Avos is right. I have just about all of these mods except for the ported heads. Unfortunately the performance companies will advertise a "best case scenario" crank HP number. Here are more realistic numbers based on personal experience (a.k.a $$,$$$ )

Standard Engine Power- 390 hp (315 rwhp)
Ported Eaton M112- 5 hp
10 % Supercharger Pulley- 15 hp
Full Custom 3" Catless Exhaust- 15 hp
ECU Tune (Paramount Performance) 20 hp **** tq went up by 40 ft lbs at the wheels though
Performance Spark Plugs- 2 hp
"Cold" Air Intake- 5hp

Total 452 crank hp or 366 rwhp (@19% drivetrain loss).

With these exact mods my car made 368 rwhp on the dyno a while back; so the 452 crank is pretty accurate.

I have since then done quote a few more mods. What I noticed gives the most power is cooling mods since the M112 becomes fairly inefficient on higher RPMs and generates so much heat. (Ice tank, meth, intercooler etc) and Nitrous. I have a 125 shot and it really throws you back in your seat. Best bang for your buck there IMO, but your car needs to be in tip top shape and have a few other supporting mods.

 

For the moment it's just an idea for a project that I'd love to do, to be honest. I know that it would end up costing the same as a used Aston Martin DB9, but the car I have in mind hasn't been done yet and I love the challenge of completing a project car build. If I somehow become very wealthy during the next few years, I wouldn't hesitate spending over £100K to create a supersleeper even though it still looks like a humble old Jag, imagine the fun you could have at drag races!

Modifying things is all about the experience, the problems to resolve and the good feelings when everything works out, it will be a joy to drive a car that you put so much time and effort into.

I need to buy the car first so £7-10K for that hopefully by the end of this year, then I figured over several years I would periodically spend several £1000s on what I mentioned on the above lists to begin with, I'm guessing it would all add up to £15-20K in mods so maybe £5000 per year.
If my finances are still in a very healthy state, I'll go for the Kenne Bell conversion. How much would that cost with installation? The supercharger kit costs $6500-7000 - http://kennebell.net/wp-content/uplo.../PriceList.pdf but it looks like a specialist task.

Once everything is installed and the power is maxed out, I'd get bored so I would continue upgrading down the lightweighting route which will be a lot more expensive. It'll take another decade to reach my sub 1400Kg target weight unless I receive a financial windfall during that time.
https://www.jaguarforums.com/forum/x...htness-243284/

My priorities after purchase will be fitting an LSD and the a custom exhaust + cold air filter kit + tune up - those will enhance the driving experience from the start.

 

Good to have a reality check, although it does feel disappointing. On the bright side, you still have some potential there to get closer to 500 (tubular headers, ported heads...) even if the results are less than claimed. Caldoofy's full exhaust system did bring a 31 BHP power boost in a dyno test.

It still sounds like you're having the kind of driving pleasure I seek.

 

If I find a dyno comparison with silver spark plugs vs iridium I'll post the results here.

I did find this visual comparison (in Polish) between Brisk's Silver (left side) and Iridium plugs (right side), the silver plug's sparks do look brighter and thicker.

 

I went through this reality check myself, but I spent thousands (dont tell my wife).

My car is a little closer to 500 (off spray) now with some of the additional mods since that dyno. 83mm TB, ported plenum, ported supercharger outlet, ported RR intake, 90 mm J pipe, and Pro M92 MAF. Makes it a little easier for the eaton to breath.

Currently my Jag is not making any power. It is down for some maintenance and also getting a few more upgrades:

all Aluminum radiator
new intercooler
extra intercooler
meth injection

Once I get it running, I will dyno again. Hoping for a little over 400 at the wheels off spray and 500+ on spray. . Best dyno yet was 390rwhp/413tq but that was with an ice tank. Got rid of the ice tank and added the nitrous and made a bit over 450 wheel on a 75 shot.

Looking back, would have loved to save a lot of time and money and just gone with the twin screw kit. Very hard to come across though.

 

Looking forward to that dyno, you wouldn't go through all those ups and downs if there was no challenge. There's always those potential gains out there if everything you try doesn't reach your expectations.

My previous project cars (a 1990 Mini Cooper (carb ) and an early 2001 Lotus Elise exceeded expectations from my mods, sometimes you get lucky.

 

Here are some diagrams explaining the kind of exhaust system I would love to get fabricated. I made my previous cars a bit too loud and boomy so it would be great to have a quiet mode at the click of a button for long journeys and to avoid disturbing the neighbours.

The first system is designed for 500-600 bhp but is upgradeable should I fit a Twin screw supercharger for 800+ Bhp later. The rear centre section from the cat back would be chopped out and modified and so would the rear silencer/muffler tail pipe sections, the majority of the system would remain intact.



The 500 BHP system is a single exit but would feature an 8 into 1 merge collector if it fits in the place of the first muffler/resonator. The collector measures 6.25 inches in height - I'm hoping that there is enough height between the propshaft and floorpan. These have become popular in the drift and off-road buggy scenes, they turn the burble of a cross plane American V8 into a savage high pitched scream - more aggressive than a flat plane crank Ferrari. Tanner Foust has one in his VW Passat drift car, it sounds insane, the single exit allows every exhaust pulse to exit one after the other from the same source so it makes the engine sound like it's doing twice as many revs than it actually is. The header/manifold runners must be equal length, they fit in to the collector following the engine firing order so that there is a rotary pulse of low pressure that accelerates the gasses exiting the neighbouring runner. I realise that scavenging and tuning isn't that helpful with forced induction engines but this should help keep the exhaust nicely free flowing.


The Gesi cat mentioned above is rated at 850 BHP per bank, so a single 4" cat will do the job. The transitions would be cut off and connected to the 8-1 collecter and exhaust pipe with some suitably sized transitions welded on.

I absolutely love the aggressive metallic sound of Spintech Mufflers,


I had one fitted to my Elise


but on V8 engines they sound the best. They actually become more efficient at noise reduction as engine speed increases but at low revs, you get a dragster like choppiness to the sound.


They exist in many shapes and sizes. For the loud mode, I would fit a single Pro Street 9000 model which is their most aggressive street focused muffler, for the quiet mode I would fit their Sportsman 3000XL which is one of their quietest mufflers, in sequence with the other, so the cat, central muffler and quietest muffler should allow stock sound levels or maybe even quieter, it will still sound sporty at WOT.

To change the noise levels, I would fit a NoWeeds diverter, this features two perpendicular valves mounted on the same shaft housed in a Y pipe so that when one pipe is blocked by the valve, the other opens, this has an advantage over the usual cutouts, which often force the gases round a 90° bend to pass through the muffler when the straight through valve is closed. The deviation in gas flow with the NoWeeds diverter is a minor chicane so gas flow in quiet mode shouldn't be restricted at all.



The 800 BHP upgraded exhaust system converts the single into a duel system for increased gas flow, the transition on the rear side of the cat would be exchanged for a 1 into 4 merge collector welded in. The 4 exits would direct the gases in to 2 separate dual circuits, at the top, a duel inlet/outlet Sportsman 3000XLF Muffler which is only 3" thick would be stacked above 2 oval (3.5" equivalent) pipes with the rear end of thee parts connected to dual NoWeeds diverters. This would provide either straight through or muffled sound entering the tail pipes which are now fitted with dual Pro Street 9000 mufflers. For the more aggressive sound the straight through pipes would be selected and the quiet setting these tail pipe mufflers add another layer of silencing to the first muffler.




Muffler deletes are a bit too anti-social, the 9000s remove just enough sound in my opinion. The 3000 series muffler almost sound effective enough on their own:


The 180°, 8 into 1 single pipe isn't your typical V8 sound, if you're a purest you might not be a fan but you have to agree, that sound is pretty exciting when you floor it.


If done right, there can be a power boost (from 8:10)


but not as much as might be possible in a naturally aspirated car. (from 7:16)

 

I'm already there...

 

On my xkr I have just a dynomax ultraflow two in two out resonated x pipe with factory cats and it’s rather loud. On my last xkr I had that same setup with dynomax ultraflow rear cans and it sounded excellent. My xjr only has an Arden cat back and it’s real quiet. The dynomax have little restriction and youde be happy with that setup.

As for the exhaust going under axle I had contemplated using oval tuning for better clearance when I finish my 4.2 conversion on the xkr. The xjr is relatively simple to get a good exhaust into and if I reinstall my twin screw I may go that route.

 

I shared this link with multiple muffler comparisons earlier in the thread, the Dynomax Ultraflows look efficient at sound reduction without giving up much power. Do you have any sound clips of it?

https://nastyz28.com/threads/muffler...mation.319940/

 

Y'all may be talking about different cars, that may have came with the eaton blower ? Achieving 500 horsepower that's easy there's several ways going about it. You could Port it and gain a little bit, keep it stock and throw some cams in there, I still seen 03 and 04 Terminator cobras that were not ported just had some cams running about 12 lb of boost and around 23° of timing and ran 560 horsepower had race fuel. Shoot I even seen the same 03 04 cobra motor in a N/a configuration still 4.6 double overhead cam just upgraded the cams replace the blower with an 01 Cobra intake that configuration produced 425hp .

 

One of the big restrictions is tuning and parts availability. Having delt with HEATon superchargers for decades one of the biggest issues is intake temps. When dealing with our XJR's its about that and parts availability/tuning. We can lessen the blow of heat soak by increasing heat exchanger capacity, or even adding something like a killer chiller. From there parts availability. The intake/TB/MAF is a huge restriction. These superchargers need unrestricted airflow as they aren't compressors but air movers. Increasing flow will reduce ACT. But at some point even though your MAF can handle the flow electronically, it physically cant.. With the cobra you can get larger inlets, intake tubes and MAFS. They make a huge difference especially when reducing pulley size for more boost. What do we have? Bored TB (no more), MAF upgrades? Pro M questionable, ABACO---ehhh. Intake tube, not rocket science but with a small maf and TB.....

Most of my experience has been with m90 Eatons on for V6's. SC inlets, Larger TB's, Intakes and MAFS on a little v6 with an m90 would make a huge difference. For example Id run an aftermarket SC inlet, 85mm TB, 3.5" intake tube and 90mm MAF as a norm even on a basically stock car. The 85MM TB 3.5" intake and 90mm MAF was an improving over a 70-75 mm MAF 3" intake tube and 76 mm MAF on that puny v6 with an m90!. Imagine just how restrictive the setup on our m112 is. Porting this gen SC also doesn't make a huge difference regardless of what people are trying to sell (sorry). On the earlier gen M112 yes. And to make matters worse, if you do happen to get your hands on one of AVOS's twin screw setups, you are stills tuck with that puny factory TB that you may have been lucky enough to have gotten bored out. But MAF options....Tuning...For me its always made me sick to my stomach that there is virtually no support for these cars aftermarket wise. A machine is only as good as its weak point. We have a few that we cant get around.

 

It's an interesting thread, and I am wondering about one thing: all the talk is about horsepower, but no one ever mentions torque, which in my understanding also increases if you increase horsepower (or am I wrong?).
The reason I am bringing this up is that the ZF 6HP26 transmission our cars use is rated for up to 600NM, and the supercharged engines are already officially rated at 541NM. I would have thought that if you increase the power to 500HP or more, you would also have to consider that you would reach the limits of the transmission?

Has no one ever faced an issue with this?

Thanks and best regards,

Thomas

 

The limit of the transmission is very conservative. Shouldnt be an issue. Plus the TCM will limit that torque for you! Another issue I dont like!