P38A Tuning the 4.0 thor

LR-hobbs · Jun 30, 2025

I have a 4.0 1999 P38 , I am looking into getting the engine tuned and was wondering is it worth waiting until I have changed the camshaft for a torque cam would it effect the tune?

norseman · Jun 30, 2025

I would have thought so as a cam change will effect the characteristics of the engine on it's own.

Thread carefully as the factory engine would have been to a spec. suited to the model.
Remember Newton's third law

Datatek · Jun 30, 2025

LR-hobbs said:
I have a 4.0 1999 P38 , I am looking into getting the engine tuned and was wondering is it worth waiting until I have changed the camshaft for a torque cam would it effect the tune?

Changing the cam is normally an integral part of tuning an engine.

kermit_rr · Jun 30, 2025

I changed the cam on mine.. more usable power where you want it. It felt a lot more spritely. if i recall it was a Piper 270..

LR-hobbs · Jun 30, 2025

Datatek said:
Changing the cam is normally an integral part of tuning an engine.

I'm talking of an ECU tune on a dyno , if I have that done before a cam change , would doing the cam cause any issues?

Loafer61 · Jun 30, 2025

Some here, tempted with the ‘auto’ / max torque one myself.

https://www.pipercams.co.uk/product...zMDk0MzckbzEkZzAkdDE3NTEzMDk0MzckajYwJGwwJGgw

kermit_rr · Jun 30, 2025

LR-hobbs said:
I'm talking of an ECU tune on a dyno , if I have that done before a cam change , would doing the cam cause any issues?

You can't remap as such, you can send the ecu off for a tornado? chip. A cam and stage 1 heads is best

LR-hobbs · Jun 30, 2025

kermit_rr said:
You can't remap as such, you can send the ecu off for a tornado? chip. A cam and stage 1 heads is best

I'm an amature mechanic at best , how difficult is it to do the cam?

I've purchased some land rover workshop manuals to try and teach myself, so I have a minor understanding.

kermit_rr · Jun 30, 2025

You need to take the upper and lower manifolds off, rocker covers, then remove and inspect the rocker shafts. Pull the push rods keeping them in order, remove the lifters inspect and keep them in order also. Then you can get to the camshaft.
You need to remove the radiator etc for the shaft to be removed.
There's more to it but that's the key points

LR-hobbs · Jun 30, 2025

kermit_rr said:
You need to take the upper and lower manifolds off, rocker covers, then remove and inspect the rocker shafts. Pull the push rods keeping them in order, remove the lifters inspect and keep them in order also. Then you can get to the camshaft.
You need to remove the radiator etc for the shaft to be removed.
There's more to it but that's the key points

Is it worth rebuilding the rockers and replacing the pushrods ? Or is that more trouble Than it's worth.

kermit_rr · Jun 30, 2025

LR-hobbs said:
Is it worth rebuilding the rockers and replacing the pushrods ? Or is that more trouble Than it's worth.

"It depends" see what they are like. The original rockers are probably better quality than new ones

Datatek · Jul 1, 2025

LR-hobbs said:
I'm talking of an ECU tune on a dyno , if I have that done before a cam change , would doing the cam cause any issues?

A totally pointless exercise, the two go together.

LR-hobbs · Jul 1, 2025

kermit_rr said:
"It depends" see what they are like. The original tickets are probably better quality than new ones

It's probably overkill, as the engine is extremely quiet no tappet noise or the dreaded liner tap, more to do with preventative maintenance. However I am at 122,000 miles.

Since this car has been hidden away for a few years this is something that will be added into my to do list.

Thanks for the help much appreciated

kermit_rr · Jul 1, 2025

LR-hobbs said:
However I am at 122,000 miles.

If that's the original cam, it's likely past it's best

300bhp/ton · Jul 1, 2025

LR-hobbs said:
I'm talking of an ECU tune on a dyno , if I have that done before a cam change , would doing the cam cause any issues?

Where are you getting it ECU remapped?

LR-hobbs · Jul 1, 2025

300bhp/ton said:
Where are you getting it ECU remapped?

My dad told me about a company called tuners garage , they apparently specialise in the P38, can do ECU and gearbox tuning.

LR-hobbs · Jul 1, 2025

kermit_rr said:
If that's the original cam, it's likely past it's best

This is where the rabbit hole started as the guy I bought it off drove it once then sold it.

He bought it off an elderly woman who's husband had died and couldn't face to see the car , so I have no idea what's been done, the interior is like brand new and exterior cleans up like fresh paint , even still has the factory underseal and a lot of the chassis is still black.

This is why I'm going through all the serviceable Items such as the camshaft.

kermit_rr · Jul 1, 2025

If the camshaft is a worn original then you'll likely see a difference by replacing it. If you upgrade from the £30 britpart oem to a piper270 which is ~£350? you'll notice a big difference
If the engine block is good, then consider replacing the stretch bolts with ARP studs, they put a lot less strain into the block

marjon · Jul 1, 2025

You sound like you are jumping in before knowing TBH.
Cam lift can be easliy checked with the right equip and just removing the rocker covers.
If its worn then fine change it. Its a lot of work.

As for tuning the ECU as far as I am aware thats not possible without changing the chips and even then its a set map, or an aftermarket ECU. So would be interested to know if anybody could actually "hack" into the ECU and change settings, gearbox tuning?
I would suggest you have a talk with these people who say they can, and find out how they will empty your wallet

.

J

kermit_rr · Jul 1, 2025

marjon said:
You sound like you are jumping in before knowing TBH.
Cam lift can be easliy checked with the right equip and just removing the rocker covers.
If its worn then fine change it. Its a lot of work.

As for tuning the ECU as far as I am aware thats not possible without changing the chips and even then its a set map, or an aftermarket ECU. So would be interested to know if anybody could actually "hack" into the ECU and change settings, gearbox tuning?
I would suggest you have a talk with these people who say they can, and find out how they will empty your wallet.

J

Yes the tornado chip is the only 'tune' I'm aware of. As far as i know it's not possible to hack the EEPROM. Otherwise Tornado would have done that.
At 100k+ miles the original cam will be worn, it might last 500 miles or might last another 30k.. who knows until you have a problem

P38A Tuning the 4.0 thor

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