Modded Mustang Forums banner
Cancel
Create thread New Garage Forums

'98 GT Requiring 93 Octane?

Jump to Latest
21 - 30 of 30 Posts
#21 ·
1989Gt. said:
Where are you getting 10.0:1 compression on stock pi motors. They are 9.4:1
machs are the only motor with a 10.0:1 compression ratio.
Click to expand...
Nice catch! I was not even fully paying attention to what he was saying. But wow, unexperienced people have to be careful to who they take advice from or they will have no engine left. Lol
 
Save
Reply Quote Like Like
#24 ·
1996 GT said:
:facepalm:

**** talk me all you want, guys. I'll keep my advice for other people then.
Click to expand...
Have you done a pi swap and tested and checked the specs on it?
And you gave out more than one instance of incorrect information. No **** talk here, just dont like posted info or advice that was never experienced or proven. Just stick with the facts that you know for sure and have done/experienced and its all good.
 
Save
Reply Quote Like Like
#27 ·
From what I understand, if you PI swap and do not re-tune, then yes, you should run a higher octane, such as 91. But it is possible to tune a PI swapped car to run on 89, although youre probably not getting the power you want because you havent adjusted timing to max out. But I thought the issue here was a non-pi car needing higher octane to run well
 
#28 ·
Why would one bother with the trouble of the swap just to tune to run 87? Lol
And it is, but it was mentioned that he might have a pi swap. And he does not, so I dont know what the interlying problem is.
 
Save
Reply Quote Like Like
#29 ·
The pinging is normal on some of our motors at this age. Mine when stock pinged like a bitch also. it means that it has a large amount of carbon build up in the motor which increases the ratio of compression. I have seen this before on several . You may also be mistaking valve train noise for pinging . These are both common on motors this old especially above 100,000 miles.
 
Save
Reply Quote Like Like
#30 ·
Here are the suggestions for checking this . Other issues may cause it also such as bad fuel regulator (often over looked) and clogged injectors.
You can check those, but I suggest running the seafoam method in the engine a few times to clear things up.

I steam clean my engine inside at least once a month (due to tuning and rich supercharger conditions)

To do this revs have to be kept above 1500-2000 rpm when hot. then slowly inject water into a place on the intake . Vaccum lines or PCV returns will work great for this. Doing this cleans up the carbon and oil build up in the engine.

if emissions are not an issue. i suggest deleting the PCV system and going to breather style, and or using a catch can. These things pollute the intake charge and the engine . this also eventually causes valves not to seat. which i have seen on my DOHC heads from a pull after 150k miles.
 
  • Like
Reactions: 1996 GT
Save
Reply Quote Like Like
21 - 30 of 30 Posts
About this Discussion
29 Replies
7 Participants
Last post:
p4ndiamond
Modded Mustang Forums
posts
6.3M
members
83K
Since
2005
A forum community dedicated to all Ford Mustang owners and enthusiasts. Come join the discussion about performance, racing, builds, modifications, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
96 - 04 Modular Mustangs 5.0 Mustangs New Members Introductions Classic Mustangs