanks for reply, VettePaul.
