Unblown R2!

[mfg]

Without the supercharger functioning, an R2 Avanti engine will make ----?---- less power than an R1 Avanti engine......1) 5%.........2) 10%.........3) 15%....or......4) 20% less

[Geoff]

My wild shot guess is -15%.

[mfg]

8 hours ago, GeoffC312 said:

My wild shot guess is -15%.

Close, but that's not it!

[studegary]

An R2 makes 18% more than an R1 or an R1 makes 15% less than an R2, so I will say 20% less for my answer due to the R2 having a lower compression ratio than an R1. 

[64studeavanti]

I would guess 5%. Supposedly, the 289 with 4bbl and dual exhaust is rated at 225. The R1 is rated at 240. The difference is only 15 hp which is around  6 % .

[mfg]

All good thoughts, however, the correct answer is #2...10%!

[studegary]

4 hours ago, mfg said:

All good thoughts, however, the correct answer is #2...10%!

Ys, I see that.  I misread the question.  I was giving the amount lost from an R2, not the amount less than an R1. 

[64studeavanti]

10% makes no sense! That is a drop of 24hp from an R1. So you are saying an unblown R2 generates only 216 hp whereas a non R engine with lower compression, milder cam, and weaker valve springs is rated at 225. Where did this 10% information come from?

 

 

Edited April 5, 2017 by 64studeavanti

[mfg]

8 hours ago, 64studeavanti said:

10% makes no sense! That is a drop of 24hp from an R1. So you are saying an unblown R2 generates only 216 hp whereas a non R engine with lower compression, milder cam, and weaker valve springs is rated at 225. Where did this 10% information come from?

 

 

It's all about the compression ratio difference between the R1 and the R2 engines, the ignition timing which would be, at that point, way off, and a carb set up considerably 'richer', to be compatible with blower boost.....A carb that WILL WORK on an R2 with a disconnected supercharger,....but not very efficiently or effectively.

[64studeavanti]

Once again, not to be a nag, but how was this measured. The compression on R2 is higher than a non R engine. I doubt seriously if the carb would make much difference as there is not much boost at the lower rpms. The centrifigual timing curve on R2 dist may make a little difference.  But i still cannot believe that just removing the S/C would produce less hp than a non R engine. 

 

Do you have any dyno runs or anything else to support this? Is this like most Studebaker lore and just anecdotal?

[mfg]

9 minutes ago, 64studeavanti said:

Once again, not to be a nag, but how was this measured. The compression on R2 is higher than a non R engine. I doubt seriously if the carb would make much difference as there is not much boost at the lower rpms. The centrifigual timing curve on R2 dist may make a little difference.  But i still cannot believe that just removing the S/C would produce less hp than a non R engine. 

 

Do you have any dyno runs or anything else to support this? Is this like most Studebaker lore and just anecdotal?

I'll get back to you with the source as soon as I can.

Your comment about the carb not mattering too much....believe me you are wrong!.....I once tried to run an R2 Avanti (with functioning supercharger) using a carb from a R1 Avanti engine........WHAT A JOKE!..........It was like I was flooring the throttle pedal, then letting off,...and I wasn't moving the pedal at all!

 

[64Avanti]

If properly tuned then the drop should only be about 3-4%.  Ignition and carb setup correctly.

[mfg]

The original 10% info came from J.P. (I believe)....however, don't quote me on that!!!