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The Insane Inline, Part 3

Posted in How To: Transmission Drivetrain on January 31, 2006 Comment (0)
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The Insane Inline, Part 3
154 0512 01z+1999 jeep cherokee xj+high front right view

The Insane Inline, Part 1
The Insane Inline, Part 2
The Insane Inline, Part 3

If you tuned in last issue drooling to see the final installment of our Golen Engine Service 4.6L stroker swap, all we can say is sorry. It's pretty common for magazine writers to have the occasional story go completely awry, but this author had three stories in one issue disintegrate into a series of setbacks. Rather than half-ass the final part of this story and leave you with unanswered questions, we decided to kick the story back an issue so we could have the vehicle properly tuned, smog tested, and dyno'd. Unfortunately, the G-Tech performance meter we had hoped to use to give you some 1/4-mile times was on severe backorder, so those numbers will have to wait for another day.

Turbo City Tune After getting the new stroker installed into the engine bay, we fired it up, checked for leaks, double checked the coolant level, and took it for a blast down the road. Even with 91-octane fuel in the tank, there was severe knocking upon mildly hard acceleration. Full throttle use was out of the question. The stock 19 lb/hr injectors just weren't capable of supplying enough fuel to feed the extra cubes and the engine seemed a bit lazy out of the hole.Rather than fumble for our asses in a dark room with both hands, we took our 1999 XJ to Turbo City in Orange, California, to have the fuel injection experts tell us what we needed to do. Turbo City has a vast amount of experience with fuel injection systems and really goes the extra mile to provide the customer with top-quality work. For example, rather than sending us packing when we unknowingly dropped off our XJ with a cracked and leaking header, the guys tore it off, welded it up, and reinstalled it without a whimper.

Before we did anything, we needed to address a slight issue with our crank pulley. The 4.2L crank used in the stroker buildup is a long-nose crank, while the stock 4.0L crank is a short-nose crank.  As a result, our crank pulley/harmonic balancer wouldn't line up with the other pulleys. We bought this machined aluminum crank pulley spacer from Hesco, which allowed our 4.0L harmonic balancer to fully seat onto the crank and bring the pulleys into alignment. Before we did anything, we needed to address a slight issue with our crank pulley. The 4.2L crank used in the stroker buildup is a long-nose crank, while the stock 4.0L crank is a short-nose crank. As a result, our crank pulley/harmonic balancer wouldn't line up with the other pulleys. We bought this machined aluminum crank pulley spacer from Hesco, which allowed our 4.0L harmonic balancer to fully seat onto the crank and bring the pulleys into alignment.
The guys at Turbo City have been working on sophisticated fuel systems seemingly forever. The company is intimately familiar with the fuel systems of both old and new Jeep vehicles and was able to diagnose and fix several trouble areas with our XJ, beginning with a severely cracked header. The guys at Turbo City have been working on sophisticated fuel systems seemingly forever. The company is intimately familiar with the fuel systems of both old and new Jeep vehicles and was able to diagnose and fix several trouble areas with our XJ, beginning with a severely cracked header.
The cracked header was throwing off the O2 sensor.  Many shops would have sent us elsewhere to have it fixed, but Turbo City removed and welded our header, then interfaced with the OBDII computer to determine exactly what was going on with the fuel system. The cracked header was throwing off the O2 sensor. Many shops would have sent us elsewhere to have it fixed, but Turbo City removed and welded our header, then interfaced with the OBDII computer to determine exactly what was going on with the fuel system.
Although the calculations Tom Miller at Turbo City made called for 21 lb/hr injectors, we stepped up to some Accel 24 lb/hr injectors since these engines notoriously run lean and to support any future performance modifications we may make. However, before swapping injectors, Turbo City needed to change our late-model injector harness connectors (shown) to the earlier Bosch style. Although the calculations Tom Miller at Turbo City made called for 21 lb/hr injectors, we stepped up to some Accel 24 lb/hr injectors since these engines notoriously run lean and to support any future performance modifications we may make. However, before swapping injectors, Turbo City needed to change our late-model injector harness connectors (shown) to the earlier Bosch style.

Although our OBDII computer basically wants to do what it wants to do and Turbo City said the correct way to dial in our system was to reflash the computer, we asked that they just put the scan tool to our system to see where they could go with the factory settings. After replacing the fuel injectors with larger Accel 24 lb/hr parts, they modified our crank position sensor to advance the ignition timing 3 degrees. With their modifications complete, another scan revealed that our fuel system was pulling back fuel both at idle and during normal cruise, trying to get the air/fuel ratio down to a lean 15:1. However, under acceleration the computer was allowing more fuel, with air/fuel ratios back to stock levels of 13:1 or richer. Compared to how lean our engine used to run with the stock 4.0L and our modifications (see Sidebar, Power Play) the fatter fuel curve on our stroker as dialed in by Turbo City nearly mirrored that of our unmodified 4.0L. Although the fatter air/fuel ratio we're running is most likely costing a bit of power, there's no pinging even with 89-octane fuel and full-throttle blasts.

The Bosch-style connector is what all 1998-earlier and some early 1999 Jeeps, as well as Ford vehicles use and Turbo City had a good supply of them in stock.  The Accel injectors are truly high-quality pieces that deliver their advertised flow rating, along with excellent fuel atomization for better economy and throttle response. The injectors are an anti-plugging type, which means they eliminate problems associated with carbon build up. The Bosch-style connector is what all 1998-earlier and some early 1999 Jeeps, as well as Ford vehicles use and Turbo City had a good supply of them in stock. The Accel injectors are truly high-quality pieces that deliver their advertised flow rating, along with excellent fuel atomization for better economy and throttle response. The injectors are an anti-plugging type, which means they eliminate problems associated with carbon build up.
To get some more snap in the bottom end, Turbo City offers its adjustable crank position sensor, PN 635-460 we advanced our timing 3 degrees. The modification increased our throttle response off idle big time. To get some more snap in the bottom end, Turbo City offers its adjustable crank position sensor, PN 635-460 we advanced our timing 3 degrees. The modification increased our throttle response off idle big time.
The 24 lb/hr Accel injectors proved a nearly perfect match for our engine. Turbo City installed its adjustable MAP sensor, PN 635-425, but removed it once determining our OBD II engine didn't need it. In all likelihood, an older OBD I system would benefit from the unit's adjustability of the fuel map. The 24 lb/hr Accel injectors proved a nearly perfect match for our engine. Turbo City installed its adjustable MAP sensor, PN 635-425, but removed it once determining our OBD II engine didn't need it. In all likelihood, an older OBD I system would benefit from the unit's adjustability of the fuel map.


Power Play
For our chassis dyno numbers we revisited The Dyno Shop in Santee, California. Owner Mark MacNeil and the rest of the gang have forgotten more about diagnosing, modifying, measuring, and extracting power from vehicles ranging from $100K turbo Porsches to carbureted dune buggies than we'll ever know. The Dyno Shop baselined our XJ back when it was stock and when we added our Gibson header and exhaust, K&N FIPK air intake, Performance Distributors Firepower Ignition Kit, Rubicon Express 62mm throttle body, and Hypertech Power Programmer (although the stroker uses factory computer calibrations).

MacNeil says our horsepower levels could be brought up quite a bit more with some computer tweaking and some leaning of the air/fuel curve. We were nervous about dinging our new engine, so we purposefully jetted our NOS nitrous system too rich. We're considering adding a larger 66mm throttle body down the road to get some more air into the engine and may tweak the computer, but for now we're happy with the added power across the entire rpm range without worrying about knocking or harming the engine.

Even though we've been experimenting with 89- and 87-octane fuel, all of our dyno testing was performed with 91-octane premium pump gas.

Test 1:
Bone Stock 4.0L

RPM: Power: Torque: Air/Fuel Ratio:
3,500       114 171 11.9:1
3,600 116 170 11.9:1
3,700 118 168 11.8:1
3,800 124 172 11.7:1
3,900 130 176 11.7:1
4,000 127 166 11.8:1
4,100 125 161 11.8:1
4,200 126 157 11.7:1
4,300 128 156 11.7:1
4,400 129 154 11.6:1
4,500 131 153 11.4:1
4,600 132 151 11.4:1
4,700 133 148 11.5:1
4,800 133 145 11.4:1
4,900 130 139 11.3:1
5,000 130 137 11.2:1
5,100 126 130 11.1:1
5,200 124 125 10.9:1
5,300 122 121 10.8:1
5,400 NA NA NA 

Test 2:
4.0L Gibson Header and after-cat exhaust, Rubicon Express 62mm throttle body, K&N FIPK air intake, Hypertech Power Programmer, Performance Distributors Firepower Ignition Kit

RPM:  Power:  Torque:  Air/Fuel Ratio:
3,500       132  197  14:1
3,600  134  195  13.7:1
3,700  136  193  13.7:1
3,800  142  196  13.9:1
3,900  146  197  14.1:1
4,000  152  200  14.2:1
4,100  147  188  14.3:1
4,200  149  187  14.3:1
4,300  150  183  14.3:1
4,400  151  180  14.2:1
4,500  152  178  14.0:1
4,600  152  174  13.9:1
4,700  152  169  13.8:1
4,800  151  165  13.8:1
4,900  146  157  13.7:1
5,000  142  150  13.7:1
5,100  139  143  13.6:1
5,200  138  140  13.5:1
5,300  NA  NA  NA 
5,400  NA  NA  NA 

Test 3:
Golen Engine Supply 4.6L with Turbo City mods & Accel Injectors

RPM:  Power:   Torque:   Air/Fuel Ratio:
3,500       149 224 11.9:1
3,600 152 222 12.0:1
3,700 154 218 12.1:1
3,800 155 215 12.1:1
3,900 162 218 12.1:1
4,000 165 217 12.0:1
4,100 167 213 11.9:1
4,200 172 216 11.8:1
4,300 167 204 11.8:1
4,400 164 196 11.7:1
4,500 161 188 11.6:1
4,600 162 185 11.5:1
4,700 163 182 11.5:1
4,800 164 179 11.5:1
4,900 161 172 11.6:1
5,000 161 169 11.6:1
5,100 158 162 11.6:1
5,200 147 149 11.5:1
5,300 123 121 11.3:1

Test 4:
Same as Test 3, but with NOS 75hp Nitrous System

RPM:  Power:   Torque:   Air/Fuel Ratio:
3,500       NA NA NA
3,600 182 268 10.9:1
3,700 177 251 10.6:1
3,800 177 244 10.1:1
3,900 173 233 10.0:1
4,000 187 245 10.0:1
4,100 203 260 10.0:1
4,200 204 256 10.0:1
4,300 204 249 10.2:1
4,400 207 247 10.1:1
4,500 211 247 10.1:1
4,600 209 239 10.0:1
4,700 208 233 10.0:1
4,800 210 230 10.0:1
4,900 211 226 10.1:1
5,000 207 217 10.2:1
5,100 203 209 10.0:1
5,200 191 193 10.0:1
5,300 NA NA NA 

154 0512 06z+1999 jeep cherokee xj+rear view

Clearing the Smog Hurdle
There's been a lot of speculation as to whether or not a stoker engine with a hotter Comp Cam's Xtreme 4x4 268 cam would pass the sniffer test. With Turbo City's tuning completed, we swung by our local smog station and had the 1999 XJ tested. Our XJ not only passed, but passed with flying colors. The HC level was half of the maximum allowable, the CO level was merely 10 percent of the allowable level, and the NO was 34 percent of the allowable level. We're all legal and in compliance. As far as the state is concerned, it's just another replacement engine that blows clean through the tailpipe.

The Insane Inline, Part 1
The Insane Inline, Part 2
The Insane Inline, Part 3

Sources

Golen Engine Service
Hudson, NH 03051
800-591-9171
http://www.golenengineservice.com
Turbo City
Orange, CA
714-639-4933
www.turbocity.com
Hesco
Birmingham, AL 35233
2052511472
http://www.hescosc.com
The Dyno Shop
Santee, CA 92071
619-562-3933
http://www.thedynoshop.com

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