Project Su­per­charger

A su­per­charger con­ver­sion has given Ja­son Mars­den’s Jeep Wran­gler a new lease on life.

NZ4WD - - JEEP ENGINE UPGRADE - Story & pho­tos by Ja­son Mars­den

Not even overly gen­er­ous mo­tor­ing jour­nal­ists would have de­scribed the 3.8 litre V6 en­gine of the Jeep JK Wran­gler as ad­e­quate. The Amer­i­can mini­van mo­tor was no doubt cho­sen as a known and re­li­able run­ner. Slightly more fuel ef­fi­cient than the revered 4.0 litre straight six found in ear­lier Wran­glers, the mo­tor soon dis­played a lack of high­way power as JK own­ers started bolt­ing on big­ger steel wheels, bars, winches and all the rest of the tens of thou­sands of up­grade parts avail­able for the plat­form. The lat­est Pen­tas­tar 3.6 en­gine re­leased in 2011 com­bined more power with bet­ter fuel econ­omy, but for own­ers of the pre­vi­ous model who had in­vested heav­ily in up­grades the prospect of start­ing from scratch again may be daunt­ing from both a cost and time/ ef­fort per­spec­tive. Small and some­times de­bat­able power gains were to be had from tuners us­ing head­ers, ex­haust and throt­tle body spac­ers. How­ever, for 3.8 own­ers the only op­tion to gain real ad­di­tional power was a V8 en­gine swap or forced in­duc­tion.

First choice

A V8 en­gine swap was my first choice for my 2009 four-door JK Wran­gler. Un­for­tu­nately the bolt on Hemi kits (com­plete with ECU to main­tain CAN bus and dash func­tion­al­ity) were only avail­able for left hand drive Jeeps. Work­ing some num­bers it also looked like such an ex­er­cise could po­ten­tially be very ex­pen­sive. Other V8 op­tions such as LS (Chev) en­gines were also con­sid­ered but the com­plex­ity of a non-stan­dard in­stall and loss of dash func­tion­al­ity soon rel­e­gated them to the too hard bas­ket. This just left forced in­duc­tion. The pri­mary process of us­ing forced in­duc­tion to get more power out of an en­gine is to cram more air and fuel into it. The more fuel and air in a cylin­der then the more work it can do. Spe­cial­ist 4WD me­chanic, Rick Cros­bie, of Sum­mit 4WD in Christchurch had done some pre­lim­i­nary work on the V8 op­tion and when that was aban­doned he sug­gested a RIPP Su­per­charger kit. RIPP Su­per­charg­ers is a Staten Is­land, New York-based de­signer and man­u­fac­turer of forced in­duc­tion prod­ucts for all Fiat Chrysler (Jeep, Dodge, Chrysler etc) ve­hi­cles. And as I dis­cov­ered, there are sev­eral su­per­charger kits avail­able for the JK along with turbo op­tions also.

Both types

Not only that but su­per­charg­ers are avail­able in both cen­trifu­gal/dy­namic and pos­i­tive dis­place­ment types. The main dif­fer­ence be­tween these two types is that the pos­i­tive dis­place­ment type de­liv­ers con­stant pres­sure but is less ef­fi­cient at high revs whereas a dy­namic cen­trifu­gal blower de­liv­ers more boost as the revs climb and is more ef­fi­cient at higher boost. And of course the main ad­van­tage of a crankshaft­driven su­per­charger over an ex­haust gas-driven tur­bocharger is a lack of lag. Typ­i­cally tur­bocharg­ers suf­fer from lag and really only come into their own at high revs. The RIPP kit we set­tled on utilises a Vortech brand cen­trifu­gal com­pres­sor, driven off the ser­pen­tine belt which then passes the com­pressed air through an in­ter­cooler to bring the gas tem­per­a­ture down (in­creas­ing den­sity) be­fore en­ter­ing the man­i­fold. I jumped on the RIPP web­site and was im­me­di­ately pleased to see “we fit RHD”. Af­ter surf­ing around var­i­ous web­sites and fo­rums I was sat­is­fied that RIPP ap­peared to be one of the most pop­u­lar and proac­tive man­u­fac­tur­ers of su­per­charg­ers for Jeeps. There are al­ways go­ing to be some neg­a­tive com­ments for any prod­uct on­line but ev­ery neg­a­tive com­ment on fo­rums seemed to be im­me­di­ately fol­lowed by a re­sponse from RIPP.

Or­der up

Sat­is­fied that RIPP was the right com­pany to go with I pushed the go but­ton and the or­der was placed. The kit comes com­plete with all the nec­es­sary parts along with very de­tailed and com­pre­hen­sive in­struc­tions. Parts not only in­clude all the nec­es­sary su­per­charger and in­ter­cooler plumb­ing and brack­ets but new spark plugs, in­jec­tors, MAP sen­sor and Di­ablo tuner for in­stalling the new en­gine map. An added ad­van­tage of the kit is that if need be it can be by­passed by just re­in­stalling the fac­tory ser­pen­tine belt, ef­fec­tively tak­ing the su­per­charger out of the loop and the ve­hi­cle will still run? The in­struc­tions sug­gest the in­stall will only take a day but with an af­ter­mar­ket trans cooler (another JK must-have) al­ready in front of the ra­di­a­tor the ques­tion was do we stack the in­ter­cooler on top or look to re­lo­cate the trans cooler. The fi­nal de­ci­sion (due in large part to lack of ob­vi­ous op­tions) was to stack them. There was just enough space be­tween the seven slot grille and ra­di­a­tor to al­low this to hap­pen.

Proof of the pud­ding

Never one to trust man­u­fac­turer’s claimed power gains we took the op­por­tu­nity to con­duct a dyno run be­fore work com­menced as a base line. With its wide wheel track the Jeep only just cleared the edges of the dyno roller pit and I had vi­sions of it drift­ing side­ways, hit­ting the edge and ei­ther jump­ing off the dyno or strip­ping the side­wall treads off my new Coop­ers. For­tu­nately the Jeep stayed straight and true for the run and two days later we were back at the dyno tuner’s re­peat­ing the ex­er­cise. The stock run pro­duced peak power of 93.1kW and 797Nm of torque. With the su­per­charger in­stalled peak power rose to 139.0kW and torque jumped to 1158Nm. That was an in­crease of 49

per­cent power and 45 per­cent torque! Be­hind the wheel the first thing you no­tice on start-up is the sound. Su­per­charg­ers have a dis­tinct whine/whis­tle. This dis­ap­pears as revs climb but is cer­tainly no­tice­able at idle, crawl and will gain the at­ten­tion of those petrol­heads who know their en­gine sounds. There is also a blow-off valve to re­lease pres­sure when com­ing off heavy boost, no­tice­able on oc­ca­sion but nowhere like the boy racer trum­pets fit­ted to most Subaru WRXs.

Sense of ur­gency

The en­gine al­most has an ur­gent feel to it now. In the past an in­crease in en­gine noise did not nec­es­sar­ily trans­late to a cor­re­spond­ing in­crease in for­ward move­ment, now the more noise means more ac­cel­er­a­tion and as the revs climb so does the boost. Up to about 3000rpm the in­take is run­ning at neg­a­tive pres­sure as the en­gine sucks air in and the ini­tial su­per­charger boost is just negat­ing this un­til it hits pos­i­tive pres­sure. The su­per­charger is rated to max boost of 11psi but in re­al­ity nor­mal driv­ing will de­liver enough per­for­mance well be­low this and within the nor­mal rev range. One ad­di­tional project was the ne­ces­sity to con­nect my Sa­fari snorkel back up. The su­per­charger sits in some of the space taken by the fac­tory air­box and if you are happy to run just an open pod fil­ter then all good. Most of us of course rely on snorkels so it was off to see Corey Tay­lor at Da Vinci Steel­works to have a cus­tom air­box made up to fit the very tight re­main­ing space. Corey did a great job work­ing around the var­i­ous pro­jec­tions in the area to end up with a wa­ter­tight alu­minium box that even used the fac­tory en­gine bay air­box mounts.

Pay back

At 2.35 tonnes the Jeep is never go­ing to be a race car but on the open road the ex­tra power makes in­clines and pass­ing a breeze. Off-road the ex­tra torque al­lows ob­sta­cles to be climbed at slower speed rather than hav­ing to rely on mo­men­tum and bounc­ing up and over. Fuel econ­omy for con­stant speed driv­ing seems to be about 2-3 litres/100km bet­ter but short trips with lots of start­ing and stop­ping or heavy ac­cel­er­a­tion will see you use cor­re­spond­ingly more fuel. One down­side is slight surg­ing when cruise con­trol is en­gaged. If you are a long dis­tance cruise con­trol user then this may be an­noy­ing. In sum­mary if you are look­ing for se­ri­ous power gains from your 3.8 and are not pre­pared to take on the cost and chal­lenges of a V8 swap then a su­per­charger is prob­a­bly your best bet. You can ex­pect to in­vest $12-13K in a RIPP su­per­charger and in­stal­la­tion (there are cheaper kits out there) but this will still be sig­nif­i­cantly less than a V8 swap un­less you are do­ing the work your­self. Big thanks to Rick Cros­bie at Sum­mit 4WD and Corey Tay­lor, owner of Da Vinci Steel­works.

The ef­fort was worth it (see be­fore and af­ter lines).

In­ter­cooler tucked in be­hind grille.

Only just fits on the dyno!

RIPPS kit parts laid out on work­shop bench at Sum­mit 4WD.

En­gine bay shot be­fore the su­per­charger was fit­ted.

En­gine bay af­ter in­stall but no snorkel con­nec­tion.

And the en­gine bay af­ter­wards.

And com­plete with cus­tom air­box for snorkel con­nec­tion.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.