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1991 Vette L98 into 89 Fbody insight

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1991 Vette L98 into 89 Fbody insight

Old 01-06-2019, 03:06 PM
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1991 Vette L98 into 89 Fbody insight

Howdy..

So after all the fuss of finding an LS2, I decided to plant that in my 70 and pick up a super low mileage L98 to replace the tired power plant in my Gta. There are some obvious differences between the two so if you have some knowledge on what I need to swap between the two Iíd appreciate it. From what I see so far my accessory drive, water pump, EGR And Map sensor are different.
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Old 01-06-2019, 07:15 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Originally Posted by Jamcousi9 View Post
Howdy..

So after all the fuss of finding an LS2, I decided to plant that in my 70 and pick up a super low mileage L98 to replace the tired power plant in my Gta. There are some obvious differences between the two so if you have some knowledge on what I need to swap between the two I’d appreciate it. From what I see so far my accessory drive, water pump, EGR And Map sensor are different.

Fuel rails are different in how the lines connect, so those will need to be swapped. You covered the MAP vs. MAF setup, Accessory drive is different (the whole front dress, in fact), plus the distributor is different, with the F-Body having an external coil.

Basically, you can use the long block, swapping the distributor and drive accessories, then removing MAP Sensor items and EGR will need to be changed over, too.

What else? Water neck is different, too. Like I said, use the long block and swap over the manifold, etc. Oh, and the bolt patten on the manifold might need to be altered due to aluminum heads vs. iron.

Hope this helps. Post pics of your 89 ASC
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Old 01-06-2019, 07:19 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Originally Posted by Big&BadGTA View Post
Fuel rails are different in how the lines connect, so those will need to be swapped. You covered the MAP vs. MAF setup, Accessory drive is different (the whole front dress, in fact), plus the distributor is different, with the F-Body having an external coil.

Basically, you can use the long block, swapping the distributor and drive accessories, then removing MAP Sensor items and EGR will need to be changed over, too.

What else? Water neck is different, too. Like I said, use the long block and swap over the manifold, etc. Oh, and the bolt patten on the manifold might need to be altered due to aluminum heads vs. iron.

Hope this helps. Post pics of your 89 ASC
The water neck is the same between two.
swap over the fuel rail and plenum if desired the 91 only difference from 89 is the map boss. The accessory drive will swap over but you need to drill and tap the stud on the passengers side head. Don’t forget to tune. Arap code would work well as tune just disable vats.The intake has a rear coolant crossover and you should just plug the steam return pipe with a 1/8 npt plug. The egr is rear feed and will not work on the internal passage on the 113 heads. To retain it you would need a pipe from your passengers header/manifold. Your right on the water pump it’s a short version.

Last edited by Tuned Performance; 01-06-2019 at 07:24 PM.
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Old 01-06-2019, 07:45 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Originally Posted by Tuned Performance View Post

The water neck is the same between two.
swap over the fuel rail and plenum if desired the 91 only difference from 89 is the map boss. The accessory drive will swap over but you need to drill and tap the stud on the passengers side head. Donít forget to tune. Arap code would work well as tune just disable vats.The intake has a rear coolant crossover and you should just plug the steam return pipe with a 1/8 npt plug. The egr is rear feed and will not work on the internal passage on the 113 heads. To retain it you would need a pipe from your passengers header/manifold. Your right on the water pump itís a short version.

whatís this bundle of joy?
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Old 01-06-2019, 07:46 PM
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Re: 1991 Vette L98 into 89 Fbody insight

That’s the oil pressure switch and gauge sender. Your might have it above the oil filter. Check the vette block it might have the same port blocked with a 1/4 npt plug.
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Old 01-06-2019, 07:50 PM
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Re: 1991 Vette L98 into 89 Fbody insight

It seems straight forward for the most part.. Once I pull the old engine Iíll do a side by side comparison and ask questions when needed.
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Old 01-06-2019, 07:51 PM
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Re: 1991 Vette L98 into 89 Fbody insight

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Old 01-06-2019, 07:52 PM
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Re: 1991 Vette L98 into 89 Fbody insight

If you use the devorced hei coil you will need to notch the lower bracket to clear the coolant port boss. If I recall correctly.
the other thing on the plenum is the vacuum booster fitting is different and can be swapped from the 89.

Last edited by Tuned Performance; 01-06-2019 at 07:56 PM.
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Old 01-06-2019, 07:56 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Originally Posted by Jamcousi9 View Post
looks ready for a heart transplant
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Old 01-06-2019, 07:57 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Originally Posted by Tuned Performance View Post
Thatís the oil pressure switch and gauge sender. Your might have it above the oil filter. Check the vette block it might have the same port blocked with a 1/4 npt plug.
I have some kind of switch above the oil filter, I will have to take a picture of it when I get back
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Old 01-06-2019, 08:00 PM
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Re: 1991 Vette L98 into 89 Fbody insight



The vette might have 3 senders. Oil pressure for the fuel pump, one for gauge oil pressure and one for oil temperature.I didnít see it mentioned above but your oil pan and pickup needs to be changed.
the piece above the oil filter the oil cooler can go.

Last edited by Tuned Performance; 01-06-2019 at 08:35 PM.
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Old 01-06-2019, 08:40 PM
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Re: 1991 Vette L98 into 89 Fbody insight


Hereís a sensor above the oil filter
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Old 01-06-2019, 08:46 PM
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Re: 1991 Vette L98 into 89 Fbody insight

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Old 01-07-2019, 02:31 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Did the Vettes use a different head LH/RH? or were they both the same part number?
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Old 01-07-2019, 03:02 PM
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Re: 1991 Vette L98 into 89 Fbody insight

Both the same 113s in 88-91
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