Partial HO conversion OK with no adverse affects?

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Partial HO conversion OK with no adverse affects?

April 09, 2009, 06:43:21 AM

I am going to update the exhaust with stock HO headers, an off road H pipe and Flowmasters, change the injectors to 19lb out of an Explorer, and change just the upper to an HO with explorer 65 mm throttle body. Should I have any problems with this setup?

Since the engine has 230,000 on it. I'm going to wait and find a lower mileage shortblock for the rest of the conversion.
(this is on an 88 t-bird)

Partial HO conversion OK with no adverse affects?

Reply #1 – April 09, 2009, 07:06:02 AM

probably gonna need an 87-88 mustang computer, DA1 is a good one

Partial HO conversion OK with no adverse affects?

Reply #2 – April 09, 2009, 08:42:39 AM

At this stage I don't think the computer will care. When the cam is swapped then the ECU will need to be changed

Partial HO conversion OK with no adverse affects?

Reply #3 – April 09, 2009, 09:19:09 AM

Oh, the computer will most certainly care. Larger fuel injectors with the stock non-HO computer = wasted fuel with zero performance gain.

Also, an HO computer will have lots of problems with the SO cam.

But the rest of your plan is solid (Mustang headers, H-pipe, HO upper, 65mm TB). You should pick up 10-15 ponies from that combo.

Remember that the 19# injectors, cam and HO computer all have to go in at the same time. Any other part of the HO conversion, including the heads, can be done beforehand.

Partial HO conversion OK with no adverse affects?

Reply #4 – April 09, 2009, 09:40:31 AM

so i can put HO heads on without a HO computer without driveability issues?

i already have the stock stang headers, HO upper, Explorer TB, and HO injectors. this stuff except the TB were done when i got the car. i have wondered if the injectors actually helped anything without the HO computer, guess that answers that question.

Partial HO conversion OK with no adverse affects?

Reply #5 – April 09, 2009, 10:01:44 AM

Yes, the heads work independent of the cam, at least in this case where we're dealing with stock Ford parts. The E7 heads should be good for another 10-15 hp. It's not a ton of power but it does help until the HO cam goes in.

Far as the injectors, I'm afraid all they're doing is dumping more fuel in. The computer assumes that 14# injectors are present and thus meters the fuel accordingly. Of course, the larger 19# injectors physically fit and hook up to the harness fine, but since they have a higher flow rate, each pulse is using more fuel than the computer has metered. This leads to a carbon-rich condition and should show up as extensive carbon buildup on the O2 sensors, and possibly carboning up or fouling out the spark plugs. Your fuel economy should also be suffering a bit. Reinstalling the stock 14# injectors will help bring your economy back up, you'll use less fuel, and you'll be back to stoichio (assuming all other emissions equipment is running in good condition).

Partial HO conversion OK with no adverse affects?

Reply #6 – April 09, 2009, 11:04:11 AM

Quote from: quick50stng;266539

I am going to update the exhaust with stock HO headers, an off road H pipe and Flowmasters, change the injectors to 19lb out of an Explorer, and change just the upper to an HO with explorer 65 mm throttle body. Should I have any problems with this setup?
(this is on an 88 t-bird)

You will not need 19 pound injectors for exhaust/intake performance upgrades on an otherwise stock SO motor.....

Keep the 14's and the SO computer until you swap out the cam.

Partial HO conversion OK with no adverse affects?

Reply #7 – April 09, 2009, 01:16:57 PM

Ok,

I have my choice of ECU's locally.

88 speed density ECU from a 5.0 Mustang AUTO $60 shipped

or

91 Lincoln Mark 7 at the Pull a Part for $12

Which is best? is the mustang ecu that much better?

Partial HO conversion OK with no adverse affects?

Reply #8 – April 09, 2009, 02:13:58 PM

those are both SD computers and auto tranny. Ive heard the Mark computers are speed governed to 108-115 mph or something like that.

Partial HO conversion OK with no adverse affects?

Reply #9 – April 09, 2009, 04:53:57 PM

Quote from: mcb82gt;266601

those are both SD computers and auto tranny. Ive heard the Mark computers are speed governed to 108-115 mph or something like that.

Effectivally they are the same as stated above. I would get the one from the mustang so you don't have a speed limiter. Unless you never plan on taking the car to a road racing track, then the mark7 one will work fine.

I have stock E7 heads on a 87 mustang block with a cam from an 86 cougar and stock upper intake and throttle body. It felt like it had alot of get up and go, compared to before. Although before was a knocking motor about ready to go. So even a stock rebuild probably would have impressed me just as much. The car also had a bad transmission. I was limited to 40mph in first gear. Rather then buying a new transmisison, I just bought a new thunderbird and sold the old one without motor for $100 and sped all the left overs for $50.

Partial HO conversion OK with no adverse affects?

Reply #10 – April 10, 2009, 08:17:35 AM

Quote from: quick50stng;266593

Ok,

I have my choice of ECU's locally.

88 speed density ECU from a 5.0 Mustang AUTO $60 shipped

or

91 Lincoln Mark 7 at the Pull a Part for $12

Which is best? is the mustang ecu that much better?

IF you don't connect the LSC EEC speed sensor input, it will work fine... OF course that's only if you use the 19lb inj and HO cam... Mixing any of these three things is going to give problems...

Partial HO conversion OK with no adverse affects?

Reply #11 – April 10, 2009, 09:46:53 AM

Quote from: Dougy_Fresh;266557

so i can put HO heads on without a HO computer without driveability issues?

i already have the stock stang headers, HO upper, Explorer TB, and HO injectors. this stuff except the TB were done when i got the car. i have wondered if the injectors actually helped anything without the HO computer, guess that answers that question.

do you see an adjustable fuel pressure unit, maybe the car have one when you got it ...

i'm doing the same upgrade and this tread answer all my questions about ecu maf and cam .
but the 14 pound are enought for a more flow and more air setup?
the mix is not gonna be lean on gas ?

thanx phil

Partial HO conversion OK with no adverse affects?

Reply #12 – April 10, 2009, 10:13:43 AM

Quote from: akh43;266729

do you see an adjustable fuel pressure unit, maybe the car have one when you got it ...

i'm doing the same upgrade and this tread answer all my questions about ecu maf and cam .
but the 14 pound are enought for a more flow and more air setup?
the mix is not gonna be lean on gas ?

thanx phil

No, if you have the HO ecu and cam you'll HAVE to have the 19# injectors, but that's only if you have the HO cam and ecu installed.
They MUST be used as a trio to maximize performance, and minimize inefficiency as Eric mentioned. There's no other feasible way.
As far as an AFPR, the problem in this particular case would be that the 14# injectors wouldn't be supplying enough fuel to start with, rather than too much...
Yes, it would be lean.

Partial HO conversion OK with no adverse affects?

Reply #13 – April 10, 2009, 11:05:12 PM

I picked up a 91 LSC ECU today. Just have to buy all the gaskets for the tear down. Thanks for your help