Jackson Racing Supecharger

[mrg666]

Originally Posted by bfrank1972

I imagine it means generating much more heat than a C38, outside of the compressor's optimal efficiency envelope

This is what I learned after asking similar questions. Speed 86 told me that the c38 kit was the better choice if HBP upgrade is planned. When the two base kits were compared, c30 and c38 were not different regarding heat and reliability. However, I was told that c30 has better throttle response for the base configuration, mainly because c30 is slightly smaller/lighter and revs up quicker than the larger c38 unit when used with standard pulley. That made sense to me, so I ordered c30 since I was not planning to upgrade any further. Hope this helps.

BTW, I have not installed the JRSC kit yet. I will post when I install in a couple of weeks.

[CSG Mike]

Originally Posted by mrg666

This is what I learned after asking similar questions. Speed 86 told me that the c38 kit was the better choice if HBP upgrade is planned. When the two base kits were compared, c30 and c38 were not different regarding heat and reliability. However, I was told that c30 has better throttle response for the base configuration, mainly because c30 is slightly smaller/lighter and revs up quicker than the larger c38 unit when used with standard pulley. That made sense to me, so I ordered c30 since I was not planning to upgrade any further. Hope this helps.

BTW, I have not installed the JRSC kit yet. I will post when I install in a couple of weeks.

There is no "faster spool". A supercharger is belt driven. It is always spooled. The C30 revs higher at a given engine RPM, because it has to spin faster to create a similar level of flow, relative to a C38.

[mrg666]

Originally Posted by CSG Mike

There is no "faster spool". A supercharger is belt driven. It is always spooled. The C30 revs higher at a given engine RPM, because it has to spin faster to create a similar level of flow, relative to a C38.

Thanks! I also noticed that I used the wrong word and edited my post before your reply. I only meant revving up the engine as in throttle response.

Do you agree that c30 has better throttle response than c38?

[bfrank1972]

Originally Posted by CSG Mike

There is no "faster spool". A supercharger is belt driven. It is always spooled. The C30 revs higher at a given engine RPM, because it has to spin faster to create a similar level of flow, relative to a C38.

Yup, that's why I was posing the question to heat output of the c30 vs c38, if the C38 spins slower and has to work "less", does it produce less heat than a C30. I have seen that the C38 consistently produces slightly less power below 4000, and a bit more power progressively above 5000 compared to the C30 - but that's different than throttle "response", that should be good on both setups. Also would be interested in the boost curve produced for each on an otherwise identical setup (which would loosely correlate to heat/efficiency). Also timing advance comparing the C30 vs C38. Maybe one of the tuners on the board with experience could chime in?

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[Psilox]

This has been the most useful reference for me when thinking about C30 vs C38:

http://blog.vittuned.com/jackson-rac...ft-86-fr-sbrz/

They swapped the C30 directly for a C38 and dynoed both with no other changes between. Not sure about boost curve, but I suppose we can assume that the delta between them roughly follows the differences in the HP curve. I'm really undecided as to which I would go with (in the future, probably after warranty), as the extra low end torque would probably feel better for daily driving?

[CSG Mike]

The C30 is more "linear" and the C38 ramps slightly steeper.

[Not_so_Breit]

Now before everyone is like " omg your an idiot what is wrong with you" let me preface this with I know very little about FI except for the fact that I want it really bad.
Now I've been told 260-270 is what to expect with a custom tune on the c38 unit. I am hoping to make closer to 300 but not alot more then 300. Now my question is if I did the c38 unit with the HBP and it was capable of making lets say 360 or so would if be possible to ask my tuner to not go much past 300? Like I dont want more then 300 out of fear for my motor?

[CSG Mike]

Originally Posted by Not_so_Breit

Now before everyone is like " omg your an idiot what is wrong with you" let me preface this with I know very little about FI except for the fact that I want it really bad.
Now I've been told 260-270 is what to expect with a custom tune on the c38 unit. I am hoping to make closer to 300 but not alot more then 300. Now my question is if I did the c38 unit with the HBP and it was capable of making lets say 360 or so would if be possible to ask my tuner to not go much past 300? Like I dont want more then 300 out of fear for my motor?

Absolute possible to detune intentionally.

[gtengr]

Originally Posted by bfrank1972

I imagine it means generating much more heat than a C38, outside of the compressor's optimal efficiency envelope

I crunched some numbers this afternoon using the C30-94 and C38-81 compressor maps and plotted pressure ratios of 1.36 and 1.90 at 4k rpm and 7k rpm, with 0.12 to 0.14 kg/s and 0.24 to 0.26 kg/s flow rate. I assumed a 1 psi loss for the intake air filter. Connecting those points with a line results in a sweep through a higher efficiency range on the C30 than the C38. I think the C38-81 really only starts to become beneficial with E85 and/or the RS pulley. The C38-71 seems to be the best choice for 93 octane, and should be a simple substitution since it uses the same exterior casing dimensions as the C38-81.

Originally Posted by Psilox

This has been the most useful reference for me when thinking about C30 vs C38:

http://blog.vittuned.com/jackson-rac...ft-86-fr-sbrz/

They swapped the C30 directly for a C38 and dynoed both with no other changes between. Not sure about boost curve, but I suppose we can assume that the delta between them roughly follows the differences in the HP curve. I'm really undecided as to which I would go with (in the future, probably after warranty), as the extra low end torque would probably feel better for daily driving?

I used some of their data to interpret the compressor maps. If only they had plotted the C30 w/hbp.