Boostec Supercharger Information

[5-90]

How is that knock detector working out for you? Do you know if it is getting any false positives?
Is that because the cable doesn't offer adjustment or because the angle of the cable?

How close was the YJ's calibration to the XJs?

False positives on knock sensors tend to be caused by crosstalk from other signals - if you examine the knock sensor wiring on RENIX (and, I believe, most other production vehicles,) you'll note that the wiring is wrapped with either a copper or aluminum foil - this is a shield, meant to intercept any errant RFI before the ECU can pick it up and think it's a knock hit.

If you install an aftermarket knock, this foil can usually be found at a decent electronic supply house (not Radio Shack,) an amateur radio supply house, or it may be approximated using aluminum foil (you know, the stuff from the kitchen) with a ground wire soldered to the foil and attached to a solid earth ground.

 

[CobraMarty]

You don't need multiple piggyback devices to get the job done, I'm sure you can set one up to handle all of it.

Who is using multiple piggybacks?

 

[Talyn]

if you examine the knock sensor wiring on RENIX (and, I believe, most other production vehicles,) you'll note that the wiring is wrapped with either a copper or aluminum foil - this is a shield, meant to intercept any errant RFI before the ECU can pick it up and think it's a knock hit.

I don't know if the renix is, but other vehicles have their knock sensor wires twisted as well. Same for some cam and crank sensors.

I'm more concerned with false positives from other mechanical sources like roller rockers.

 

[CobraMarty]

I don't know if the renix is, but other vehicles have their knock sensor wires twisted as well. Same for some cam and crank sensors.

I'm more concerned with false positives from other mechanical sources like roller rockers.

I would think that the 'stock rockers' would produce more 'noise' for the knock sensor than roller rockers.

 

[5-90]

Awright.

I went from the end back to Page 5, and scrubbed out any post that looked like it was either non-technical or non-contributory.

Don't make me do it again.

Since I don't want to go back and figure it all through, consider this your public warning - all at one shot.

If I've got to go through and clean up this thread again, I'm going to:
- Scrub the thread (there is some useful information here I'd rather we didn't lose...)
- Close the thread (same comment.)
- EVERYONE who gets a post deleted GETS AN INFRACTION. Not a warning (this is your warning.)

Moderation is tough enough - without people getting into p***ing matches that we have to clean up.

You All Have Now Been Warned...

 

[5-90]

I would think that the 'stock rockers' would produce more 'noise' for the knock sensor than roller rockers.

Not necessarily. The automatic lash adjustment offered by the hydraulic tappets seems to keep tappet noise down significantly - I've never noted any falsing with any of my RENIX rigs. A knock is usually a vibration in a fairly specific frequency band, which seems to differ from just two metal parts (one or many sets) smacking together anyhow.

 

[5-90]

I don't know if the renix is, but other vehicles have their knock sensor wires twisted as well. Same for some cam and crank sensors.

I'm more concerned with false positives from other mechanical sources like roller rockers.

Twisted-pair wiring helps to bring down crosstalk as well, but I know the RENIX wiring is shielded with a drain foil.

Kinda like how you can get Unshielded Twisted Pair CAT 5 or Shielded Twisted Pair CAT 5.

The two factors together (twisted pairing and drain foil) probably knock crosstalk signals down to zero.

As far as mechanical falsing, see previous comment. Considering that our 6-242 runs at zero lash - and is assembled at zero lash - and considering that the frequency of spark knock tends to be different from that of mechanical noise, I don't think it's as much of an issue as you'd first think.

 

[kastein]

Twisted-pair wiring helps to bring down crosstalk as well, but I know the RENIX wiring is shielded with a drain foil.

Kinda like how you can get Unshielded Twisted Pair CAT 5 or Shielded Twisted Pair CAT 5.

The two factors together (twisted pairing and drain foil) probably knock crosstalk signals down to zero.

As far as mechanical falsing, see previous comment. Considering that our 6-242 runs at zero lash - and is assembled at zero lash - and considering that the frequency of spark knock tends to be different from that of mechanical noise, I don't think it's as much of an issue as you'd first think.

I'd have to agree with this - unless you get a sticky lifter, that never happens on a 4.0 :gee:

(but it's still probably at a different frequency than an actual knock, as you noted)

 

[5-90]

I'd have to agree with this - unless you get a sticky lifter, that never happens on a 4.0 :gee:

(but it's still probably at a different frequency than an actual knock, as you noted)

Dunno - even collapsed tappets on my RENIX didn't cause any falsing that I could detect.

It's simple enough to tell if you have a spark knock - see if the sensor is generating a signal. As I've explained several times before, the only time the knock sensor generates a signal is when a spark knock happens - and piezo signals are low enough that crosstalk can be easily misinterpreted as a knock signal (piezo output is a pulse of DC current - a pulse of DC current can be generated in a conductor by a DC pulse in an adjacent conductor via magnetic fields...)

 

[O-Gauge Steamer]

How is that knock detector working out for you? Do you know if it is getting any false positives?
Is that because the cable doesn't offer adjustment or because the angle of the cable?

How close was the YJ's calibration to the XJs?

The knock sensor works well and I can turh the detonations on and off by changing the ignition table. I did have to increase the sensitivity a tad but that is easily done. By my way of thinking, if you can turn a problem off and back on at will, you have the solution to the problem well in hand.

YJs.. The TV cable being at the wrong angle chaged how it operated as the TB opened thus altering the shift points. We assembled the stock setup on a bench, took a measurement and cut/welded the bracket to get the angle corrected. Transmission issue fixed.

F/IC calibration. Believe it or not, and some of you won't, I took the calibration I was running at the time, derated the fuel table to reflect the lower fuel pressure of the YJ (we run the same injectors) and plugged it in. Within a couple of hours of blasting up Powers Blvd we had, for the most part, the calibration dialed. What was needed was the fine tweaks.

I would happily do another YJ. All of the Sensors (Crank, Cam the TPS) operate on the same 5VDc reference. This is an OCDI Heep. Could a Renix be done? Not sure as I do not have any experience with Renix.

IMO, one of the best reasons to use a F/IC is that the PCM does not matter. Not At All...

 

[5-90]

How is that knock detector working out for you? Do you know if it is getting any false positives?
Is that because the cable doesn't offer adjustment or because the angle of the cable?


The knock sensor works well and I can turh the detonations on and off by changing the ignition table. I did have to increase the sensitivity a tad but that is easily done. By my way of thinking, if you can turn a problem off and back on at will, you have the solution to the problem well in hand.

YJs.. The TV cable being at the wrong angle chaged how it operated as the TB opened thus altering the shift points. We assembled the stock setup on a bench, took a measurement and cut/welded the bracket to get the angle corrected. Transmission issue fixed.

F/IC calibration. Believe it or not, and some of you won't, I took the calibration I was running at the time, derated the fuel table to reflect the lower fuel pressure of the YJ (we run the same injectors) and plugged it in. Within a couple of hours of blasting up Powers Blvd we had, for the most part, the calibration dialed. What was needed was the fine tweaks.

I would happily do another YJ. All of the Sensors (Crank, Cam the TPS) operate on the same 5VDc reference. This is an OCDI Heep. Could a Renix be done? Not sure as I do not have any experience with Renix.

IMO, one of the best reasons to use a F/IC is that the PCM does not matter. Not At All...

ChryCo OBD-I is ChryCo OBD-I - and OBD-I didn't really care about body styles, weight classes, or anything like that. So, a system that will work with 1991-1995 Jeep 6-242 should work fairly easily with all 1991-1995 Jeep w/6-242 (XJ, MJ, YJ, ZJ.)

OBD-II starts getting pickier.

(I figured that "OCD-I" is a typo - although I sometimes refer to OBD-II as "OCD-II" because it fits better. I don't know if it's a typo, or something you did "accidentally on purpose" [cf: "Freudian Slip,"] but I find it rather amusing and almost appropriate!)

 

[O-Gauge Steamer]

Yup, Typo. But... It does kind of work, eh?

I do believe that I could fit the Sprintex SC onto any 4.0HO out there. If it will fit into an XJ, it will fit into anything...

The compressor is undersized for Stroker applications and as far as I know, Sprintex has no intention of providing an intake manifold to accept thier larger compressors. Not for the XJ. Maybe the TJ.

I have looked into using a Whipple compressor and, if I had the resources, I would do it. I get a maximum of 6lbs of Boost with this compressor. On a Stroker, I estimate that you would be lucky to get 4 pounds out of it. On a good day.

Back in the Dawn Of Time (OK, '81) I was running a '79 Ford Mustang Turbo Ghia. At the time, the Colorado State Troopers were running them as well. My Wife's Uncle was a Trooper and when we showed up at a Family gathering down in Canon City...

He got this strange, sort of, evil gleam in his eye and told me to bring the Ford into the garage. Parked it next to his Cruiser (another Ford Mustang) and popped the hood. He then proceeded to remove the air injection pump, plug the hole in the exhaust manifold and we adjusted the waste gate to get more boost. He said "We run 10lbs, you should too". So, we adjusted the waste gate until 10lbs were achieved. Talk about waking up that 2.3L 4 popper... The Factory setting was for 6 pounds.

Point? The Ford, just like the Sprintex, did not have an intercooler. IMO, 8 - 10 pounds of non-intercooled boost are a definite possibility. But, and it is a big but, it will never happen with this compressor. Sprintex went with what is actually an under-rated compressor (originally destined for a 3.0L engine) specifically to hold the boost down to levels they knew, for sure, were completely safe. They did this for legal reasons as they wish to avoid a lawsuit from an idiot. Evidently, they have had idiot issues in the past and do not care to repeat them. Can't blame them for attemptint to idiot proff the system.

Imagine a blown stroker. I have ideas for an intercooler but finding a place to mount it and rout the plumbing is tough at best. As has been noted, by others, our Heeps were originally designed to take the 2.5L I4 and the 2.8L V6. So the engine bay is small. Too small. Whereas, the Wranlers were designed with the 4.2L I6 and the V8s in mind. Tons of room.

 

[kastein]

The 4.2L I6 is almost exactly the same size as the 4.0 - in fact the motor mounts from a 4.2 bolt right onto a 4.0. Hell, so will a RENIX intake/exhaust manifold, AFAIK.

The CJs were in fact designed with smallblock AMCs in mind though, came with the 304 and could be had with the 360 or 401 as an option iirc. I know I've seen them bolted in.

 

[bpas328xi]

Imagine a blown stroker. I have ideas for an intercooler but finding a place to mount it and rout the plumbing is tough at best.

You must be thinking of an air-to-air intercooler...

If someone was good at welding, they could put a water-to-air intercooler in between the supercharger and the head. Kinda like how the guys at ESS do it for bimmers.

 

[gradon]

I'd love the Eurosport twin-screw for my M3 :drool:

 

[O-Gauge Steamer]

CJs and V8... Well, you see, it's like this. All of the AMC V8s are exactly the same size, externally, and share the same mounts and bell housings. Best way to identify an AMC block is to read the displacement that is cast in the lifter valley. Come to think of it, the 4.2/4.0 has the same bell housing. But... AMC must be the least efficient V8s ever made. Nothing a set of Edelbrock heads and EFI can't cure though. Did this on the Wife's 90 Grand Waggy. It was like a new car...

Intercooler plumbing. I have only considered a liquid to air heat exchanger. Where to mount the radiator? I know, from careful data gathering, that even placing a stacked plate transmission cooler in front of the radiator increases the average engine operating temperature by 5C. Which is alot. An air to air would take less room under the hood but...

How do I know about the engine temps? When I was going through the fun task of getting the Davies-Craig EWP115 electric water pump to behave itself. That is when...

Plus, on the mechanical side, not much in the way of space available at the manifold for that exchanger to sit.

Wish there was though...

Have looked at disconnecting the compressor from the manifold, rotating it widdershins (anticlockwise) and up to gain room for an exchanger of sufficient BTU handling. At issue is hood clearance. As in not really any to be had. Maybe it vould just be pulled out away. I do not run the stock air box and running the box is integral to the Sprintex Design. Will revisit that.

Also, the manifold would require an enormous amount of rework. Better to just build another one. Which, is out of my reach owing to my recent financial issue with the Kid and his University... Nothing quite like dumping near $10k out of pocket to dampen one's project list.

But there is a light in the tunnel. Whilst the Kid is Home (in August) for his break, I am going to have him start getting the train collection ready to sell off. It is a half century collection.

Anyone on NAXJ that is a Member can have the collection for a measly $45k. A give away price that. Most likely it will have to go by pieces and that will take time.

Hundreds of items... Boggles the mind really.

 

[CobraMarty]

The mind is thinking, If you had the CAD file for the Sprintex manifold and the CAD file for the ESS manifold and 'merge them together' and build them in 'cyberspace' and get Sprintex to cast it... Just Dreaming. But mind you this dreaming would add $1000-1500 to the cost of the kit.

 

[kastein]

Cool idea... but if you think the Sprintex 'kit' is expensive, just wait till you see the prices on custom castings

 

[5-90]

The 4.2L I6 is almost exactly the same size as the 4.0 - in fact the motor mounts from a 4.2 bolt right onto a 4.0. Hell, so will a RENIX intake/exhaust manifold, AFAIK.

The CJs were in fact designed with smallblock AMCs in mind though, came with the 304 and could be had with the 360 or 401 as an option iirc. I know I've seen them bolted in.

Intake, maybe. Exhaust, no. The #3 and #4 exhaust ports are Siamesed on the 6-258 - at least, on the #2685 head that I have.

 

[kastein]

Interesting. From reading various amc boards (I am preparing to help a friend of mine cconvert his 87 YJ from 4.2/32rh/np207/d35 to 4.0/ax15/np231/c8.25) it seemed that the ports matched. We decided to put a 4.0 in it anyways so I didn't look into it much past checking if people had swapped 4.0 manifolds onto a 4.2 head.