I am looking to mod my 05 S-type R in the summer. Does anyone know what the stock shortblock can hold? Has anyone heard of the motors breaking? and what is the weak link? I am looking into a Steigemeyer Port, 3.5 lb. Pulley, CAI, and exhaust. I just want to make sure the motor will hold another hopefully 50-75 hp.

 

Greetings,

I don't have any practical experience that relates directly to your question: as far as modifying supercharged engines, I'm just a bench racer. I've read alot on the subject, and recalled a post from another forum by a guy named "billions":

I've been reading some wonderful stuff about twin screw blowers etc. and whilst I don't wish to cast any doubts on these claims 'tho a 50%+ increase over an already blown engine is hard to believe there is a problem that no-one seems to address.Anyone remember Jaguars racing in the Le Mans series,and the petite Le Mans,and the Sebring et al?No more and you want to know why?When Ford went on it's buying spree years ago it also picked up a little company called Cosworth which had been doing miracles with crap Ford products for decades along with Coventry climax.Just like Mercedes did with Ilmor.Anyway most of the brains left because they were unable to work with corporate ****heads but some of us hung around for a while.I believe I signed something years ago but the statutes of limitation must be up so here goes.The AJ8 castings are incapable of holding up to more than 500 HP for sustained periods.There is an inherent weakness in the design of the main bearing carriers and they develop spider web cracks initially and result in total failure if pressed.

***end of excerpt***

Now I don't know this guy, andI never tried to fact-check any of his information. But it makes alot of sense to me as to the subject of your question, overstressing an aluminum block designed for minimum weight in a road vehicle.

Mike at Eurotoys has experience with high output supercharged engines, and didn't feel as though this was a significant concern. avos is another S/C HP wizard, but I don't recall reading any comments from him or any other engine builderson the subject.

Perhaps billions' point is moot as it pertains to a street racer, since "sustained periods"at full load ain't gonna happen. Still, the only way to know would be to tear down aboosted output engine after significant use, and at a minimum check for unusual main bearing wear...I'm thinking that would be the result if the stock bedplate ("main bearing carrier")was insufficiently rigidto handlethe increased loads. Crack testing the bedplate and block would be my next move. Otherwise, I guess you just let it eat and hope it doesn't end up in alot of pieces...billions, even.

Comments on the subject are welcomed by anybody reading this, I'm not the guy claiming it's a real-world problem and myperspective is that of a stock engine builder...beyond that, this is onlya theoretical exercise to me. Hopefully it's relevant food for thought for you, and you'll get some real-worldanswers.I think you're asking one ofthe right questions.

 

One other point to add: I haven't torn down any 4.2L engines, so I don't know if any changes to the block or bedplate were introduced that may affect the rigidity. I'm assuming billions' comments were based on 4.0L engines.

 

05, you may want to read some of the post on here and reconsider the CAI and the pulley.. I think most HP junkies on here will confirm that the K&N is the only suitable intake upgrade for this car, but your on the right track with the exhaust and porting. I have the Steig port and I am very happy with it and I also have a custom exhaust system with performance mufflers as well as electric dumps right behind the cats..

In regards to the strength of the block I think 400 *REAR WHEEL* HP is probably the realistic safe limit for our motor. Beyond that and I think your getting into uncharted water..

 

Thanks for the info. Does K&N make a whole intake or just the filter?

 

K&N just makes a drop in panel filter for this car, not a ram air or cold air intake.. The filter makes an almost unnoticeable difference (maybe 4+hp), and my advice would be to save your money and get an ECU tune from EuroTek or EuroToys.. Most of the untapped power from STRs comes from changing the shift points.. Once you drive the car hard you will start to notice it upshifts very early and you could easily pick up a few tenths in the 1/4 just from that. The other power comes from adjusting the air/fuel ratio, the timing, and allowing the MAF to take an increased reading due to S/C or intake upgrades.. The stock programming that comes with every car is always very conservative and often runs the car rich to account for changes in altitude and air density wherever the car will be driven.. I am not a fan of the "leaner is meaner" policy, but the stock tunes are always VERY conservative..

 

And also: The porting of the S/C will not only increase the airflow, but it was also help to lower you IAT more than 10 degrees at full boost and will increase the blowers efficiency.. Thats why I think its a very important upgrade if your consider boosting the car more.

Cooling is sooooo important on forced induction cars because you lose massive amounts of power to heat soak and if you can get it to run cooler it will run better.

 

The question is how long parts will last under what amount of power. One could even wonder how long a stock 4.2 block will last if it were to be raced if you see what I mean.

But it is not just power, upping pressure (heating the mixture), leaning the mixture and altering ignition in favor of power, is also getting you closer to the boundaries. The ECU might control pre-ignition/detonation; but it only reacts if one has already occurred. An ECU tune is the last what one should do after modifications, and it should be done by professionals on a dyno whilst measuring at least the A/F ratio (and decide a safe ratio pending on the longevity you desire).

There is no easy answer here regarding power/longevity. I have no doubt that the 4.2 block is capable for 400-450 rwhp for short periods and you could have a long life if used with care (only when engine is warm and oil, no prolonged usage etc), but if race with these power levels you might probably break it very quickly.

Andre.

 

Thanks guys... I did a search but couldn't find why not do the pulley upgrade and CAI... What are the downfalls of each? Thanks...

 

The problem with the pulley is that essentially all your doing is spinning the M112 faster.. and on our cars they are already pretty closed to maxed out. You will pick up mid range power, but at WOT the Eaton is spinning so fast and creating so much heat that your pushing it right out of its efficiency range and actually decreasing your top end power.. Stock boost on our cars is supposed to be 13.1 lbs and with a very good porting job about 15-15.75 is really the max your can make with the M112.. You can spin it fast enough to generate 20psi if you really want to, but once you break 16psi you need to cool it with nitrous or it will be WAYYYYY too hot.. Your ceiling with the stock ported blower is really about 15.5psi, more than that and your working against yourself..

The problem with the intake is that its garbage.. lol they spent about 7 minutes with a pipe bender to make it and our cars are wayyy too sophisticated to use an intake like that. The other problem is that its not a CAI, it would fall into the short ram intake if I had to categorize it.. With a supercharged car, cold air is the key to power.. The hotter the air, the worse the car will run.. Also the secondary air intake flap in the front of the intake box does not transfer over to the new intake and the car was designed to work with that and wont work without. I was in the process of designing a new feed tube for the stock box, but I am too busy at work right now and cant find the time. If you had a custom tune that was designed to work with a short ram air intake like that it could run okay, but the stock ECU will say hell no if you install that.. The reading from the MAF with be ridiculously too far outside acceptable parameters and your car will probably throw a CEL and restricted performance..

 

Just for comparison a Cobra with the same Eaton M112 and a 4.6l engine with a stock pulley makes 8.6 psi with the blower spinning at 13,500 rpm.. at 13.1 psi like ours your at about 16,300 rpm.. and at 16 psi your at 20,000 rpm. You need to see what the adiabatic efficiency at high rpms like that would be..

 

Thanks a lot for the help... I will be doing the Steigemeyer port over the summer (About 30 miles from him) and probably just throwing the 1.5 lb more pulley on it at the time. That way the blower will be a little more efficient with the extra lb or two of boost. I just need to find someone that can tune a STR without sending my ECU away.

 

Yeah, the best part about the larger 1.5 pulley is that you dont have to grind down the nose of the S/C and if you do have a warranty, you can put it back to stock before you take it in if your engine blows..
There are probably a half dozen people looking for the very same someone that can tune the Jag without shipping the ECU out, but unfortunately since we have such an obscure car, I doubt your going to find anyone.. But if you do, please let us know..

 

Oh yeah, and if you bring your new pulley to Steigemeyer when he does the porting (they dont sell them there) they have to disassemble the S/C to port it anyways, so they should put the new one on for free..