Thread: Questions re 4L to 4.6L and more...

Yep traditionally too much volume like too large valves actually reduces torque. Cheers

hey fellas ive recently put the triumph rover spares 5L in my p38, which was a 4L. I re used the 4l heads manifolds etc and am running a trs recommended cam to suit the engine, cam specs; duration at .050 is 204'' on both inlet and exh, 450'' lift and lsa 112 degrees. I also had to upgrade to the hp24 box. it goes a LOT harder and even chirps the 32" tires off the line however as it starts to go the computer pulls the power back untill about 1800 revs and then pulls like a steam train till 5700 before it changes (in sport mode). i also had to tow a 623b cat scraper tranny (bout 15-1800kg) from bris to toowoomba a week ago and had no problem pulling it. could still hold 100k's in fourth on most hills. now for the problems, the std 4L management cant handle it, wont idle under 1850 rpm cold and hunts like a ***** warm. im running bigger injectors and higher fuel pressure and the computer is still adding more fuel, fuel trim +2-15 percent, and the most annoying thing is the std brand new rad is not enough to keep it cool. it runs at 90 degrees untill it gets into traffic or starts going up hills and then it starts to climb ive never let it get over 97 degrees but it still means pulled over on the side of the road cooling it down, up the toowoomba range i had the wiper washer dropped in front of the rad and held in on. next on my list is to get a triple pass radiator made, a piggy back ecu and and rebuild the transfer case. if you can afford to do it its well worth it for the extra power and a small increase in fuel economy the only thing i would do different is to get 8.5-1 comp pistons instead of the 10-1 so you can add a pair of turbos later on. it takes about 200 meters to go from 0-100 but is still only comparable to a std vt v8 comodore and if ur spending that kind of money it really wants to leave a cayenne staring at you rear end. hope this helps.

You might want to see what you can find out about the ECU and it'd available built in tunes. Apparently the D2 (possibly NAS spec only) has both 4.0 and 4.6 tunes in the box, and these can be changed in testbook. But since the P38 came with both engines (as per the NAS D2) it might also have both. It might be able to cope with it better with the bigger capacity tune, the 4.6 running on a 4.0 ECU seems to come ok as long as you run premium unleaded (else it pings really badly).

Moose - nice. Makes me wonder what a decent amount of head work would do to it - 400hp? with that work ... Cheers

Marks adaptors do a full kit now for disco rover to LS don't they. Go an alloy chev and still as light as rover but largely bullet proof and a Hp wet dream. Cheers

Edit: yes they do...but 8500k and that is without the motor..if you get their full engine management but as I read it perhaps a few k less if using an adaptor kit to suit ls1 only? You can get a lot of rover v8 for that.

Originally Posted by ozscott

Moose - nice. Makes me wonder what a decent amount of head work would do to it - 400hp? with that work ... Cheers

Marks adaptors do a full kit now for disco rover to LS don't they. Go an alloy chev and still as light as rover but largely bullet proof and a Hp wet dream. Cheers

Edit: yes they do...but 8500k and that is without the motor..if you get their full engine management but as I read it perhaps a few k less if using an adaptor kit to suit ls1 only? You can get a lot of rover v8 for that.

with head work and a different camshaft the 5L is soposed to be a 500hp motor but i wanted a high torque application, apparently mine is supposed to be around the 250+hp and 370+ft/lb.

Originally Posted by rovercare

You can change the transmission in the Becm on a D2 to manual, the engine ECU and trans will be standalone, very achievable I think

Also you'll need to use a 4L80e which is far more costly, but these are the only mass produced adaptor, also you'll need to shift transfer case and make new shafts

I've been revisiting this LS1 idea, one that had not gone away. Your statement rovercare has me very curious. I wonder what input the BECM needs from the existing ECM whether it is auto or manual? If indeed I can switch it off and have no input from the ECM, this would be another thing in my favour.

• The LS1 ECU would get its own VSS signal from the 4L80E so it would be a case of LS1 and 4L80E as standalone;
• Existing VSS signal comes from the SLABS ECU straight to the speedo(dash);
• I'd have to double up on oil pressure and temp senders for the dash;

• I have ACE and there is a engine speed input from the ECM. The SLABS ECU also needs an engine speed input. It would be nice if the LS1 ECU could provide this but I'd seriously doubt it. Nevertheless, I still need a tacho so I'd have to give this some more thought;
• HDC would get thrown out as this is controlled by the Motronic.

The hardest part would be manipulating existing systems to work with a different engine. If this could be done easily then it's just a case of making everything fit in the chassis. The mounts for the engine and LT230 would be straight forward I think as would the driveshafts. A set of HD Ashcroft CVs and axles would make the drivetrain more reliable too.

Is there anything else that I've missed or should look at?

Originally Posted by banarcus

I've been revisiting this LS1 idea, one that had not gone away. Your statement rovercare has me very curious. I wonder what input the BECM needs from the existing ECM whether it is auto or manual? If indeed I can switch it off and have no input from the ECM, this would be another thing in my favour.

• The LS1 ECU would get its own VSS signal from the 4L80E so it would be a case of LS1 and 4L80E as standalone;
• Existing VSS signal comes from the SLABS ECU straight to the speedo(dash);
• I'd have to double up on oil pressure and temp senders for the dash;

• I have ACE and there is a engine speed input from the ECM. The SLABS ECU also needs an engine speed input. It would be nice if the LS1 ECU could provide this but I'd seriously doubt it. Nevertheless, I still need a tacho so I'd have to give this some more thought;
• HDC would get thrown out as this is controlled by the Motronic.

The hardest part would be manipulating existing systems to work with a different engine. If this could be done easily then it's just a case of making everything fit in the chassis. The mounts for the engine and LT230 would be straight forward I think as would the driveshafts. A set of HD Ashcroft CVs and axles would make the drivetrain more reliable too.

Is there anything else that I've missed or should look at?

I have a P38 guru who will do me a loom and take care of all interfacing, I'd do my own loom, but its part of the deal in getting him onboard to make it worth his while, which I'm happy with, BeCM mods etc, BeCM switched to manual, engine inputs are easy, Delphi has tuneable signals, VSS may be a concern, that will be overcome when I machine an adaptor, if I can't fit the factory holden one, Ill just pull a signal from the rover and convert it to suit, just use standard rover oil/temp senders, Delphi uses coolant temp, fit rover gauge into port on head, all relatively easy

Unfortunately its a job that will cost me time and money and currently with a 3 series BMW getiing an LS7 mounted, a rover with an LS1 and a triumph with a supercharged LS3, plus a bluebird rebody, a 12hr shift job, selling/installing solar systems and general sparky stuff backlogged, a couple kids, house reno's, its hit the backburner

I'll also be machining an adaptor so as to utelise a 4L60e, but that will be to borg warner, it hopefully will allow the transfer case to stay in position, with the diff's being on the passenger side, it looks to allow the shafts through without moving the transfer, my speculation and measurements only, not a given yet