Engine: Supercharger / Heads to suit

[studevic]

Hello All , I am working on a 1962 Hawk , 289 v8 , i wish to add a 1963 Paxton supercharger , at the moment the engine has heads with the casting number 537555 , will these heads be ok with the supercharger or do i need to fit the low compression heads ,casting number ending in 582 i think , this Hawk will only be used for club runs , no fast trips , let me know what you think , cheers,

[Dwight FitzSimons]

I have only partial information; others can add to it.
1) Has your engine been bored, and if so, what pistons does it have: flat-top or dished? An overbore will increase the C.R.

2) Yes, the 582 heads were the ones Studebaker used on R2 engines. With flat-top pistons the C.R. with these heads is 9.00:1. With dished pistons the CR would drop maybe a point (?) to 8:0:1 (depending on the dish). (BTW, the 582 heads have a tendency to crack, although I assume that depends on whether they were abused or not.)

3) SDC's info on cylinder heads should be here: https://studebakerdriversclub.com/?page_id=25049 (won't load for me at the moment)

4) IIRC, the 555 heads, in stock form (dished pistons) should produce a CR of about 8.5:1, which should be fine with a blower.

5) With a supercharger you will need higher octane gasoline (petrol). I use 93 in the U.S.

6) Remember that you will get no real HP gain with a blower until you reach about 3000 RPM (with stock pulleys). An R1 will outrun an R2 up to 25-30 MPH (because of the R2's lower CR and the blower's parasitic drag).

7) You will need the higher flow fuel pump the R2s used (or an electric pump) and an R2 carb. Dave Thibeault can make these up. R2s also used a fuel return line to the fuel tank.

8) An R1/R2 cam will improve power output in the RPM range where the blower gives you a net positive HP gain.

--Dwight

[studevic]

Thank you for your response , the engine has been rebuilt at some stage and has flat top pistons, not sure of the oversize , cheers

[PackardV8]

Flat top pistons change the equation. That's why Studebaker Engineering used the 582 heads on the R2.

Having said that, some rebuilder pistons are destroked because they assume the heads and block will have been surfaced.

Third, don't take anything for granted. All the iron is sixty years old, may have been rebuilt or modified. Start with the short block and measure the deck height; that is how far the top of the piston is below the top of the block. Then measure the combustion chamber volume; never assume it is now what it was when new. There is a calculator to estimate static compression. https://www.uempistons.com/p-27-comp...tio-calculator

Finally, you say, "this Hawk will only be used for club runs , no fast trips," so all the above is moot. If all you want is the blower bling, just build it as is, use the thick head gasket, keep the RPM below 3500 RPM and you'll have no problems.

jack vines

[6hk71400]

Jack,

Sound advice. My only question has to do with human nature rather than mechanical engineering. Since the engine does not feel healthy until 3,000 rpm it may be that the 500 rpm power range will be exceeded. My GH does not have the blower hooked up but feels healthy.

Question: are you recommending your RPM limited based on the internal engine condition of the car in question? Knowing that valve float occurs @ 4,500 rpm in a normal V8 is that why you recommend the 3,500 rpm?

[StudeRich]

I would think that Jack is more concerned with TOO Much Compression doing damage (Rod Brgs.) after the static Compression is exceeded by the Blower Pressure above 3500.

That is why he recommended a Thick Gasket, to keep the Comp. down a little, the combo of More Bore, High Comp. Pistons, Standard (higher) Comp. Heads AND the Paxton will be TOO Much.

[PackardV8]

I would think that Jack is more concerned with TOO Much Compression doing damage (Rod Brgs.) after the static Compression is exceeded by the Blower Pressure above 3500.

That is why he recommended a Thick Gasket, to keep the Comp. down a little, the combo of More Bore, High Comp. Pistons, Standard (higher) Comp. Heads AND the Paxton will be TOO Much.

For true, Rich. With the '57-'58 GH, Studebaker Engineering strangled the Paxton with a 2-bbl carb and low compression and soft valve springs, limiting the boost by limiting the RPM via valve float. It was the only way they knew to make it not self-destruct.

When Studebaker Engineering went to the R2, they used a bit more compression, but offset that with more camshaft duration, rich carburetor jetting and a better ignition advance curve. However, it was still possible to melt down an R2 with a long full throttle run, especially uphill on a hot day.

jack vines