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Author Topic: Chevy TBI tuning  (Read 13660 times)

SiFlyBy

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Re: Chevy TBI tuning
« Reply #30 on: August 26, 2010, 12:21:31 PM »

What software were you using? I will be tuning mine very soon and I'm trying to decide how to handle this. This truck will get boosted, but not for 12 months or so

TunerPro. It seemed more of a hardware issue/losing communication, etc.. FINDING the right bin files and something else that I cant remember was the biggest PITA. My buddy who is an electrical engineer and computer nerd was doing the tuning so I am not savvy on what all he was doing. I would have been totally fucked if I had to try to figure out what he did.

[/quote]
UPDATE:

we tried tuning last Monday. Results were very mixed. The software was a little touchy as was the hardware. After the tuning experience it was decided to recheck compression. Compression is between 115 and 125. Spec is 150. By the VIN, this truck is supposed to have a 350...by the ECU it is a 305..We ordered heads for a 350 and I am starting to believe that we put 350 heads on a 305, which I am guessing would lower the Comp ratio. Gonna try to find the casting numbers and see if that gets us anywhere.

FUCK

That ASSumption is correct.

IIRC, the 305 heads of that era were ~58 cc chambers whereas the 350 heads wer in the neighborhood of a 67 cc chamber.

looks like the block is a 350...Comp test was done cold and wet comp didnt change but about 5 psi...I guess we'll keep plugging away at it and see where it ends up.
« Last Edit: August 26, 2010, 12:24:24 PM by SiFlyBy »
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PhilStubbs

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Re: Chevy TBI tuning
« Reply #31 on: August 26, 2010, 12:39:26 PM »

I was thinking tunerpro myself since I already have Honda tuning shit.

Why not lookup the numbers on the back of the block to figure what it is?
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obd1>gtgtall

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92CXyD

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Re: Chevy TBI tuning
« Reply #32 on: August 26, 2010, 12:41:23 PM »

I was thinking tunerpro myself since I already have Honda tuning shit.

Why not lookup the numbers on the back of the block to figure what it is?

They usually say liter size '81 and up.  :?:

SiFlyBy

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Re: Chevy TBI tuning
« Reply #33 on: August 26, 2010, 01:18:11 PM »

I was thinking tunerpro myself since I already have Honda tuning shit.

Why not lookup the numbers on the back of the block to figure what it is?

They usually say liter size '81 and up.  :?:


It says 5.7 on the block
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92CXyD

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Re: Chevy TBI tuning
« Reply #34 on: August 26, 2010, 01:30:10 PM »

I was thinking tunerpro myself since I already have Honda tuning shit.

Why not lookup the numbers on the back of the block to figure what it is?

They usually say liter size '81 and up.  :?:



It says 5.7 on the block

Then you have a 350 unless somebody overbored it or put 400 crank in it.  ;D
« Last Edit: August 26, 2010, 04:28:46 PM by 92CXyD »
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snm95ls

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Re: Chevy TBI tuning
« Reply #35 on: August 26, 2010, 04:27:44 PM »

5.7 == tree fiddy

SiFlyBy

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Re: Chevy TBI tuning
« Reply #36 on: August 26, 2010, 04:29:44 PM »

5.7 == tree fiddy

Goddamn Lochness Monsta!!
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Joseph Davis

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Re: Chevy TBI tuning
« Reply #37 on: September 13, 2010, 03:03:19 AM »

Talking to him it seems as if this engine should not really have needed a tune based on what we did.

Machine shop guys without engine dynos shouldn't comment on what does, and doesn't, need tuning.  Especially speed density setups.

PhilStubbs

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Re: Chevy TBI tuning
« Reply #38 on: September 13, 2010, 07:01:34 AM »

From what I have been reading lately, all of gm's tbi engines could benefit from a tune even the day they rolled off the assembly line.
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obd1>gtgtall

 fucking box started smoking and i saw a flame start up so i grabbed a bucket of water and splashed it on the breaker box.

snm95ls

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Re: Chevy TBI tuning
« Reply #39 on: September 13, 2010, 07:09:18 AM »

From what I have been reading lately, all of gm's tbi engines could benefit from a tune even the day they rolled off the assembly line.

Correct.

SiFlyBy

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Re: Chevy TBI tuning
« Reply #40 on: September 13, 2010, 11:44:17 AM »

From what I have been reading lately, all of gm's tbi engines could benefit from a tune even the day they rolled off the assembly line.

Well, I believe that every vehicle could be tuned much better from the factory. Of course they tune the engine to make the EPA happy...not the customer. We do a DPF( Diesel Particulate Filter) delete and put a +275 HP tune programmer on a truck and all of a sudden fuel economy doubles. And the truck is making 550+WHP and 1200+WTQ.

As this chevy project sits, we are sending the heads to the machine shop to get checked. we had cyl leakage of 25% on some cylinders.
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PhilStubbs

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Re: Chevy TBI tuning
« Reply #41 on: September 13, 2010, 12:28:39 PM »

The problem with the tbi trucks isn't so much that it's tuned for emissions, it's cause the fuel pressure can vary 4psi. When you are only running 9-13psi to begin with that's a big difference in fuel flow on the same tune.

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obd1>gtgtall

 fucking box started smoking and i saw a flame start up so i grabbed a bucket of water and splashed it on the breaker box.

snm95ls

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Re: Chevy TBI tuning
« Reply #42 on: September 13, 2010, 01:16:00 PM »

At least it has good atomization going for it, too bad it uses a wet flow manifold.

 :P

SiFlyBy

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Re: Chevy TBI tuning
« Reply #43 on: September 16, 2010, 05:59:09 PM »

Well, looks like we found the base problem: the brand new summit aluminum heads that we got for the chevy...warped .006 and .007...some of the valve guides had less than .001" clearance causing them to stick, I would suppose, when the engine got hot and shoot fireballs out the intake... :?: THE FUCK?

Ill update with what summit is going to do for us. We have ordered about $10k worth of shit from them in the last 4 months or so.
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highroller54

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Re: Chevy TBI tuning
« Reply #44 on: September 16, 2010, 11:00:27 PM »

summit brand heads?
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snm95ls

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Re: Chevy TBI tuning
« Reply #45 on: September 16, 2010, 11:58:46 PM »

summit brand heads?

Yeah, probably the Trick Flow 23 degree heads without TR engraved on them.

Summit brand stuff is private label parts form various mainstream vendors.

SiFlyBy

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Re: Chevy TBI tuning
« Reply #46 on: September 17, 2010, 06:25:03 AM »

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klyph

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Re: Chevy TBI tuning
« Reply #47 on: September 17, 2010, 03:20:58 PM »

summit brand heads?

Yeah, probably the Trick Flow 23 degree heads without TR engraved on them.

Summit brand stuff is private label parts form various mainstream vendors.



I heard they are Brodix heads.
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PhilStubbs

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Re: Chevy TBI tuning
« Reply #48 on: September 17, 2010, 04:38:13 PM »

Looking forward to the results. I am very happy with how my truck has perked up tuning it with tunerpro. I should wrap it up tonight.
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obd1>gtgtall

 fucking box started smoking and i saw a flame start up so i grabbed a bucket of water and splashed it on the breaker box.

SiFlyBy

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Re: Chevy TBI tuning
« Reply #49 on: September 17, 2010, 09:19:20 PM »

WE called Summit. They said we can send the heads back so they can check them and decide what to do. If they are bad they will send us a new set.

Well, sure as fuck we're not gonna put em on without getting them checked beforehand. So, we decided to just let the machine shop do what they need to do and FUCK SUMMIT.
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PhilStubbs

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Re: Chevy TBI tuning
« Reply #50 on: September 18, 2010, 07:47:28 AM »

yea, the shipping cost on those heads is probably close to the machine shop bill, + waiting and who knows what they will send back to you
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obd1>gtgtall

 fucking box started smoking and i saw a flame start up so i grabbed a bucket of water and splashed it on the breaker box.
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