New Rotrex C38R Supercharger

Jinxx · 03-08-2018, 07:03 PM

88mm supercharger pulley

This is a chart on impeller speed calculation...last time I talked to rotrex they confirmed the calculation as well .....and that is why GTM wouldn’t sell a pulley under 86mm

The 84mm is at 91280 at 7k rpm......a 80 mm would put you over 100k ...
Also TOPGUN is correct ..if you blow the supercharger you could damage much more than just the bottom end .. we all take that risk when boosting but ....I wouldn’t go that far over specs on a blower

I might be reading the charts wrong soooo ......im still not sure

tiller · 03-08-2018, 07:10 PM

Quote:

Originally Posted by TopgunZ

The down side could be contamination. If your supercharger chews itself up and metal debris and shavings get into the oil system you could have big problems. This unit is direct fed and not self contained, correct?

Just like the guys that say.. Well if my engine goes then Ill just rebuild the bottom end with new pistons and rods so Its not that bad. Well, my engine went when I was Turbo'ed back in the day and took out the crank, both heads and left a window in the block so I needed an entire new Long block. Cost went way up.

Oh sorry forgot to mention the long block sitting on the engine stand next to my z in garage out of a crashed z

See when I do something I do it big and push the limits to see how much I can get out of whichever system, turbo, sc , etc wether it’s thought by some to Be the best or the worst, I try everything and push all parts, let’s just call it life experiences

tiller · 03-08-2018, 07:11 PM

Quote:

Originally Posted by Jinxx

88mm supercharger pulley

This is a chart on impeller speed calculation...last time I talked to rotrex they confirmed the calculation as well .....and that is why GTM wouldn’t sell a pulley under 86mm

Ya I have all that, don’t you have the 85mm installed on yours?

Elmo370z · 03-08-2018, 07:12 PM

Quote:

Originally Posted by Jinxx

88mm supercharger pulley

This is a chart on impeller speed calculation...last time I talked to rotrex they confirmed the calculation as well .....and that is why GTM wouldn’t sell a pulley under 86mm

When is the car going to up and running

Jinxx · 03-08-2018, 08:26 PM

Quote:

Originally Posted by Elmo370z

When is the car going to up and running

Mine is running with the 85mm pulley ...12 lbs boost

Jinxx · 03-08-2018, 08:28 PM

Quote:

Originally Posted by tiller

Ya I have all that, don’t you have the 85mm installed on yours?

Yes the 85 mm

Jinxx · 03-08-2018, 10:49 PM

The 85 mm pulley is running 96k impeller speed at 7.5 k rpm and 90k at 7k rpm

Using a 80mm would be running 102k impeller speed at 7.5k rpm and 95k at 7k rpm

That might be stressing the rotrex pretty hard

tiller · 03-09-2018, 05:30 AM

Quote:

Originally Posted by Jinxx

The 85 mm pulley is running 96k impeller speed at 7.5 k rpm and 90k at 7k rpm

Using a 80mm would be running 102k impeller speed at 7.5k rpm and 95k at 7k rpm

That might be stressing the rotrex pretty hard

Yes, I ran mine all last summer with 85mm at 7.5k with no issues as of yet, I’ll retune n try the 80mm at a 7k redline, like I said I usually don’t redline the car often I’d like to see what type of power differences there is lower in the rpm range where I like it, also may even try some different rear gear ratios as well

Jinxx · 03-09-2018, 08:31 AM

Quote:

Originally Posted by tiller

Yes, I ran mine all last summer with 85mm at 7.5k with no issues as of yet, I’ll retune n try the 80mm at a 7k redline, like I said I usually don’t redline the car often I’d like to see what type of power differences there is lower in the rpm range where I like it, also may even try some different rear gear ratios as well

I think it will be a wash in difference....what you gain from smaller pulley will be lost from lower rpm
And I have different gearing as well .. the nismos came with I think. 3.96 gear...non nismo was a little lower ... 3.69 if I remember right

TopgunZ · 03-09-2018, 08:36 AM

Quote:

Originally Posted by Jinxx

Mine is running with the 85mm pulley ...12 lbs boost

What are your whp/wtq numbers on 12psi? What fuel are you tuned on?

tiller · 03-09-2018, 09:22 AM

Quote:

Originally Posted by Jinxx

I think it will be a wash in difference....what you gain from smaller pulley will be lost from lower rpm
And I have different gearing as well .. the nismos came with I think. 3.96 gear...non nismo was a little lower ... 3.69 if I remember right

guess we will see, it sure was a big difference between the 90mm and the 85mm after installed, it brought the boost in earlier but I think a little bit earlier would be even better, but that's just me and where I like my power and boost to come in, I think roughly a 7100k redline wont bother me to much, I reviewed my logs from last summer and they show a redline of 7587k redline with the 85mm while tuning with seb, if I don like it then its only 6 bolts to put the 85mm back on.

Jinxx · 03-09-2018, 02:55 PM

Quote:

Originally Posted by TopgunZ

What are your whp/wtq numbers on 12psi? What fuel are you tuned on?

I’m tuned with 93 octane

Jinxx · 03-09-2018, 05:28 PM

Quote:

Originally Posted by tiller

guess we will see, it sure was a big difference between the 90mm and the 85mm after installed, it brought the boost in earlier but I think a little bit earlier would be even better, but that's just me and where I like my power and boost to come in, I think roughly a 7100k redline wont bother me to much, I reviewed my logs from last summer and they show a redline of 7587k redline with the 85mm while tuning with seb, if I don like it then its only 6 bolts to put the 85mm back on.

I agree with the boost sooner ..that’s why I went with the 85mm ....the 80mm would be another notable difference early in the boost range which is what’s we are wanting ....that’s why the c38r should be a big improvement for our platform

tiller · 03-09-2018, 05:59 PM

Quote:

Originally Posted by Jinxx

I agree with the boost sooner ..that’s why I went with the 85mm ....the 80mm would be another notable difference early in the boost range which is what’s we are wanting ....that’s why the c38r should be a big improvement for our platform

Ya for sure, extremely curious to see c38r results

Jinxx · 03-09-2018, 07:31 PM

Quote:

Originally Posted by tiller

Ya for sure, extremely curious to see c38r results

I would expect at least 3-4 lbs increase for the whole rpm range .. which would be huge difference

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