R2 heads a necessity?

[mfg]

Avanti R1 owners who have desired to add a Paxton supercharger to their car have hesitated due to the complexity and relative unavailability of factory R2 heads… I’ve often wondered if the R1 heads really need to be changed at all?

Period Paxton literature indicated that their standard 5 lb. boost supercharger was compatible with compression ratios up to 11 to one (using premium fuel) … and up to 12.5 to one with “the proper camshaft and fuel”

Has anyone ever heard of an Avanti R1 engine failing after a Paxton was added to it (without changing the heads)?

Did Studebaker make this compression ratio change strictly out of warranty caution?

Opinions?

[Dwight FitzSimons]

In my experience with several R2s, both back in the day and today, you will need to use gasoline of higher octane than the current 93 if using R1 heads with a blower.  Going from 9.0:1 to 10.25:1 C.R. will increase the chance of pinging considerably (& increase power considerably too).  You could add some racing or aviation gasoline to 93 octane.

A while ago someone on the SDC Forum said that he was running 570 heads (R1 heads) with a blower successfully, but I suspect he was using something above 93 octane gas.

Yours is an intriguing thought.  As we know an R1 will beat an R2 up to 30-40 MPH, and that is partly (mostly?) due to the higher compression ratio of an R1.  With the small number of miles most of us drive our cars today the additional cost of higher octane gas would be insignificant.

BTW, an R3 has a 9.75:1 C.R., so gives us an indication of what happens when increasing the C.R. on a supercharged Stude.  I had an R3 in the late 1960's and it required Sunoco 260 (which is NLA) or it would ping.  (I can't address the ping resistance of an R1 head versus an R3 head, however.)

As far as what happens when using insufficient octane gas in a Studebaker: A local '63 Avanti with an R4 engine experienced failure because the owner didn't buy only Sunoco 260 gas and ignored the pinging.  R4s have a C.R. of 12:1 (but no blower).  When the engine was pulled apart EVERY ring was broken and one or two cylinders needed to be sleeved.  You must NOT ignore pinging.

--Dwight

Edited 12 hours ago by Dwight FitzSimons

[mfg]

I agree that today’s sub par gasolines would probably be the big caveat here.

Although, using the highest grade gasoline available, with a good brand of octane booster, might eliminate any pinging issue the driver may encounter.

And this is with the assumption that any supercharged ‘63-‘64 Stude Avantis being driven today are strictly limited use automobiles!