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Post supercharger modifications - need more HP!

9K views 46 replies 12 participants last post by  Boost LI 
#1 ·
Hi Guys, great forum, really impressed with some of the builds and the knowledge base here.

I'm from Australia and recently bought a 2014 WK2 SRT with a Ripp supercharger kit installed. It runs a dual 3inch stainless system with extractors, front mount and I assume the standard supercharger which is sold with the Ripp kit. I've measure the pulley at about 88mm (very outside diameter) which is 3.45 inches in US talk.

Dyno report I got with the car states 535hp at the wheels, im guessing this is on 6PSI boost?
Car, motor and drive train are in perfect condition having done 20,000 miles.

I've done a best of 3.5 seconds 0-100kph, which is equivalent to 63 mph, regularly is more like 3.8 though.
1/8 mike runs are around 7.5 seconds depending on launch.

I'm from the coldest part of Aus, typical summer good day is around 75 (25 celcius) with much of the year 50 to 60 normal.
I live at sea level too.

Please offer you're advice on the following, happy to be lead on the right track if I'm off.

My goal would be to have 750 wheel horsepower, which should be very comfortable 10 sec 1/4 miles.

The first thing I've learned from reading is these bottom ends are too fragile, so strengthening is recommended.
With workshop costs in Aus being so high, it's actually going to be cheaper for me to import a short block (strengthened and decompressed) than it is to rebuild my current motor, and put that in.

The logic there is that if anything goes wrong, or I want to take the car back to stock, I've got the original, unmolested block ready to go again too.

Is there any reason not to go 440ci here? They don't seem to cost much more, and I figure it just makes the hp easier to achieve.
Most companies selling short blocks offer different compression ratios, is 9.5 - 1 a good compromise or will that make it lazy off boost?

Next, is it possible to retain the Vortech Ripp supercharger and have it modified with my goals in mind? If so, what internal changes are done?

Funding all this isn't really an issue, however it will be satisfying if I can retain some existing bits.

Finally, struggling to get info on the transmissions, seems to be varied opinions on how much power they can take. What mods (if any) can be done to them?

Advice from those who have done this before is much appreciated.
 
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#2 ·
I'd run meth to protect that set up. So many questions, I'm tired right now...lol...I would do a compression test, leakdown test and camera bore inspection to see all is well with current motor. I have 750-800awhp that I'm able to use due to transmission torque management and it's not a comfortable 10...it's a 10.998. The transmission may hold together but it will also hold you back. I know of one transmission that recently gave up. You'll have to wait for transmissions/trans. tunes that guys are working on. Perhaps the HP95 from the new Hellcat Jeep will work, who knows? The rear end will hold as long as you don't abuse it and/or run it in rwd...I've wrecked two. There is a heavy duty rear end out now. I would go 9-9.5:1 and personally I kept the stock 392 size to keep some meat on the block and am trying to run higher boost to make up the hp. 392 is how this motor was designed and I figure SRT knows something. This allows for a hone/bore down the road. We have a 448 in a 16 Ram and it's powerful at 11:1 but it will never be boosted. The Ripp s/c will have to go as it's too small to support anymore hp than you already have. In fact, a lot of guys have blown ring lands with that kit. I blew ring lands in my stock 6.4 with a D1 due to running too lean. I like the whipple kits and Procharger. I have an F1A and maybe going bigger. The crazy people (& trust me they're here...lol) run a turbo or two and I think that's cool and I would probably try that next time just to try something different and see what it's like. The fastest hemi is a Procharged one but the fasted Jeep is turbo. Glad you're asking for advice to learn from others mistakes but if you're like me you'll ask a lot of questions and then do what you want to do anyway...that's what I did...lol! You don't want to be denied living out the experience of your decisions....good or bad!! Good luck with that bad boy...lots of guys here will help you.
 
#3 · (Edited)
Congratulations on your purchase! Im the guy with the twin turbo rig. I really think from your post it sounds like you need to ditch that mini sucker. I think u should go with a nice single turbo or twin turbo and ur jaw will drop 2 years after its built like the first day u got it. Or go with a bigger blower like a whipple or a f1 like passmg2. As for a 440. 90 percent of the guys running 440s ar N.A guys with 11 to 1 comp. U can make 1000 hp+ on a forged 392. Doesnt make a difference. Buy a 426 and ship her up there. 9 to 1 or 9 and a half to one is perfect for a forced induction motor. Unless ur running a higher octane in the tank. U could go 10 and a half to 1 on ms109 or greater but for a daily keep ur compression low and feed her some boost. Ull forget u even asked about more compression.

So.... forge ur motor doesnt matter if u do a 392 or 426 or whatever. Keep ur compression 9 and a half to 1. Drop that baby blower. Grow a pair and put some hair dyers on that thing!!


Welcome to the forum these guys are great
 
#8 ·
Thanks for all the input.

Fair point on the 426 vs a 440ci.
If a motor is built well then surely something would have to go catastrophically wrong to need a rebore?
The 426 seems to be getting the nod by many, so I'll look into that.

Regarding the Procharger, Passmg2 is there any special specs your blower runs or is that item an off the shelf Procharger F1A?
If you go bigger, what unit are you considering next?

Sillyhp, I could find a few single turbo kits which are pre made, but I figure something like your twin turbo job is fully custom?

The biggest problem for me in Aus is that I will be purchasing as much as possible which is proven from the US, so I want a setup as complete as possible.
We have nowhere near the range of workshops that you guys do who deal with Jeeps, so I'd like to remove as much guess work as I can by getting exactly what I have to from the US.

Do you guys recommend anyone for short blocks and the supercharger? (supply not tuning).

High Horsepower Performance appear to be recommended here.
 
#9 ·
Go with demon. Hell set u up with a hell of a motor and a blower and or turbo. My guy is workin on a twin kit for our jeeps but hese the only one. I think demon can set u up with a single turbo. And yes just a off the shelf f1a. Go twin screw like a whipple. Make lots of toise and lots of torque. Fun street blowers
 
#10 ·
I'm not sure of drivability and street manors of a whipple however I do know grandma could drive my Jeep if she were still alive and ever got her license. It drives beautifully. The power of a centrifugal blower ramps up linearly with rpms and is not as instant as a pd blower which I guarantee you will be easier on your rear end and transmission. I know of no whipple Jeep that has run a 10 yet if that matters.
 
#11 ·
Im not saying the Procharger isnt legit. It makes power thru and thru. But ive had three different kenne's and a whipple on different set ups. As well as a d1 thru f1a. For street driving i got rid of the centri for how fun the kenne bell was. It was just a blast to drive. I think there just isnt enough people putting whipples on because of a few reasons. One the whipple is a tad more expensive. 2 there was a few early problems tuning it on the wk2. But in the charger challenger world they are everywhere and such a blast. Just like turbos i think if people were able to jump from a twin screw to a centri setup they would stay in the twin screw most the time for what u get on the street. Im not arguing the reliability of a centri setup. Its great. But i also got 30k miles out of my 6.1 kenne bell setup. I think a few more people in the wk2s need to get into the twin screws and turbos and start moving this platform a little. But on the other end if u watch any vids of george goin down the track in his white f blown jeep its a hell of a setup.
To each is own. I love the noise and the power down low of a twin screw. But i prefer turbos because u get the best of both worlds if u do it right.
 
#17 ·
On a very similar topic I have been strongly considering going the FI 426 route.

Here is a list of what I was recently quoted. I am not a mechanic. Is this all worth it to get safe / great results or is some of it overkill? What boost / hp do you think this setup will run reliably?


The 426 will run $5500 for boost using Callies crank, rods and diamond pistons with ARP studs.
Camshaft and phase limiter/lock $900
Gaskets/Bolts $350
Spring kit $400
Whipple $6800
Labor $3600
Tuning $550
Dyno time $200
If you want ported heads add $2399.

Thanks in advance guys!
 
#20 ·
To be perfectly honest; if I am going to be getting into the block to forge it, I may as well take a couple extra steps and add more power that im probably going to want down the road anyway. No point in getting into it twice and paying for the extra labor. Also, to me, having the 426 instead of the 392 just sounds/feels more unique. Even though a lot of SRT owners have gone the 426 route. It's a bit of a "my jeep is custom" kind of feel to it.

Do you have reasons why I should avoid that route and just forge the 392? I have read that it is great to keep the cylinder walls thicker... And obviously cheaper to not go the stroker route.

Btw thank you for responding.
 
#22 · (Edited)
^^^ I hear what you're saying although the motor was designed at 392 cubic inches and I just decided I would stick with those dimensions and decent parts and up the boost a little. I think it's a pound or two of boost will make up 25-50 cubic inches (correct me if I'm wrong). We have a 448 cubic inch (7.3 litre) 11:1 6.4 based hemi in a 2016 R/T pick up and it's fun and will never be boosted. Sometimes I wonder about 426 up with my set up but I can't use all the power my motor is capable of now until the transmission torque management is tamed. This way, I also got a brand new block instead of a used one bored out and that might have partly been luck and for sure because I didn't go bigger. Next go 'round, I can go bigger and my current block will have a good chance of being reusable...lol.

P.S. Plus the smaller motor gets better gas mileage.:eek:
 
#24 ·
Is there any evidence that a 440 is taking things too far in terms of wall thickness?
I have no idea how much meat is left in the block after these mods, but I guess it would be a shame to waste a block as you blew a motor after taking things too far.

The Procharger vs Whipple is an interesting debate, more tempted to go Procharger as there seems to be a greater number of these around properly worked.
 
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