4.6L Stroker Dyno Results

[CRASH]

Yes, that's kinda my thinking on it. I still need some more timing advance, especially since I live at 3,000 feet of elevation. I think the high altitude CPS is a cheap part that may be worth trying.

I probably need to drive my rig to the Central Valley one of these days and run the wide-band at MSL to get see if my results differ, or if I'm in the range of OEM mapping adjustment.

CRASH

 

[XJHOX]

The Mustang dyno always produce a lower number than say Dynojets. I think they use an electric current to produce more accurate results. Good friend of mine owns a shop and we just put a Mustang dyno in about 6 months ago. We have seen as much as 50rwhp difference from dynojets to the Mustang dyno. The 1/4 mile feature is a blast, especially in a higher hp stick shift car. Watching it from the outside you would think there going to jump off the rollers.

 

[MrShoeBoy]

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?

What else have you done to your motor? If you are after every single HP and effiecenty this cant hurt anything other than your wallet.

When you first wire in the Apexi it wont change anything until you program it. It will only modify the the MAP signal based on what you program. The best way to program the Apexi is to get on a dyno and do multiple pulls and watch the A/F curve VS RPM like the graph below. The way I have mine tuned is that the Apexi does not mess with the MAP signal when under 20% throttle. Between 20% and 70% throttle the Apexi only slightly modifies the MAP signal and then above 70% throttle (usually WOT) it changes the MAP signal to what ever you had programed. So when I am WOT, the Apexi automatically changes the MAP signal to the ECU which makes the ECU add or remove fuel based on the input from the Apexi. My motor runs at 13.5 A/F when WOT. For a naturally asperated engine this is fine and I did not see any power gains at WOT by adding more fuel. When crusing around at partial throttle or on the interstate the A/F is 14.4. This setup so far has gotten my lifted brick on 32s 16mpg I can handle that

Dino, I agree completly even with out a bigger T-body its very easy to bounce off the rev limiter in the first 3 gears The mustangs and other assorted rice have no idea whats going on when they see a Jeep ahead of them

AARON

 

[Gojeep]

My engine mods are minor and just external including bored T/B, headers and late model intake and injectors plus an adjustable fuel regulator. I have my MAP adjusted to 12.8 at WOT and at cruise in sits at 14.5. Never goes higher than that even when backing off it will go to around the mid to high 13's. I have tested a number of stock XJ's and most seemd to do that except one which would lean off. I swapped in his MAP, T/B, IAT and O2 sensors into mine and it still would not lean off on mine? Even running all my stuff in his still let in lean off when backing off the throttle so swapped the ECU as well and still no different? The only thing I can think of is that he did have a crack in the stock header, so maybe under vacuum it was drawing in extra air? Have read that it is often better to richen up when backing off as it cools off the pistons and is better for longer engine life. What do you think?

 

[MrShoeBoy]

Go,

The only thing I know about adding fuel when backing off is that it makes a really cool kackel crackel in the exhaust that sounds sweet The extra fuel that is not being burnt by the motor gets ignited by the hot exhaust header as its exiting the cylinder head thus making the noise. Anything more than that, I have no idea. Good question though.

AARON

 

[mississippi_xj]

I can atest to the *ultimate* coolness factor of teh SAFC II....

I have a buddy that has one in his monsterous '94 supra.... he is using that with larger injectors to get up near 500 hp in that car...

the tunability (is that a word?) is outstanding....

scotty

 

[Gojeep]

Quite a few on eBay at the moment.
http://search.ebay.com/Apexi-Safc-Ii_W0QQfkrZ1QQfnuZ1QQxpufuZx
Is this the exact one you use? Does the 95 XJ have a knock sensor? If I remember right, some XJ's had it and others dont? It is just this unit has a knock sensor warning and want to know if I can hook that up as well?

 

[MrShoeBoy]

Yes, I use the Apexi SAFC 2. Mine is black since it matchs my grey interior better than the silver There is a wire on the Apexi for a knock sensor but only the older renix motors used a knock sensor so the newer XJs wouldnt need one. The Apexi doesnt need a knock sensor to function. Mine is running just fine with out one. I am considering installing a knock sensor just for use with the Apexi to be super safe that I am not blowing anything up since there is no way I can afford another motor in the near future.

AARON

 

[CW]

Would you say the Apexi is worth the money? I'm having trouble keeping my stroker stoich. throughout the rev range, I have the MAP tuned to 5 volts now but I had it at 4.5 before I installed the msd6 ignition, It runs rich at idle and is pretty lean at WOT but my plugs look perfect. I got signifigant benafits with the msd too even though most people say it's a waste of money, it pulls harder at low rpms and it cured my hesitation and backfiring around 2000rpms that I had with the stock ignition, it overal just made things a lot smoother. My stroker seems to like less fuel than others for some reason, maybe because of the HO parts and 24# injectors with a Renix computer. Does it just hook up to a laptop?

 

[Gojeep]

Yes, I use the Apexi SAFC 2. Mine is black since it matchs my grey interior better than the silver There is a wire on the Apexi for a knock sensor but only the older renix motors used a knock sensor so the newer XJs wouldnt need one. The Apexi doesnt need a knock sensor to function. Mine is running just fine with out one. I am considering installing a knock sensor just for use with the Apexi to be super safe that I am not blowing anything up since there is no way I can afford another motor in the near future.

AARON

Adding a knock sensor, how would you do that? Do they just bolt directly to the block somewhere to detect knock? Can you use the same spot where the old non HO's had it prehaps?
Thanks for all the info so far
I really thinking about doing it unless I can get a full stand alone system like a Motec one if they are not too much. How difficult do you think that would be to setup?

 

[rsalemi]

Re: 4.6L Stroker Dyno Results - Knock Sensor

GoJeep - the knock sensor screws into the drivers side of the block just behind the motor mount at the pan rail. I beleive the hole is already tapped - it is on a 99 block that I have but I haven't looked at an earlier HO.

 

[MrShoeBoy]

GoJeep, rsalemi pretty much answered the question about where the knock sensor goes. As for hooking it up, its a one wire job to the Apexi. The Apexi is very cheap compared to a full stand alone ECU and should get the results you are looking for way less than a full stand alone ECU.

CW, I think the Apexi was worth the money just becasue I can adjust any fueling issues at any point through the RPM range. Also I like the fact that I know from the dyno runs that the A/F is right on the money and the motor isnt running too lean or rich. I plan on getting the newer intake and a bigger T-body as well as playing with the timing and I know that I can take care of any fuel issues with the Apexi.

I agree that the MSD box helped out with the smoothness of idle and lower RPMs plus the power gain. I beleive the added gain from the MSD on the stroker is because of the higher CR ratio compared to stock. I think most people say its a waste because they are basing the facts off a stock motor with a 8.8:1 CR ratio. The MSD's out put of multiple sparks helps the stroker because of the 9.5:1 CR ratio. You dont need a laptop to tune the Apexi. It has its own screen and menus that you just run through to add or remove fuel.

Now the only way you are going to get the FULL benifet of the Apexi is to go to a dyno and make multiple runs and compare the A/F readings from a wideband O2 sensor vs RPM graph. That way you know exactly where you need to add or remove fuel. Looking at an A/F gauge as you are going down the road is not as accurate as a dyno with a wideband O2 sensor and also its a danger to yourself and anybody thats around when driving. Doing that you are trying to drive a very powerfull vehicle as well as looking at the A/F gauge trying to tune it. Most people suck at multi-tasking :dunce:

AARON

 

[Gojeep]

Thanks very much for the info and it really sounds like good idea to add a knock sesor then. Are they a expensive item like a Os sensor?

How do you think I would go tuning it on the street using a wide band exhuast analyser like this one which I used when setting up my map adjuster?

It is big and has suction cups to stick it the the windscreen in front of you. My wife usually reads it out for me which is safer again
Do the instructions give you what fuel ratios for what loads and revs are best?

 

[JungleXJ]

GoJeep.

That's nice! Where did you get it?

Thanks

 

[rsalemi]

Re: 4.6L Stroker Dyno Results --- Tuning

I found that the AF guage needed a few seconds at constant load to register correctly. While a Dyno is best - finding a long uphill grade works acceptably for road tuning.

 

[MrShoeBoy]

Thanks very much for the info and it really sounds like good idea to add a knock sesor then. Are they a expensive item like a Os sensor?

How do you think I would go tuning it on the street using a wide band exhuast analyser like this one which I used when setting up my map adjuster?

It is big and has suction cups to stick it the the windscreen in front of you. My wife usually reads it out for me which is safer again
Do the instructions give you what fuel ratios for what loads and revs are best?

From the look of it, you have the O2 sensor needed to do the tuning. Thats a good idea to have your wife help with the tuning. The instructions tell nothing of what works best, only on how to use the Apexi and make adjustments. There are too many variables with too many different vehicles for the instructions to give good fuel ratios and RPM. At WOT, I run 13.4 or so which is fine for a NA motor and 14.7 when on partial throttle cruzing down the road. I found that adding fuel when in WOT made no more horsepower so its a waste of fuel to go anything higher than 13. If this was a forced induction application, then it would need to be higher.

AARON

 

[Gojeep]

Thanks for the update. I have mine set at 12.8 at WOT and the factory setup looks after the rest when in closed loop mode. It will sit at 14.5 and never any leaner than that at cruise but drops quickly into the high 13's as soon as you hit a hill and gently increase the throttle to keep the same speed or back off the throttle even. I wonder now though is it is worth it for me then as might not have to change it that much at all?
As for the wide band O2 sensor I use, it is not mine but just borrow it off a friend who owns a workshop and is what he sets the LPG vehicles WOT with. I might be able to set the basics with this and then hire a dyno to set it properly which should cut down the time needed a bit.

 

[pabloconrad]

sweeeeet!

 

[mississippi_xj]

MrShoeBoy...

I know I would as well as many other people would really appreciate a write up on sticking the apexi in an xj..... you would be doing a real service to the community....

been thinking of it for a while with the future turbo setup.....

scotty

 

[MrShoeBoy]

mississippi_xj,

When I have time, I will put together a write up together on the specifics of how to wire in the Apexi. There is a show going up this week that I am a designer for and I wont have any time to do the right up. Look for an Apexi write up next week or the week after.

AARON