Harrop Supercharger Stage 5 vs 6

[Capt Spaulding]

Originally Posted by Irace86.2.0

Aww, I too didn’t read carefully enough. So these are flywheel estimates so whp will be less, so maybe 45 extra hp going from 8 psi to 11.5 psi according to them with a pulley change and a catback. 305 kW = 410 hp. Assuming a 15-20% drivetrain loss, that is 328-348whp, but probably closer to the lower numbers. That is probably possible on the 85mm pulley on E85 with an aggressive tune, but it is a little high for a conservative tune. I think those numbers would come more from the 75mm pulley. This is a forum member with the 75mm pulley with E85, and I believe he said it was a conservative tune, but I can’t remember, yet he is making 360whp, which a decent amount more than the numbers they gave as an estimate for a 85mm tune, which might be aggressive. The more boost, the more headers and exhausts will make a difference too, as there is more potential for a restriction.

Man, every time I see that plot I have to make a discreet trip to the mens room for some "me time."

[Irace86.2.0]

Originally Posted by 86TOYO2k17

Dropping compression when not being knock limited will drop power a lot. Especially true with ethanol almost to the point of losing power proportionately to the percent of drop, IE 12.5 to 10 will drop power 20% unless you can make up for that drop with lots of timing/boost (turbo) it’s pointless with a supercharger on ethanol. Perfect example is the few people who went sprintex 335 on E85 with 10:1 compression on small pulley made same power as everyone else on sprintex 210 E85 same pulley. Even though they making way more boost. Or in his case on harrop ethanol 65mm pulley. Maybe arguments for safety margin on track or when ethanol isn’t available. But its a big power sacrifice when sub 20psi on ethanol. Maybe a minor 12:1 or maybe 11.5:1 drop tops.

I agree. I would only drop compression if I was on pump gas or was going for huge numbers. Gains from adding boost are greater than adding compression, so it only makes sense on pump gas or if I was going for 20+ psi, but like you said, that isn't available on these superchargers.

[grumpysnapper]

Originally Posted by Irace86.2.0

Your low compression build isn't as relevant, but you are still putting down around 435hp at the flywheel or 324kW. What is your compression ratio?

Its the IAG 10.6, primarily because E85 is actually very hard to get here in Australia, so in reality I run on (bad) 98ron for 95% of the time.

Nah, certainly don't call foul on Harrop, because as ever, dyno's, temps, operators, humidity, fuel quality, etc etc etc etc .... always make direct comparison's difficult to interpret.

[grumpysnapper]

Originally Posted by 86TOYO2k17

Dropping compression when not being knock limited will drop power a lot. Especially true with ethanol almost to the point of losing power proportionately to the percent of drop, IE 12.5 to 10 will drop power 20% unless you can make up for that drop with lots of timing/boost (turbo) it’s pointless with a supercharger on ethanol. Perfect example is the few people who went sprintex 335 on E85 with 10:1 compression on small pulley made same power as everyone else on sprintex 210 E85 same pulley. Even though they making way more boost. Or in his case on harrop ethanol 65mm pulley. Maybe arguments for safety margin on track or when ethanol isn’t available. But its a big power sacrifice when sub 20psi on ethanol. Maybe a minor 12:1 or maybe 11.5:1 drop tops.

E85 is hard to find in Oz, so I'm on 98ron for the vast bulk of the time (and Oz ron ratings are rubbish too).

[86TOYO2k17]

Originally Posted by grumpysnapper

E85 is hard to find in Oz, so I'm on 98ron for the vast bulk of the time (and Oz ron ratings are rubbish too).

Even a 30% mix does wonders.

I have 6 - 5 gallon justrite safety can type 2
in a 30 gallon eagle flammable cabinet in my garage.

Add 1 - 5 gallon jug to 5.5gallons Pump got me E43 every time. and combined with WMI I had same timing as I would with full E85.
with Bi weekly fill ups. Id make the 1 1/2h round trip once every 3 months.
Not bad for all the benefits of ethanol.

[Irace86.2.0]

Originally Posted by 86TOYO2k17

Even a 30% mix does wonders.

I have 6 - 5 gallon justrite safety can type 2
in a 30 gallon eagle flammable cabinet in my garage.

Add 1 - 5 gallon jug to 5.5gallons Pump got me E43 every time. and combined with WMI I had same timing as I would with full E85.
with Bi weekly fill ups. Id make the 1 1/2h round trip once every 3 months.
Not bad for all the benefits of ethanol.

I do the same with 30 gallons worth of E85, but I have such a short commute that I can do 3 months on full E85. I’ll be starting nursing school in the fall, so I’ll be commuting more, so I’ll consider doing more of a mix. We are suppose to get two stations locally, so I won’t have to drive 25 miles to fill up. What boost level are you at?

[86TOYO2k17]

Originally Posted by Irace86.2.0

I do the same with 30 gallons worth of E85, but I have such a short commute that I can do 3 months on full E85. I’ll be starting nursing school in the fall, so I’ll be commuting more, so I’ll consider doing more of a mix. We are suppose to get two stations locally, so I won’t have to drive 25 miles to fill up. What boost level are you at?

I was at 13.5psi according to my boost gauge w/ 69mm on sprintex 210.
I believe injecting wmi pre compressor is chemically changing my VE and adding 1psi of boost as 69mm should be 12.5.