Whats the difference? 350i 390i
Discussion
I think theyre the same. the 390SE has a different fuel regulator to give more fuel for the bigger engine. I dont think that the throttle pot difference depends on engine size. There seems to be a cutoff point when Rover started using a different pot. Dunno why...
The later cars went over from the Flapper injection (Lucas 4CU) to hotwire air flow meter (14CU(X)). This is the only major difference, and it doesnt depend wholly on the model of car: again, Rover begun using a new system in about '89.
Ed.
The later cars went over from the Flapper injection (Lucas 4CU) to hotwire air flow meter (14CU(X)). This is the only major difference, and it doesnt depend wholly on the model of car: again, Rover begun using a new system in about '89.
Ed.
The rampipes inside the plenum chamber on the 3.9 are bigger than standard. dunno if the same is true of the 350. You'll be able to tell if youve got, ahem, big ones, cos the larger rampipe trumpets are steel, as opposed to aluminium.
The throttle body and AFM is the same as an SD1 as far as I know. You might consider replacing the air flow meter with a "SEAC meter", also known as an XJ6 Jaguar meter. Theyre larger bore, and will flow a bit more air. But we're talking 1 or 2 BHP here.
The 390SE heads are certainly ported quite aggressively, and they run a slightly lumpy Crane cam. Pistons are Cosworth derived, and the Rods are heavy duty items. I spoke to Dom Trickett at TVR Power about my 390 engine (he used to build them back in the 80s!), and he confirmed these details, so I take them as gospel. Incidentally, Dom is a really nice guy.
To be honest, I think you would do better to spend the money on making sure that your 350 engine is well set up. Make sure the Dizzy is in good condition and that the fuelling is right. The standard ECU does run the engine very lean at mid throttle (So I understand from various specialists) to improve MPG: not strictly designed with maximum power in mind! Also, getting the injectors cleaned can help if theyre gummy (has the car been laid up for long periods? This'll gum the injectors up).
Although if you do want monster power, Steve Heath has proved that the Wedge rear transmission will cope with a Supercharged 5.2 Griff engine. Power is well over 400 Horses. Ouch.
Ed.
The throttle body and AFM is the same as an SD1 as far as I know. You might consider replacing the air flow meter with a "SEAC meter", also known as an XJ6 Jaguar meter. Theyre larger bore, and will flow a bit more air. But we're talking 1 or 2 BHP here.
The 390SE heads are certainly ported quite aggressively, and they run a slightly lumpy Crane cam. Pistons are Cosworth derived, and the Rods are heavy duty items. I spoke to Dom Trickett at TVR Power about my 390 engine (he used to build them back in the 80s!), and he confirmed these details, so I take them as gospel. Incidentally, Dom is a really nice guy.
To be honest, I think you would do better to spend the money on making sure that your 350 engine is well set up. Make sure the Dizzy is in good condition and that the fuelling is right. The standard ECU does run the engine very lean at mid throttle (So I understand from various specialists) to improve MPG: not strictly designed with maximum power in mind! Also, getting the injectors cleaned can help if theyre gummy (has the car been laid up for long periods? This'll gum the injectors up).
Although if you do want monster power, Steve Heath has proved that the Wedge rear transmission will cope with a Supercharged 5.2 Griff engine. Power is well over 400 Horses. Ouch.
Ed.
ed_Crouch said:
...Although if you do want monster power, Steve Heath has proved that the Wedge rear transmission will cope with a Supercharged 5.2 Griff engine. Power is well over 400 Horses. Ouch...
Though it is tamed by the techno-trickery of traction control. Otherwise I suspect he would be able to make drive-shafts look like curly whirlies and the diff would be transferred into the realms of the consumable.390 engine spec seems to vary quite markedly. On my car the trumpets (rampipes), airflow meter and all the other injection parts apart from the fuel pressure reg are standard 350i items. The inlet manifold and heads are ported quite aggressively (bit of a waste of time since the trumpets are standard?). Pistons are flat-topped Omegas although I think the rods are standard.
Valvegear is stock though the cam has higher lift.
With respect to the throttle pot, the 390SE's is the same as the 350i's. Whether the one from a 3.9 Range Rover is useable I don't know (but would suspect it is).
Fitting the Jag airflow meter opens a can of worms regarding the fuelling. Yes it can add a lot more power (more than 1 or 2 bhp as suggested) but only when considered as one of several mods. It's probably not worth just bunging one on and hoping you can get it right.
Valvegear is stock though the cam has higher lift.
With respect to the throttle pot, the 390SE's is the same as the 350i's. Whether the one from a 3.9 Range Rover is useable I don't know (but would suspect it is).
Fitting the Jag airflow meter opens a can of worms regarding the fuelling. Yes it can add a lot more power (more than 1 or 2 bhp as suggested) but only when considered as one of several mods. It's probably not worth just bunging one on and hoping you can get it right.
leorest said:
ed_Crouch said:
...Although if you do want monster power, Steve Heath has proved that the Wedge rear transmission will cope with a Supercharged 5.2 Griff engine. Power is well over 400 Horses. Ouch...
Though it is tamed by the techno-trickery of traction control. Otherwise I suspect he would be able to make drive-shafts look like curly whirlies and the diff would be transferred into the realms of the consumable.Not just that BTW. I did have to replace the diff after 110k miles - lifted a rear wheel while going through St Mary's at Goodwood. Wheel spun upto 160 mph while the other side was doing around 90. Diff went crunch. Could hear it during the in car video. The rear suspension is quite modded to control the suspension movement which was causing problems like lifting rear wheels. By product is that the UJs don't go out of alignment so much and they survive better.
PS It is not a Griff engine... it is a custom build Wedge engine....
PPS found a bit more boost yesterday!
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