4.6L Stroker Dyno Results

I finally got enough miles on my stroker to take it to the dyno to tune it as well as see how much power is being put down. I am very happy with the results of the stroking
I went to www.p1auto.com for the dyno tuning. I have an Apexi SAFC 2 installed which adjusts the MAP sensor voltage fed into the ECU to add or remove fuel based on RPM points. On my motor, the fuel curve between 2k and 3k had to be increased by 4% and from 3200 to 4600 the fuel curve was leaned out 4% and then 4800 to redline was leaned out 5%. The tuning was done using a wideband O2 sensor in the tail pipe.



AARON

This is a comparo of my old 4.0L which had some work done compared to the new stroker.

The only things different from my old motor to the stroker are the cam and the added displacement. I had alreatty done intake, head work, exhaust, etc.... So I gained almost 25hp and 50lbtq from just the added displacement!



AARON

Another cool thing about the Mustang dyno is that you can do 1/4 mile runs The accuracy is 0.1 compared to a track. A 14.8sec at 89mph with a 1.9 60 foot time! Can you say fast as hell for a LIFTED XJ with 32s :viking:



AARON

And if the numbers don't mean anything to you...its fast as hell and a whole lot of fun. Oh, and Aaron, none of this could even happen if it wasnt for my excellent reassembly of the drivetrain, ha.

What gears do you have in that thing?
Nice results btw. Bet it is alot more fun to drive!
Alan

I thought a 4.6 would be above 250ft/lbs easy? Drivetrain losses? Doesn't Hesco rate thiers at 300+ or is that just off the flywheel? Good info though.

i was thinking the same thing, this is probably power to the wheels

A HUGE thanks goes to my dad as he helped me out with assymbling the motor. BigDaveXJ also helped install the motor in the chassis.

The horsepower numbers are at the wheels. I think the loss through the drivetrain is somewhere around 20% but I cant remember. Hesco rates their strokers at the crank. I have 4.5" of lift and 4.10s in the axles with 32 A/Ts.

AARON

Man this really makes me want to save up for a stroker now.-------Kyle

What's a rough figure of what you spent on your stroker?

WobblesXJ said:

What's a rough figure of what you spent on your stroker?

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Machine work including the '96 block, ground and polish the crank, rebuilt 258 rods, new pistons, new bearings, freeze plugs, gasket kit, and a valve job cost $800. The Apexi cost me a little less than $300. The Crane cam, lifters, and springs cost $300. MDS ignition box was $50 and the new 2.5" downpipe cost $50. I alreatty had the intake, Tbody, ported and polished head, header and all other bolt on speed parts.

So over all cost was about $1600 including fluids if I had to rough estimate

AARON

MrShoeBoy said:

Machine work including the '96 block, ground and polish the crank, rebuilt 258 rods, new pistons, new bearings, freeze plugs, gasket kit, and a valve job cost $800. The Apexi cost me a little less than $300. The Crane cam, lifters, and springs cost $300. MDS ignition box was $50 and the new 2.5" downpipe cost $50. I alreatty had the intake, Tbody, ported and polished head, header and all other bolt on speed parts.

So over all cost was about $1600 including fluids if I had to rough estimate

AARON

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Plus $400 for the pre-oiler. Dude, you're probably the only Cherokee driver with one of these under the hood, how can you not brag about it?!

I read some where that an XJ has a 22% loss in the drivetrain.
Can you tell me more about the Map adjuster and where to get one? I have built my own but that only effects things when in open loop mode.

You have little to complain about. The numbers look very reasonable.

You have to like the way the Mustang chassis dyno spits out the numbers and allows quick tests. I have been told the numbers are likely read a little on the low side compared to other dynos, but the tuning capability is reported to be better than what can be done with Superflow or DynoJet equipment.

After I rebuilt my 88 (mildly built RENIX 4.0L) I had to richen the FoMoCo 19# injectors ~5% (with the homebuilt MAP adjuster). I need to find the test sheets but even with tuning my 4.0L delivered only ~148 hp (just under 150hp, when the G-Tech meter testing indicated ~160hp). The dyno tests, however, indicated over 180ftlbs of torque before 1700 rpm (peak torque was ~208 at 2800) so the performance was not too weak (although I could not get truly accurate low rpm readings with the torque converter and 31's with 3.55's). The RENIX head,TB, and mild cam choked off the top end power at about 4500 rpm (peak just under 3900). Unfortunately, the owner of the shop with the dyno sold (and I lost my free test opportunity).

I was going to try a number of things to increase the power of my 88 but ran out of time before the shop sold. The timing change with the high altitude CPS was one change that recorded well on the G-Tec but I did not get to try on the dyno (but I expect it is not a 10hp difference). I was also planning to increase the fuel pressure and drop the MAP voltage to try to get a better fuel curve. IIRC my runs were lean at top end, and way lean before adjustment on the low end. I could target the A/F ratio at peak torque (over three tuning runs increasing the MAP voltage) and still run lean at both ends of the rpm range (I ended up running 5.2v, a 7% increase over stock). I do not know if the RENIX fuel maps run leaner than the OBDI system, or of they have more curve to the mid-rpm range. The little testing I did seemed to indicate a generally lean open loop map with RENIX, biased to a really lean condition at low rpm (something the higher fuel rail pressure should help).

What cam (the Crane 901 or mild 905)?

What injectors (24#/hr)?

Have you advanced the timing (moved the CPS)?

In any case it's nice to see some real numbers.

Go Jeep, If you search online I am sure you can find it. I think www.P1auto.com has a online store you can purchase an Apexi through or you can call them and they can ship it to you. Let me know if you are intrested and I can see if I can get it discounted.

Ed,

I have not messed with the CPS and timing mainly because I didnt want to spend more money to purchase it. If I had the cash and time I would love to mess with timing. Free dyno runs are not an issue since my family is part owner

I am running the Crane 753905 cam. With this cam the dyno graphs show it slopes off above 4700RPM so it makes its power down low. This cam and motor are really streetable and work well for the mixed on and offroad driving style I do so I am happy with it.

I am running the FMS #24 injectors. I need a bigger Tbody as I know its restrictive. I want to get a Mustang Tbody like Dino did but again time and money comes into play and prevents that from happening. I think that the Apexi is the best thing I have done from a tuning standpoint. I can tune the fuel curve at the exact point where it needs to be tuned. There are no compromises in the fuel curve with it.

I want to get a bigger Tbody, try a CPS to get more timing, and roller rockers and call it done with this motor. Its fun enough now and I am positive it will get me in trouble as is with out any more power :viking:

AARON

How much does one of these Apexi things cost? Is it the EMS product on the P1Auto website?

MrShoeBoy said:

Go Jeep, If you search online I am sure you can find it. I think www.P1auto.com has a online store you can purchase an Apexi through or you can call them and they can ship it to you. Let me know if you are intrested and I can see if I can get it discounted.

Ed,

I have not messed with the CPS and timing mainly because I didnt want to spend more money to purchase it. If I had the cash and time I would love to mess with timing. Free dyno runs are not an issue since my family is part owner



AARON

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Thanks mate. This seems like a lot better idea than the ones I can get here though Unichip. They only alter the timing advance through out the rev range and do not alter fuel mixtures at all. I'm not nessesary after more performance but to make it as effiecent as possible to get the the best fuel mileage to extend my range when Outback as far as possible so I dont have to carry as much fuel. Some of the tracks I want to do require over 200 litres or 44 gallons just to a make it to the next fuel dump. The less I have to carry the better from a weight perspective as it reduces strain on componates in the dunes.
I looked at the site but there are a few to choose from. http://p1auto.com/shop/advanced_sea...Csid=5997d46deb87953657d0d0b001d33c87&x=8&y=6
Which one are you using and is it for the OBDI system? Looks like the first two are just a color difference and the third more expensive one for VTEC cammed engines? Is it hard to set up the fuel curves and do they give you base lines to work from which lets you know optimum settings for economy verse power for instance?
Do you think this is the way to go for me?

MrShoeBoy said:

I am running the FMS #24 injectors. I need a bigger Tbody as I know its restrictive. I want to get a Mustang Tbody like Dino did but again time and money comes into play and prevents that from happening.

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I'm also running Ford 24lb injectors, stock regulator, and MAP adjuster. As I've added more miles on my stroker, I've been gradually dialing back the voltage on my MAP adjuster and now I have it set at just 5.2v (it was 5.9v a while back). The engine has become more fuel efficient especially since I switched to Mobil 1 3000 miles ago (6000 miles on the stroker now), and it also pulls stronger at higher rpm. The ported head and Mustang 65mm TB certainly help there; it's very easy to get the engine bouncing off the rev limiter in the first three gears.
___________________________
Dino's "Mean Green Machine"
1992 XJ Laredo 4-dr - 4.6L I6 HO Stroker - 181k miles - AX15, NP231, D35c, D30

263hp@4900/321lbft@3300-3800, 1/4 mile = [email protected], 0-60 = 5.8secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

Good Dyno results, that is about the power that I feel my Renix stroker is putting out. 24lb injectors, Isky 1331125/26 cam, 9.3 to 1 pistons, 4.0 rods.

I am also tuning with a wideband, but merely the coarse adjustment of a homebrew adjustable MAP. In fact, the MAP is currently right at factory spec 5.0 volts, and the motor runs 12.8 to 1 A/F at WOT. The motor is just starting to loosen up though, so I may need to do some more pulls. I think I can go a bit leaner, maybe around 13.2 A/F and still be safe while building more power.

This cam pulls very hard from 3,000 to 6,000 but is not as impressive off idle. I'm thinking of playing with the cam advance, as I have adjustable cam gears that allow 2 degree increments of advance/retard, to get some low end back into the motor.

CRASH

If you advance the cam 2 degrees, it will pull the torque curve back a bit. The increase in effective swept volume increases the charge volume. The only downside could be a tendency for spark knock under heavy low rpm load.

I had that problem with my 2.5...I couldn't run much ignition lead...ended up retarding the cam so I could run some ignition lead, which is needed for high rpm. If I have the motor apart again, i'm going to mill the bowl in the pistons to get the CR in line.

I'm watching the stroker threads closely...the 4.0 HO in my MJ uses a little too much oil...