What we need for the XJS enthusiast is a forced induction kit like they have for the Porsche 928 - several kits actually, and $5k + installation will reliably get you into the 450HP club! There's also Kuhn Performance twin turbo 928 kit which is on another level re: performance, aesthetics, and price. Looks like their website is down. Pity.

 

Flint nice idea ,but a tuning nightmare, i have built many turbo engines and the tuning is most important!
when engine starts boost up , fuel AFR changes drasticly! inlet manifold pressure goes from a vacuum to a positive pressure, computors can go nuts!
and a slight mistake you may build a new motor!
where NA engines you can be off a mile and still have an something to work with!
BUT go for it and show what you got!

 

Thanks. Are you using your own ECU on this engine? Have you built any large displacement performance V12?

ps great to see some new tech applied to the V12.

 

My circumstances would have to change drastically, but this would be a tremendous project and learning opportunity!

 

Motec on this one, but that is just because of the dyno operators preference, and the internals of my ecu is not my design anyway, I just made a box for it with relays and fuses built into the design so people dont need to do any electric work and have it all as a compackt unit. And since I made it look like a jaguar nobody is arguing about the brand anymore. Its a modern well known ecu in there ready for anything..

I am building a 6.1 liter right now, but from a 5,3 and by big bore pistons. Not a original 6 liter. This one is like a research engine.
And a customer have ordered a Marine engine, but I have not desided on stroke yet. I ilke the 70 stroke and want to show that it can deliver both torque and rpm.
I need to see some money first, before I start.
I have some new cam designs ready for it. And I need to finish the cnc port HE head range also as there are not so many good Pre HE heads to find.

Ole M

 

Ole very exciting. I will be keenly following your progress.

 

so are there 12 injector drivers or are you batch firing 2 or 3 at a time? And can that same ecu run the waste spark coil packs you have? I assume you're not getting a cam signal to do sequential?

What octane fuel is this set for?

Good stuff BTW

 

Hi
This race engine has injectors coupled in pairs and fire one a revolution in correct sequence, and I use one coil and distributor. This is because of FIA Historic regulations.
The Bolt on kit I make has two choises, one std witch use one coil and distributor, this one fire two and two injectors in batces. No cam signal as it is really bolt on, customer dont need to understand anything.
The other choise is waste spark, where you remove the distributor and run two six pack coils. Also here I pair the injectors. And completely bolt on. No special timing needed, unless someone want to make the map themselves.

Sequential injectors with 12 channels and cam sensor has no real HP increase, but you may be able to get the idle superduper smooth if you dont think the idle of the normal setup is not super smooth enough. Witch it is..

Sequentioal injectors dont make more hp, end of discussion :-)

And on my bolt on kit I run 95 octane

Ole M

 

I’ve watched many people go down the endless modification of the ECU trying to basically reprogram the engine for more power. To my knowledge none have proven it with before and after dyno runs.
Plug and play is adequate for the vast majority of us. That’s hard for me to say, I’m a racer. I’m always looking for more power.

 

Thanks Ole, no HP discussion intended as you are doing great work. Just a controls and calibration engineer wondering on some of the details.
I'm looking for better reliability, best possible performance without major engine mods and less finickiness. This is a good solution for that.

 

Many think that the bigbore throttles and larger injectors will give them more power, that is not so.. but yes maybe a few hp but nothing you will write home about.
The gr.A engine was with std throttles and 209cc injectors at 4 bar. The thing that make power is an increase in Volumetric efficensy regarding the amount of air moved through the engine at two revolutions, and the injectors must just act accordingly to that.

Many also think an aftermarket ecu can be mapped in a couple of hours. well, yes a full trottle map and some transistions ca.
But I spent a month on the road afterwords driving and adjusting in the end.
Things like cold starts and transistions, slow driving, cruice control driving, slight downhill and not having the converter pulsing at cruice control, and fuel cut at all those situation, and avoiding hunting at idle at different temperatures and so on.

It is a lot of work to make a map that can be sold to anyone and that work perfect like that when actually driving slow like most do. That I something I would like people knew when considering time and cost of aftermarket ecu solutions...

Ole M

 

Well said! A given engine will burn only so much fuel and air at a Given rpm. To change that requires either boost in the form of super/turbo charging
or fuel that carries air with it like alcohol does.
Then larger injectors might ( might) be required or just longer dwell time.

 

Yes, or increase the VE like I did on the Gr.A engine by being friends with pulsetuning because of matching cams, compression, maifold runner diameters and an length, ports with correct cross section and flow. This way we can get up to 120% VE, its like adding boost..
But to go passt 100% you must have a good plan and a good recipie, to get passt 110% you have full control of what you are doing. And 120% I have done only on 3 engines in my life. Some mention the helmholtz and plenums, well this is beyond that.

 

The problem is that the HE engine has too much compression for a bolt on Turbo/supercharger kit, and its the HE that most people have, So to make a boost kit for this one force you to open it and change pistons anyway, witch makes most people fall of. And that is a pity.

Ole M

 

preHE inlet manifolds are EXTRUDE honed,takes out a lot of humps and bumps and a smooth runner entrance!
pic of my V12 with a a modded distributor, it uses a Crane ignition box, i adjust curve by altering weights(bothersome), but adjust total curve moving distributor! i also use a set of Crane custom grind cams, had a chance to run them on a cam profile machine(they are a copy of 1973 Porsche NA race engine profile) whooda thought?
for fuel i use a standalone SDS EFI sysytem, plenty of room for adjusting AFR using Gage! i use 12 HONDA injectors O-ring top and bottom, also 45psi adjustable! Plus a bunch of internal engine mods
YES old fashioned but works for me, rev easily over 6500 + rpm!
oh i spent the best part of a year getting a usable MAP, a learning process for sure!
and i still have minor readjust winter/summer!

 

to add to above,, i do run 6MM oversize throttle bodies!
so when i open throttles the 1st 25% open lets much more air in and gets it moving faster , so throttle response is quicker!
probably wide open may not help much but lower opening is noticable, coming off a corner at slow speeds!
and with my lower gear rear drive(3.73 LSD), all is good!
ron

 

Yes I agree Ron. But there is something with the std setup that makes the throttles oper very slowly in the start, its about the geometry of the rods and links. It is possible and also smart to move the idle stop of the top disk quite a lot. Maybe 10mm to make the rods move faster in the start. Because if not the tps will go from 0 to 15 % without much happening at the throttle body, and a hot setup with a chrisp throttle response is difficoult to get with that original "over progressive" actuation. The original geometry is made for easy crucin with a sloppy auto trans I think.

 

Yes, but also customers unused to injection engines. The carburetted engines most people were familiar with, including early V12 customers, required more welly to get going. Rudimentary as we may see the D-jetronic today it was quite a revelation when new.

 

I believe a TPS mod to move the TPS to one of the actual throttle blades would fix a lot of performance issues with the old system.

 

the few V12’s with the Flathead and the Turbo 400 transmission is less than 3000. World wide. That dates from 3/4 of 1977 through 1980. America got 7.8-1 compression ratio while the rest of the world got 9.0-1 compression
The few hundred left 40+ years later do not make a valid market.