Fuel questions

[Guest Spitfire1970]

I have a 1970 Spitfire, I'm currently using 93 premium pump gas, and was looking to switch .or mix with VP's StreetBlaze 100. Questions or comments <meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 9"><meta name="Originator" content="Microsoft Word 9"><link rel="File-List" href="file:///C:/Users/PATRIC%7E1/AppData/Local/Temp/msoclip1/01/clip_filelist.xml"><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:DoNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style>

[Dave@Moon]

I have a 1970 Spitfire, I'm currently using 93 premium pump gas, and was looking to switch .or mix with VP's StreetBlaze 100. Questions or comments <META content=Word.Document name=ProgId><META content="Microsoft Word 9" name=Generator><META content="Microsoft Word 9" name=Originator><LINK href="file:///C:/Users/PATRIC%7E1/AppData/Local/Temp/msoclip1/01/clip_filelist.xml" rel=File-List><STYLE> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </STYLE>

The 1296 cc engine originallin in 1970 Spitfires only had a 9.0:1 compression ratio. Unless you've done major modifications to the motor, using anything over 89 octane pump gas is just wasted. Even some 87 octane pump gas will likely be fine. The engine will run and perform exactly the same.

I run 87 octane in my 8.5:1 TR6 with no problems at all.

Unless it's pinging, no well-tuned street engine needs a higher octane fuel.

[Guest Xprefix28truck]

Exactly!!

[Guest Robin Coleman]

Spitfire...Many folks do not understand what higher octane is actually for...It actually "burns" slower and therefore less likely to detonate prematurely...AV-gas is 110 octane, and one used to be able to purchase 130 octane av-gas...An aircraft engine will destroy itself in seconds due to pinging, and the pilot can't hear it like you can in a car. Used to sell the heck out of it to dune buggy sand bar racers for their high comp VW engines. The biggest problem with modern fuels in older engines is the lack of lead, which was to cushion the exhaust valves against their seats...Farmers who converted their pick ups to butane would get about 10,000 miles out of the original heads, then have harder seats installed.

[Peter J.Heizmann]

Spitfire...Welcome to the AACA Forum.

I concur with Dave and Robin to use 87 except I add a pint of Lead Additive in each fresh tank full. Can buy it at any auto store. Have a 1972 TR6 since new and absolutely no problems.

Best regards,

Peter J