5.0 TBI LO3 dyno + 081 heads swap
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5.0 TBI LO3 dyno + 081 heads swap
Hey guys, just wanted to share.
I'm going to throw 081 heads on my Firebird among some other stuff, and decided to dyno it before and after.
So here are the results for a stock LO3 with few bolt-ons.
These are the engine figures, there are ~50hp less on the wheels.
I'm going to throw 081 heads on my Firebird among some other stuff, and decided to dyno it before and after.
So here are the results for a stock LO3 with few bolt-ons.
These are the engine figures, there are ~50hp less on the wheels.
Last edited by maxpain; 07-28-2015 at 05:08 AM.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
I dont think that 460 trq value is possible given the hp. If dyno measures torque and back calculates hp, then it should be making more hp at that rpm. If those were projected flywheel numbers from wheel hp measurements it must be using incorrect conversion factors.
Just dont see that motor making diesel like torque off idle
Just dont see that motor making diesel like torque off idle
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Re: 5.0 TBI LO3 dyno + 081 heads swap
I dont think that 460 trq value is possible given the hp. If dyno measures torque and back calculates hp, then it should be making more hp at that rpm. If those were projected flywheel numbers from wheel hp measurements it must be using incorrect conversion factors.
Just dont see that motor making diesel like torque off idle
Just dont see that motor making diesel like torque off idle
Here are the wheel measurements.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
I dont think that 460 trq value is possible given the hp. If dyno measures torque and back calculates hp, then it should be making more hp at that rpm. If those were projected flywheel numbers from wheel hp measurements it must be using incorrect conversion factors.
Just dont see that motor making diesel like torque off idle
Just dont see that motor making diesel like torque off idle
RBob.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
With a stock to mild cam and dual plane intake they will LOSE under 4500 rpm and gain very slightly from 4,500 to 5,000-5,500. Dewey 316 and I both did testing with that result. Dewey's test was ported 416s.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Cam is going to be
Duration (Int/Exh): 279/287
Valve Lift (Int/Exh): .447/.471
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Any other specs on that cam??? What was the seat to seat duration measure at? .004 or .006 or?? What is the 0.050" duration. What about the Intake centerline or LSA?
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Re: 5.0 TBI LO3 dyno + 081 heads swap
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Keep up the good work, this is really cool!
That bird really 4WD ??? if so you need to share some pics and input!
That bird really 4WD ??? if so you need to share some pics and input!
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Car: 1988 Pontiac Trans Am GTA.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Where did you get the spoiler?
I want one
I want one
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Re: 5.0 TBI LO3 dyno + 081 heads swap
I believe it would be impossible to make it 4wd on even close to stock chassis - just no room for a TC or a front axle. Or it would have to be a monster truck.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Engine's done.
In the process of tuning right now.
In the process of tuning right now.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
I see the heads and intake manifolds ports have been cleaned up and gasket matched, how far did you go with the porting on the heads?, any work done to the bowls?
Looking forward to seeing the dyno after the tune, I been working on a similar350 TBI build myself
Looking forward to seeing the dyno after the tune, I been working on a similar350 TBI build myself
Last edited by 89-S-dime; 08-04-2015 at 06:39 PM.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Yes, ports have been gasket matched and cleaned as far as the cutter reached. Also both valves are larger than stock, pretty much the largest you can fit in these heads. I actually have an LS3 exhaust valve laying around and it is smaller than the ones I got. Needless to say everything under the valves has also been cleaned and ported.
You can also see how fat stock valves' necks are. You could get a little gain just by swapping those for thinner and polished ones.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Did the heads just bolt on?
Or did you head to do some adjustments to make them fit?
And what are the other bolt ons you have on the stock LO3?
I have bonestock LO3 TBI and i'm still figuring out what mods I'm going to do :P
Or did you head to do some adjustments to make them fit?
And what are the other bolt ons you have on the stock LO3?
I have bonestock LO3 TBI and i'm still figuring out what mods I'm going to do :P
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Re: 5.0 TBI LO3 dyno + 081 heads swap
During the dyno i had headers, ultimate tbi mods, 170F thermostat and a tune.
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Car: 88 Camaro
Engine: 305 LO3 TBI
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Re: 5.0 TBI LO3 dyno + 081 heads swap
But what I know from the stock LO3 TBI is that it makes around 170HP.
Do those upgrades you have, only add the Torque?
Or do I miss something?
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Re: 5.0 TBI LO3 dyno + 081 heads swap
You are missing the fact that its a 30-year old engine. It should have been like 150 or 130 hp.
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Re: 5.0 TBI LO3 dyno + 081 heads swap
Ran into all kinds of problems with vacuum after the build - almost none.
Had to take the engine apart several times to recheck the seals, ports, valve tightness, etc. Even tried to change the cam - no luck.
Even Brian from TBI Chips had no more ideas.
So I just took the whole thing out and sold it.
Going with LS now.
I'm thinking the problem was in the valves, too big maybe, should have left them stock and just ported the heads.
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Re: 5.0 TBI LO3 dyno
Those are stock Rochester TBI units that have been modified. The lip around the bores is shaved off, the bores are enlarged, new larger throttle plates, throttle shaft is thinned, small button head screws are used to hold them on. Often an adjustable fuel pressure regulator is added at this time as well. If you search GM TBI on eBay, you will find vendors who sell parts and completed units, and their prices.
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Re: 5.0 TBI LO3 dyno
TB is by SPR performance 46mm TBI with 5235206 350 injectors at stock 12psi fuel pressure.
If I remember correctly, around 300-400$ new.
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