I have been toying with the following idea, and no external signs of SC:
Twin SC but in parallell feeding a common duct branching to each bank. One Lysholm and one centrifugal, each nominally suitable for a 3 litre engine.
Pro: Lysholm better at low rpms, centrifugal better at high rpms while heating the air less than Lysholm or Roots. Centrifugal costing little in power at lowish rpms.
Con: More complex than single SC and somewhat more costly.

Ignition and fuel: Megasquirt or similar, wasted spark. I want to think about knock sensing and what kind of algorithm I would use to control knock.

Thoughts?

 

if you could do it all for $10,000. youd be a magician.

 

Having access to basic mill/drill/turn, quality plasmacutter and MIG (and in a pinch the very best NC equipment money can buy) I believe I can do it for about USD 7,000.- (Helps that I have worked as a HW/SW robotics engineer in a distant past too.)

We'll see, I have 1 1/2 other tasks to complete first

 

Lysholm TS (twinscrew) are a very efficient SC, this was the first option I investigated I like them. I even mocked up a cardboard Whipple (3.3L) to fit it into the engine bay, it was very tight. AMG fitted IHI TS to their supercharged models and these made good power right across the 6500rpm range. The only downside to them (apart from cost) is the high parasitic drag on trailing throttle, Mercedes fitted a magnetic clutch to these SC to overcome this. The SC was disengaged on light throttle cruise and trailing throttle.

I do think with the TS and CF you could end up with compressor surge on the CF. With the TS I don't think you will need the CF if you size it right.

 

I am sure it will be possible to use TS only, but with heat being the issue it is I want to keep it as low as possible. With TS it must be run at higher rpms than a linear increase in boost would require due to the increased temperature, which in turn generates even more heat. I could of course add cooling to the SC and intercooler but that means more piping etc etc. I find it more attractive to add some complexity to avoid generating the heat in the first place.

As for surge that should not be an issue at lowish rpms with a simple flap valve right after the CF and at high rpms the TS should indeed be selfprotected as it as a positive displacement type.

I suppose the question is the proportion of bost coming from each but with the mix as indicated some tuning could be done by swapping pulleys.

 

I don't think heat will be an issue with a TS these run significantly cooler than a Roots. Would adding an IC be more pipe than an addition SC? and cost. I know the twin Whipple XJS was not ICed and made 700hp

If you are going down this route why not a twincharged? TC into Roots PD

 

Roots is not on based on heat. But I will have a chat with a couple of bonafide professionals. I will bring their views back to the forum.

 

the way i see it is you could do the whole SC project for relatively cheap if you

A: quit screwing around with the **** poor Engine Control Unit and fueling files and went to an old school carbuerator setup. then install a wideband O2 for each bank and put your AFR right at 11.7:1

B: quite screwing around with electronic ignition and distributorless ignition and just run as much timing as you can possibly run on the highest octane fuel you can find.

C: pick a moderate blower like a Gen V eaton M90 or an M112. something that doesnt run too awful hot. or a remote mount variation of an m90.

D: install larger SC pulley to limit boost to about 4psi until youve got all the bugs worked out.

E: when your good and ready, find a way to drop CR. decompression plate, aftermarket pistons, bored out combustion chambers, etc, drop to around a 3.5 inch pulley which will bring you back up to about 10lbs of boost. intercool, cam, etc.

seems pretty straight forward honestly. the biggest problem is getting the thing tuned right with a stock ECU.

remember: AFR > Timing > Boost.

the second biggest problem is the compression ratio of the HE, which could be easily fixed by going to a flathead setup, boring the chamber, increasing displacement, or possibly scooping HE pistons by a small amount.

i think a turbo would be an even simpler build. remote mount to the trunk or whatever, intercool relatively easy. etc. Meth injection on 93 octane should be enough to run a small amount of boost with no major compression modifications.

P.S. if you have to run less timing so that you can run a few lbs of boost, then your project is already hemorrhaging power.


BTW. heres the jag im getting ready to pull the trigger on.
http://pittsburgh.craigslist.org/cto/2745398383.html

i should have enough by the middle of next month.

 

OK im subscribed!!!!

so which one of you guys are really gonna do something?

like a V12 , 500whp,, that actually drives on the street without problems!

no need for magic #s like 700-850hp,

we can meet at the Texas Mile, and ill have my trusty old V12 Jag. a standing start mile, would be fun, and we can meet in person! oh yah.

thinkin about it nobodys talked a serious drivetrain yet, OOPS more money.

 

I want a simple setup with an engine that is as standard as possible mechanically. Fuel consumptuon and flexibility for normal road use. I have a wrecked flathead and a new crank waiting. Target is 450 - 500 HP and a minimum of extra heat. AC compressor to stay where it is. No external signs of change.

 

Carb is not going to be easier the manifolds I posted will not sit carbs under the bonnet. You will have to cut holes and them poke through. If you want carbs under the bonnet there are 2 options use the carb E Type manifolds and 4 carbs or downdraft Webbers with short trumpets.

As I said before there is NO WHERE to mount a remote turbo without cutting the body. I don't see how this is simpler than a CF SC

Looks good just check very well for rust especially around the rear wheel arches, buttress on the LHS and the rear screen. I like the green with that interior.

 

Damn thats a long road trip for me

Tell me about it I have started under the car, new shocks bushes and a rebuilt diff with 4.09 gears at the moment, I have a 4L60e waiting in the wings, once I have rebuilt the front suspension I'll pull the engine.

 

I think this is a good approach. 450-500hp is not too difficult without FI and 6.5L so a 5.3 should make this number with a SC.

 

Hey, M90,, buyin the car is the least expense you will have.

 

speaking of different posts on XJS site.

one of the guys has a problem picking the proper sparkplug,
i would say turbo project is past that stage!! haha.

a little humor here.

 

hey Ronbros.
are you mad because your jag is nothing but a loud exhaust on a useless keg?
couldnt even spring for the hard top?
nice enormous fender arches BTW. lol

 

Heh, I know I'm not in a position to blaze this trail. I'd need to buy another daily driver first. Too bad the only things I like are 2 door, 12 cylinder coupes (Exceptions granted for Porsche 928 & Aston Martin V8 Vantage). I'll start with making sure everything is up to par on my XJS, then doing a growler and a 4 speed tranny.

Speaking of which, anybody have hard #s on exactly how much a 4 speed peps up acceleration on the XJS? (sorry for mini hijack).

 

4 speed should take several seconds off a=of any car. 3 speed IIRC = intermediate, drive, overdrive.
4 speed = low, intermediate, drive, overdrive.
i can tell you that ive got a 4 speed in my GP. running 230WHP with 2.93 gears, slightly lower(numerically higher) than an XJS.
and its a real struggle to keep the tires planted in first.

also flint, you keep talking about a growler intake. honestly its a lot of money for next to nothing. you can make better air cleaners, or you could probably even gut a stock cleaner to get as much performance. just look at rons intake. its just a Hot air intake with a 90* elbow and a cone filter

 

HEY Guys,, check out the video on the XJ220 for sale , just down aways on this list.

that car is 18yrs old and looks better than most Supercars, shows what money can do!!

 

correction , go to the last link in that XJ220 post, a utube post.

a very nice car!