Whipple supercharger Installation

POTTERJLUR · Mar 2, 2026

I've got a good friend wanting me to install one on his 392 was reminded with your picture about pinning the crank. How horrible was it to drill and pin in the tight engine bay?

hardhat · Mar 2, 2026

POTTERJLUR said:
I've got a good friend wanting me to install one on his 392 was reminded with your picture about pinning the crank. How horrible was it to drill and pin in the tight engine bay?

Was really not bad at all. Used a dewalt 20v right angle drill and clearance was not really a problem. The pinning kit did not include the bolt and the instruction were different than the pinning kit i received, but I had a bolt in my bins that worked just fine. Used tap magic and took my time. Went pretty smoothly. This was the part of the install that had me the most spooked, but really was not a big deal. Just take your time. Don't drill too fast. Check bit to make sure drill not getting too hot. Just took a few minutes and then blew all the crap out with compressed air, cleaned everything up and installed pins. Had to stick some bolts and a pry bar in the harmonic balancer to hold the crank to get the final torque on the crank bolt when reinstalling everything.

There are quite a few things in the instructions that could use improving. I could not get the TMAP connector on with the alternator and vacuum hoses installed. Had to take belt and alternator back off and then take a vacuum hose loose and ulitimately remove tmap to get connector on there. Would've been easy to hook it up and leave wire hanging earlier in install process and avoid double work. Some bolt sizes were listed wrong, but the right part was in the bag. Nothing that you won't be able to figure out.

hardhat · Mar 4, 2026

So install completed and jeep runs fine. So far so good, but afraid to go WOT.. I've dipped into the boost a fit and everthing seems fine AF ratio 11.5:1 under heavy throttle. No spark retard on VM scanner. Idles and drives great. Definitely can hear the supercharger and much more responsive at light throttle. I'm going to do some datalogging this weekend before I stand on it, but so far happy with results. No leaks, no funny noises and drives nicely. Temps are lower than stock due to 180 degree t-stat and fuel economy looks like it has not taken too much of a hit, but I'm driving it easy for now.

Notes on install. Connect the TMAP wiring before installing pcv vacuum hoses and putting alternator on. This was way out of order in the instructions. I had to take stuff off to get back to it. Some bolt sizes are wrong in instructions, but right part is in the bag. Looks like whipple is updating the labs on the bags that have the hoses. The replacement hose had its location on the bag and not just a part number. Hopefully they will update the hose instructions to match, but again, it is not rocket science and you can figure it out.

I did the homemade fosters whine mod by putting a 1/2" heater hose into the intake and piping that into the cabin and it is way too loud. Took that right out and can still hear the supercharger whine which is super cool. Now I just need to not blow it up for the next 40k miles.

This video was from the initial startup and that loud gear noise quit after a few minutes. I guess it was just the gear seating or something, but it is very quiet at idle now

RubiconHemi · Mar 4, 2026

hardhat said:
So install completed and jeep runs fine. So far so good, but afraid to go WOT.. I've dipped into the boost a fit and everthing seems fine AF ratio 11.5:1 under heavy throttle. No spark retard on VM scanner. Idles and drives great. Definitely can hear the supercharger and much more responsive at light throttle. I'm going to do some datalogging this weekend before I stand on it, but so far happy with results. No leaks, no funny noises and drives nicely. Temps are lower than stock due to 180 degree t-stat and fuel economy looks like it has not taken too much of a hit, but I'm driving it easy for now.

Notes on install. Connect the TMAP wiring before installing pcv vacuum hoses and putting alternator on. This was way out of order in the instructions. I had to take stuff off to get back to it. Some bolt sizes are wrong in instructions, but right part is in the bag. Looks like whipple is updating the labs on the bags that have the hoses. The replacement hose had its location on the bag and not just a part number. Hopefully they will update the hose instructions to match, but again, it is not rocket science and you can figure it out.

I did the homemade fosters whine mod by putting a 1/2" heater hose into the intake and piping that into the cabin and it is way too loud. Took that right out and can still hear the supercharger whine which is super cool. Now I just need to not blow it up for the next 40k miles.

This video was from the initial startup and that loud gear noise quit after a few minutes. I guess it was just the gear seating or something, but it is very quiet at idle now

Pretty cool. Just trying to get a frame of reference on the complexity of the installation. Are you a mechanic by trade or a mechanically inclined DIYr? Thanks

hardhat · Mar 4, 2026

Mechanically inclined DIY. I have a lot of tools though and parts of the install would've been almost impossible with just regular hand tools. U joint sockets came in handy as did short wrenches and ratchet wrenches.

RubiconHemi · Mar 4, 2026

hardhat said:
Mechanically inclined DIY. I have a lot of tools though and parts of the install would've been almost impossible with just regular hand tools. U joint sockets came in handy as did short wrenches and ratchet wrenches.

I read the directions and it also mentioned on Whipple's website that no modifications are required for the 392. Seems relatively straightforward to me. It looks like you had it powdercoated. Did you provide the powdercoat? (Update: nevermind, I reread one of your previous posts). I like the color. Please keep us updated, this is really cool and something Im putting on my near future project wish list. There has been a lot of negativity around putting a supercharger on a stock 392 and it seems Whipple might have it sorted out.

POTTERJLUR · Mar 4, 2026

Do you send the pcm to whipple to have it tuned and unlocked, or do they send you stuff in the kit to do it yourself?

hardhat · Mar 6, 2026

POTTERJLUR said:
Do you send the pcm to whipple to have it tuned and unlocked, or do they send you stuff in the kit to do it yourself?

So the way it works is whipple sends you the rtd to read and flash pcm. Send pcm to hptuners (included in cost of kit). Get code from whipple and they unlock and send pcm back. Then whipple sends tune locked to your rtd and car to flash tune to pcm. This all went smoothly. I got the MPVI4 so I can flash my own tunes or use a local tuner.

All went well with install. Got a belt chirp on cold start which sounds awful but supposedly this is common and gets better as belt wears in. Time will tell on that. All the pulleys look fine and chirp goes away after a minute. Awesome power at part throttle and cool blower whine sound inside cabin. I do not like the vacuum actuated bypass valve. It bypasses the blower while under vacuum and when you go heavy throttle, the valve closes (rather suddenly) and you get a burst of boost. This can come unexpectedly if you are rolling into the throttle is not a smooth transition. It is fine if you just stand on it, but I like rolling into the throttle and nice smooth predictable behaviour. Ordered a smoothboost boost controller that opens and closes bypass valve based on throttle position and lets you adjust boost with a knob. This seems like a good solution to make it stock smooth again. The hellcats come with an electronic bypass valve and this is similar to that.

Overall happy with install...just some teething problems to sort out. Hopefully will get it all sorted out over the next couple months, but still just going easy on it letting everything get a few miles on it before pounding on it much.

RubiconHemi · Mar 14, 2026

Hardhat.
Did you ever compare the Magnuson 392 supercharger to the Whipple? If so, what was your opinion? Thanks.

hardhat · Mar 14, 2026

I looked at both of them. The whipple has more room to grow I believe and is supposedly more efficient. Ultimately went with whipple in anticipation of dropping in a built engine down the road and felt the whipple would run the higher airflows better. Nothing wrong with magnuson however and it may be fine at the higher output as well. Still waiting on the smoothboost controller to get here and get tuned. Talking to christopher ward at saywhentuning. Reasonable prices and good reviews. Will keep you posted on how this goes. Belt chirp has improved. Only does it at cold start up and goes away pretty quickly. May try to troubleshoot it down the road, but just watching it for now.

RubiconHemi · Mar 14, 2026

hardhat said:
I looked at both of them. The whipple has more room to grow I believe and is supposedly more efficient. Ultimately went with whipple in anticipation of dropping in a built engine down the road and felt the whipple would run the higher airflows better. Nothing wrong with magnuson however and it may be fine at the higher output as well. Still waiting on the smoothboost controller to get here and get tuned. Talking to christopher ward at saywhentuning. Reasonable prices and good reviews. Will keep you posted on how this goes. Belt chirp has improved. Only does it at cold start up and goes away pretty quickly. May try to troubleshoot it down the road, but just watching it for now.

Thanks, really appreciate it.

hardhat · Mar 25, 2026

Update. Things are progressing nicely. Jeep drives great and no problems. Had some belt chirp/squeal that is probably due to an idler pulley being slightly out of line. Found a continental belt on amazon for $7 delivered and gave it a shot and it helped. Figured out why it was 7 dollars. Had a 2018 build date. Got a new continental for $37 from summit with 2025 build date and so far no recurrence of belt noise. These belts are quieter due to the softer rubber compound they use supposedly. Got the base tune from saywhentuning. Chris Ward has been great to work with so far. Got datalogs sent in. Jeep drives great. Only did the first drive at part throttle and have not done WOT tuning yet. Smoothboost controller should be here tomorrow and hopefully have the whole thing wrapped up soon.

hardhat · Mar 27, 2026

Shout out to Chris Ward at SayWhenTuning. He is doing a great job dialing this thing in. Got AFR right in mid 11's and started adding timing. This is a real beast. Max boost right at 5psi with 3.75 pulley which should be well in the safety zone. Hilarious how hard it spins the rear wheels even with traction control on

. Big jump in power over stock and drives great. Plan on getting smoothboost installed when I get back next week and do a few more pulls to finalize things, but makes the jeep even more crazy. Absolutely no detonation or triggering of knock sensors. Temps look good. Power is impressive. Hoping to drive it for a few years like this before getting a 426, cam and smaller pulley

. Temps rock solid at 185 cruising and have not seen 200 degrees yet, but it's not summer yet either so will see. Towing the boat will be next big test.

Say When Tuning & Performance

Say When Tuning & Performance specializes in high-performance tuning and engine packages for automotive enthusiasts. Achieve your performance goals today!

saywhentuning.com

These are good folks to work with and reasonable prices as well.

Losing traction in 1st gear and hitting limiter before it can shift....Sick....He just sent me an update to address this.

Srtmodmaster · Mar 30, 2026

prodriquez said:
Keep us updated. I’m trying to talk my wife into putting one in her 392

Run her easy brother! Stay with your intended boost range!!! I had my 392 in for bad lifters and head gasket leak, I probably should had done drop ins but my dealer did agree to use the scat pack nonmds cam and lifters along with a hellcat oil pump and this alone was a real nice surprise in power as they claim the manual skat cam has a much stronger power delivery! Runs super strong now but I refused to touch the pcm and all parts are mopar.

hardhat · Mar 30, 2026

Tried some launches in off-road plus today and it is hitting limiter and pulling torque. Will have to get that data logged when I get back from vacation. Tuner got the 1-2 shift fixed in regular mode. Guess off-road plus is a different table. Jeep is significantly faster than stock at 5 psi. Hopefully next few datalogs will finish everything up and I can just drive it

Noobicon · Mar 31, 2026

Is SayWhen tuning you remotely or are you local to them? Are they using HP Tuners?
I’m about to install a cam and headers this weekend and will need a tune. I would like to use someone familiar with the JL392’s

Srtmodmaster · Mar 31, 2026

hardhat said:
Was really not bad at all. Used a dewalt 20v right angle drill and clearance was not really a problem. The pinning kit did not include the bolt and the instruction were different than the pinning kit i received, but I had a bolt in my bins that worked just fine. Used tap magic and took my time. Went pretty smoothly. This was the part of the install that had me the most spooked, but really was not a big deal. Just take your time. Don't drill too fast. Check bit to make sure drill not getting too hot. Just took a few minutes and then blew all the crap out with compressed air, cleaned everything up and installed pins. Had to stick some bolts and a pry bar in the harmonic balancer to hold the crank to get the final torque on the crank bolt when reinstalling everything.

There are quite a few things in the instructions that could use improving. I could not get the TMAP connector on with the alternator and vacuum hoses installed. Had to take belt and alternator back off and then take a vacuum hose loose and ulitimately remove tmap to get connector on there. Would've been easy to hook it up and leave wire hanging earlier in install process and avoid double work. Some bolt sizes were listed wrong, but the right part was in the bag. Nothing that you won't be able to figure out.

Noobicon said:
Is SayWhen tuning you remotely or are you local to them? Are they using HP Tuners?
I’m about to install a cam and headers this weekend and will need a tune. I would like to use someone familiar with the JL392’s

Hp tuners will handle everything with a laptop

Noobicon · Mar 31, 2026

Srtmodmaster said:
Hp tuners will handle everything with a laptop

It’s the person controlling the laptop that I’m concerned with!

hardhat · Mar 31, 2026

It is remote tuning. Using hp tuners. Using wideband and vcm scanner to catalog. This guy specializes in nailing drivability as well as wot performance. Going well so far. Will get smoothboost installed when I get back from vacation and hopefully get it nailed down with 2 or 3 more revisions. Wanting safe tune that drives like stock just more power.

hardhat · Mar 31, 2026

Noobicon said:
Is SayWhen tuning you remotely or are you local to them? Are they using HP Tuners?
I’m about to install a cam and headers this weekend and will need a tune. I would like to use someone familiar with the JL392’s

Having a wide band is very helpful and many of the tuners require you to have one otherwise they are guessing at air fuel ratio. The cam will significantly change volumetric efficiency at different RPMs so a wide band might be needed.